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Fuel Trims are high and + with vented oil cap

my o2 sensor has a burned wire on the harness and it sent my trims to -22.6. when I unplugged the o2 sensor the o2 reading went to 450 and my trims came down to to -12, so I would say its entirely likely your o2 readings are skewing your fuel trims
 


SgtMarshal said:
my o2 sensor has a burned wire on the harness and it sent my trims to -22.6. when I unplugged the o2 sensor the o2 reading went to 450 and my trims came down to to -12, so I would say its entirely likely your o2 readings are skewing your fuel trims
Click to expand...

I will have to double check my harness. But last i saw no melting.
 
SgtMarshal said:
I was just giving that as an example of how much the o2 sensor can throw off the fuel trims
Click to expand...

Thank you. I just installed a genuine GM sensor now I guess I will see how it reacts on the drive home.

Side note

At idle my fuel pressure is 45psi. At 2500 rpm it is at 44. When I got wot it will hit 62. Prime is 54 and will drop to 40 and rise back to 48.
 
A little update.

I brake cleaned anything that involved a seal/oring. My trims did not change. I then poured water all over the sc/ic and injectors. Still no change (in running or trims)

Now my last step was spraying brake clean around the boost bypass valve. I then sprayed it tords the orange seal on the bottom and my trims went to high -8s instantly.
I will be trying a new boost bypass valve. I see the previous owner tried the "free mod" of repositioning the bracket. Are there really any benefits? Should I just put it back to stock configuration when bolted?

I am thinking this may or may not be my culprit on my trims being ok at times and then are off the charts.

Any input?
 


Definitely could be. Mine were setting a cel at +25 on my van, and it was only a little seal where rod on the intake air controller went through the plenum. Now sitting at +-3 with new one on.
 
if the boost bypass valve has failed it will create a vacuum leak. I would say you probably found your problem, as far as the free BBV mod, its up to you if that is how you want to do it, really just personal preference, and however you do it shouldn't cause any problems.
 
The only source for boost bypass actuators was ZZP at $77 plus shipping. I managed to get ahold of NEW GM boost bypass valves with correct port location and stud for valve.

http://pages.ebay.com/link/?nav=item.view&alt=web&id=121643812582

dd21791badaf63f8ed5ccc4540dab541.jpg
 
SO the bbv diaphragm had a tear in it. I thought oh perfect a new one will fix my issue!! Nope....made another problem and still hits high + ltfts at times.

My other problem is that the foot rests on the sc at idle which it is wrong (brand new bbv). I swapped in 2 other spare solenoids (no idea if they are good) and same outcome. But I have never had a problem with hitting full boost.

Now I have 2 other spare bbv that I discovered had a tear In them. I even swapped in the spare solenoids on each and the foot stays up at idle as designed to. Maybe if they were not torn the foot would rest on the SC???

If I disconnect the vac line as seen in the vid the foot rests up at idle. Would this mean that the solenoid is bad? I went as far as deleting the solenoid and taking it for a drive.


My trims do not make sense........One moment my ltft will hover around +16 in the lower 4000hz cruise range then sometimes it will be +/-4. WTF
Could my map sensor be leaking? Or my 02 not switching fast enough?

Maybe I disturbed something? Acts up randomly? I am 100% positive I do not have a vac leak. Brake cleaned/watered the IC/SC and any vac line.

If my rear pcv was almost plugged could this be a factor?


https://www.youtube.com/watch?v=rZB6EBJqyEo
 
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Could be an exhaust leak. Not sure is the o2 sensor or map sensor could affect it like that, but I did have a plugged pcv port on my intercooler and I was running rich
 
You would be correct but i have no evap on the car.

That is very possible on the exhaust leak. Considering zzp has that band clamp on the crossover. But i dont hear any abnormal exhaust noise.
 
feeling for the air coming out of the exhaust is the best way to find the leak, just be careful not to burn your hand. when I installed my sd headers, I ended up using copper rtv and band clamps to get it to seal. only had a leak at the front connection, which was good because its nearly impossible to feel for a leak at the back one without burning your hand.
 


Pull the EGR to LIM tube. Pull back the metal retaining piece at the LIM end and look for any cracks where it's held to the LIM.
 
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