HELP - new motor doesn't run

[Bob Valentine]

I've had simular problems if there's a connection problem between the eprom
and the ECM, or a bad eprom burn, or bad checksum in the eprom.  The bad
checksum would be the easiest to check if you don't have a stock virgin
memcal available.

-> Bob Valentine
-> bob at tecmark.com


At 09:05 PM 3/17/2001 -0500, you wrote:
>Here's what I posted on thirdgen.org and corvetteforum.com with few
>results.  I hate to bring it up here, but you guys are smarter and more
>helpful.  Plus, I'm thinking it's a computer problem.
>
>"I've got what sounds like a rich rolling condition.
>This is the first time I've started the new motor. I have great heads,
>edelcrap high flow base and runners, SVO 24# injectors, 218/226 510/510
>114LSA cam, and 355 cubes. I have to modulate the throttle to get it
>started and then keep a little on the throttle to keep it alive. It runs
>up to ~1500 rpm, drops down to ~900, almost dies, throws a quick SES, and
>revs back to 1500, and over again. 
>
>I set my chip for 26# injector constant. Timing is 4 adv when it almost
>dies and runs up to 30 adv when it revs up. Base timing does not affect
>the condition. Took out a bunch of turns off the AFPR, which moved the
>rolling range down a couple hundred rpm. Of course, my AutoXray is not
>connecting and the quick SES flash is not storing a code. Car smells
>rich. 
>
>I'm going to buy a fuel pressure gauge tomorrow to see if I'm in the
>ballpark. I'll also check for vacuum leaks with a butane torch. I thought
>the chip may not be working, but it's not throwing a code."
>
>Today, I checked the fp which was way low.  I put it back to stock and
>I'm running very rich.  The afpr also has a vacuum leak, but fuel is not
>making its way into the cap.  I just unplugged the vacuum  hose to it and
>plugged that hose.  I'll save that problem for later.  The AutoXray is
>not giving me any useful data.  They have had problems reading Vettes. 
>One scan gave me good data before I started the motor.  Another gave me
>bad data while the motor was running.  The rest of the scans say vehicle
>not responding.  Key on engine off field service mode gives code 12 only.
> Key on engine off gives constant SES.  Unplugging MAF helped condition,
>but car would not idle at all.  Unplugging IAC did nothing.  Rechecked my
>eprom and it matches what I programmed into it.  If someone can look at
>it (32B) in their favorite software and compare, I'd appreciate the help.
> 
>
>I am feeling that the ECM is not reading or following my new program.  I
>think a lot of the problem is from my super rich condition.  ECM could be
>fried.  How do I tell?  It's giving me code 12 in field service.  I
>didn't find any vacuum leaks.  I can't get a handle on timing or IAC or
>TPS until the car is stable.  The one seemingly good key on engine off
>scan showed TPS at .52.  I owe whoever figures this one out their
>favorite drink. 
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