4runner running strange/Where to start?

[phattyduck]

Tonight, I let it warm up good and the STFT went to 19.5 again. So, is 19.5 normal for idle or are we pretty sure that is jacked up? Thanks.

That trim is probably reported in %, so no, not normal. And that's probably the max adjustment that the ECU can do, since it is reporting Bank Lean too, right? (it is adding 19.5% fuel and still reading lean, if we believe the STFT and Lean code)

I haven't seen any fuel trims bigger than 3 either way on my '99...

Dirty MAF? Leaking/cracked exhaust before the O2 sensor?

-Charlie

 

[68ChargerJMP]

That trim is probably reported in %, so no, not normal. And that's probably the max adjustment that the ECU can do, since it is reporting Bank Lean too, right? (it is adding 19.5% fuel and still reading lean, if we believe the STFT and Lean code)

I haven't seen any fuel trims bigger than 3 either way on my '99...

Dirty MAF? Leaking/cracked exhaust before the O2 sensor?

-Charlie

I've cleaned it multiple times, its definitely not dirty. I swapped several maf sensors in and out, no difference. No exhaust leaks. No vacuum leaks I can find. My torque app says stft at 19.5, my friends Snap On Modis scanner says stft at 0 but ltft at 29.5???

I'm too busy at the moment to keep digging into this thing. Not to mention, it's my only ride right now. I do all of my own work and all, but I cant keep throwing good money after bad to find a fix. Is there any specific diagnostic test I can request at a dealership or a tuner around town to narrow this down a little? I'm thinking of selling it, so I can fund a little build on my other 97, but I don't want to try to sell it if its not running like it should. Thanks guys.

 

[68ChargerJMP]

I was running the torque app this morning and the sftt and fuel trim bank 1 sensor 1 were both at 19.5 at idle. At cruise, they were anywhere from -10 to +10

I was searching for similar issues and ran across the ect sensor as a possible culprit. Sound plausible?

 

[phattyduck]

I was running the torque app this morning and the sftt and fuel trim bank 1 sensor 1 were both at 19.5 at idle. At cruise, they were anywhere from -10 to +10

I was searching for similar issues and ran across the ect sensor as a possible culprit. Sound plausible?

That would explain the erratic temp readings via OBD-II...

-Charlie

 

[68ChargerJMP]

Well, it dawned on me that I have left out an important piece of information about my issue. I had swapped out the old style MAF for a 99+ style MAF last year or so ago. It ran fine until recently, so I didn't think much about that. Well, I swapped the old style back in and Voila!, idle cleared up instantly. Runs much better. I have a little boost/vacuum leak between the throttle body and IAC, which I think may be contributing to my other symptoms. I'm going to try to carefully seal it up one day this week. Thanks for the replies.

 

[phattyduck]

MAF sensors are pretty sensitive to placement, leaks, etc. Also, re-check the wiring (they have different plug styles, right?) - if you had a bad connection or two that would also contribute to the problem.

Sounds like you are on the right path though.

-Charlie