EGTS Up Why?

[10G]

Since doing the Canning, the EGTs on the 3 litre CRD are up higher than they've ever been.

Used to very rarely see it hit 600, now it's only got to be in the mid twenties and it hits 600.

On the Canning we suffered through very nasty corrugations, lots of mud and water.

I think the exhaust is now emitting fuf fuf fuf noise instead of the normal bop bop bop, which sounds like an exhaust leak somewhere.

So the question is, what can make the EGTs increase?

Restricted exhaust? Mud caked radiator? Buggered EGT probe? Leaky exhaust? Leaky join at dump pipe?

I've also noticed an increase in PCV smoke as well.



Thanks for any help.

[Hodge]

Have you noticed any changes in boost ??
Low boost = Egts up, as they have to be in a certain harmony .
Just a brainstorm idea . Maybe the boost controlling vacuum setup dislodged a hose or a leaking intercooler pipe somewhere due to corrugations you mentioned.

Sent from my Pixel 6 using Tapatalk

[10G]

Boost may be down a little. Boost gauge is currently busted, I'll get that fixed up and see what it tells me.

Thanks Hodge, that's a good start.

[mudski]

EGR valve could be jammed due to the corrugations?

[Coldcomfort]

Clean your MAF sensor. Very easy job but often ignored.

[10G]

Now the MAF could be the problem, it was very dusty in sections.

Thanks for the help folks.

[Bidja]

Just to add here, do a quick check of VNT actuator function (vacuum):

at idle, is the actuator rod in the raised position, ensure that the lever is resting against vane limit stop screw? yes/no (should be yes), and

then still at idle, pull the vacuum hose off the actuator rod should drop to bottom of stroke promptly? yes/no (should be yes)


As mentioned _ Check that all boost hoses are fitting securely, check for splits/damage, loose clamps. Check your boost reference take off point, hose and connection for leaks.

[10G]

Just to add here, do a quick check of VNT actuator function (vacuum):

at idle, is the actuator rod in the raised position, ensure that the lever is resting against vane limit stop screw? yes/no (should be yes), and

then still at idle, pull the vacuum hose off the actuator rod should drop to bottom of stroke promptly? yes/no (should be yes)


As mentioned _ Check that all boost hoses are fitting securely, check for splits/damage, loose clamps. Check your boost reference take off point, hose and connection for leaks.

Thanks Bidja, I'll do all that. Just got out of the truck. She's running about 100 degrees hotter than it should and low on boost I reckon.

[Bidja]

She's running about 100 degrees hotter than it should and low on boost I reckon.

High EGTs, Guess this with eng under high load / hauling?

Important to rule out any vac or boost faults / issues first. Good to get boost gauge working.

What boost control method do u use?

What engine mods?

Let us know how it goes.

[10G]

Got the gauge going, it's only making half boost.

Normally it'll peak at 15psi and sit on 13psi at 100kmh on the flat in 5th, that gives me 300+ EGTs.
Today at 100kmh I was boosting around 5.5 with EGTs at about 500+

I got both a Dawes and Needle valve.

The only thing that I have done that could affect it was that I tightened up the large hose from the IC a while back, that's the only thing I've touched. That could have produced a leak I guess, it's the original hose, maybe it's overtightened?

No engine mods.

I'm going to check/replace all the small vacuum hoses around that area.

[mudski]

Have you cleaned the air flow meter?

[10G]

Have you cleaned the air flow meter?

No, not yet. Have to wait until the weekend.

[Bidja]

Got the gauge going, it's only making half boost.

Normally it'll peak at 15psi and sit on 13psi at 100kmh on the flat in 5th, that gives me 300+ EGTs.
Today at 100kmh I was boosting around 5.5 with EGTs at about 500+

I got both a Dawes and Needle valve.

The only thing that I have done that could affect it was that I tightened up the large hose from the IC a while back, that's the only thing I've touched. That could have produced a leak I guess, it's the original hose, maybe it's overtightened?

No engine mods.

I'm going to check/replace all the small vacuum hoses around that area.

Check the actuator rod function, at idle by having vacuum hose connected to actuator (rod up and lever resting against stop screw) and then disconnect the vacuum hose (rod is to drop down).

Strip Dawes boost controller and clean inside of the body, seat and ball. Mark where it is currently set with marker pen for Ref.

[mudski]

No, not yet. Have to wait until the weekend.

Do that before you touch anything.

[Hodge]

Do that before you touch anything.I think if he's got a Dawes and and needle set up , and his boost is that low, MAF sensor won't matter would it?? Because now it doesn't influence the boost ??
I can't remember ....
Remember those days Marko? Lol

Sent from my Pixel 6 using Tapatalk

[10G]

Thanks for all help fellas. I have to wait until the weekend before I can fiddle with it all.

Another question. I have one of the Nissan snorkels, the ones with that Nissan badge riveted onto them, ex TJM Airflo snorkels I think?

Anyway, how many joints do they have? Just need to make sure it's all watertight. Thanks alot.

[mudnut]

Thanks for all help fellas. I have to wait until the weekend before I can fiddle with it all.

Another question. I have one of the Nissan snorkels, the ones with that Nissan badge riveted onto them, ex TJM Airflo snorkels I think?

Anyway, how many joints do they have? Just need to make sure it's all watertight. Thanks alot.

To double check how watertight my snorkel was after installation, I disconnected the filter housing from the engine. After taping the pipe off with duct tape, I filled the snorkel with water and looked for leaks. That is when I found that the preheat system on a RB30 is not water tight.

[10G]

That's a good idea Craig, I think I'll see if I can do that. Might save me pulling it all apart for no reason.
Thanks.

[mudnut]

That's a good idea Craig, I think I'll see if I can do that. Might save me pulling it all apart for no reason.
Thanks.Just make sure there are no sensors in the part you test. I also used a shop vac and air hose to suck out any remaining water.

[mudski]

I think if he's got a Dawes and and needle set up , and his boost is that low, MAF sensor won't matter would it?? Because now it doesn't influence the boost ??
I can't remember ....
Remember those days Marko? Lol

Sent from my Pixel 6 using Tapatalk

Yeah but it does influence fuel. I'd be making sure the MAF if clean or working 100% before anything if it were me. Otherwise you might be just chasing your tail.

Im kinda glad to forget those days to be honest. I like my dumb motor.

[10G]

Well went through and cleaned electrical connections, replaced some vac hoses and disassembled and cleaned the Dawes valve.

Nothing made a difference until I cleaned the Dawes valve.

I marked the Dawes valve before disassembly, but when I put it back together I put it back to where I reckon it was, but it's now boosting it's brains out. I keep blowing pipes off. I'm getting up to 22psi at about 1/3 throttle on the flat.

When I put the Dawes back together, I put the ball in the small half and the spring in the large half which I'm pretty sure is correct.

I'm winding the two halves apart to lower the boost. Is that correct???

I can't remember the procedure for setting the boost. From memory it's something like go up a hill (or put the vehicle under load) at about 3000 rpm until you get a boost of 15-16 psi. Is that correct??

Thanks for any help.

[Bidja]

Well went through and cleaned electrical connections, replaced some vac hoses and disassembled and cleaned the Dawes valve.

Nothing made a difference until I cleaned the Dawes valve.

I marked the Dawes valve before disassembly, but when I put it back together I put it back to where I reckon it was, but it's now boosting it's brains out. I keep blowing pipes off. I'm getting up to 22psi at about 1/3 throttle on the flat.

When I put the Dawes back together, I put the ball in the small half and the spring in the large half which I'm pretty sure is correct.

I'm winding the two halves apart to lower the boost. Is that correct???

I can't remember the procedure for setting the boost. From memory it's something like go up a hill (or put the vehicle under load) at about 3000 rpm until you get a boost of 15-16 psi. Is that correct??

Thanks for any help.

10G Good news, u having success _ But appears that Dawes is assembled incorrectly as u describe.

Dawes assy:
Drop ball in large body end first, followed by the spring. Large body section goes nearest to cooler.

Wind the male threaded "smaller section" in (clockwise) to increase boost.


I can't remember the procedure for setting the boost. From memory it's something like go up a hill (or put the vehicle under load) at about 3000 rpm until you get a boost of 15-16 psi. Is that correct??

In 3rd gear, hauling @ 3000rpm (with needle closed) and when no limp (approx 15-16 psi) open needle valve so lever is just resting against stop screw or spool rate that suits _ do not make it laggy. May need to wind Dawes in a little if boost drops when u adjust needle valve.

Suggest that you remove all boost hoses and wipe off any excess oil residue, clean mating parts and re clamp.

Get it working and I can then suggest an alternate arrangement that may improve drivability _ if interested.

[10G]

Well that's all resolved.

Nothing changed until I disassembled the Dawes valve, cleaned it re-assembled the correct way.

EGTs are back to where I'm used to seeing them, which is helping the coolant temp to drop a bit. Boost is back up to 14-17 psi, spiking at 20-22. Power is back, it's actually pulling pretty well, it accelerates from 100 in 5th which is good.

Took it up a hill in 3rd at 3000rpm and boost was around 15-17psi.

Feels all free and happy once more. :-)

Thanks everyone for the help.

Now what's that alternate arrangement you mentioned Bidja???

[Bidja]

"10G firstly great that all working well.

There are 2 other VNT boost control method u can try. Give it a couple of week, leave Dawes and needle valve as configured for now just to make sure all keeps performing well.

Wil post alternate boost control methods in a couple of days as am a bit flat out with shed build at the moment.

[10G]

"10G firstly great that all working well.

There are 2 other VNT boost control method u can try. Give it a couple of week, leave Dawes and needle valve as configured for now just to make sure all keeps performing well.

Wil post alternate boost control methods in a couple of days as am a bit flat out with shed build at the moment.

Yep, no problem.

Drove to work up hills etc today. Running like a dream, couldn't get rid of the smile.

[10G]

Just when you think you've got it solved.

I've noticed my boost creeping back down again in the space of 1 week.

The Dawes is just about screwed right in.

When I pulled the Dawes apart last week, the only thing that I could see wrong was that there was a reasonable amount of oil in there. I didn't stretch the spring, just cleaned and re-assembled.

I'm still using the original hose clamps that Nissan use on the turbo pipes, would it worth using better ones? If so, what type?

The vacuum hose I'm using is 6mm, but it's softish. Could that be being sucked closed? I noticed it's way softer than the original vacuum hose.

Can anyone remember how to set the needle valve? I can't remember the procedure. I didn't do this the other weekend.

Thanks fort any help.

[Bidja]

10G my comments in RED


Just when you think you've got it solved.

I've noticed my boost creeping back down again in the space of 1 week.

The Dawes is just about screwed right in.Pull Dawes apart again, check for contaminants, clean it with cotton wool bud_ reassemble it and try it out first

When I pulled the Dawes apart last week, the only thing that I could see wrong was that there was a reasonable amount of oil in there. I didn't stretch the spring, just cleaned and re-assembled.Leave spring as is, what Dawes do u have "Brass coloured body" or "Black 3BarRacing"?

I'm still using the original hose clamps that Nissan use on the turbo pipes, would it worth using better ones? If so, what type?If clamps tighten securely they should be fine. Check for splits/cracks etc in hoses and make sure they fit tight (clean away oil residue.

The vacuum hose I'm using is 6mm, but it's softish. Could that be being sucked closed? I noticed it's way softer than the original vacuum hose. I prefer 3mm ID hose and secure with small cable ties

Can anyone remember how to set the needle valve? I can't remember the procedure. I didn't do this the other weekend.

As I have said last week _ In 3rd gear, hauling @ 3000rpm (with needle closed) and when no limp (approx 15-16 psi) open needle valve so lever is just resting against stop screw or spool rate that suits _ do not make it laggy. May need to wind Dawes in a little if boost drops when u adjust needle valve.

Suggest that you remove all boost hoses and wipe off any excess oil residue, clean mating parts and re clamp.

Thanks fort any help.

[10G]

Thanks Bidja.

I have a brass Dawes.

My needle valve is under the bonnet, so I can't adjust while driving at 3000 rpm.

When we setup these valves initially, I can remember adjusting the needle valve so it's just sitting on the stop screw, I guess that was done at idle or is that what I should do with idle set at 3000 as you mention?????

[Bidja]

Thanks Bidja.

I have a brass Dawes.

My needle valve is under the bonnet, so I can't adjust while driving at 3000 rpm.

When we setup these valves initially, I can remember adjusting the needle valve so it's just sitting on the stop screw, I guess that was done at idle or is that what I should do with idle set at 3000 as you mention?????

haha_Yes adjust needle with eng at idle / stationary. Tell U, I would not be hanging out of the drivers side window, hauling in 3rd gear @ 3000rpm, with bonnet up trying to get a visual of the actuator lever resting against the vane limit stop screw.:smileyvault-cute-bi

Darren Dawes had a replacement spring for the early Brass Dawes boost controller. Send him an email and he may send you one for elimination purposes (explain the boost situation briefly) _ info@3BarRacing.com

Clean the Dawes you have and see how she performs after a clean. CRD can run happily at max spool, so u can shut needle right off.

I have a Tillix boost controller here and needle valve that I could loan to you to see how boost behaves.

Do you still have vac solenoid under the bonnet and plugged in to elec harness keeping ECM happy when using manual boost control?

I currently run VNT vac solenoid with the ECM, in conjunction with a Dawes (3barracing) and needle valve for boost limiting. Can try a couple of other things but give your current setup a go again first for info.

[BillsGU]

Usually higher EGT's can be boiled down to two main issues. Less air than normal (air leak or turbo problems) or more fuel than normal (injector pump or injector problems).

I would start by looking at air leaks and if none can be found - a good tune up may fix or at least find the problem.

[10G]

haha_Yes adjust needle with eng at idle / stationary. Tell U, I would not be hanging out of the drivers side window, hauling in 3rd gear @ 3000rpm, with bonnet up trying to get a visual of the actuator lever resting against the vane limit stop screw.:smileyvault-cute-bi

Darren Dawes had a replacement spring for the early Brass Dawes boost controller. Send him an email and he may send you one for elimination purposes (explain the boost situation briefly) _ info@3BarRacing.com

Clean the Dawes you have and see how she performs after a clean. CRD can run happily at max spool, so u can shut needle right off.

I have a Tillix boost controller here and needle valve that I could loan to you to see how boost behaves.

Do you still have vac solenoid under the bonnet and plugged in to elec harness keeping ECM happy when using manual boost control?

I currently run VNT vac solenoid with the ECM, in conjunction with a Dawes (3barracing) and needle valve for boost limiting. Can try a couple of other things but give your current setup a go again first for info.

I'll stick my head in and take a look. I know we removed that solenoid from the equation, vacuum wise, but I don't know about electrically.




Usually higher EGT's can be boiled down to two main issues. Less air than normal (air leak or turbo problems) or more fuel than normal (injector pump or injector problems).

I would start by looking at air leaks and if none can be found - a good tune up may fix or at least find the problem.

Is it possible to tune the standard setup? Standard ECU etc?

Last night I was adjusting the needle valve. At some settings I could hear something that sounded like something opening, like when a vacuum seal is broken, you hear that release of a suction seal. I assumed it was the actuator opening and closing, but I'm not 100% sure????

[Bidja]

I'll stick my head in and take a look. I know we removed that solenoid from the equation, vacuum wise, but I don't know about electrically.

Is it possible to tune the standard setup? Standard ECU etc?

Last night I was adjusting the needle valve. At some settings I could hear something that sounded like something opening, like when a vacuum seal is broken, you hear that release of a suction seal. I assumed it was the actuator opening and closing, but I'm not 100% sure????

CRD requires the vacsol electrically connected (plugged into harness). or if vacsol is removed a resistor (330ohm 1/2 watt) is to be placed across the sol electric harness connector terminals. The ECM requires this load or limp type fault will occur.

A tune will be a remap of ECM (postal or a live on dyno).


Last night I was adjusting the needle valve. At some settings I could hear something that sounded like something opening, like when a vacuum seal is broken, you hear that release of a suction seal. I assumed it was the actuator opening and closing, but I'm not 100% sure????

Was the noise a drone sound and did u notice that actuator rod had dropped down at the same time?

Make sure that the needle valve fresh air bleed and vac hoses are of good condition and fit securely (3mm ID hose).

Much oil residue again in Dawes boost controller?

[10G]

The noise sounds like a combination of a hot engine component cooling down, you know how some things give a crack sound when they begin to cool down and that sound you hear when you remove a suction fitting.

It's too hard to try to determine where it comes from, but I'll keep an eye & ear out for it.

Yep, the vascol is still plugged in.

There was some oil residue in the Dawes, not alot, but more than I was hoping to find. I'm going to take another look, but I think I may have lost a rubber seal out of the Dawes, if it has one??? I have been wiping out the inside, so I may have accidently flicked it out, again, if it has one?

[Bidja]

If it is a metallic click sound, wonder if the VNT vanes are sticking (ie: carbon build up).
With eng at idle with Dawes and needle valve connected, check again and see if the rod is up with lever against stop screw then pull vac hose off actuator (eng still at idle). Do you hear the noise and does the rod drop freely and quickly?

Good that vacsol is still plugged in.

Not sure if the Dawes "Brass Body" has seat insert. Would you like me to post/loan a Tillix boost controller to try that (trouble shooting)?

[10G]

Thanks Bidja, I'll check that arm tonight.

Thanks for the kind offer of the Tillix, I'll hold off on that for now, thanks again.

Found a Tuner, 1 hour from home. Hmmmmm, I wonder.

[10G]

Just checked the rod. It's up with vac and goes up and down when I remove the actuator vac hose, moved quite freely. Couldn't hear that noise I mentioned.

Did some tests the other night, forgot to put the figures up.

I get around 18psi doing 130 in 4th or 5th, can't remember. EGTs were in mid to high 400s.

Sitting in 5th at 100km/h I get around 10psi with EGTs mid 300s. I'm sure boost used to be up around 13 psi at 100, but it's not bad I guess.

Here's a pic of how far my Dawes is screwed in:

86625

Could that indicate that something's maybe not plugged into the correct spot or some other fault/error?

Doesn't give me much room to play with.

And this is how I have the vacsol hooked up:

86626

That lower left hose is bent over and clipped with a zip tie.

Is that all blocked off correctly?

[Bidja]

Those boost and EGTs figures are fine. 10psi cruise @ 100kph is what some strive for to provide good ECO. I do have some concern with the Dawes being wound in so far.

With the Dawes wound in just about all the way, makes me think that the ball is not seating correctly and there maybe has a small leak past the ball at seat. If it is leaking there would be +ve air pressure from cooler entering the vac line at very early/low boost and the VNT vanes may not stay closed enough early for the turbo to spool up fast enough.
Could be the seat or spring lets see.

Could remove the Dawes, connect a small length of vac hose to each end of the Dawes and apply compressed air supply with a regulator fitted to simulate it being connected to the cooler boost take off. Using the regulator on the air supply, slowly increase the pressure from zero to the pressure where you feel slight air passing through the Dawes and this will give you an indication of boost level set of the Dawes.
Let me know result.
U can put the outlet piece of hose near your face and feel the passing air starting to pass through.

Your vacsol is blocked off correctly and as said: the electric connector needs to be plugged in.

Really think u can sort this out without giving money to a tuner.


mudski does the Brass body Dawes have a seat insert for the ball to nest against?

[mudski]

Those boost and EGTs figures are fine. 10psi cruise @ 100kph is what some strive for to provide good ECO. I do have some concern with the Dawes being wound in so far.

With the Dawes wound in just about all the way, makes me think that the ball is not seating correctly and there maybe has a small leak past the ball at seat. If it is leaking there would be +ve air pressure from cooler entering the vac line at very early/low boost and the VNT vanes may not stay closed enough early for the turbo to spool up fast enough.
Could be the seat or spring lets see.

Could remove the Dawes, connect a small length of vac hose to each end of the Dawes and apply compressed air supply with a regulator fitted to simulate it being connected to the cooler boost take off. Using the regulator on the air supply, slowly increase the pressure from zero to the pressure where you feel slight air passing through the Dawes and this will give you an indication of boost level set of the Dawes.
Let me know result.
U can put the outlet piece of hose near your face and feel the passing air starting to pass through.

Your vacsol is blocked off correctly and as said: the electric connector needs to be plugged in.

Really think u can sort this out without giving money to a tuner.


mudski does the Brass body Dawes have a seat insert for the ball to nest against?

Yeah the Dawes has like a tapered seat for the ball. Can't say for the Chinese copies floating around though.

[mudski]

Just checked the rod. It's up with vac and goes up and down when I remove the actuator vac hose, moved quite freely. Couldn't hear that noise I mentioned.

Did some tests the other night, forgot to put the figures up.

I get around 18psi doing 130 in 4th or 5th, can't remember. EGTs were in mid to high 400s.

Sitting in 5th at 100km/h I get around 10psi with EGTs mid 300s. I'm sure boost used to be up around 13 psi at 100, but it's not bad I guess.

Wind your needle valve in more. The gap between your cruise boost and max is way too far apart. ideally 5psi difference.


Here's a pic of how far my Dawes is screwed in:

Could that indicate that something's maybe not plugged into the correct spot or some other fault/error?

Doesn't give me much room to play with.

Something is not right thats for sure. You should be seeing 25psi +

And this is how I have the vacsol hooked up:




That lower left hose is bent over and clipped with a zip tie.

Is that all blocked off correctly?

Yes its blocked off. You don't even need to do that to be honest as its not doing anything anyway.

[10G]

Wind your needle valve in more. The gap between your cruise boost and max is way too far apart. ideally 5psi difference.



Will do. I set my needle by watching the rod go up and down and tightening the set screw on the needle just as the rod touches the stop screw. I'll wind it in more and see what happens on the drive home in a few hours.

[10G]

Those boost and EGTs figures are fine. 10psi cruise @ 100kph is what some strive for to provide good ECO. I do have some concern with the Dawes being wound in so far.

With the Dawes wound in just about all the way, makes me think that the ball is not seating correctly and there maybe has a small leak past the ball at seat. If it is leaking there would be +ve air pressure from cooler entering the vac line at very early/low boost and the VNT vanes may not stay closed enough early for the turbo to spool up fast enough.
Could be the seat or spring lets see.

Could remove the Dawes, connect a small length of vac hose to each end of the Dawes and apply compressed air supply with a regulator fitted to simulate it being connected to the cooler boost take off. Using the regulator on the air supply, slowly increase the pressure from zero to the pressure where you feel slight air passing through the Dawes and this will give you an indication of boost level set of the Dawes.
Let me know result.
U can put the outlet piece of hose near your face and feel the passing air starting to pass through.

Your vacsol is blocked off correctly and as said: the electric connector needs to be plugged in.

Really think u can sort this out without giving money to a tuner.


mudski does the Brass body Dawes have a seat insert for the ball to nest against?

Thanks for all the help Bidja. Unfortunately I don't have any compressed air.

The Dawes is one of mudski

[Bidja]

Thanks for all the help Bidja. Unfortunately I don't have any compressed air.

The Dawes is one of mudski

All good, will be good to sort it mate.

Per mudski advice: With your Dawes, should have a seat insert_not sure if machined into body (brass) or a fitted type seat. Check and let us know?


Yeah the Dawes has like a tapered seat for the ball.

With the needle valve adjustment, 12 psi would be a good cruise target boost. IMO_For now, until we get Dawes/Boost sorted I would close needle completely and run max spool to remove a variable.
With needle closed go for a drive, check cruise and max boost with the Dawes set as now and then unwind Dawes one turn at a time and see how max boost changes.

Can check Dawes target boost with a bike pump with gauge but no big deal.

[10G]

Well. I wound the needle almost all the way in, left a 1/4 turn out, boost was great, I was getting 23 PSI at 90 kmh in 4th without trying.

Pulled over, undid the Dawes 2 turns. That made it terrible. Screwed it back in 1 turn, still terrible, wouldn't boost over 10PSI. Stopped again, turned off motor, unplugged battery in case the thing had gone into limp.

Wound the needle right the way in and noticed that the actuator rod bounced up & down off the screw.

Set the needle valve so the rod is just touching the screw and fiddled with the Dawes a bit more and I think I've got it to as good as it will get.

Now getting 11psi at 100kmh with EGTs on the 200s in todays weather.

I'm happy with that, the vehicle drives nicely enough.

The only thing I'm unsure about is that the Dawes is pretty much screwed completely in. There's still some room left for adjustment, but not alot.

[mudski]

Somethings amiss.

What intercooler are you running too?

[Bidja]

Yeah this performance would not cut the mustard with me. If cooler is in good condition I would change out the boost controller (Dawes) to start with.

[10G]

Somethings amiss.

What intercooler are you running too?

I got the stock IC.

It does boost higher than 11psi, its sits on 11 at 100kmh on the flat with cruise control on. When I come across a hill with cruise on, it'll boost up to 14 to maintain speed.

Maybe I could borrow that Tillix of yours Bidja and see what happens?

[Bidja]

I got the stock IC.

It does boost higher than 11psi, its sits on 11 at 100kmh on the flat with cruise control on. When I come across a hill with cruise on, it'll boost up to 14 to maintain speed.

Maybe I could borrow that Tillix of yours Bidja and see what happens?

What I think is happening is:
Dawes spring has become worn and has a reduced spring rate which allows the ball to bounce on/off its seat even at very low boost pressure (ie at idle). Maybe this why you see the actuator arm rise/drop rapidly at idle with the needle closed because the Dawes ball is bouncing on/off its seat causing sudden fluctuations of +ve air (boost) pressure from cooler side into vacuum hose (downstream of Dawes). This rapidly changes vacuum to actuator causing the rod up/down movement especially at max turbo vane closure (needle closed).

Also with Dawes screwed nearly right in the spring maybe compressed to a solid height forcing the ball very hard up against seat not allowing any boost / +ve air to pass thru Dawes to vary the vacuum to actuator. Hence allowing full vacuum to actuator (nom 24”Hg) causing max vane closure and this produces the max boost from turbo (say 24psi), but as you open the needle this reduces vacuum to actuator and opens the turbo vanes slightly causing boost to reduce.
This is what you are currently doing along with opening Dawes slightly.
Could try stretching the spring but any improvement may not last long.

Yes I can send you my spare Tillix boost controller and see how goes. PM me you address.
Will also send a Tillix needle valve as this can be installed down stream of the boost controller (Dawes or Tillix)_use two needle valves. In your case, would set the Tillix to 10psi and adjust the downstream needle to a target max boost of say 16psi and you retain your current needle valve for spool adjustment. Called Boost controller plus two needle valves. This is for later.

[10G]

Pulled the dawes apart again today. Measured the spring, 18.75mm. Stretched it to about 24mm.

Put it back together. Wound in the needle valve right in, the actuator no longer bounces off the stop screw. Set the rod to just sit on the stop screw and wound out the dawes, about the thickness of the lock nut. Test drive gave me nice linear boost up to 16psi while accelerating up to 100kmh. Took up the same stretch of road and am now getting 14-15 psi at 100kmh with cruise on, up from 11psi.

Boost is peaking at around 16-17 psi which is where it should be if I understand correctly.

EGTs are under control, high 200s low 300s.

Going to keep an eye on it and chase up some springs to keep in the spare parts bag.

Thanks everyone for the help.

[mudski]

I got the stock IC.

It does boost higher than 11psi, its sits on 11 at 100kmh on the flat with cruise control on. When I come across a hill with cruise on, it'll boost up to 14 to maintain speed.

Maybe I could borrow that Tillix of yours Bidja and see what happens?

Hmm. Remove the IC and see if there is any oil deposits on the bottom side. If there is, you’ll have a boost leak, which it seems to me you are experiencing.


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[mudski]

Just read your last post. You must have one of the first revisions of the Dawes if you had to stretch the spring.
But, still check the IC for oil deposits in my opinion. Stock IC’s are known to spring a leak.


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[Bidja]

Pulled the dawes apart again today. Measured the spring, 18.75mm. Stretched it to about 24mm.

Put it back together. Wound in the needle valve right in, the actuator no longer bounces off the stop screw. Set the rod to just sit on the stop screw and wound out the dawes, about the thickness of the lock nut. Test drive gave me nice linear boost up to 16psi while accelerating up to 100kmh. Took up the same stretch of road and am now getting 14-15 psi at 100kmh with cruise on, up from 11psi.

Boost is peaking at around 16-17 psi which is where it should be if I understand correctly.

EGTs are under control, high 200s low 300s.

Going to keep an eye on it and chase up some springs to keep in the spare parts bag.

Thanks everyone for the help.

Yes needs a replacement spring as proven. As said earlier, contact Darren Dawes for replacement spring _ worth a try:


Darren Dawes had a replacement spring for the early Brass Dawes boost controller. Send him an email and he may send you one for elimination purposes (explain the boost situation briefly) _ info@3BarRacing.com

Not surprised that you have high cruise boost (14-15psi), vanes are most likely nearly closed all the time, yes lower EGTs at the expense of high exhaust manifold pressures and reduced air flow rate (grams/sec). Worth checking that the actuator lever is still just resting against stop after adjusting.


Also worth improving your air intake in time to let it breathe easier, this will bring cruise boost down as well. Aim for a nom 12psi cruise boost.

Do check your intercooler as it most likely does leaks.

Be interesting to hear how she goes with a serviceable boost controller. Room for improvement yet though.

[10G]

OK, a follow up, been a few weeks now.

Fitted an upgraded IC. Fits the same mount as the stock IC but is deeper.

Sits on 14-15 psi boost everywhere now. Very noticeable improvement in performance, best it's ever driven.

Brake pedal has come up as well, so vacuum must be in better shape than when I started.

Also noticed a reduction in lag between changing gears.

EGTs are under control, sits in the low to mid 300s when doing 100kmh.

The 2 things that made the biggest improvements were, 1 - stretching the spring in the Dawes, 2 - New IC.