91 vette idle surge

[84Elky]

In all my years of doing this, I've never seen that XDF or that Scalar text (EXPERIMENTAL spark angle). Whoever developed this XDF did not know what they were doing or they were using if for an engine that had a Distributorless Ignition System (DIS). The parameter at the address of that Scalar (0x28) is the Maximum Retard allowed for a distributor 8 cylinder engine and SHOULD NEVER BE CHANGED!!!!!. That's why it's not in any valid XDF except for S_AUJP.

First thing you MUST DO is to correct your BIN to get this value back to -3.87 degrees max retard:
-Using your weird XDF, change the value back to 90 and save it
-Select the Hex Editor icon in the TunerPro banner
-You should see at address 0x28 and 0x29: FF F5
-If that's not what's there, change it to FF F5
-Save the BIN

Next, dump your XDF and only use the attached. You can now make changes to the BIN with confidence. This is the XDF that can be downloaded from tunerpro.net, modified to edit some additional items as described in the attached documentation.


Not to complicate things, but when you get the spark straightened out, you need to upgrade to S_AUJP v6. Very easy to do and can tune/change/report virtually everything.

[dbstainbrook]

how do i do this upgrade to s-aujp v6.

[84Elky]

You haven't reported on the status of your spark issue resolution. I'd hold off on v6 until that's resolved.

Regarding v6, respectfully, detailed instructions are provided in the included READ ME.

[dbstainbrook]

sa-ref seems to be fixed. i had to replace the ecm. now there is no codes. still not sure if the rest of the timing is where it should be. and the engine will just shut off after running for 10-15 min. if i put into neutral and crank it wont start. if i cycle the key it will fire right up.

[84Elky]

sa-ref seems to be fixed. i had to replace the ecm. now there is no codes. still not sure if the rest of the timing is where it should be. and the engine will just shut off after running for 10-15 min. if i put into neutral and crank it wont start. if i cycle the key it will fire right up.

I wouldn't worry about spark for now.
-VSS showing in 4th gear when idling, etc. Something not wired correctly.
- Look at sample 7750. Weird data and a software interrupt error. This just cannot occur. There's likely an electrical connection problem to the ECM.
- Also, is this log when it quit running? If not, best if have a log that shows it stopping and recranking to start running.
- You say will not start in neutral. What about Park? P/N switch issue? Need to describe the symptoms when it dies. Immediately off, sputters for a while, etc.

[dbstainbrook]

the car shuts off immediatly no sputter no nothing just off. when it shut off i was moving i put into neutral and coasted trying to start without going to the off position. once i cycle back to off and then try to start it will start right up. i will try to log again.

[84Elky]

the car shuts off immediatly no sputter no nothing just off. when it shut off i was moving i put into neutral and coasted trying to start without going to the off position. once i cycle back to off and then try to start it will start right up. i will try to log again.

Great. Log may be helpful. In the meantime, any chance you're building up gas tank pressure in that 10-15 minutes of driving? This can happen if tank not properly vented or exit line clogged, preventing proper return flow, and it will die.