New Coil - Tachometer Jumpy affecting TCU

[Bigrig]

Ok kids, here goes. Put a new Crane Cams high performance coil in the truck and subsequently, the tacho is now all the shop. As per other posts, it appears the Transmission Control Unit relies on the tacho feed in 'some' way for use of the torque converter (apparently and ohm or two either way of incorrect reading, it won't lock up - which mine now isn't). I took advice from a range of people an ended up going today and buying a new coil with inbuilt resistor to try and reduce the 'feedback' through the wiring and hopefully resolve the issue. Nope - still does the same thing. I swapped the dizzy module also, but it should have no affect at all.

Sooooo ... can anybody offer suggestion of what needs to happen? I've got a mechanical Scorcher dizzy that was sort of ok with the original coil (it was a bit jumpy also but the TC was working), and apart from that, nothing has changed - new valve body should have nothing to do it as it went in after the coil and the TC not locking up problem.

Thoughts?? Pleeeeaaase!!! Now I've tried 2 different coils (tried an EB falcon V8 coil also with the same effect).

Would like my tacho working again properly, but moreso does anyone understand how it affects the TCU as I would prefer to have the TC working again even more so.

Thanks a million in advance one and all ...

Not overly keen to drive another 2400klms down to Victoria and back with it in its current condition.

[Yendor]

I was just speaking with Scotty.

I think the problem might be the resistance of his replacement coils, does anyone have the workshop manual for a 1995 onwards model GQ that can look up the resistance value of the coil for us? or has one and can measure the value of their coil?

Thanks Rodney

[patch697]

I was just speaking with Scotty.

I think the problem might be the resistance of his replacement coils, does anyone have the workshop manual for a 1995 onwards model GQ that can look up the resistance value of the coil for us? or has one and can measure the value of their coil?

Thanks Rodney

If thats the issue then why was it having the same issue on the STD coil?

[NissanGQ4.2]

Considering your not at my place drinking beers / bourbons I have no sympathy for you or TANK what so ever.....On that note.........think I might just go poor myself another bourbon now :)

[NissanGQ4.2]

If thats the issue then why was it having the same issue on the STD coil?

agree with Paul on this one

[Yendor]

If thats the issue then why was it having the same issue on the STD coil?

The tacho and TC problem only started after he replaced the coil.

[Yendor]

He is not currently running a standard coil.

[NissanGQ4.2]

The tacho and TC problem only started after he replaced the coil.


I've got a mechanical Scorcher dizzy that was sort of ok with the original coil (it was a bit jumpy also but the TC was working).


Ok the TC was locking with original coil but sounds like there where problems 2 begin with

[patch697]

.4 to 2 ohms Primary & 6k to 16k ohms secondary

[NissanGQ4.2]

Scotty, I assume the tacho you are talking about is the Rev Tacho?

Is it just the Tacho doing crazy things or is the the revs of the motor itself?

[NissanGQ4.2]

Some things I can think of:

If the water temperature sender for the computer (not the dash gauge, there are two senders) is faulty or the wire is off or not making a good connection, then the torque converter lock up clutch will not work.
Check the connections near the battery where they come up from the automatic transmission.



Incorrect throttle sensor or inhibitor switch adjustment,

line pressure or engine RPM signal,
faulty revolution sensor or speed sensor,

lock-up solenoid,
fluid temperature sensor,
control valve assembly,
Torque converter itself


Not enough bourbon!

[Yendor]

Ok the TC was locking with original coil but sounds like there where problems 2 begin with

Yes I know, but I asked him that question directly and he said "the tacho and TC started playing up after he replaced the module and coil, before replacing the valve body".

[Yendor]

.4 to 2 ohms Primary & 6k to 16k ohms secondary

That's a big variance, I was expecting the lower end of that scale.

[patch697]

Yes I know, but I asked him that question directly and he said "the tacho and TC started playing up after he replaced the module and coil, before replacing the valve body".

Replaced the module with what exactly?

[Yendor]

Todd slow down, I can't post that fast.....ahahahahahha

I'm not sure if Scotty can get online at the moment.

[Yendor]

Replaced the module with what exactly?

Sorry I don't know what brand it was.

But I don't think that is the problem.

[patch697]

That's a big variance, I was expecting the lower end of that scale.

there not overly specific thought Rod.

In most cases you'd work on around 5K +/- 1k but mines 7.3k

Im surfing the net new trying to find out more.

[patch697]

Sorry I don't know what brand it was.

But I don't think that is the problem.

Don't be so sure...... It was in mine.

[Bigrig]

Okey dokey - here goes:

The coil died, put a second hand one on from another car (don't know brand and it was a stop gap whilst a new one and module were ordered). The problem started as soon as the coil was replaced - this was days before the valve body, the new coil and the new module.

The tacho is jumping all over the shop, but the revs aren't - the TC apparently takes some reading from the TCU that is sourced from the tacho and if outs out, the TC won't lock up.

The new coil (Crane Cams High Performance) got installed with a new module (standard Bosch replacement) at the same time I swapped the valve body over - problem still remained. Got to Sydney and that's when I first posted about it - spoke to Wholesale Automatica etc and went out today and got another coil with in built resistor (also tried a coil from an EB falcon to no avail). Put the new coil with resistor in and same problem although very marginally less jumpy.

The Crane coil comes in at 0.8 ohms resistance, and the one with the resistor measured 1.6 ohms ...

Currently still running the Crane Cams one and thinking of getting a standard GQ Patrol coil, but was trying to find out what resistance they are to compare to the ones I have ...

Thanks all - sorry for the sporadic responses - with family, not at home and relying on the occasional 3G connectivity as we travel to use tapatalk.

[Bigrig]

Don't be so sure...... It was in mine.

Problem is old mate - started before the module was replaced and it's a stock standard Bosch replacement.

[patch697]

If its a resistance issue why can't Bigus just use a 1watt 0 to 50k trim pot in line & just screw the thing up until it finds its mark?

Even a 1/2 watt will do the job

[patch697]

Problem is old mate - started before the module was replaced and it's a stock standard Bosch replacement.

Yeah..... Got that after I read your last update post.

[Bigrig]

If its a resistance issue why can't Bigus just use a 1watt 0 to 50k trim pot in line & just screw the thing up until it finds its mark?

Even a 1/2 watt will do the job

Tell me more mate - Derek mentioned an in line resistor also, but both Rodney's (YENDOR and Wholesale autos) suggested not to ...

I'm willing to try anything ...

[Yendor]

there not overly specific thought Rod.

In most cases you'd work on around 5K +/- 1k but mines 7.3k

Im surfing the net new trying to find out more.

My mine concern is with the primary resistance.

[patch697]

Tell me more mate - Derek mentioned an in line resistor also, but both Rodney's (YENDOR and Wholesale autos) suggested not to ...

I'm willing to try anything ...

Here's the thing old mate............. They use a 1/2 watt 2k resistor inline with the Tacho factory.

Rod know he's stuff & if he says not to then theres a reason behind it im sure.

[NissanGQ4.2]

Todd slow down, I can't post that fast.....ahahahahahha

I'm not sure if Scotty can get online at the moment.

Not typing fast, cut and paste from an email I had.....Scotty is meant 2 be offline and @ my place drinking bourbons! *L*

[NissanGQ4.2]

Probable won't help but have you plugged your lappy in 2 see if there are any fault codes or anything else that the software might be able 2 pin point?

[Bigrig]

Not typing fast, cut and paste from an email I had.....Scotty is meant 2 be offline and @ my place drinking bourbons! *L*

I'll make it there mate - I did say today or tomorrow, and I'm working on it fella!!! lol

[Yendor]

Not typing fast, cut and paste from an email I had.....Scotty is meant 2 be offline and @ my place drinking bourbons! *L*

I wish I was there right now.........bourbon......yum!!!!!!!

[Yendor]

Here's the thing old mate............. They use a 1/2 watt 2k resistor inline with the Tacho factory.

Rod know he's stuff & if he says not to then theres a reason behind it im sure.

My concern is that he will need to put this in series with the coil, not just in series with the tacho.

I am not sure what effect this will have on his secondary voltage output (especially seeing as he runs on gas), let alone what effect it will have on the tacho input to the auto.

[patch697]

"My concern is that he will need to put this in series with the coil, not just in series with the tacho."

I am not sure what effect this will have on his secondary voltage output (especially seeing as he runs on gas), let alone what effect it will have on the tacho input to the auto.


Can you elaborate on that a bit more for me please Rod cos im not understanding what it is your referring to.

[NissanGQ4.2]

The tacho is jumping all over the shop, but the revs aren't - the TC apparently takes some reading from the TCU that is sourced from the tacho and if outs out, the TC won't lock up.

I have very limited understanding of all things mechanical and electrical, you all lost me talking about modules and coils....... but wouldn't the TCU readings come from the ECU or Engine sensors and not from the Tacho itself???

[patch697]

I have very limited understanding of all things mechanical and electrical, you all lost me talking about modules and coils....... but wouldn't the TCU readings come from the ECU or Engine sensors and not from the Tacho itself???

It reads from both Todd.

[NissanGQ4.2]

It reads from both Todd.

Thanks for enlightening me Paul, not that i still understand.

If The tacho is jumping all over the shop, but the revs aren't as Scotty says, I don't see the Tacho as causing the problem.

I'm not 100% but when my Tacho became faulty, my TC still locked up when it was suppose 2.................could be wrong

[growler2058]

Time for a burbon toddy by the sounds of it :/)

[patch697]

Thanks for enlightening me Paul, not that i still understand.

If The tacho is jumping all over the shop, but the revs aren't as Scotty says, I don't see the Tacho as causing the problem.

I'm not 100% but when my Tacho became faulty, my TC still locked up when it was suppose 2.................could be wrong

What we seem to think is going on is the resistance values of the new coil being hi performance is to high for the Tacho's sensitivity which is throwing it all over the shop & being as the Tacho itself is being effected we're of the thought the TC is suffering the same fate.

So the question remains whether we swap the coil for one with the right values to begin with or do we try to achieve the correct values by adding variable resistor (trim pot) to the tacho signal wire & achieve the required sensitivity that way.

We don't have much room to find an optimal balance but a trim pot to do the job is very cheep & if successful will be an easy fix, where as another brand new coil is the more expensive but may very well be the only option.

We'll have tp wait & see.

[patch697]

Time for a burbon toddy by the sounds of it :/)

Mines working well..... How do you think I managed to type that last post out........hahahahahahahaha

[growler2058]

That was a very fancy response Pauli I must say, but I've been out for dinner and sunk various cockamatails and beer and vino and cannot comprehend a word i read hahaha:-)

[growler2058]

Aaand i normally like to
Have something useful to say (snigger snigger) as ya know but my final comment tonight is rock on the diesel all mechanical reliability:-) (geez I hope aggy doesn't sh1t herself next time out)

[patch697]

Aaand i normally like to
Have something useful to say (snigger snigger) as ya know but my final comment tonight is rock on the diesel all mechanical reliability:-) (geez I hope aggy doesn't sh1t herself next time out)

You'll get no argument form me on all counts..............hahahahahahahaha

[Maxhead]

.4 to 2 ohms Primary & 6k to 16k ohms secondary


Hey Paul, that looks very low mate.

From the manual I'm reading
Primary: 1.08 to 1.32 ohms
Secondary : 9k to 14.4 K

Also, I can't understand how the TCU gets its RPM from the tacho? I would of thought the ECU needs the correct RPM to keep the motor running properly.

Isn't there a Engine Revolution sensor in these motors????? If there is then the ECU and tacho should be getting readings from it? I would assume the tacho is then just a display of the rev sensor and seeing the engine is running fine and tranny shifts OK then the sensor must be OK, so may be just the tacho is faulty. and there is another fault with the TC??

Just throwing it out there for a different perspective on the fault....LOLOLOL coming from someone who has no idea!

[NissanGQ4.2]

So the question remains whether we swap the coil for one with the right values to begin with or do we try to achieve the correct values by adding variable resistor (trim pot) to the tacho signal wire & achieve the required sensitivity that way.


Good explanation for someone that was drinking.......... as I said know nothing about nothing, so my sober question is can't Scotty just take a standard coil put it in and see if he still has the same problem? If the TC locks up it is the coil If not then it is something else at fault?

[NissanGQ4.2]

Isn't there was a Engine Revolution sensor in these motors?????

Certainly is

Edit: I really don't know..........from what I have read, there is

[patch697]

Hey Paul, that looks very low mate.

From the manual I'm reading
Primary: 1.08 to 1.32 ohms
Secondary : 9k to 14.4 K

Also, I can't understand how the TCU gets its RPM from the tacho? I would of thought the ECU needs the correct RPM to keep the motor running properly.

Isn't there a Engine Revolution sensor in these motors????? If there is then the ECU and tacho should be getting readings from it? I would assume the tacho is then just a display of the rev sensor and seeing the engine is running fine and tranny shifts OK then the sensor must be OK, so may be just the tacho is faulty. and there is another fault with the TC??

Just throwing it out there for a different perspective on the fault....LOLOLOL coming from someone who has no idea!

Brilliant job Kris that att is what I couldn't find yesterday, I could only find some vague sh1t thing that read more like a general guide rather then actual figures.

In answer to your question there is no ECU at the moment mate, with the setup Bigus is running currently. His TC is stand alone (same as on carby models) & they do run a pulse pickup off the coil from what I understand. I haven't seen the Rig in person yet so its only a working theory, but I'll be taking a look at it Next weep at AB's to try & get it all sorted for he's trip home.

[patch697]

Good explanation for someone that was drinking.......... as I said know nothing about nothing, so my sober question is can't Scotty just take a standard coil put it in and see if he still has the same problem? If the TC locks up it is the coil If not then it is something else at fault?

Yeah he can try that mate & in theory that should fix the problem given thats what seemed to have coursed it in the first place & that may well be the avenue he decides to take.
The problem here is nothing is Factory STD anymore & we need certain things like the tacho & the TC to think it is. I will talk with him today sometime about it.

[NissanGQ4.2]

Yeah he can try that mate & in theory that should fix the problem given thats what seemed to have coursed it in the first place & that may well be the avenue he decides to take.
The problem here is nothing is Factory STD anymore & we need certain things like the tacho & the TC to think it is. I will talk with him today sometime about it.

Scotty I think Paul is trying 2 say you should take the Turbo off and go back 2 standard....... and I just happen 2 know someone that would be willing 2 take that turbo of your hands for a good price *L*

[NissanGQ4.2]

Scotty, Standard coil in my car if ya want 2 try it..........bring beers *L*

[Bigrig]

Found this from the original sale thread - starting to think it wasn't a standard coil anyway ...

Tb42 intercooled gas research turbo engine, all items 26000 ks old except bottom end, big front mount intercooler hidden behind grill, all mandrel bent pipe work, got brand new head (not reco) with gas valves and heavy duty crow cam valve springs, have receipt for $1989, gas research s440 throttle body and b2 converter and balance pipe, full electronic scortcher replacement high energy dizzy and coil to suit turbo with advance and retard, turbosmart dual port plumb back blow off valve, genuine temp sender, thermostat, and gaskets used in build, including head gasket, custom made spark plug leads, cooler range spark plugs, new 120amp altenator, monsta t3to4e turbo, denco highmount turbo manifold, all new belts, speco boost gauge, two gas tanks with a usable 168 litres of gas and equalizer valve, gas safety swich, all flexy gas lines, exedy clutch, new 3 inch exhaust from turbo, dumped at diff, sounds great, great oil pressure, runs perfect temp wise also, serviced with nulon oils, has made nearly 200rwkw on 35s. This is a complete engine ready to put in and go, runs great. ENGINE STILL IN CAR.

[Yendor]

Can you elaborate on that a bit more for me please Rod cos im not understanding what it is your referring to.

On the non-fuel injected vehicles the tacho is driven directly from the negative side of the coil via the inline resistor.

On the EFI vehicles the tacho is run by the ECU, the engine speed signal is sent to the ECU and from there it calculates what the tacho should be reading, plus according to the other Rod is a major input for the auto

It is this engine speed input signal to the ECU that I think is suffering from electrical noise.

Now seeing as both problems occurred after the coil was replaced I would like to make sure he has the correct coil fitted.

[Bigrig]

On the non-fuel injected vehicles the tacho is driven directly from the negative side of the coil via the inline resistor.

On the EFI vehicles the tacho is run by the ECU, the engine speed signal is sent to the ECU and from there it calculates what the tacho should be reading, plus according to the other Rod is a major input for the auto

It is this engine speed input signal to the ECU that I think is suffering from electrical noise.

Now seeing as both problems occurred after the coil was replaced I would like to make sure he has the correct coil fitted.

Thanks mate ...

[Yendor]

Hey Paul, that looks very low mate.

From the manual I'm reading
Primary: 1.08 to 1.32 ohms
Secondary : 9k to 14.4 K

Also, I can't understand how the TCU gets its RPM from the tacho? I would of thought the ECU needs the correct RPM to keep the motor running properly.

Isn't there a Engine Revolution sensor in these motors????? If there is then the ECU and tacho should be getting readings from it? I would assume the tacho is then just a display of the rev sensor and seeing the engine is running fine and tranny shifts OK then the sensor must be OK, so may be just the tacho is faulty. and there is another fault with the TC??

Just throwing it out there for a different perspective on the fault....LOLOLOL coming from someone who has no idea!

Those values you have posted are for a points ignition system.

In the picture it gives a value of 1 ohm for electronic ignition, does your manual cover the 1996 onwards TB42E?

[Yendor]

Brilliant job Kris that att is what I couldn't find yesterday, I could only find some vague sh1t thing that read more like a general guide rather then actual figures.

In answer to your question there is no ECU at the moment mate, with the setup Bigus is running currently. His TC is stand alone (same as on carby models) & they do run a pulse pickup off the coil from what I understand. I haven't seen the Rig in person yet so its only a working theory, but I'll be taking a look at it Next weep at AB's to try & get it all sorted for he's trip home.

Ok that changes everything.

If his tacho is running directly from the coil then yes try the pot.

[Bigrig]

Apparently that coil that was in it was an XD Falcon 6 Cylinder jobbie to match the ignition (which is based on early Ford????).

There's no F in confused, but I'm f'in confused!!! lmao

[Yendor]

Make sure that the engine does not have a miss fire.

You may have damaged a HT lead when changing the coil.

[Bigrig]

Make sure that the engine does not have a miss fire.

You may have damaged a HT lead when changing the coil.

Definitely no misfire at the moment boss, but will be sure to take note.

Thanks so much to all for the input/responses!!!

[Maxhead]

Those values you have posted are for a points ignition system.

In the picture it gives a value of 1 ohm for electronic ignition, does your manual cover the 1996 onwards TB42E?

It's from the GQ Workshop Manual, does not specify a year exactly but in that picture being Electronic Ignition figures I would have thought it is for TB42E. I don't think there was any other variants???

[patch697]

It's from the GQ Workshop Manual, does not specify a year exactly but in that picture being Electronic Ignition figures I would have thought it is for TB42E. I don't think there was any other variants???

That sound about right to me as well unless someone can tell us otherwise.......

TB42s (carby/ points)

TB42e Injected/electronic)

Was my understanding.

[Bigrig]

So we sticking with the plan of putting the trim pot in? Or should I continue to hunt for a coil?

Happy either way, and thanks again everyone!!!

[patch697]

So we sticking with the plan of putting the trim pot in? Or should I continue to hunt for a coil?

Happy either way, and thanks again everyone!!!

In all honesty I think you should try a STD replacement coil in it first to see if it fixes your issue or at least changes something about it so we know we're on the mark & for the sake of around $30 dingwares its not a big loss if it doesn't but it will be a massive gain on fuel consumption if it does fix it.

Just my thoughts.

[growler2058]

In all honesty I think you should try a STD replacement coil in it first to see if it fixes your issue or at least changes something about it so we know we're on the mark & for the sake of around $30 dingwares its not a big loss if it doesn't but it will be a massive gain on fuel consumption if it does fix it.

Just my thoughts.

X2 yup I'm with you Paul chuck a new stocky in Biggus and give that a crack

[NissanGQ4.2]

In all honesty I think you should try a STD replacement coil in it first to see if it fixes your issue or at least changes something about it so we know we're on the mark & for the sake of around $30 dingwares its not a big loss if it doesn't but it will be a massive gain on fuel consumption if it does fix it.

Just my thoughts.

x3 now that I have a beer in my hand :):):) Think I said the same thing a few bourbon post ago :)

[Maxhead]

I still fail to see how the resistance of the coil windings has any effect on the tacho. The resistance would only change the voltage of the spark(pulse), would it not? The pulse(which tacho relies on) is generated by the ignition module, which is getting its timing from the pick-up reluctor(rotor).
The motor is running fine so your timing and spark pulses are OK, right?
The transmission changes gears at the right time, right? If that is the case the TCU relies on speed/RPM to change the gears...I think... so that would prove the TCU is seeing the right RPM.

Now I am really confused!!!!!! that is not hard though

Can someone confirm my understanding, and feel free to shoot me down as I am no expert....lol

[Bigrig]

In all honesty I think you should try a STD replacement coil in it first to see if it fixes your issue or at least changes something about it so we know we're on the mark & for the sake of around $30 dingwares its not a big loss if it doesn't but it will be a massive gain on fuel consumption if it does fix it.

Just my thoughts.

Righto - going to get one shortly and will give it a go ...

[Bigrig]

Got an XD falcon coil and tried it as apparently that was what was in it?? Anyway - same problem. Got a standard Patrol coil also, but haven't tried it yet as its a different plug ... will get that tomorrow ... fingers crossed ...

Building up a nice little collection of coils if anyone wants one!!! lmao

[Maxhead]

What a bastard! You can setup a little stall at Andy's selling coils...LOLOLO
Good luck with the other one tomorrow

[patch697]

Got an XD falcon coil and tried it as apparently that was what was in it?? Anyway - same problem. Got a standard Patrol coil also, but haven't tried it yet as its a different plug ... will get that tomorrow ... fingers crossed ...

Building up a nice little collection of coils if anyone wants one!!! lmao

I by one off ya as a as a spare old mate......lol

[Bigrig]

What a bastard! You can setup a little stall at Andy's selling coils...LOLOLO
Good luck with the other one tomorrow

Haha .. thanks mate ... ab's new black market!!!

[Bigrig]

I by one off ya as a as a spare old mate......lol

lmao ... you can have one champion - all yours for services rendered ... just let me use the right one first!!!! lol

[AB]

$50 per stand and you can sell whatever you like big guy..lol

[patch697]

$50 per stand and you can sell whatever you like big guy..lol

hahahahahahahahahaha...............Get a load of the opportunist would ya.................LMFAO

[patch697]

lmao ... you can have one champion - all yours for services rendered ... just let me use the right one first!!!! lol

hahahahahaha......................Done deal......

[Bigrig]

$50 per stand and you can sell whatever you like big guy..lol

Cool ... send out the flyers, Bigrig's Bargain Basement Backyard Blitz Bizarre is coming to town!!!! lol

[patch697]

I still fail to see how the resistance of the coil windings has any effect on the tacho. The resistance would only change the voltage of the spark(pulse), would it not? The pulse(which tacho relies on) is generated by the ignition module, which is getting its timing from the pick-up reluctor(rotor).
The motor is running fine so your timing and spark pulses are OK, right?
The transmission changes gears at the right time, right? If that is the case the TCU relies on speed/RPM to change the gears...I think... so that would prove the TCU is seeing the right RPM.

Now I am really confused!!!!!! that is not hard though

Can someone confirm my understanding, and feel free to shoot me down as I am no expert....lol

Rod might shed some more light here but from what I understand its all to do with the sensitivity, not the fact that the ignition itself is working (cos it obviously is).

I can't say for sure where the TCU is concerned but I know with the tachos in these things there is a very narrow margin in which they will operate & can be very temperamental when this is altered.

I was working on the theory that the TCU was seeing the noise created by the tacho's erratic behavior & going out in sympathy.

[Bigrig]

Had a hunt around for any stray sparks tonight also after talking with Rodney. Can't see any anywhere along the wiring etc, but am going to double check all the wiring in the morning as well ...

Gotta be getting closer to isolating the problem now ..... surely!!!! lmao

[patch697]

Had a hunt around for any stray sparks tonight also after talking with Rodney. Can't see any anywhere along the wiring etc, but am going to double check all the wiring in the morning as well ...

Gotta be getting closer to isolating the problem now ..... surely!!!! lmao

I spoke with Rod myself & we're both on the same page..... If you can't get it sorted then I will take a look when I meet up with you in Melb.

[Bigrig]

I spoke with Rod myself & we're both on the same page..... If you can't get it sorted then I will take a look when I meet up with you in Melb.

Thanks mate - will check plugs etc this morning and short of that, it waits till Monday.

[NissanGQ4.2]

have you checked and cleaned your earth straps?

[Bigrig]

have you checked and cleaned your earth straps?

Will do today mate - something else that was mentioned ... might do it at this blokes house I know over a beer later this morning!!!! lol

[NissanGQ4.2]

Will do today mate - something else that was mentioned ... might do it at this blokes house I know over a beer later this morning!!!! lol

Sounds like a good idea, that bloke has bugger all tools at his place, so be warned. Has beer though *L*

[Bigrig]

Sounds like a good idea, that bloke has bugger all tools at his place, so be warned. Has beer though *L*

Haha!! All good mate - I have all my tools with me ... throwing some brekky down the throat shortly and will be heading up ... will text you as I'm leaving!

[Bigrig]

Quick one also - does anyone with access to the manual know if there's some sort of "safety mode/switch" on the TCU that prevents the TC from locking up if it's receiving an incorrect reading from the tacho? If this exists, then at least I know I'm dealing with a single electrical issue and not two separate issues that happened at the same time by pure coincidence.

Cheers all !!!!

[Yendor]

I still fail to see how the resistance of the coil windings has any effect on the tacho.
I'm not really sure how to answer that without getting really technical.

But if you think of the coil (primary side) as a resistor and the tacho as a resistor.

Now if both resistor are the same value and you connect them in series to a 12 volt battery you will get an equal 6 volt drop across each resistor.

Now if you change the value of one resistor this will change the voltage drop across both resistors , the 12 volt battery remains the same, one resistor might have a voltage drop of 8 volts across it now so the other resistor must have a voltage drop of 4 volts.

Still using the example above, if the tacho normally sees 6 volts and then all of a sudden it is now 4 volts, which could be outside its normal working range. Make sense? While the above is not 100% technically correct with the tacho circuit hopefully it gives you some understanding.


The resistance would only change the voltage of the spark(pulse), would it not?
Yes different coils generate different secondary voltages


The pulse(which tacho relies on) is generated by the ignition module, which is getting its timing from the pick-up reluctor(rotor).
The motor is running fine so your timing and spark pulses are OK, right?

Yes it sounds like the primary side of the coil is collapsing nicely generating a lovely spark in the secondary windings. Scotty keeps telling me the engine is running fine with no misfire.


The transmission changes gears at the right time, right? If that is the case the TCU relies on speed/RPM to change the gears...I think... so that would prove the TCU is seeing the right RPM.

Ok autos really aren't my thing, but I didn't think the engine RPM signal from the coil was a major input to the TCU either, it was Scottys auto guru that puts us onto this. Yes there is a revolution sensor fitted in the auto. Why the TCU needs 2 RPM signal inputs sorry I don't know.

Yes Scotty tells me the gear changes a right, so this tells me that the TPS and vehicle road speed inputs are working correctly. One of the RPM signals possible not according to auto guru.

I haven't got the vehicle in front of me so it makes it really hard to try and diagnose this problem, especially with Scotty highly modified vehicle.

The coil theory at the time fitted in with the what, how,when and why the problem started and with what the auto guru said. That is why I asked if anyone knew the resistance of the standard EFI coil so I could test the theory before Scotty bought another coil.

Now having said all that, it is possible that the two problems may not be related. If someone came to me ( made no mention of the tacho problem) and said that TC was not locking up, the gears changes were normal and all gears were present the first thing I would think of would be the auto temperature sensor, then if they said I just had the pan off and replaced the valve body. I would then be thinking about something electrical not being reconnected in the auto or an earth lead left off.

[Yendor]

Quick one also - does anyone with access to the manual know if there's some sort of "safety mode/switch" on the TCU that prevents the TC from locking up if it's receiving an incorrect reading from the tacho? If this exists, then at least I know I'm dealing with a single electrical issue and not two separate issues that happened at the same time by pure coincidence.

Cheers all !!!!

I have had a look in the manual and I have been unable to find a reason why there are 2 RPM inputs to the TCU and what would happen if one had issues.

[Maxhead]

Great explanation, thanks mate.

Scotty, try and disconnect the tacho and see if the problem changes. If it dosn't then it could be the tach or the coil. If it does then you know the problem is something else....I think
Sh1t I'm confused....LOLOLO

[Bigrig]

I have had a look in the manual and I have been unable to find a reason why there are 2 RPM inputs to the TCU and what would happen if one had issues.

Sweet - so we're on the right track yes??

[Bigrig]

Great explanation, thanks mate.

Scotty, try and disconnect the tacho and see if the problem changes. If it dosn't then it could be the tach or the coil. If it does then you know the problem is something else....I think
Sh1t I'm confused....LOLOLO

Ok - being somewhat mechanically inclined, but auto electrically declined (lol) how do I disconnect the tachometer? Lord I'm hopeless!!!! lmao

Todd may know - I'm five off leaving to go to his joint anyways ... we can rip stuff apart there and see if it never works again!! lol

[patch697]

Ok - being somewhat mechanically inclined, but auto electrically declined (lol) how do I disconnect the tachometer? Lord I'm hopeless!!!! lmao

Todd may know - I'm five off leaving to go to his joint anyways ... we can rip stuff apart there and see if it never works again!! lol

Hay..... What the????......... Don't think you two can go hack & then you just rock up to AB's joint & go here Patch fix this mess.........................hahahahahahahaha

[Bigrig]

Hay..... What the????......... Don't think you two can go hack & then you just rock up to AB's joint & go here Patch fix this mess.........................hahahahahahahaha

Why not???? lmfao ....

[Maxhead]

Ok - being somewhat mechanically inclined, but auto electrically declined (lol) how do I disconnect the tachometer? Lord I'm hopeless!!!! lmao

Todd may know - I'm five off leaving to go to his joint anyways ... we can rip stuff apart there and see if it never works again!! lol

Haha, try these...LOLOL
http://www.nissanpatrol.com.au/forums/images/imported/2011/12/69.jpg

[Bigrig]

Haha, try these...LOLOL
http://www.nissanpatrol.com.au/forums/images/imported/2011/12/69.jpg

What are they?? lmao

[patch697]

Haha, try these...LOLOL
http://www.nissanpatrol.com.au/forums/images/imported/2011/12/69.jpg

Hay Kris, pull my finger.......hahahahahahahaha

[Bigrig]

Well, well, well ... here's one for the mechanical archives!! Put the Patrol coil in and whilst still a little jittery, the tacho is working again, aaannnnnd ... my TC is locking up!!!! Yip yah!!!!!!!!

As per photo below, need to mount it properly, but at least it's working ...

Thanks to all for your input and effort- greatly appreciated! Might still look at putting that tacho resistor on though just to tweak it ...

That all said - the TC might be burnt out or something as it shudders when it engages going up hills. Small price to pay to have it for cruising again though!!!

11280

[Maxhead]

Well, I'll be.....Good stuff boys,, you deserve a beer or a dozen...LOL

[growler2058]

Sh1t hot biggus

[NissanGQ4.2]

it has failed again............ Locked up once just down the road from my place on his way 2 his temp accommodation and failed.

Tank must want 2 come back 2 my joint 4 another beer.

Back 2 the drawing boards boys and time for another beer :)

[NissanGQ4.2]

Hay..... What the????......... Don't think you two can go hack & then you just rock up to AB's joint & go here Patch fix this mess.........................hahahahahahahaha

why not????? I'm the master of hacking and breaking things.

Scotty is taking up my laptop for you 2 fix as well.

Thanks in advance Boss *L*

[Maxhead]

it has failed again............ Locked up once just down the road from my place on his way 2 his temp accommodation and failed.

Tank must want 2 come back 2 my joint 4 another beer.

Back 2 the drawing boards boys and time for another beer :)

Bummer...........Ok, what next

[NissanGQ4.2]

Bummer...........Ok, what next

Another beer :), I'll need about 24 before I head back 2 this thread :)

[NissanGQ4.2]

I know on some 4wd / cars the alternator output runs the rev counter. Anyone know if this is the case with the Patrols?????

[Silver]

Sounds to me like a dodgy wire or connection that comes good occasionally when fiddled with.

[NissanGQ4.2]

I think it only worked because i had a beer in my hand. After Scottie left I didn't..............no that is a lie

[NissanGQ4.2]

Brand new day, Brand new beer. OK TANK what is wrong with you today?

Would it be worth while for Scotty 2 do a stall test to eliminate the TC itself?

[Bigrig]

Didn't end up doing anything on it yesterday arvo as I ended up on the hooley!!

Right - TPS adjustment time!!!

Will let you know how I go.

[NissanGQ4.2]

Didn't end up doing anything on it yesterday arvo as I ended up on the hooley!!

Right - TPS adjustment time!!!

Will let you know how I go.

I would go through all the sensor plugs and earth straps first Scottie...........so you coming around for another beer? *L*

[Bigrig]

I would go through all the sensor plugs and earth straps first Scottie...........so you coming around for another beer? *L*

Haha - would love to mate, but alas I have things to do!!

Now ... where would start to look for earth straps and sensors!!! lmao

[NissanGQ4.2]

Haha - would love to mate, but alas I have things to do!!

Now ... where would start to look for earth straps and sensors!!! lmao

I thought you would know the position of every sensor by now *L*

[Bigrig]

I thought you would know the position of every sensor by now *L*

Just about!!! lol

I'm going to give wiring and plugs a once over and aim at the TPS in hope of jagging a simple fix!!

[NissanGQ4.2]

Just about!!! lol

I'm going to give wiring and plugs a once over and aim at the TPS in hope of jagging a simple fix!!

Hope its that simple mate, we should of done it yesterday, but after it locked up on the test run didn't worry about it....oh well.

Would leave the original coil in for the time been, no point in swapping for another.

After checking the sensor plugs etc, if still not working I personally would check 2 see if the lock up clutch is working properly, but in saying that I don't know if the fluctuating tacho would cause any probs with the test.

[Bigrig]

I genuinely wouldn't know how to test the clutch pack anyway mate ...

Fingers crossed its something simple ... like the owner!!! lol

[NissanGQ4.2]

I genuinely wouldn't know how to test the clutch pack anyway mate ...

Fingers crossed its something simple ... like the owner!!! lol


http://www.nissanpatrol.com.au/forums/showthread.php?7595-How-to-check-the-stall-speed-of-your-torque-converter

[Bigrig]

Stalls just shy of 2000 rpm

[NissanGQ4.2]

Stalls just shy of 2000 rpm

stalls as in motor dies?

[Bigrig]

Righto - who was to know a TPS does that much!!!! I now have a perfectly working TC, the gears aren't flaring and are changing well (early, but firm and quite frankly, I'm ok with that).

I reckon there was a range of problems all at once and the coil problem just bought them to the surface - TC now working, gears smooth, and funnily enough the air con which was playing up and working when it wanted will now not fault!! Add to that, the gearbox is now noticeably cooler (not working as hard). This will do quite frankly till I get the ignition system and petrol back in a couple of weeks time.

What a saga for something so seemingly innocuous ...

Thanks all so much for your input and help - always greatly appreciated !!!

[Clunk]

good to hear you got it sorted Biggus, but please excuse my lack of knowledge....... what's a TPS or what does it stand for????

[growler2058]

Good job mate glad its sorted, well done those who offered constructive help unlike meself:-)

[NissanGQ4.2]

good to hear you got it sorted Biggus, but please excuse my lack of knowledge....... what's a TPS or what does it stand for????

This will explain it

http://en.wikipedia.org/wiki/Throttle_position_sensor

[NissanGQ4.2]

Good job mate glad its sorted, well done those who offered constructive help unlike meself:-)

I drank lots of beer, does that count as been constructive?*L*

[NissanGQ4.2]

Glad you got it sorted mate, sorry I was of no help. At least we had a beer and quick catch up :)

So does the tacho still fluctuate?

[Bigrig]

good to hear you got it sorted Biggus, but please excuse my lack of knowledge....... what's a TPS or what does it stand for????

Thanks mate - TPS = Throttle Position Sensor

[Bigrig]

Good job mate glad its sorted, well done those who offered constructive help unlike meself:-)

Thanks champion - your advice was invaluable!!!! lmao

[Bigrig]

Glad you got it sorted mate, sorry I was of no help. At least we had a beer and quick catch up :)

So does the tacho still fluctuate?

The slightest of flutters here and there, but bloody good compared to two days ago!!

[growler2058]

Thanks champion - your advice was invaluable!!!! lmao

Yup go the mechanical wonders of diesel and manual cog swapper ;-0

[Bigrig]

Yup go the mechanical wonders of diesel and manual cog swapper ;-0

Hahaha ... maybe I'll be that lucky one day!!!!

Either way - Victoria here I come!!!!

[patch697]

Yup go the mechanical wonders of diesel and manual cog swapper ;-0

Should be mandatory in all 4x4's

[patch697]

Hahaha ... Victoria here I come!!!!


STOP!!! right where you are


I don't think Victoria's ready for you yet...........hahahahahahahaha

[Bigrig]

STOP!!! right where you are


I don't think Victoria's ready for you yet...........hahahahahahahaha

Too late!!! The process has begun!!!! lmao

[patch697]

Too late!!! The process has begun!!!! lmao

God help us all......................hahahahahahahahahahahaha