Logic Question

[eboggs_jkvl]

LTFT on bank 1 is +25. The other bank 2, is -2

Does this signify a probable bad O2 sensor on bank 1? Possibly an injector on full gush?


Car mileage has gone down the crapper.



Elmer

[joecar]

Hi Elmer,

Bank1 LTFT at +25% indicates the ECM is adding fuel to bank1... the reason the ECM would do this is because it sees the B1S1 O2 sensor indicating lean...

the lean condition may be caused by:
- air leak in exhaust header,
- air leak at intake manifold,
- one or more injectors clogged,
- there may be other reasons.

[eboggs_jkvl]

Darn, I was hoping for an O2 sensor!

OK, When I get up to Ohio (and the car) I'll check into those situations and see if I can find the problem.

Thanks,

Elmer

[redhardsupra]

If +25 is lean, then you're either talking about a massive air leak, or the injector is dead/disconnected.

[eboggs_jkvl]

Well, I'm working remote right now. There was a large leak in the bottom plate on the intake manifold (weiand polished aluminum) that my son said he fixed by taking off the intake and sealing the plate (loose bolts). He used a gasket sealer and reafixed the bolts with locktite. I will run a scan when I get there. He went out and bought HPT for tuning (I recommended a different product) and is relaying to me what he is reading. He hasn't a clue how to tune, like father, like son, but I think we can find an air leak on the manifold or a dead injector. The car has been sitting in the garage for the winter and an injector might be plugged. He didn't want to take the car out in the snow and salt of Ohio's winter.

I'm going up there on July the 2nd and we'll dig into the car when I get there.

Elmer

[swingtan]

I saw something like this a couple of weeks back and it was the O2 sensor. When logging, log the O2 sensor voltages and put the car in CL. If the sensor is bad, you wont see it the voltages swinging back and forth. Another test is to bleed some additional fuel into the intake ( LPG or gas lighter refueling bottle ) and see if the O2's go rich.

Simon.

[eboggs_jkvl]

I saw something like this a couple of weeks back and it was the O2 sensor. When logging, log the O2 sensor voltages and put the car in CL. If the sensor is bad, you wont see it the voltages swinging back and forth. Another test is to bleed some additional fuel into the intake ( LPG or gas lighter refueling bottle ) and see if the O2's go rich.

Simon.

Thanks for the info. I planned on monitoring the O2s, the bank1 injectors & fuel trims. Something will look butt ugly and give us a clue as to the culprit.

[5.7ute]

The first thing I always do is swap the O2 sensors between banks & see if the problem follows the sensor. Takes a heap of guesswork out.

[eboggs_jkvl]

The first thing I always do is swap the O2 sensors between banks & see if the problem follows the sensor. Takes a heap of guesswork out.

Well, the turbos make even touching the O2 sensor an exercise in total agility and frustration. If they're switching, I'll give them a pass as the first thing to change.