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High Idle Fuel Trim


Tehnation

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I hope its this as well, have school and work atm, waiting for the weekend to get back under car. lets recap

 

-horrible gas mileage

-lv says fuel trim is lean, or is dumping lots of fuel rather to compensate for higher air readings/leak.

-tested for leaks found and fixed them all.

-cleaned maf sensor with maf cleaner

 

Car still runs strong, so I guess if I change it and it fixes it, those listed above would be how to spot a bad front O2 sensor.

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  • 2 weeks later...

Rear o2 does nothing but verify that your cat-converter works.

 

I just got tuned and I have something fishy with my LV is near pegged at -15 in A cell.

 

I replaced my o2 sensor a few months ago and cleaned maf before tune.

 

Thinking I have a defective o2 sensor.

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I'm fighting with this at the moment also. No other symptoms that I can discern other than the high idle fuel trim in cell A. I had a leak at the BPV, but believe it's fixed now and it still seems to be having the same issue. PITA.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Rear o2 does have an effect on fueling.

 

http://www.romraider.com/forum/viewtopic.php?f=15&t=3588

 

I found this out after thinking I could use the rear o2 bung for my wideband since I don't have a cat. I soon realized with my newly installed wideband that my AFRs were way richer than the 14.7 it should be in closed loop. Live and learn I guess. Out came the DP and in went a new bung for the wideband.

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I'm away on vacation, so I wont be able to take the car out until next monday, hopefully when I get back and drive it for 15 minutes I will have a proper lv.

 

I was under the same assumption that the rear o2 did nothing, but I had a brand new one laying around so I thought it cant hurt. Normally my idle trim shoots up to 15 without even having to move the car, but its just sitting at 3 for now.

 

Hopefully this solves everything because I know a lot of people are having this issue. I'm sure pretty sure most people on this forum state that the rear o2 does not effect fuel trim so this will be a good test.

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I was getting a p0171 i believe, whichever is for running lean. My gas mileage is absolute garbage, and my sensors where blackened, I dont even know where to begin with this nightmare. Are you guys having these same symptoms?
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  • 2 weeks later...

WTF I fixed a leaking uppipe/exhaust manifold gasket. Got my boost back on track and then a couple hours later its got no power under boost...... and I have a misfire cylinder 3 memorized code....

 

could it be that my tgv gaskets are getting worse or is this an entirely different problem. Any ideas?

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FWIW, my high idle fuel trim seems to be fixed. The culprit ended up being an aftermarket panel filter that didn't seem to allow the airbox to seal completely. Odd since it's pre-MAF and since I've used the same filter previously for thousands of miles.

 

Anyway, nothing else made a difference and going back to a stock paper filter definitely fixes the issue.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Changed both tgv gaskets and spark plugs. Now my idle trim shoots to 15 right away after ecu reset before it took some time ..... sigh. I have no idea whats going on at this point. Now im guessing turbo maybe intercooler. Im pretty close to throwing a wrench through my windshield.....
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After some research it may be my fuel injectors, guess its time to go big.

http://www.romraider.com/forum/viewtopic.php?f=33&t=7202

 

From reading that article, I gathered that if it only effects idle or AF Learning #1 A then it may not be a leak. So i'll just keep saving and buying better parts until it goes away... not such a bad strategy. For now i'm going to get the dw 65cc fuel pump and 740 or 850cc fuel injectors for possibility of e85. If that doesnt fix it then I'll change turbo to something like a td06 20g.

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Going to go to junkyard and get a set for about 100 bucks, swap mine out for those to see if anything changes, and while I have the junkyard set in I will send my current injectors away to get cleaned and modded. That way no downtime, I'll have 2 sets of injectors and it will only cost me around 325 , 100 for used injectors and 200 for them to be modded and cleaned and 25 for shipping or less.
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