What's max boost before setting a code?

[Gypsyman]

Has anyone been able to find this information. I'm looking at shimming the waste gate a small amount but I don't know how far I can go with the boost before setting a code.

 

[thejeepdude]

Keep going until you get a code! Then let us know! It will most likely go away with a battery disconnect anyways, right?

 

[lmills]

When I took my EZ off and ran my truck with the boost elbow, I frequently took it to the point that it would defuel. (about 30 psi) I never did set the CEL.

 

[Gypsyman]

Did you feel or see any difference over stock with just the elbow installed?

 

[lmills]

no, it actually had less power. I couldn't pull the mountains with my trailer and a skid loader without dropping into 5th gear. The little hy spools so fast that when you put a load on it, it would spool up to 30 psi before you knew it and then the motor would defuel. After a week of driving like that, I put the stock elbow back in till the TST box came

 

[Gypsyman]

Thanks for the info. Been wondering about that for a long time. Is 30 psi the defuel point?

 

[lmills]

yeah somewhere in that neighborhood. I think from the SOTP meter that it might start to defuel slowly as the pressure reaches that, but then it flattens out totally and loses power

 

[sfr1047]

OverBoost Code

So the motor seems to defuel at 30-PSI but at what boost # will the over boost code be set? Is that somewhere below 30-PSI or does defueling and code setting happen at the same time?

 

[rbattelle]

I am not able to find a specific number for the overboost condition in either the service manual or the powertrain manual. But the service manual, vol. 1, page 11-11 indicates that a pressure of greater than 27 psi indicates a fault. Perhaps we may assume from this that the overboost code will be set for any pressure greater than 27 psi.

 

[lmills]

I have never seen an overboost code. And as I stated above, I have seen as high as 30 psi with no boost fooler of any type.

 

[sfr1047]

Overboost

I found that page 11-11. for the 04. 0 it is page 11-12.

It says Full load boost pressure at rated speed will be 23-27 psi depending on engine hp rating. If not in this range inspect the following. Then it lists things to check.

That just says what it should be but does not say at what point a code will be generated.

On my 04 HO I am seeing 23 psi max, I wish it was 27. I wonder what hp rating is set for 27psi?

 

[rbattelle]

Re: Overboost

Originally posted by sfr1047

I found that page 11-11. for the 04. 0 it is page 11-12.

It says Full load boost pressure at rated speed will be 23-27 psi depending on engine hp rating. If not in this range inspect the following. Then it lists things to check.

That just says what it should be but does not say at what point a code will be generated.

On my 04 HO I am seeing 23 psi max, I wish it was 27. I wonder what hp rating is set for 27psi?

With my HO I can sometimes get up to 23. 5-24. This seems to be normal, so don't worry that your boost isn't high enough. I think they allow the range up to 27 "just in case". Or, with a heavy load at WOT and max RPM you might see 27?

 

[ESTELJ]

In my 04 I run a releif valve and a bullydog box. I have it set up to about 32#'s I haven't fealt it defueling but I do know that on the dyno it made no more power after that. I took it all the way to 38#'s and I did not set a code. HOw does the ECM know what the boost is?? If the wastegate remains closed is it fooled??

I would love to know. thanks

 

[rbattelle]

Originally posted by ESTELJ

In my 04 I run a releif valve and a bullydog box. I have it set up to about 32#'s I haven't fealt it defueling but I do know that on the dyno it made no more power after that. I took it all the way to 38#'s and I did not set a code. HOw does the ECM know what the boost is?? If the wastegate remains closed is it fooled??

I would love to know. thanks

There is a MAP sensor that tells the ECM what the manifold pressure is. There is no sensor on the wastegate, so the ECM doesn't know what the status is on it.