Fuel trim help

[Bry1234]

Been there, hence if there is a air leak I can’t find it, the intake on these, bolts in vertically and there is a 2 parter to it where it comes apart in half. Which also sits vertically. I’m running out of cans of brake cleaner and carb cleaner, lol

 

[incognito_2u]

Been there, hence if there is a air leak I can’t find it, the intake on these, bolts in vertically and there is a 2 parter to it where it comes apart in half. Which also sits vertically. I’m running out of cans of brake cleaner and carb cleaner, lol

And just to confirm, no codes?

 

[Bry1234]

No codes

 

[fitrucker]

How did you reset fuel trims?

 

[Bry1234]

Unplug maf sensor, start car for 5 second, turn off car. plug maf sensor back in, clear maf code. Start car and voila.

 

[fitrucker]

You might have a few bad injectors. You should start over with a compression and leak down test.

 

[fitrucker]

Unplug maf sensor, start car for 5 second, turn off car. plug maf sensor back in, clear maf code. Start car and voila.

Erase code by battery disconnect or by scanner clearing codes. I do it once a year with my scanner. Did you change oil. Last oil change at dealer made my fuel trims go all over the place.

 

[Bry1234]

I was hoping it was not injectors, whole intake has to come off for that, possibly too much fuel pressure as well I guess which would be easier to test first.

 

[Bry1234]

I was hoping it was not injectors, whole intake has to come off for that, possibly too much fuel pressure as well I guess which would be easier to test first.

Oil is only 1000km on it, however it has a reddish hue to it which googling it appears to be a normal thing,

 

[Bry1234]

1

 

[incognito_2u]

No code

Oil is only 1000km on it, however it has a reddish hue to it which googling it appears to be a normal thing,

Does the Oil smell of gasoline?

 

[SC Maintenance]

Im unable to record, so as it stands, Ltft is -5% and stft is -12% at idle and at 1500 rpm’s ltft is 0 and stft is -18%. Upstream 02 sensor is oscillating normally from .03 volts to .88 I put a new one in, and down stream 02sensor is at 0.16volts constant.

LTFT at -5% is well within normal range.

STFT data is meaningless data. The fact that its moving all over the place means its working.

Also, the negative LTFT means the ECU is taking fuel away hence It can't be a vacuum leak. Vacuum leaks add unmetered air into the system, so you would be running lean, and the LTFT would add fuel by going positive - ie your fuel trim would be +10% or whatever.

+/-5% LTFT is what you want.

 

[Bry1234]

LTFT at -5% is well within normal range.

STFT data is meaningless data. The fact that its moving all over the place means its working.

Also, the negative LTFT means the ECU is taking fuel away hence It can't be a vacuum leak. Vacuum leaks add unmetered air into the system, so you would be running lean, and the LTFT would add fuel by going positive - ie your fuel trim would be +10% or whatever.

+/-5% LTFT is what you want.

Ok, great. It could have been a lazy 02 sensor as once I changed it today , Ltft went from - 12 to -5%

 

[Bry1234]

Also side note I picked up a Bosch 02sensor and the 02 sensor special socket doesn’t work with it, as Bosch makes the belly of it wider. Facepalm, won’t be buying a Bosch again.

 

[Bry1234]

Does the Oil smell of gasoline?

It does not, however if the bad 02 sensor was causing a rich condition it could have degraded my oil

 

[Lubener]

Hello all, nissan 06 xtrail 2.5l. Trying to figure out a issue with these fuel trims at idle.
Ltft -10%Stft +8 to+13% with a short blip every 10 or so seconds of -100%. Upstream 02 sensor oscillates but hangs out more in low voltages even going below .1 volt to .04 volts. Thoughts?
Symptoms are hard start when cold- 20 and pinging from engine when cold while driving until it warms up a little.

Don't overlook low fuel pressure.

 

[SC Maintenance]

Don't overlook low fuel pressure.

His fuel trims were taking fuel away (negative). If fuel pressure was low I would expect it to be running lean, hence he would have a positive LTFT to add fuel - longer pulse width. I think his issue is sticky or clogged injectors, or a bad sensor somewhere.

 

[fitrucker]

Having fuel trims of 18 percent is still a problem even though its better than your first post. I still think you could clear the codes which is stored in the pcm and not ecu. Two different computers. It makes the pcm use ecu values to rebuild the random access memory. EGR valve is probably the issue or bad injector. I did say it could be a lot of things.

 

[Bry1234]

No egr in this vehicle. Wouldn’t resetting the fuel trims be the same.

 

[fitrucker]

So its a vvt. Which acts like a egr. Does your scanner read both banks separately? You don't want to clear learned memory and I would agree if there was a code to a point. Fuel trims are o2 readings. You have a MAF along with speed density. I would clean the vvt solenoid. Its sounds like its stuck in a retard position. Which adds fuel when you don't need it and the pcm is trying to take it out. Your fuel trims should add up +-10 percent.

18 percent means it operating at a 12 to 1 fuel air instead of 14.7.