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?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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.
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?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
crapola...should I have him pull A and/or B out of the ALDL?
? 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?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Even if he gets the Diagnostic Mode off I don't think data is going to help with vacuum that low at idle... something mechanical is wrong!
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
yeah, we are looking at everything. I have him adding a heated o2 for long tubes. then take the 10 k chip out.
With vacuum that low, data or heated O2 is moot.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Ok, so he sent me a log, I told him to unplug the cts, reading drops to -40* and he apsaid it started running real good.
Why would it straighten up at -40, and run pig rich at 70*? Ideas?
Last edited by jameslleary; 11-20-2012 at 09:48 AM.
Hard to tell what a cold motor is doing open loop, but as you know going to -40C is adding fuel! What I saw when he added fuel was vacuum go up?
EDIT: Diagnostic mode still on?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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