Hi again everyone, still trying to tackle this issue,
Hope someone can give a little insight.
so I've Been watching my fuel trims on different drives, and noticed a trend, no matter what the ltft are the car is always able to compensate with a rich command while in idle or low revs, the minute I rev to fast especially under load/uphill .. (or reach Highway speeds) The stft sky rocket straight to 25% and sticks there no matter what speed or rpm for the rest of the journey dragging the ltft up along with it, ( this only happens when in gear) it literally stays there and I can feel the car drive funny, misfiring.
The only way to make it "unstick" is to get in neutral and snap the throttle a few times it it then goes to 0% on stft until I put it in gear and it goes back to correcting the high ltft.
The other way is to start the car again it all goes back to normal with high ltft and equally negative stft. Both these methods allow the car to compensate Until the ltft goes down gradually back to 4 or 5% lean with 3 or 4% rich commands on stft. But only if I drive very very easy accelerating slow at all times.. If this was a intake leak I would be getting the opposite no?

What's happening here? I can't make any sense of this

 

That's a very hard way to try to figure if it's an air leak.

Instead just do it like everyone else: hot engine, parked. Check STFTs are smallish and look at LTFTs. Rev to 2500 or so and see if LTFTs drop a lot. If they do it's a leak.

If not then life gets tougher, sadly. (And if this is where you're at then might be clogged cat/cats.)

 

Thanks bud, I will try to do that.
BTW I did 2 or 3 cycles of cataclean in the tank as I thought I might be getting back up from down there but no results, also worth mentioning the sensor for that bank post cat reads rich, about 940v with very little fluctuation. While pre cat very lean.
Does that sound like cat troubles? If it were how would I unclog it I tried cataclean 3 times.

 

At least I think they are lean, it gives me a different measure for voltage 9.0 aM when it's stuck reading 25% lean . Ma or something like that..
Or.. the sensor could have gone bad? I had a massive leak from the thermostat just before all this happened, and the O2 sensor is right below the thermostat housing where the leak was generating . Could be a contaminated sensor thats on its way out no?

 

Hi again v8

I did what you said, and firstly the short trims were stuck as always 25% and the long trims were not moving either 17.5%

So I snapped the throttle a bit to unstick the short trims.

Once I saw the short trims compensating again with high negatives - 17% I got back to 2500rpms,
the long terms were actually going back up +19.5%
At 2500 rpm and back down to 17% with my foot off. Did this a few times with the same results. (all along short trims were compensating with negative commands)

​​​​​​I got off the throttle and let it idle now that short trims were unstuck and saw the short trims slowly drop from high negatives along with long trims dropping from high positives to the point of fluctuating quite well. That's when I took the picture you see uploaded.
Can we rule out air leak?? Lol

 

The pic is mainly reflection but those readings are a mess.

Could be almost anything, from bad cat(s) to dirty MAF to ... anything.

If you're sure your tool properly supports the kinds of O2 sensors the car uses then at least one bad cat would be #1 suspect. Don't bother with additives in that case. You can have a try to diagnose via looking (borescope), IR temperature, listen or whatever.

 

I think it does, Im gonna do that have a friend take a look at the cat.
Thanks for your help so far

 

You haven't (I don't think) mentioned checking out the PCV on the front cam cover. That could give you an 'internal' vacuum leak. You might think that would affect both banks, but who knows? It would certainly affect fuel trims.

 

The pcv hose was replaced but not the valve, I heard they can stick open or closed but I'm not really sure how you could test it

 

Try this video, although the PCV removal bit doesn't start until the 2.00 minute point - about halfway through.

 

Thanks astromorg, did that was a bit oili but it was clicking fine, still gave it a clean fit it back and no change, guess we can cross that out the list.
Any other ideas I'm fresh out

 

Ok , only just noticed my bank 2 lambda are reading lean upstream and rich down stream. That's what's causing limp mode (telling pcm to go lean and rich at the same time) I know cause I drove hard with one and then the other unplugged. Both sensors persistent on reading lean pre cat and rich post even individually. Cell on but neither time I had one or the other unplugged did the car go into limp mode.. No matter what . . . Lol
Can I assume they are both gone caputt?