Fuel trim question

[TalonTSi-AWD91]

I just got a datalogger a couple weeks ago, and ever since I've had it all three of my fuel trims have not moved from 98.8. The o2 voltage is ok and the o2ft is fine also. What could cause the fuel trims to stay at 98.8? I've changed the boost anywhere from 8psi to 14psi and the fuel trims still don't change at all. Only mods I've done so far are intercooler pipes and a K&N air filter.

 

[Green93TalonTSi]

the ideal range is 90%-110% , so ur in the range where the car should be running pretty damn good. My fuel trims on the other hand are pig ass rich, at like 81% and 86% , my low fuel trim is at 117% wich is good. So i wouldnt really have a conern with a 98.8% fuel trims, i wish I had those, and mayb then I could get some decent gas mileage and pick up some more power. But I woldnt worry bout those fuel trims, seems pretty good to me.

 

[90AWDTalon]

Originally posted by TalonTSi-AWD91
I just got a datalogger a couple weeks ago, and ever since I've had it all three of my fuel trims have not moved from 98.8. The o2 voltage is ok and the o2ft is fine also. What could cause the fuel trims to stay at 98.8? I've changed the boost anywhere from 8psi to 14psi and the fuel trims still don't change at all. Only mods I've done so far are intercooler pipes and a K&N air filter.

Is your o2trim cycleing, if so I would be happy with what your getting. Mine are much uglier, my low trim changes from 96 - 118, my mid wont change from 83 no mater what I do, the o2 trim is pegged at 199 when i'm between 2k and 2.5k, its trying to lean the mid out but it wont for some reason. My high trim is 108, I'm pretty happy with this value.

 

[90AWDTalon]

Originally posted by 90AWDTalon


Is your o2trim cycleing, if so I would be happy with what your getting. Mine are much uglier, my low trim changes from 96 - 118, my mid wont change from 83 no mater what I do, the o2 trim is pegged at 199 when i'm between 2k and 2.5k, its trying to lean the mid out but it wont for some reason. My high trim is 108, I'm pretty happy with this value.

Also, changing your boost wont affect your trims. These are for part throttle crusing and idle. Full throttle is completly seperate.

 

[TalonTSi-AWD91]

The o2 trim is ok. I was just wondering since it's always been exactly 98.8 and not one of the three have ever changed at all. I thought it was supposed to change at least a little.

 

[Bohrn]

It will only change if you do something to make it change.

IE; safc tuning, hacking maf, different injectors, more fuel pressure etc.

Yours are a bit rich for my liking. If you were able to lean out your low and mid fuel trims to around 120% or so you would see a large increase in fuel economy.

You could do some minor porting of your mas airflow sensor if you don't have an safc, or you could go nuts if you do.

I'd suggest at least to remove the lower honeycomb and back out the screw on the bottom so it is flush. this will allow more air to flow here, leaning you out and getting better mileage. Also it will delay the onset of fuel cut. Both good

 

[98eclipseRS]

sorry to hijack your thread/ bring it back from the dead but i just checked a logged run that i had the other day and i have a few questions for you all who helped him. first off my o2 readings stay at 4.98v the whole time next my fuel trims seem to be a bit high my low is at 121.8% mid at 137.5% and high at 118.7% they didn't change throughout the whole run(1st through top of 3rd gear) is this normal for my car to be running like this. once againg sorry to hijack your thread.
-zach-

 

[nine5raptor]

do you have a wideband??

if not, then 02 voltage is between 0.00 and 1.00

4.98v would suggest a wiring problem.

 

[98eclipseRS]

no i don't have a wideband and thats what is strange to me. My o2 sensor is dyig don't know if that has anything to do with it. I will be getting another one soon.

 

[Bohrn]

get the O2 changed and then drive it for a while.

See what readings you are getting then and post back.

If all was good now, all you'd have to do is add a bit of fuel. Not too much. Infact I like to run a bit lean on my low and a wee bit lean on my mids. It promotes good mileage.