Ultra rich at cold start???

[jameslleary]

ok, i have a few logs from him. Everything goes pig rich on the blm and int on cl, but in open loop, after start, the blm and int look normal, but the vac is very low, and the iac is wide open like a barn door, which i am banking that is the reason for the 8Hg vacuum.
He is bored 30 over, comp cam, no part number, but jegs swore up and down it was a computer compatible cam.
holly replacement throttle body. he says it was acting the same way before the rebuild.

[EagleMark]

BLM won't help CL.

60 MAP at 800 idle?
DTC 45, O2 rich?
High IAC count I think is trying to keep it running but a quick 1/4 to 1/2 turn in will prove it.
Diagnostic Mode Enabled isn't helping either, but he has issues your not going to find unless you get your hands on it. Start with everything...

[dave w]

holly replacement throttle body. he says it was acting the same way before the rebuild.

Holley TBI have Adjustable Fuel Pressure Regulators? Try less fuel pressure. Was the Holley TBI on the engine before the rebuild?

dave w

[jameslleary]

Holley TBI have Adjustable Fuel Pressure Regulators? Try less fuel pressure. Was the Holley TBI on the engine before the rebuild?

dave w

No, he had the stock rochester and all sensors have been replaced 3 times trying to track down this issue. fuel pressure is currently at 12 psi.
Mark, all he has is an ALDL cable, and TPRT....is there a way to just log without diag. mode?

[EagleMark]

I don't know how he got in Diagnostic Mode? ALDL mode is when 10K is applied which is the mistake people usually make. Diagnostic mode was IIRC 3.9k and I don't even remember what for? Or is diagnostic mode when A and B are crossed?

Does his CEL work correctly?

1project2 many may know what Diagnostic mode is or how it got there?

[1project2many]

Diagnostic mode is 10K across A-B. 3.9K enables Backup fuel / LHM and Field Service is enabled when A-B are shorted. Once upon a time the 7747 wouldn't even give out data unless you were in diag mode. Some of the cables come with DIAG mode automatically enabled.

[EagleMark]

Thanks 1project2many!

Well then he has the 10K on cable, should be open. But there might be more wrong because I have seen other data from people with ALDL mode enabled with 10k?

[jameslleary]

crapola...should I have him pull A and/or B out of the ALDL?

[EagleMark]

? I just plug my cable in and don't use the jumper for 10k. Or use my AutoProm and don't use 10k switch. What is he using for cable?