poor acceleration

[Christian Steffen]

Yup one to one oem. How ever when i unplug maf the issue goes away. So im thinking it may just be the downstream 02s

Downstream o2s just check that the cats are working, if the issue went away when you unplugged the MAF then something is going on with that. Unplugging the MAF forces the computer into speed density mode.

 

[stutaeng]

Wait, how do you know it's lean "only" when it happens?

Do you what your fuel trims are?

I had a P0174 lean code on bank 2 for a long time. Checked all over for vacuum leaks, but never found any. SES light on dash came and went, but code was always stored.

Finally got a scanner with live data and showed fuel trim stayed around +25% along I crease of RPM. I now suspected injector issue and did a injector balance test and revealed sticky #6 injector.

I swapped the spider injectors and have driven it a bit and fuel trims are now negative, meaning ECU is self correcting.

If lean code is only on one bank, then likely not fuel delivery, as that would affect both banks. Check for vacuum leaks or injectors.

 

[[email protected]]

I had the same issue after replacing heads and head gaskets. One of my catalytic converters were clogged. Replaced it and was back around 85% but still noticeable. Like you I was getting codes when I jumped on it a bit. After chasing it down I realized my spider was bad. One cylinder popper was leaking and others on the same bank were running lean so it fooled the O2 sensors. After I replaced it, I am back to full power and crisp throttle. No more codes

 

[seth9199]

So it seems like its either getting too much fuel or not enough after pushing it i lock into first when it starts acting up and rev up and itll act normal again. Could a sensor cause the engine to not work right at temperature? Or after working hard. Or even the spider injectors?