Help needed
Thread Starter
Instructor
Joined: Nov 2011
Posts: 135
Likes: 0
From: toronto ontario
Help needed
Hi fellas, I have a question for you fellas with tuning experience who can help me with a issue I have with my 02 zo6. It has a ls3 now with a very street able comp cam and street tuned. Everything else is stock. I recently bought a scanner to the check sensors and found the LT FTRM1 (%) @ 2.3 @ idle and drops to 0.0 with light throttle, the LT FTRM2 (%) @ 0.0
ST FTRM1 (%) @ -2.3
ST FTRM2 (%) @ 0.8
ST FTRM11 (%) @ -2.3
ST FTRM21 (%) @ 0.0
Upstream o2 sensors switching between 100-800v normally.
Downstream 02's stay around mid to high 700's and steady.
Now for my question. Does the LT FTRM1 (%) indicate a rich condition ? If so where ?
I've checked for vacuum leaks but found nune. I'm leaning more towards a bad injector.
ST FTRM1 (%) @ -2.3
ST FTRM2 (%) @ 0.8
ST FTRM11 (%) @ -2.3
ST FTRM21 (%) @ 0.0
Upstream o2 sensors switching between 100-800v normally.
Downstream 02's stay around mid to high 700's and steady.
Now for my question. Does the LT FTRM1 (%) indicate a rich condition ? If so where ?
I've checked for vacuum leaks but found nune. I'm leaning more towards a bad injector.
Last edited by triple black vette; Dec 19, 2015 at 10:54 AM. Reason: Error
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Never worry about or even log the STFT's as they are no help in tuning-----Only the LTFT's should be of any concern-----As Ron said any LTFT that is below = or- 5% is of NO concern----as your ECM has the ability to eventually "learn out" these fuel trims and finally settle at "0"
FYI a positive LTFT fuel trim at P/T means the ECM is adding fuel for a LEAN condition
a negative LTFT fuel trim at P/T means the ECM is removing fuel for a RICH
condition
AT WOT the 02's are NOT being used--HOWEVER if you have a positive LTFT at P/T that same % is also added at WOT as a lean safety and can make your WOT rich
BUT if you have a negative LTFT at P/T the ECM will NEVER remove fuel at WOT and locks on "0" again as a lean safety
FYI a positive LTFT fuel trim at P/T means the ECM is adding fuel for a LEAN condition
a negative LTFT fuel trim at P/T means the ECM is removing fuel for a RICH
condition
AT WOT the 02's are NOT being used--HOWEVER if you have a positive LTFT at P/T that same % is also added at WOT as a lean safety and can make your WOT rich
BUT if you have a negative LTFT at P/T the ECM will NEVER remove fuel at WOT and locks on "0" again as a lean safety
