New to tuning need help, car misses and fuel trims dont match. please look at log

[spencer28]

85 monte carlo, 05 5.3, 706 heads, fuel pressure 45psi, 80lb simens deka injectors, stock coils, stock pcm, on3 78mm turbo, has a miss and i can not figure out why, was wondering if someone could look through my tune and log with some answers??? my fuel trims are looking goofy but i have no idea what im looking at, completely new to this. i would really appreciate the help thanksSpencer good tune 1.hpttest drive down 14.hplAttachment 51941

[2xLS1]

MAF is not failed. Correct that first.

[mowton]

Remove MAF, LTFT's, single bar MAP, misfire rpm from your PID table list and add Dynamic airflow. Why is there no vehicle speed?

Ed M

[spencer28]

No vehicle speed due to the th400 tranny with no speed sensor hooked up

Thank you for your response

[mowton]

What are you using to tune the VE, hopefully not the AFR err PID because that is merely telling you how close your wb is to the commanded, not the actual error. The short term trims tell you the error so you should be logging them to correct the VE, are you?

Ed M

[spencer28]

Yes I was using the 7 screen in the histogram to tune the VE table by multiplying the data by %

[mowton]

Yes I was using the 7 screen in the histogram to tune the VE table by multiplying the data by %

Then why do you think the trims are still 10-20% off....did you reset the trim each time before logging?

Ed M

[spencer28]

Yes, I just don't know if there suppose to be both around the same number, I figured so but not sure, I'm new to this whole thing. This is the first motor Iv tried to tune. Still kinda lost but getting there. I believe I may have a bad coil after doing some more reading of symptoms, going to test them tomorrow morning and see if that is the cause of my misfire

[mowton]

Yes, I just don't know if there suppose to be both around the same number, I figured so but not sure, I'm new to this whole thing. This is the first motor Iv tried to tune. Still kinda lost but getting there. I believe I may have a bad coil after doing some more reading of symptoms, going to test them tomorrow morning and see if that is the cause of my misfire

I didnt see any misfire counts on the misfire PID in the log you provided?The check engine light should flash if the misfires are bad enough. still wonder why the trims are so far off.

Ed M

[spencer28]

just read Speed Density Tuning using Wideband O2 Input by William Henn, 'foff667' , made all the changes he says to make,there was a few values in my tune not corresponding to what he said, i made those changes and am going to take it for a drive tomorrow, will let you know the outcome

thank you for all your input

[THE CHAD]

I didnt see any misfire counts on the misfire PID in the log you provided?The check engine light should flash if the misfires are bad enough. still wonder why the trims are so far off.
Mowton, mate don't want to hijack this post but with tuning the VE with STFT do you disable/turn off DFCO while tuning or leave them as is cheers Bret@ultimatelsxtuning
Ed M

[THE CHAD]

Mowton, mate don't want to hijack this post but with tuning the VE through STFT do you disable/turn off DFCO while tuning it or leave it as is cheers Bret@ultimatelsxtuning

[mowton]

Mowton, mate don't want to hijack this post but with tuning the VE through STFT do you disable/turn off DFCO while tuning it or leave it as is cheers Bret@ultimatelsxtuning

Hey Bret, I either disable it or use a map and tps% filter like 40 kPa and +2% above idle TPS%.

Ed M

[spencer28]

Also when I rev it up and the rpm comes back down it does not catch it, it just dies, target rpm is set at 1000

[THE CHAD]

cheers Ed M appreciate it mate..Bret

[spencer28]

Problem solved, 2 plug wires melted inside the sleeves. Car runs great now

[mowton]

Problem solved, 2 plug wires melted inside the sleeves. Car runs great now

Great to hear you got it solved. When we were tuning a clients car in Norway, the same situation arose. Popping in the the exhaust was another one of his symptoms. Wonder why the misfire didn't show up?

As I always say, another one to add to the "little black book of tuning" I keep.

Cheers

Ed M