LQ9 Swap S10 Pulls Timing at Random

[Slow94Formula]

The motor in this truck is all stock right out of an escalade. Has a 5.3 pcm that I put a stock tune from an escalade in. If I remember correctly the only changes that were made compared to stock were shift pressures and torque management. The first day I flashed the tune into the vehicle it ran great. No issues. Now when the engine has a load on it it seems to just randomly pull timing all the way down to 6* at times and runs like garbage. I improved on this by changing the timing table where it starts to taper off (towards negative numbers) in the higher cylinder mass cells to a flat number. Even after doing this it still pulls timing.

I used the scanner to fix timing to 17* and see what it did at one point. When I did that the timing stayed constant and the truck seemed to run better than before, but still seems to pop and miss (no misfires scanned) at WOT. Any tips on where to start looking to take care of this? I'll attach the tune... I know it's a pain to look through an entire tune to find a problem, but if someone has an idea and can check it out it would be appreciated.

[Ranger6202]

post a scan so we know what you're watching and what you possibly should add to your watching. ;-)

[Hotwire]

If your S10 is like mine, you have an open air filter on the end of a tube.. The engine bay gets hot, especially with uncoated headers. Watch your IAT, again if like mine, the high incoming air temps are what's causing the ecm to pull timing. I'm working on closing the air filter off so it pulls in fresh air from outside the engine bay.

[gagliano7]

Make sure you check your fuel pressure. I swapped a 5.3 in a 1992 chevy pickup. Truck would idle great and part throttle was good but WOT was bad. I found I only had 20 psi. My hose came loose on my fuel pump in the tank. Fixed 3 years ago and been great ever since.

[Slow94Formula]

Thanks for the replies guys. I should have thought to share a log... so here it is.
Config for Josh.cfg
s10 1054.hpl

I did change the IAT timing table so it doesn't pull timing until 104* and like I said in the original post I was able to lock timing at 17*. While that improved the way it felt (and timing did not fluctuate) it still felt like it was missing.

The owner says he checked fuel pressure and it stayed right around 60 psi.

[Ranger6202]

First thing i noticed right away is that your LTFT's are pretty high. Adding 5-10% fuel...you're initially running lean. And your ECT is pretty high and that it is pulling timing too, as much as 220°F.

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[Slow94Formula]

Sorry I haven't been good about responding in here. Been busy finishing up classes the last couple weeks.

I did know about the numbers in the ECT table, but was leaving it just for a little extra cushion in the timing. I adjusted the IAT timing because that was interfering as well. The ECT table still doesn't account for why the computer is pulling timing down to 8* from the main spark table that is telling it to run 17* though. So, what else is missing? Will the fuel trims trigger a timing retard?

[Slow94Formula]

Another dumb question: I'm used to tuning with a wideband in speed density on my car, and was going to switch this pcm over to 1 bar speed density, but it appears that a custom OS isn't an option for this computer. Is that possible or am I missing something there? Also, if this person doesn't want to buy a wideband am I able to tune based off of fuel trims rather than using a wideband?

Thanks for the help guys. It is appreciated!

[jimmyblue]

For intermittent problems, look at the connections to the sensors
on the motor. I found a bad ECT sensor once which would really
jack the truck around, similar to what you describe. Affects the
timing and the enrichment, puts it in and out of closed loop, etc.
If you can get it to happen frequently then start logging raw
sensor voltages / values, and look for any unusual activity that
seems coincident.

If timing is jumping a lot, try logging all of the "contributors"
of which there are many in the retard and advance adders.
Some will stand out and maybe you will see one that's not
supposed to be so busy, which will lead you somewhere.