limp mode mod

[Rickie3]

Is there a link on the forum to a how to do the mod to stop limp mode, i'm interested in looking at doing this mod on my 3 litre DID engine, I figured ive modded that much already may as go the whole hog

[my third 256]

not a good idear rickie as the limp mode tells you something is wrong with the engine
and limp mode is connected to many sensors

[threedogs]

As above but if you are thinking of NADS then have a search as there
is heaps and I mean heaps written on the Subject, check anything written by Chaz Yellowfoot[Guru]
First thing to do would be fit Boost and EGT[pyro] gauges on a pillar pod. then take it from there with your Dawes
and needle valve ,catch can and erg block,
PM Mudski as he carries most bits you want

[Rickie3]

As above but if you are thinking of NADS then have a search as there
is heaps and I mean heaps written on the Subject, check anything written by Chaz Yellowfoot[Guru]
First thing to do would be fit Boost and EGT[pyro] gauges on a pillar pod. then take it from there with your Dawes
and needle valve ,catch can and erg block,
PM Mudski as he carries most bits you wantive already fitted all my mods, just curios about the limp mode mod I would like to see how its done

[Hodge]

ive already fitted all my mods, just curios about the limp mode mod I would like to see how its done

Are you talking about the voltage adjustment to the MAF ?

[threedogs]

Bit confused but that's not hard to do.
Your Dawes valve will limit your boost ,thus reducing lime mode

Will need more info

[Rickie3]

Are you talking about the voltage adjustment to the MAF ?Yes thats the one LOL

[threedogs]

Mudski might be the man for this one he's forever changing things on his Patrol

[Rumcajs]

Yes thats the one LOL

Well, head to Jaycar and purchase JDVM (Jaycar digital voltage modifier) and hand controller, assemble the units and than start manipulating MAF voltages. Good stuff but needs to be done carefully.
If you just want to eliminate limps altogether than installing some sort of voltage "clipper" which keeps MAF voltages bellow 3.99V at all times should do the trick however you will still get what is termed cold limps because there are some instances where ECU will react differently.
JDVM will assist to manipulate the MAF voltage as required so there will be no limps whatsoever. It takes time to get right and as side bonus you can manipulate he voltage in such way that you can change AFR (air fuel ratio) as well so it will get addictive to try to "squeeze" as much as you can out of it.

Handcontroller
43397

43398

Voltage modifier
43399

43400

[Rickie3]

looks complicated, is there any info about how to rig it up? probably wouldnt mind trying the voltage clipper mod first

[Rumcajs]

looks complicated, is there any info about how to rig it up? probably wouldnt mind trying the voltage clipper mod first

It is complicated (JDVM), soldering and electronic skills (a little) are required but not necessary. The results are incredible.
I don't get impressed easily but this must be one of the best mods I have ever done to ZD30.

For something more simple you could try Jaycar fuel cut defeat kit
(http://www.jaycar.com.au/productView.asp?ID=KC5439&form=CAT2&SUBCATID=965#11)

43402

Cheers

[Hodge]

This is what my local mechanic/turbo place does. He doesn't subscribe to any of this dawes/needle stuff. He's had 4-5 blokes come in with dawes valves and stuff, and hes ripped it out, tinkered with the MAF voltage, and the owners couldn't believe the difference when they picked the car up.
They also do this when they fit a chip. He didn't reveal specifics, but showed me some dyno sheets to prove it.

[Rumcajs]

This is what my local mechanic/turbo place does. He doesn't subscribe to any of this dawes/needle stuff. He's had 4-5 blokes come in with dawes valves and stuff, and hes ripped it out, tinkered with the MAF voltage, and the owners couldn't believe the difference when they picked the car up.
They also do this when they fit a chip. He didn't reveal specifics, but showed me some dyno sheets to prove it.

Meddling with MAF voltages is/can be dangerous to the engine and is more advanced stuff. I keep Dawes valves and needle valve as added mechanical safety.
Cheers

[Rickie3]

For something more simple you could try Jaycar fuel cut defeat kit
(http://www.jaycar.com.au/productView.asp?ID=KC5439&form=CAT2&SUBCATID=965#11)

43402

Cheersi'm pretty good with a soldering iron, and pretty good on having a crack at electronics, with that simple circuit shouldnt be hard, my biggest problem would be locating the MAP signal input and the output to ECU?

[Rumcajs]

i'm pretty good with a soldering iron, and pretty good on having a crack at electronics, with that simple circuit shouldnt be hard, my biggest problem would be locating the MAP signal input and the output to ECU?

Well, both MAF (Manifold Air Flow sensor) and MAP (Manifold Absolute Pressure sensor aka boost sensor) will need to be "clamped" or not go over 3.99 V so I'd use two of those units together for both, boost sensor and MAF voltage because both of those sensors will play the role in Limp mode.

If you are good at soldering and electronics than I suggest getting JDVM and hand controller instead, you gonna be impressed what can you do with it.

Locating signal wires for MAF and MAP are easy/trivial indeed the easiest part of the job.

Cheers

[Rickie3]

Well, both MAF (Manifold Air Flow sensor) and MAP (Manifold Absolute Pressure sensor aka boost sensor) will need to be "clamped" or not go over 3.99 V so I'd use two of those units together for both, boost sensor and MAF voltage because both of those sensors will play the role in Limp mode.

If you are good at soldering and electronics than I suggest getting JDVM and hand controller instead, you gonna be impressed what can you do with it.

Locating signal wires for MAF and MAP are easy/trivial indeed the easiest part of the job.

CheersI thought boost sensor was disregarded with dawes and needle valve installed?, unfortunately dont have the cash to buy the JDVM unit, so I couldnt just use one fuel cut kit for the MAF?, if the boost controller is still used then I would buy the second fuel cut unit? I purchased 1 unit last night online, when I get some extra coin will buy JDVM unit

[threedogs]

Sounds interesting any links to item you purchased.
You say impressed , what does it do, does it allow better performance for EG

[Rickie3]

Sounds interesting any links to item you purchased.
You say impressed , what does it do, does it allow better performance for EGhttps://www.jaycar.com/productView.asp?ID=KC5439&form=CAT2&SUBCATID=965#11

[Rickie3]

Just went out and removed air filter and the airbox had water in it, so that explains where the water came from, I recon it was in my snorkel, I did wash the car yesterday, anyway, disconnected everything and dried everything thoroughly, re-asemmbled, now the big girl is hitting 16psi and flys and no signs of limp mode yet, but I am looking forward to doing the other mods

[threedogs]

I'm interested on what it achieves I'm like Mudski with 20psi max and 10psi at 100ks,
never looks like going into limp mode.If it improves economy or boosts performance
I'm all ears. Diesel smart have some system that will give you 50% performance increase
but at a high cost, maybe that is along these lines

[Rumcajs]

I thought boost sensor was disregarded with dawes and needle valve installed?, unfortunately dont have the cash to buy the JDVM unit, so I couldnt just use one fuel cut kit for the MAF?, if the boost controller is still used then I would buy the second fuel cut unit? I purchased 1 unit last night online, when I get some extra coin will buy JDVM unit

Boost (MAP) sensor is used as engine protection only in other words it is not considered for overall AFR calculation, only MAF is used for that.
There is clearly a relationship between those too as boost pressure over 18 psi in any RPM will bring on fuel cut (limp) and MAF voltage over 3.99 bellow 3000 RPM will do the same. There is also this so called "cold" limp (engine temp bellow 70°C) which occurs when MAF voltage is over 3.75 or so and around 2500 RPM.

You could/can adapt the Jaycar fuel cut defeat unit to MAF only but you still have the boost (MAP) sensor to watch/consider if you want to allow Dawes at higher pressure where boost spike can take it past 18 psi at lower RPM (<4000).
One still needs to find out what voltage reading is MAP output at 17-18 psi. Jaycar unit seems to be preset to keep the voltage bellow 3.9 V so lets just assume that ==>
this simple Fuel Cut Defeater (FCD) to eliminate the standard factory fuel cut which typically occurs at boost levels about 16-17psi. The unit is not adjustable, so no external controls are required. would than be sufficient to keep the boost pressure related limps from occurring.

In any case it has been proven that ZD30 Di with boost pressure over 18 psi is doing nothing beneficial from either performance or engine reliability prospective.

What JDVM unit gives you is ability to control the "holy grail" of performance especially on ZD30 that is low to mid range torque/power thanks to fooling ECU in to thinking that more air is supplied hence the fueling increase thus bypassing the smoke maps limits . The ability to tweak the loading points individually where possibly limp might occur is another bonus.

Once set right it will be another "OMFG why didn't I do this earlier!" moment. If you thought Dawes and needle valve transformed the car wait for the JDVM effect....

Cheers

[mudski]

This is what my local mechanic/turbo place does. He doesn't subscribe to any of this dawes/needle stuff. He's had 4-5 blokes come in with dawes valves and stuff, and hes ripped it out, tinkered with the MAF voltage, and the owners couldn't believe the difference when they picked the car up.
They also do this when they fit a chip. He didn't reveal specifics, but showed me some dyno sheets to prove it.

Unfortunately what Mark, the said mechanic, does, it half correct, or right. By ripping out BOTH dawes and neelde valve and only playing with the MAF voltages only gives you half of the control over the turbo. Messing with the maf voltages cannot give you spool up rate control where the needle valve does this.
So when the owners pick up there Patrols and feel the extra power, its only because of more boost and the spool up rate is still controlled by the POS ecu.
While it may be a cheaper option to mod the maf voltages you technically still have no control over it.
I myself went down the somewhat expensive track and purchased a HPD hi flow air box lid and HPD hi flow maf housing. Once fitted there was zero difference. IT was only when I raised my boost levels beyond what it could before, whilst still retaining the needle valve, I felt the difference. I went as high as 25psi and there still was no limp mode. I didn't go any higher. Currently running 20psi...
Next on the list is to modify the intake of the turbo to accommodate a larger intake pipe as the macca's straw used now is by far the biggest restriction on the motor.



In any case it has been proven that ZD30 Di with boost pressure over 18 psi is doing nothing beneficial from either performance or engine reliability prospective.



Cheers

While I don't doubt your expertise on this Rummy I'd have to disagree on this. While there is minimal performance increase from 16-20psi, when I drove mine with 25psi it was really a different car to drive. I could have gotten used to the extra ponies it had at 25psi but I was a bit worried that something was to go bang quite quick. Maybe not as the turbo is quite capable of providing this type of boost pressure, I was concerned for the motor not handling it.

Cheers.
Mark.

[Rumcajs]

..................
I myself went down the somewhat expensive track and purchased a HPD hi flow air box lid and HPD hi flow maf housing. Once fitted there was zero difference. IT was only when I raised my boost levels beyond what it could before, whilst still retaining the needle valve, I felt the difference. I went as high as 25psi and there still was no limp mode. I didn't go any higher. Currently running 20psi...
.................
While I don't doubt your expertise on this Rummy I'd have to disagree on this. While there is minimal performance increase from 16-20psi, when I drove mine with 25psi it was really a different car to drive. I could have gotten used to the extra ponies it had at 25psi but I was a bit worried that something was to go bang quite quick. Maybe not as the turbo is quite capable of providing this type of boost pressure, I was concerned for the motor not handling it.
............


While you welcome to disagree you are still confirming what I have said, the second part about engine reliability that is. Now having HPD lid and housing changes a thing or two but on stock ZD30 there is very little benefit going past 18 psi and this isn't just my observation but a few Patrol gurus too.

I have both, HPD MAF housing and airbox lid and without JDVM I would need to bump boost up past 18 psi to get extra ponies. In this case diesel chip would definitely be beneficial but I don't like to cough up that much for a bunch of resistors on a circuit board in a plastic box.

I have observed that in lower boost setting (12 psi) tractive effort of the engine is way better than at higher boost mode (18 psi)
(I have dual Dawes setup) I can really explain it. The downsize is cruising at 100 km/h at lower boost raises EGTs to the point I'm not comfortable with.

Cheers

[Rickie3]

You could/can adapt the Jaycar fuel cut defeat unit to MAF only but you still have the boost (MAP) sensor to watch/consider if you want to allow Dawes at higher pressure where boost spike can take it past 18 psi at lower RPM (<4000).
One still needs to find out what voltage reading is MAP output at 17-18 psi. Jaycar unit seems to be preset to keep the voltage bellow 3.9 V so lets just assume that ==> would than be sufficient to keep the boost pressure related limps from occurring.


CheersI'm more than happy running my bus at the 16psi, cant see any point pushing it any harder, after i'm not towing with it, so for the time being i will be more than happy to do the MAF mod, but when funds do improve JDVM is on the cards, I will no doubt need some advise on installing the fuel cut unit for the MAF, and I really appreciate the time you have taken to post your very helpful informative comments

[mudski]

While you welcome to disagree you are still confirming what I have said, the second part about engine reliability that is. Now having HPD lid and housing changes a thing or two but on stock ZD30 there is very little benefit going past 18 psi and this isn't just my observation but a few Patrol gurus too.

I have both, HPD MAF housing and airbox lid and without JDVM I would need to bump boost up past 18 psi to get extra ponies. In this case diesel chip would definitely be beneficial but I don't like to cough up that much for a bunch of resistors on a circuit board in a plastic box.

I have observed that in lower boost setting (12 psi) tractive effort of the engine is way better than at higher boost mode (18 psi)
(I have dual Dawes setup) I can really explain it. The downsize is cruising at 100 km/h at lower boost raises EGTs to the point I'm not comfortable with.

Cheers

Yeah I was mainly referring to the performance benefit by my rambling kinda gets in the way. At 25psi there was a massive difference to performance. But not a great deal at 18psi.
As for the dual Dawes. You think its worth it? I considered doing it. I have all the gear here to do it. But I realised I would just have it on the high setting anyway so I didn't bother.

[Rumcajs]

As for the dual Dawes. You think its worth it? I considered doing it. I have all the gear here to do it. But I realised I would just have it on the high setting anyway so I didn't bother.

For me it is, as I look for fuel eco as well. I have it both automated via accelerator pedal and manual overide with low,high,auto, in the city and when engine is cold I force low boost mode only, on open road I sometimes keep it on low to get some economy especially on flat roads subject to EGTs than I flip it over to automatic control.
Mine is set up to change over from low to high at about 20% accelerator pedal or 1.6 V.

Main reason is fuel economy as mine is atrocious when cruising in high boost mode sitting on 12 psi @100 km/h will drink over 13 L. There is something about GU4 series as earlier versions don't have that problem or so it seems. Some guys are getting around 10L or even lower. Forcing it to sit at 8-10 psi I can manage 10-11 L too.

And I can have fairly aggressive spool up (needle valve is just about closed) and I get no cold limps this way.

Cheers

[mudski]

Now what you have just said makes me think I should do this mod. As it stands, I'm running 20psi boost and 15psi at 100ks. If I go 10psi, my spool up rate is too slow and the car just won't go. Maybe I should do this and use the low boost for highway driving, which I do a lot of too. Yuo may need to start a new thread on this mate on how you set it up to work via your acc pedal. Very interesting indeed.

[Rickie3]

From what ive read a simple inline diode between the MAF and the ECU will drop the voltage caused by blanking the EGR, cheap mod just a matter of snipping the red wire and soldering in a diode if its not any good easily taken back out

[oddkid82]

Does this work

[threedogs]

@ Rickie what value diode did you use

[Rickie3]

Just an ordinary diode, fit the silver end away from the MAF sensor, and yes it does work

[Rumcajs]

Just an ordinary diode, fit the silver end away from the MAF sensor, and yes it does work

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

[oddkid82]

So does this cut out the cold limp mode. I get limp mode on cold mornings only in 3rd gear going up a slight hill.

[mudski]

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

Yeah I'm confused how a blocking diode will work.

[Yendor]

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

A characteristic of a diode is it will also have a voltage drop of 0.5 to 0.6 across it.

So in theory you should also see this voltage difference at the ECU.

[Pokey]

Ok I just tested the diode theory. No limp mode at 20 psi. BUT very sluggish engine. I'm guessing with the lower maf voltage through the rev range the ecu is not allowing the required fuel needed.

[Rickie3]

A characteristic of a diode is it will also have a voltage drop of 0.5 to 0.6 across it.

So in theory you should also see this voltage difference at the ECU.That is correct! EGR blocking increases the voltage to the MAF, the diode drops the voltage by 0.5 to within specs, but yes you will notice sluggishness, but me I can put up with that, far better than hitting limp mode

[Pokey]

I haven't blocked my egr yet as I'm waiting for a mod plate inspection from the transport dept and it won't pass with egr blocked. So with egr blocked plus diode , voltages should be back to nearly normal. Btw i can't live with a sluggish engine. After spending thousands of dollars chasing more grunt sluggish isn't an option. I have a diesel smart interface that caps the maf voltage just under limp mode but I'm not convinced that I'm getting full fuel delivery after the voltage cap. Still playing with ideas and probably doing what many have done before but I think these little Renault engines are capable of some serious pulling power if they are treated right

[mudski]

Will the transport dept actually check if the egr is blocked? They would only know if they remove the pipe.

[Rumcajs]

.............. I think these little Renault engines are capable of some serious pulling power if they are treated right

You will find that these are not Renault engines at all, just pure Japanese POS. ZD30 has very strong bottom end (crank, big ends, block etc) but the pistons are made from Rockford cheese. Therein is the problem as majority of ZD30s expire via hole in the piston.
If one could source cast iron "skeleton" type pistons you could push that engine to 200 hp easily.

Cheers

[Rickie3]

A question, my bus has been running sweet since fitting dawes, but every now and then when I start my bus the check engine lights stays on, turn the key off and start it again check engine light goes off? ive got a OBD 2 but it wont communicate with the computer as I want to know what the check engine fault could be, can anyone recommend a correct OBD to buy so I can run my checks and to clear fault codes?

[Rumcajs]

............... ive got a OBD 2 but it wont communicate with the computer as I want to know what the check engine fault could be, can anyone recommend a correct OBD to buy so I can run my checks and to clear fault codes?

Although plug/socket looks like OBD2 it doesn't support OBD protocol, it is still Consult proprietary protocol.


ECU Talk interface cable and software works. Other alternative is Nissan Scantech but you could also use flash codes. Check ZD30 reference document on this site to see how to.

Cheers

[Pokey]

Yep they will as I'm currently trying for a mod plate. They have just been given new regulations regarding emissions and checking everything now :-(

[Rickie3]

Although plug/socket looks like OBD2 it doesn't support OBD protocol, it is still Consult proprietary protocol.


ECU Talk interface cable and software works. Other alternative is Nissan Scantech but you could also use flash codes. Check ZD30 reference document on this site to see how to.

CheersCould I use this unit? http://www.ebay.com.au/itm/Newest-TurboGauge-V-Auto-Computer-scan-tool-digital-gauge-5in1-SP143-63color-LCD-/171062864604?pt=AU_Car_Parts_Accessories&hash=item27d4242adc

[Rumcajs]

Could I use this unit? http://www.ebay.com.au/itm/Newest-TurboGauge-V-Auto-Computer-scan-tool-digital-gauge-5in1-SP143-63color-LCD-/171062864604?pt=AU_Car_Parts_Accessories&hash=item27d4242adc

Definitely not on pre 2007 models (non common rail diesels) That unit seems like rebadged Scangauge which only operates on OBD II protocol.

Cheers

[Paule]

That is correct! EGR blocking increases the voltage to the MAF, the diode drops the voltage by 0.5 to within specs, but yes you will notice sluggishness, but me I can put up with that, far better than hitting limp mode

How does blocking your egr increase the voltage to the maf? I m still getting limp mode at low psi when the engine is cold, would replacing the maf help? And why don't I get limp mode when when it's warmed up?

[mudski]

How does blocking your egr increase the voltage to the maf? I m still getting limp mode at low psi when the engine is cold, would replacing the maf help? And why don't I get limp mode when when it's warmed up?

Mate. Mafs can do wonders when they play up. It may not be your maf but could well be a ill adjusted dawes and needle valve. Unfortunately I am in a real busy time right now, I have two weeks to finish my backyard for the wifes 40th. It's a real bog hole right now and I have f all time to do it. As discussed mate via pm, I am more than happy to re tune your car and throw a maf in to see what happens. But it's just a insanely busy time for me. Be patient mate. We'll yet there. I just wish I had the coin to open up an actual shop to complete my dreams....