2 bar tune for Turbo LT1 F-body possible with '93 ECM? DA3

[hotrodf1]

Update:
spent most of today trying to figure this out. Still nothing.
The odd thing is: the first time it failed to run, it did start for just a brief couple seconds before shutting down, then won't do much. Get a pop once in a while.
Used the GM service manual to check a few things.
FUEL:
fuel pressure when key is on is 50psi, little high, but that's probably because of the 340lph pump in the tank and stock 5/16" return line.
Have 12 volts at the injector connectors, fuses OK. Also noted blinking test light while cranking, so that system I would say appears to be functioning. Also still think it smells like raw fuel after cranking.
Thought perhaps it was flooded like I said before, but you can't floor it to clear it out, or pull the inj. fuses to clear it either. I pulled a couple plugs as well, and they weren't really wet with fuel, and no fuel poured out of the cylidner or anything.

SPARK:
Using the Scan9495 program, I can see that the opti appears to be giving signals to the ECM.
I checked spark at #2 with a inline spark tester, and can see some light there, so it also appears to be functioning.

Tunes:
I tried the old 1 bar tune that worked well, along with a change to proper injector flow. Still nothing
Tried the old 2 bar tune that worked well, etc., still nothing.

The only thing I can think of is it's in the opti somehow. Not triggering the ECM at the proper time or something. Odd that it would just fail all at once?? Per the scan program it appears to work?


I'm not sure what else to try. The injectors are new in the equation, as is the fuel pump. I can't see how the pump is doing all this. If the injectors decided to all leak or something I guess that could do it? I haven't run the car long at all with the Siemens 60's, but I did drive it for at least 10-15 minutes yesterday morning. So the tune / values etc. were working. A/F wasn't way out of whack either.

UPdate: Swapped in the old 32lb injectors, and known good tune from before, which again produces the same results. ALmost like a carb'd motor that's got the dist. a couple teeth off. Maybe get a partial puff about once per 2 revolutions or so. Not much happening. ALso tried second ECM again, same results there too.

[hotrodf1]

Ok it seems the Opti is not delivering spark the way it should be. New cap and rotor on the way. Gonna try the MSD vented conversion style.

[hotrodf1]

OK, so long story shorter, I guess the cap and rotor was the problem. Why it just failed to start all of a sudden, I'm not really sure. Still running the original GM Opti, but now it's the vented style. Cool. Also added a hotter coil for good measure (MSD 8226 replacement drop in). Was able to jump the spark further on my tester than with the stock coil, so it's actually measurably better. Good deal.

Anyhow, the patch that's in the code doesn't seem to work as intended. It doesn't seem to "set" the baro reading manually as we intended, and the ECM is still updating the baro reading later it seems.

There is a reason I thought it worked before. When I use the unpatched code, it will update the baro setting as usual - and come up with 54-55 kPa or so based on 2 bar MAP. Then I go and use the patched code it will stay that same reading for a while, but at some point just putting around it will update again. I don't know what triggers this, but it throws the tune way out. Like from idling at 13.9 or so to idling at 15.7. Bam, all at once.

TunerPro and Scan9495 both report the ECM sees 10.35kPa as the baro reading at that point. (This was what I was seeing when the car failed to start, which sent me down the path of thinking it was fuel related. THey just HAD to be connected right??? )

The car runs and drives even with the baro set at 10.35, which is surprising to me. But at least it can get home. It's actually not even that lean under boost when this happens, though not where i want to be. But using the patched code, the Baro does not update at key on, so it's kinda stuck at 10.35kPa.

I'm kinda thinking of trying the unpatched code a little more just to see what it does. Is it possible we fixed something that wasn't broke?

Or should I switch to unpatched code (to get back to 55kPa) , then go back to patched and try to see what circumstances are triggering the reset of baro reading? I think perhaps I can datalog for a bit, and should be able to see that in the log. Scan9495 seems to work better on my old laptop than TunerPro for some reason.

[steveo]

too bad that patch didn't work, if i have time i'll look and see what i missed

I'm kinda thinking of trying the unpatched code a little more just to see what it does. Is it possible we fixed something that wasn't broke?

there are always update conditions, and if you meet those conditions in boost somehow, it's going to reset to a false value. you definitely want to disable that routine

[hotrodf1]

Ok, it appears it's finding the right conditions during boost. I've seen it update to 65kPa, and then 69 kPa as well. That makes it like 10:1 rich at 4-5 psi. Still not at WOT. She's moving though. haha.

I figure I better take it easy before I do something I'm going to regret. I guess the next thing is to figure out how to get the baro update solved. I don't get why it updates at all different random times. Sometimes at 0% throttle and coasting down (not sure how else it could read 10.3kPa), and sometimes during boost.

[Xnke]

posts 18-20 explain why this was gonna be an issue, and how it was solved in the P66 code.

[hotrodf1]

Ok, am I reading this right?

A3CF : LDAA $00DA [load accum A] with value in MAP sensor input *****
A3D1 : CMPA $003F [compare A to memory] compare accum A (volts from MAP sensor) to stored value (current BARO value)
A3D3 : BLS $A3D7 [branch if lower or same] so if MAP sensor current reading is lower than the stored BARO reading, then disregard and skip to A3D7
A3D5 : STAA $003F [Store accumulator A into memory] So, if the MAP sensor reading is Higher than BARO, it stores this value to memory
A3D7 : LDAA $003F [Load accum A from memory] - now loads current BARO value to accumulator A

Can seemingly only make the stored baro reading higher. Course, this is one small snip of code.