[lundy's guiv]

Gday all, I have an 05 3.0 ltr and was driving around some uphill twisty roads on Sunday in 35 degree heat and was getting boost readings that were staying at 18-20psi, my egt's were holding normal and it was happening all the time when the throttle was over approx 50 percent, the car has done 68,000km and it is very rare that I get a boost spike that high let alone having it stay at 18-20psi, when I serviced the car at 65,000km I removed all the intake piping, intercooler and Maf to clean but was very surprised that there was no oil in there after reading all the posts about how oily they get, I cleaned it all anyway as it was apart and replaced the air cleaner, when it was happening I pulled over turned the car off and removed the air cleaner and checked the Maf to make sure nothing looked to be out of place all seemed ok, I had about 30km left of this happening till I made it to the highway where the psi returned to between 11-13psi and everything was normal, I have towed my camper trailer in higher temperatures than this and never had a prob, has anyone got any ideas on anything I should check or has anyone else experienced this aswell? Cheers in advance, forgot to mention I had my 33's on and it also has a 3 inch exhaust

 

[dan-0]

Have you fit a dawes valve? If not I highly recommend fitting one. I have limited my Patrol to 14 psi.

 

[lundy's guiv]

No I haven't fitted a Dawes mate as it has been all good up until that day, might be time now though,
Can u fit the Dawes without the needle valve?

 

[the evil twin]

Seen similar things over here on very high 30's to 40 degree plus days AND highish engine temps (high 90's low 100's) but not at high throttle settings. From the limited times i have noticed it the boost sits about 3 or 4 PSI higher at low throttle and drops back to "normal" under higher load... Never does it on cooler days IE less than 35 degrees.

I have considered it a possibility that there is a parameter in the ECU mapping trying to jam as much air as possible into the engine under these conditions IE abnormally hot ambient air and engine.

Could be similar happenings to what your seeing could be totally different as mine is a CRD... and... I have the boost wound back about the same amount as the higher readings (3 to 4 PSI) due to some (cough cough) mods

 

[lg 91]

ive got preaty much the same issue as you mate when driving around on hot day with aircon on when i put my foot down around a corner with about 2000 to 2500 rpm it will spike to about 15 to 16 psi and then drop back down when i back off but when i hold my foot down the revs build up to about 2500 to 3000 it will stay on about 15 psi and i have seen it go up to 19 psi. mine is an auto and i have just orded a dawes valve and needle valve to try and slow the boost down abit

 

[dronus4x4]

My boost will spike to 18psi, but then quickly go to 14 - 15psi and stay there while accelerating. Dawes and needle valve fitted.

Trying to find someone in Adelaide to make a 2.75 or 3" exhaust for me to keep those EGT's down... bueller, bueller

 

[lg 91]

My boost will spike to 18psi, but then quickly go to 14 - 15psi and stay there while accelerating. Dawes and needle valve fitted.

Trying to find someone in Adelaide to make a 2.75 or 3" exhaust for me to keep those EGT's down... bueller, bueller

hay dronus what revs are you doin when yours is on 14-15psi. is it bad to have that much boost with revs under 3000rpm. chears lg91

 

[dronus4x4]

hay dronus what revs are you doin when yours is on 14-15psi. is it bad to have that much boost with revs under 3000rpm. chears lg91

If i accelerate slowly it can get up to 15 by say 2500rpm. I had my setup installed and calibrated by Chaz (the guru), so im confident it is set correctly... If im cruising it will come down to like 12psi and sit there..

 

[lg 91]

If i accelerate slowly it can get up to 15 by say 2500rpm. I had my setup installed and calibrated by Chaz (the guru), so im confident it is set correctly... If im cruising it will come down to like 12psi and sit there..

thanks dronus i guess i shouldnt be woried then when i see 15psi befor 3000rpm thanks alot mate. sorry for the hyjack lundy

 

[paul.helm]

Mine is doing the same, high boost 18-20 psi, unusual high boost, but no symptoms to overboost or too fast a spool rate, which would normally occur in temps of 20-30deg.

Got me buggered as to why this is happening...........Possible Barometric pressure reading or water temp being higher than normal thus ECU makes adjustments & not allow overboost? ? ? ECUTalk reads 92degC instead of normally being between 85-88.

Paging Chaz or whitie...............we want answers.

 

[lg 91]

Mine is doing the same, high boost 18-20 psi, unusual high boost, but no symptoms to overboost or too fast a spool rate, which would normally occur in temps of 20-30deg.

Got me buggered as to why this is happening...........Possible Barometric pressure reading or water temp being higher than normal thus ECU makes adjustments & not allow overboost? ? ? ECUTalk reads 92degC instead of normally being between 85-88.

Paging Chaz or whitie...............we want answers.

hay paul do you have ur egr blocked and have u fitted a dawes and needle valve iam still tossing up wether i should do these mods or not

 

[geeyoutoo]

Mine is doing the same, high boost 18-20 psi, unusual high boost, but no symptoms to overboost or too fast a spool rate, which would normally occur in temps of 20-30deg.

Got me buggered as to why this is happening...........Possible Barometric pressure reading or water temp being higher than normal thus ECU makes adjustments & not allow overboost? ? ? ECUTalk reads 92degC instead of normally being between 85-88.

Paging Chaz or whitie...............we want answers.

Hey Paul,

Did this just happen out of the blue? I haven't had temp etc effect the boost and we have had all the hot weather and conditions you can think of up here on the Sunny Coast recently.

 

[whitie]

Mine is doing the same, high boost 18-20 psi, unusual high boost, but no symptoms to overboost or too fast a spool rate, which would normally occur in temps of 20-30deg.

Got me buggered as to why this is happening...........Possible Barometric pressure reading or water temp being higher than normal thus ECU makes adjustments & not allow overboost? ? ? ECUTalk reads 92degC instead of normally being between 85-88.

Paging Chaz or whitie...............we want answers.

:iconbana:

Ok, gave this a bit of thought and I am with the evil twin on this one "there is a parameter in the ECU mapping trying to jam as much air as possible into the engine under these conditions IE abnormally hot ambient air and engine".

With regards to the manual setup, needle valve / dawes valve, to get a similar EGT reading at cruise on a hot day you need more boost which means that we wind in the needle valve a bit to give the VNT more vacuum.

When you do that, you change the max boost setting of the dawes valve as it now needs to overcome a higher vacuum on the VNT side, this results in the dawes valve allowing higher boost than usual.

The ECU will allow higher boost than 16psi as long as it is with a reasonable amount of throttle (say over 20%), the ECU backs off the fuel under the same conditions but with lower throttle input (generally caused by too high a spool rate).

The engine can handle higher boost than 18psi as on the DI we know that it can go well into the twenties from factory, we lower the boost to provide better economy and to place less load on the engine however - EGTs are what we need to watch out for...

So if you need to raise the boost to keep the EGTs below say 500c post turbo then do it, then look at ways of making the engine more efficient so that you can get the same EGTs with lower boost.

That's my story and I'm stickin to it :lol:

:cheers:

 

[the evil twin]

Hiya Whitie,

Hmmm... interesting... esp glad to hear your view is possibly similiar to mine.

Bit of further info (even tho mine is a CRD it may be relevant) from the last week or two.

1. I adjusted the Boost Actuator to give me max of 31 PSI MAP on my scangauge (about 16 PSI Boost depending on ambient) several months ago.

2. Weather conditions of 38 degrees plus (38 to 45 degrees) and pulling my 1250 KG Camper. A/C on and roaring. Engine temps regularly over 100 on the scangauge so as reported to the ECU.

3. At about 40 to 60% engine load observed consistent pressures IE not spikes up to 38-39 PSI MAP (23-24 PSI Boost allowing for local ambient).

4. Back off or increase throttle and boost immediately dropped to around 30 MAP (normal)

5. EGT's stayed around normal expected at all times ( I have an underslung intercooler fan which was on the whole trip)

6. Fuel consumption was if anything better over the 3 days of travelling under these conditions at around 14.5 to 15 LPH when normally getting 16 LPH

7. At lower ambient temps IE below very high 30's before and after the trip out and back thru the guts of WA I have never seen the Boost above 31 MAP. Prev trip towing Camper was in October over 2,500 K's but was more coastal and cooler so never above 35 degrees ambient.

8. I did need a change of undies when I first noticed it but in outback WA what do ya do... I made the decision to push on closely watching EGT's, Fuel, and Coolant parameters and with nothing else out of spec and also with the Boost acting normally other than high MAP at cruise I gradually figured out the ECU must be doing it and that nothing else untoward was happening.

Note, MAF sensor was checked and seems fine and was last cleaned about 3 months ago and because of normal fuel useage and EGT's I ruled out as suspect.

 

[whitie]

Hiya Whitie,

Hmmm... interesting... esp glad to hear your view is possibly similiar to mine.

Bit of further info (even tho mine is a CRD it may be relevant) from the last week or two.

1. I adjusted the Boost Actuator to give me max of 31 PSI MAP on my scangauge (about 16 PSI Boost depending on ambient) several months ago.

2. Weather conditions of 38 degrees plus (38 to 45 degrees) and pulling my 1250 KG Camper. A/C on and roaring. Engine temps regularly over 100 on the scangauge so as reported to the ECU.

3. At about 40 to 60% engine load observed consistent pressures IE not spikes up to 38-39 PSI MAP (23-24 PSI Boost allowing for local ambient).

4. Back off or increase throttle and boost immediately dropped to around 30 MAP (normal)

5. EGT's stayed around normal expected at all times ( I have an underslung intercooler fan which was on the whole trip)

6. Fuel consumption was if anything better over the 3 days of travelling under these conditions at around 14.5 to 15 LPH when normally getting 16 LPH

7. At lower ambient temps IE below very high 30's before and after the trip out and back thru the guts of WA I have never seen the Boost above 31 MAP. Prev trip towing Camper was in October over 2,500 K's but was more coastal and cooler so never above 35 degrees ambient.

8. I did need a change of undies when I first noticed it but in outback WA what do ya do... I made the decision to push on closely watching EGT's, Fuel, and Coolant parameters and with nothing else out of spec and also with the Boost acting normally other than high MAP at cruise I gradually figured out the ECU must be doing it and that nothing else untoward was happening.

Note, MAF sensor was checked and seems fine and was last cleaned about 3 months ago and because of normal fuel useage and EGT's I ruled out as suspect.

That all sounds normal and good as far as I am concerned. The CRDs MAF has a temperature sensor in it so it seems that it has been put to good use in this case

I am curious about your point number 1, were you getting boost spikes or higher boost in the low end of the rev range (say to 2600rpm) and lowering the grub was able to control this?

 

[geeyoutoo]

That all sounds normal and good as far as I am concerned. The CRDs MAF has a temperature sensor in it so it seems that it has been put to good use in this case

I am curious about your point number 1, were you getting boost spikes or higher boost in the low end of the rev range (say to 2600rpm) and lowering the grub was able to control this?

Hi Whitie, my 2000 build ZD30 boost range does not seem to be as sensitive to atmospheric changes as what I have read about in this thread.

Could this be put down to the early ECU's being less sophisticated? I understand there would be significant difference with CRD's but Paul's is only a few years older than mine with the same or very similar mods.

 

[paul.helm]

hay paul do you have ur egr blocked and have u fitted a dawes and needle valve iam still tossing up wether i should do these mods or not

Yes mate, all NADS installed. (EGR blocked, Dawes & Needle valve too)

I would strongly suggest that you do install these mods to ensure a moore responsive & reliable vehicle.

 

[paul.helm]

Hey Paul,

Did this just happen out of the blue? I haven't had temp etc effect the boost and we have had all the hot weather and conditions you can think of up here on the Sunny Coast recently.

Both tests were with the needle valve closed.

Yesterday 42 deg & today 39 deg & when putting the boot into it from a set of lights, the boost would climb to 18-20 psi & stay at 18 or 19 without symptoms of overboost or too fast a spool rate.

This morning with the cooler temps ~27 deg, same senario from a set of lights she overboosted or a too fast a spool rate was detected and then had to lift off the throttle then reapply to reset the fault.

 

[the evil twin]

I am curious about your point number 1, were you getting boost spikes or higher boost in the low end of the rev range (say to 2600rpm) and lowering the grub was able to control this?

Uuuuummm, I get a bit paranoid about "lurkers" up to no good on the Forums (not you Whitie) so usually don't list modifications etc but in order to answer your question I was a little concerned about MAP on my truck due to 3 inch Exhaust and (cough cough) "enhanced fuel management" adjustments.

I bought the vehicle of a mate with those Mods already done but no Scangauge or EGT which I put on immediately. Never had Boost spikes per se but she used to spool up and cruise at pretty high MAP which I associated with the Mod's.

So after consulting the Bible I tweaked the VNT adjustment back a tad (1/4 turn). That slowed the spool up marginally and dropped the MAP about 3 PSI from what it was previously.

 

[paul.helm]

:iconbana:

Ok, gave this a bit of thought and I am with the evil twin on this one "there is a parameter in the ECU mapping trying to jam as much air as possible into the engine under these conditions IE abnormally hot ambient air and engine".

With regards to the manual setup, needle valve / dawes valve, to get a similar EGT reading at cruise on a hot day you need more boost which means that we wind in the needle valve a bit to give the VNT more vacuum.

When you do that, you change the max boost setting of the dawes valve as it now needs to overcome a higher vacuum on the VNT side, this results in the dawes valve allowing higher boost than usual.

The ECU will allow higher boost than 16psi as long as it is with a reasonable amount of throttle (say over 20%), the ECU backs off the fuel under the same conditions but with lower throttle input (generally caused by too high a spool rate).

The engine can handle higher boost than 18psi as on the DI we know that it can go well into the twenties from factory, we lower the boost to provide better economy and to place less load on the engine however - EGTs are what we need to watch out for...

So if you need to raise the boost to keep the EGTs below say 500c post turbo then do it, then look at ways of making the engine more efficient so that you can get the same EGTs with lower boost.

That's my story and I'm stickin to it :lol:

:cheers:

I agree whitie BUT,

How does the ECU on mine read the ambient temp?

AND

Under full throttle with the needle valve closed, why am I not seeing overboost symptoms with too fast a spool rate.