struggling with a heads/cam 5.3

[2000_SS]

i have a 3rd gen camaro i'm working on and it's been nothing but trouble from the start. I have it where it won't die at idle, but it is surging very badly, but consistently. It has chinese 80# injectors in it and i think that could be the root of the problem. I've had a hell of a time getting fueling correct, and it still is nowhere near correct. i started tuning the MAF and it was running at .75 lambda all the time. i took 25-30% out of the entire MAF table several times. Now, it shows rich as before, but randomly shoots up to 1.09 lambda when driving, but still runs around .75-.79. i questioned my wideband, but tuned a bolt on 6.0 truck yesterday and it was perfect.

this car had some kind of mail order tune in it already i believe and was set up for a 5.7. i've tried getting it right for the 5.3 but i'm starting to think there's a mechanical or wiring issue. It had a ported and epoxied throttle body that was causing major issues. i got rid of that and it runs a LOT better. I will say my current tune is a little on the hacked up side as i obviously dont have data for chinese 80's and it's currently in SD mode because i was starting the think the MAF was jacked up, even though it seemed to read as it should. Anybody got any suggestions or see any major issues? i've attached the current tune and an idle log. i ususally dont have this much trouble tuning a heads/cam car, but i also usually have good injectors in it, so i'm curious is that's my problem here...$200 ebay 80's. TIA

[2000_SS]

ok update...


I got sick of screwing with it. i threw in a set of LS6 injectors i had laying around. I pulled up a stock 5.3 file i already had licensed and make a startup tune and it runs the best it ever has. the NEW problem is the speedo isn't working. It has a T56 behind it and i cannot find a manual trans OS with the same OS id i have, which is 12208322. The car gets going down the road the just cuts power & spark. i'm looking into why now, hoping it isn't related to the transmission....Here's what i have now:

[2000_SS]

another drive log....it's just killing spark and i can't figure out why. is it related to the trans segment needing swapped?

[5FDP]

Try doing a segment swap with a 2001 Chevy Blazer, there is one in the tune repository with a manual transmission and same OS.

[2000_SS]

I totally forgot to look for one of those...i just kept searching for a 4.8 or 5.3 manual file.

Thanks man, i'll try that

[2000_SS]

did the segment swap, still cuts spark for a reason i cannot yet identify. here's a log. Jump to about 2:21 and you see a good example of what it's doing. i made a WOT attempt in my driveway heading towards my shop and it just gives it 0 degrees until i lift off the throttle. it does it other places in the log, but that's the best example i think.

[2000_SS]

ok now that i actually looked at the spark table, it's getting timing from there as commanded. When i give it much throttle, it shoots up to .7g cylinder airmass at only 1100-1300rpm or so...

So what's that mean? Massive vacuum leak? i guess i'll start picking over the engine tomorrow...i hate working on stuff other people built

[2000_SS]

I did a visual inspection of the engine compartment and sprayed all around the hoses and intake with starting fluid to no avail. I can't see or find anything that looks like a vacuum leak.

The engine has a fairly large cam and PRC heads with a LS1/LS6 intake....could it really be consuming that much air at such light loads/rpm? I can't really see that being the case. Is it somehow a scaling issue? i flashed a 5.3 file/OS, so i can't see that being the case either. What would cause it to think it's consuming .79g at just ~1200rpm with a stab of the throttle? When it does that, it jumps to the appropriate cell in the spark table, which is 0, and basically feels like somebody stuck the clutch in. It doesn't appear to defuel, but the engine just stops accelerating until you lift off the throttle. It will accelerate up to a reasonable speed, but you can't go over ~10-20% throttle because it will jump to the lower region of the spark table and cut out. I haven't let the car see much RPM as i've just started tuning it.

[2000_SS]

should i just "shift" the spark table over so it gets ample spark at low engine speed with a load? Maybe paste in a LS1 spark table and tune from there? i feel like i'm covering up a real issue, but i've never tuned this combo before, so i don't know what to expect for airmass values.

[dermotw]

That spark table is way off imho... As you say, just get e.g. 2000 LS1 table(s) and dump them in to begin with, including the idle ones... heres a comparison between a standard '99 firebird and your hi table;

Capture.JPG

Eek! Big differences!

Plus, here's me 'tapping' the throttle in neutral... so yes, it can report .79g...

Capture.JPG


-D

[2000_SS]

Updated spark table and it didn't change anything, it still behaves as it did in the logs I've posted

[2000_SS]

Ok I've never encountered this before....i noticed it always seemed to be stalling out at around 1600rpm. That was the only half way constant factor. I noticed that Drivetrain Abuse enabled at 1600 rpm...i disabled drivetrain abuse and voila....problem solved.

I've never had to mess with that. What causes the vehicle to enter abuse mode? Why would driving a warmed up car under light throttle cause it to kick in?

[dermotw]

You got me on that one, I don't own an auto, lol... have to wait for someone familiar to answer!

[2000_SS]

It has a T56....the file WAS from an auto, but has been segment swapped