LT4 B2S1 stuck

[Cobradoc]

I have a 69 Camaro with a LT4 8L in to be tuned from another shop. Started working on it and noticed a 30-40% trim increase on B2. Swapped sensors bank to bank and issue stayed on B2S1. So I did all the basics, wrung out harness checked grounds, smoked intake and exhaust. All good. So I installed my wideband in bank 2 and sure enough getting .73 lambda at idle. O2mv stuck at .9 on bank 2 only. So PCM is doing what it is supposed to do. B1S1 is nearly perfect with a 3% trim at idle. Had a spare PCM and swapped it no change. BTW this is a GMP Crate deal with control pack. Can't for the life of me figure out what's up. Anyone run into this?

[Ben Charles]

If not exhaust leak there, of course is a problem/miss on passenger side

[Cobradoc]

If not exhaust leak there, of course is a problem/miss on passenger side

Runs ok no miss, no exhaust leak. Pull the plugs and you can tell right bank is rich versus left bank. Car makes crazy power but I can't be sure tune is correct if right bank is correcting +30-40%. My external w/b verifies its adding fuel like it should but the primary o2 is parked at 900mv.

[Ben Charles]

What happens if you pull 30% does bank 2 get close to 0 or stay at -30

[Cobradoc]

You know, I haven't tried that because left bank is dead on at +3%. Worth a try I suppose,

[Ben Charles]

Could be something up with bank 1 and you’ve been focusing on bank 2....

[dertobi]

had this issue on a customers car here in germany too, exactly the same issue after header install.
the O2 sensor was located too far from the engine, causing the sensor not to heat up correctly and reading lean, when car was driven "properly" all was fine
final soution was to relocate the sensor closer to the engine.

[Ben Charles]

On any header install transport delay should be modded to allow the ECM to know the sensor is further downstream!

Ok boost setups it’s not as bad typically, but NA needs it

[Cobradoc]

On any header install transport delay should be modded to allow the ECM to know the sensor is further downstream!

Ok boost setups it?s not as bad typically, but NA needs it

Using factory exhaust manifold setup. Moved O2 Sensor closer to engine, no change. Pulled 30% and left bank followed right bank stayed and ran like crap. Still plugging away.

[Cobradoc]

Well spent some time with this today. If I turn LTFT off via the scanner and zero them all is well. Tuned within 3% across the board. I have not figured out how to turn off LTFT in the tune.

[Ben Charles]

Set disable temp to 284 coolant temp and set map to 255

[Cobradoc]

Tuned like a champ with LTFT off. Made 706/757 on 14lbs. Drives great.

[Ben Charles]

Cool

[BDPhoto519]

On any header install transport delay should be modded to allow the ECM to know the sensor is further downstream!

Ok boost setups it’s not as bad typically, but NA needs it

Can you elaborate on this a little. I cant find a "transport delay" table and I would like to play with this a little on my setup. I have played with the Proportional & Integral delay before with varying success, but ultimately went back to factory settings.

Thanks