P0171 and P0174 - Stabilitrak...only under certain conditions.

[Jimxms]

bank2 looks off, for the backpressure test you would need to either buy a tool or make one
it would just take say a pipe fitting that fits in the 02 bung, hose and a low pressure psi gauge
I think the tool just has nozzle fitting that you stick in the forward 02 sensor bung
looks like harbor freight sells a tool for $35

https://www.harborfreight.com/engine-and-transmission-oil-pressure-test-kit-64872.html?event_id=183642&utm_source=google&utm_medium=cpc&utm_campaign=17890472041&campaignid=17890472041&utm_content=140972256953&adsetid=140972256953&product=64872&store=3091&gad_source=1&gclid=Cj0KCQjw3bm3BhDJARIsAKnHoVUH8A5CTuf4pWpfDBmBRKSj3rQLn3afg92-vCsAbmL2BUSu6s4P-o0aAkhhEALw_wcB

if I start with B2, is that passenger side do you know?

 

[Doubeleive]

if I start with B2, is that passenger side do you know?

bank1 is drivers side, bank2 is passenger side
bank 1 sensor 1 is the sensor before the cat, bank 1 sensor 2 is after the cat and so on
for backpressure test do it thru sensor 1 bung

 

[Jimxms]

Hey doubeleive, I just wanted to say a tentative THANK YOU for directing me to blocked cats as a cause.

I couldn’t do a back pressure test, so instead I pulled the exhaust off (what a mission that was). The cats actually looked visually fine, but as I broke 3 studs in the process, and because I was so deep in at that point I decided to just smash the cats out anyway Bolted it all back together and no more codes + extra power and noise

I never would have thought about the cats. I literally had new intake gaskets, injector seals, maf, map and even new headers on order to try and fix it!!

 

[Doubeleive]

Hey doubeleive, I just wanted to say a tentative THANK YOU for directing me to blocked cats as a cause.

I couldn’t do a back pressure test, so instead I pulled the exhaust off (what a mission that was). The cats actually looked visually fine, but as I broke 3 studs in the process, and because I was so deep in at that point I decided to just smash the cats out anyway Bolted it all back together and no more codes + extra power and noise

I never would have thought about the cats. I literally had new intake gaskets, injector seals, maf, map and even new headers on order to try and fix it!!

well that's good news, you might discover the 02 codes come back without the cat's working properly, a tune can turn them off but not sure how that works for passing a smog test if it is required where you live.

 

[Jimxms]

well that's good news, you might discover the 02 codes come back without the cat's working properly, a tune can turn them off but not sure how that works for passing a smog test if it is required where you live.

Yeah I’m going to run those little extenders on the rear o2’s for the moment to make sure I don’t get any codes. I did used to have hptuners but sold it with my vette a few months back. I might need to buy that again.

 

[RogerK]

As far as I can tell I still have all of the exhaust bolts. However the manifolds look like the titanic with big chunks of rust flaking off.

I’ve held a piece of paper all around the manifold while the engine was idling to see if a slight leak could be detected, but there was nothing. I may try blocking the exhaust with a rag tomorrow to see if additional pressure reveals a small leak some more.

That’s annoying about the Bosch sensors. I thought I was buying the best

You will only find the leaks when you start it up, they seem to disappear when you have engine temp up.