30TH_TA

My car has been running really rich. After I drive for about 30 minutes, my back bumper has black **** ALL over it. I got AutoTap and a MAFT and have been doing some logging. In Autotap are you supposed to average the LTFT's in fuel trim cells 1-19? That's what I have done, and they are at -2. Some of the cells are as low as -12 and some as high as 12. Is this normal to have such variations? Please let me know, so that I can get rid of this black ****.

Also, is it possible to have close to zero LTFT's and be really rich at WOT. Since my LTFT's were so close to zero, I can't figure out exactly what the black stuff is from?

Thanks

30TH_TA

Just to add on:
One place I read to average cells 1-19 and when I do that my ltft's are at -2. Pretty good.

However, another place I read to average cells 17-20. When I average these cells my ltft's are -10. This is a big difference, so I need to know which ones to go by.

30TH_TA

One last thing that I forgot to mention is that my WOT readings were as follows:

O2 Voltage - average of 941 mV (very high)
Knock Retard - None whatsoever
Timing - from 25 to 28

Sorry for all the posts, just trying to figure out what the hell is going on with my car. <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

TaTommyWS6

I usually average cells 6-14.
It seems those cells are used most for "spirited" driving...
Anyway, if you average 1-14, the numbers probably won't be much different.

.941mv seems pretty high, but I would not worry about that until you het the LTFTs in check..

Good luck!

Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

J&JsTA

I just did some extensive LTFT logging over the past 2 weeks with EFIlive and I am showing cells 4-5 being used 75% of the time on the highway while cruising at 65-70 mph with an 02 TA so I would have to include those 2 cells as well for load cells. So I would say 4-14

GrannySShifting

iTrader: (10)

Explain what you uys are averaging i thought LTFT were shown in DOS, as a right and left bank?

Ragtop 99

iTrader: (7)

Jeff:

There are LTRIMS for each bank of cylinders, that is what you are thinking about. If bank 1 is way off from bank 2, you probably have a leak or bad O2 sensor.

LTRIMS exist for each fuel trim cell, and the values will vary accross fuel trim cells. There are about 22 - 24 fuel trim cells for a LS1 PCM. Not all are used in an F-body. The fuel trim cells are selected by the PCM depending upon driving conditions, load, and TPS. Most people ignore fuel trim cells for idle, closed throttle coast down, and WOT and thus analyze cells through 16 (or 19, I've forgotten at the moment where I cut off. <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> ) when exporting the data to excel.