Recently I have noticed my psi reading on my tuner hovers around .25 to .35 in the morning right when I start my truck. Normally it reads zero or is in the negatives. After driving around and stopping at red lights it will hover between .80 and 1.25. Now, I know that not a lot but its not what it normally reads.

Last week I went off road and my exhaust took a hit and loosened up and caused a small leak near the rear axle. I unbolted it and for the most part fixed the leak minus some alit air flow coming from the slits in the pipe. I'm not getting any codes and haven't noticed any decrease in performance. It does however seam to slow down quicker when I let off the throttle. I'm running an SCT X4 with dpf and erg delete and have a S&B CAI.

I called a performance exhaust shop and the tech said a small leak shouldn't cause any issue like that especially because its so far back. Another respectable vendor told me it might be that my vein are sticky.

Do you have any thoughts on this? I'm kind've worried. Thanks much.

 

Mine will show just off the 0 on the boost gauge at idle. I consider it normal for the turbo to turn a few rpms at idle. It is moving even with idle exhaust flowing through it.


As for a small leak after the muffler or around that area...that will effect nothing more than some noise and smell. Maybe on a cold day some fumes in the cab. So get it fixed.


Your turbo vaines are not stuck. If it were you would have a check engine light or codes. That just does not have on any of the trucks except like the 6.0.

 

Thanks for the reply. I went out and fixed the leak this morning and then started it up. Boost gauge showed over 1psi at idle. I let it warm up and gave it a little bit off throttle and dropped to about .50. I'm not hearing any abnormal sounds or anything.

Hopefully im worried about nothing. Thanks again.

 

sounds normal to me.

 

what are you using to read the boost psi? the sctx4?

 

Yes, the X4.

 

dont shoot me if I'm wrong but i haven't seen anything that measures boost that accurate as far as the .25psi .80psi etc. and the fact that it was reading negatives on the boost psi would indicate that there is vacuum in the boost tubes which doesnt happen on our trucks.. i think that the X4 is giving you a false reading which means i don't think you have anything to worry about as far as something being wrong with your truck. turbo vanes would defiantly throw a code if something was happening in that department.

 

Good to know. Thanks man. Your actually the second person to mention the false reading scenario. What concerned me was the fact that the boost reading changed at all and that I noticed the change after I had noticed the leak in my exhaust.

Again, I haven't noticed any change in performance so, I think your right. Thanks for getting my head back on straight. I've already been looking at new turbos in the event this one was toast. But, now, after your inputs i don't think thats the case. I really appreciate it.

 

At cold temps, mine will run 5 psi boost for about two minutes at 1400 rpm high idle.

 

It's probably just colder out, and truck is trying to cause back pressure and boost to warm up.

 

You sure about that? Could there not be a bit of negative pressure if the engine and exhaust system are cold i.e. Turbo not turning, it would act like a throttle valve causing some vacuum

 

IMHO, For a small fraction of a second, potentially... When the engine and exhaust is cold the truck ups the RPM to compensate.

So in essense the computer prevents your scenario from happening.

I've seen slightly positive movement in the boost gauge when idling in park even with a cold soak start. Granted, I have a 2015 now and it has a different turbo in it than my 2011... But the cold start behavior was the same.

 

Wouldn't it be throwing codes if there was a problem?

Is there a sensor related to the turbo I could check?

 

the turbo wheel is spinning as long as the engine is running. depending on the ambient air temp these trucks will have slight boost pressure for a few minutes after a cold start no doubt about that. if there was an issue with any components a code would defiantly be thrown.

 

Thanks. I kinda figured a code would pop if something was wrong. I'm kind've wigging out because of the up in pressure. It must just be the cold.