wierd fuel trims at idle

[Fos]

Hy, my stft is showing ~9,5 and my ltft is showing 12,5 at idel (~800 rpm)... Is that normal?
I changed the fuel filter this week.
Im running complete stock setup. (95 talon tsi fwd) 4g63t with T25, 450cc inject. and stock fuel pump and regulator (idle and 0 vac pressures are fine)
No pre turbo leaks that could cause the lean condition.

Are these fuel trims meaning that my ecu is adding + 22% of fuel on ~800 rpm??

 

[olmytsi]

Yeah, your ecu is adding fuel. Something isn't right. Try resetting the ecu, driving for a lil while and seeing where the fuel trims are.

 

[Fos]

what can cause this large need of fuel in in idle? Any ideas? Shouldn't be O2, at least readings are variable, doesn't act like a ded one.

 

[olmytsi]

No clue but i would reset the ecu (disconnect the battery) and see if it occurs again .

 

[WFO-TSi]

You mentioned you have no "Pre turbo boost leaks." Does that mean you have a leak post turbo? I would check once again for leaks, and update your profile so I can tell what options you might have for trouble shooting this issue.

If you have the ability to log airflow per revolution I would check that out. You should be getting about .27lbs/min/rev at idle. If it is lower, then you have un-metered air entering the engine thus causing the lean condition that your ECU is trying to correct

Hope that gets you headed in the right direction

 

[Fos]

sorry, I dont know, what is "airflow per revolution" im Estonian, can't understand everything.

I have the abiliti to use obd2 logger "Vehicle explorer" and It shows me
~2.8 gm/s at ~800 rpm. (im not sure they are gm/s, because my logger is set on SI(metric), not english.

when I set to English, it shows ~0,8 gm/s at 800 rpm

HOPE you understand.


I did reset my ecu, and it learned pretty fast that on idle it needed about +17% stft.

Allso got this kinky problem yesterday that got me worried, my exhaust started to smoke protty nasty and water is purging out when i press gas. The colour of the smoke is hard to tell , but it doesn't smell like oil burning... no shaftplay in turbo allso. No oil in coolant or no coolant in oil.Sparks are not wet. Could it be related to the extra 17% fuel?

I'm not sure that i dont have pre turbo leaks, did a leak test a long time ago... will do it again tomorrow.
What can you say about the smoking thing?

 

[olmytsi]

Your english is very good!

If the car is smoking, the first thing i would do is a compression test. After that, i would check the turbo. But that really shouldn't explain the fuel trims. I really don't know what it could be.

Good luck.

PS: try replacing the fuel filter and checking the fuel pump as well as the injectors.

 

[Fos]

Your english is very good!

If the car is smoking, the first thing i would do is a compression test. After that, i would check the turbo. But that really shouldn't explain the fuel trims. I really don't know what it could be.

Good luck.

PS: try replacing the fuel filter and checking the fuel pump as well as the injectors.

I did a compression test just about 2-3 weeks ago. It was 180 psi across the table with a cold engine! Checked the turbo for shaftplay... would say less than 0.5 mm axial play. allmost cant feel with bear fingers. I replaced my fuel filter 4 days ago and i dont really think my pump is dead because the fuel pressures are just fine.43psi, 34psi, 60psi (I have a fuel pressure gauge installed)

 

[Fos]

Problem solved boost leaks test helped me.

Cause: post turbo - pre throttle body leak. Broken clamp. Unmeterd air enterd the engine and caused the lean condition witch was registred by lambda witch orderd the ECU to increase fuel trims.

PS! the smokeing allso went away, so it probably was smoke of unburned fuel. Though the "water" that came out the exhaust had no smell or taste. Probably becouse I still have the cat. Working on new "straight out" exhaust right now.

Thanks for all the replys.

 

[olmytsi]

Niiiiiiiiiiice!