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Old 06-20-2005, 05:42 PM
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Hey DocVette...ECM question

Docvette....I am having a problem I hope you can give me an answer to. It concerns the ECM, PROM, and a 4.3 to a 350 engine swap. We did this in my '93 Chevy truck. I have been told a multitude of things so I am now asking you. We retained the factory harness although we had to change a couple of connectors due to the engine having a Holley throttle body. So we had to swap connectors for the injectors that came with it. No problem there. The engine is in and everything is wired except for an EGR that I am waiting for an EGR relocator for. We got it fired but it ran terrible. I am assuming from the 4.3 computer and PROM that was still in it. Looking at a few other sites I found out that the ECM for the '93 is only made for that year and it runs either a V8 or a V6 but the PROM needs to be swapped for a V8 PROM. I failed to mention the truck has the 4L60E tranny that I am keeping in it. My question is...can I go to the wrecking yard and get a different PROM, or is there a couple of years that I can get one from, or does it have to be '93 specific. I did find a place that can burn one for me for less than 2 bills but I hate to spend the money yet, if I am having other problems. I am hoping that I can pull a V8 PROM from another vehicle to get mine running then work out some bugs that way. So anyways....ANY INPUT???????? Thanks Doc and whoever else has input.


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Old 06-20-2005, 07:22 PM
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Doc here,


First I'm not a programmer by any means..I'm a PARTS changer where this is involved.. (except when it comes to my own stuff...then I'll dig into the motherboard..) But what I do know I will share with you...

First (and I haven't a real clue if this will work or not...It does in Vettes with new Correct<--read.. memcal apps..)Try Starting / Stopping the Truck up to 25 times to program in new values...Although the standards by which they operate are usually burned in...prior reference data can be discarded and new reference data fed in..by inducing up to 25 Ignition cycles..It's possible it may work..but couldn't tell you for sure...but easy enough to try..

However, What I think your fighting here is timing and sync setup (by flash/burn in on the memcal) For a 6 cyl on an 8 engine...In theory, It should have backfired a lot in addition to running rough...unless that has a calpack (limp home feature) in it and that was what you were running on...

What I do Know is...1993 truck was the new memcal..should be a 27c512 ..28 pin DIP chip...prior was the 2732 Memcal 24 pin dip..(1987-91) So in answer to that question..yes it must be 93 (or up specific..)the other memcal won't even plug into the computer..The new Memcal also allowed for the electronics on the transmission..

What I'd try First, is find a 93 (or up specific) Truck at the bone yard with a 350 original application, and same set up as you have now...pop the chip out of it..be sure it's a 28 pinner..on both your computer and the donor chip..

Insert that one in your computer, and fire it up..If it runs crappy , but better than before try the Ign cycle thing and see if the new engine values won't upload..(they should as new reference data)

Not sure what they are getting for bone yard chips in your area, around here they are about $10 to $40 bucks...

Who REALLY know his stuff about this is Ghetto Jett or Siggy...can't remember which..., he (I think, read a book) or Took a class...AND bought a programmer...and if I followed his posts correctly has had good success with programing chips..you may want to PM him..Worst case scenario, he may be able to Burn a chip for your application..(probably won't charge ya 200 bills for it either!)


Last edited by docvette; 06-21-2005 at 05:13 AM.
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Old 06-23-2005, 06:49 PM
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Doc...just to let you know...I picked up a computer out of a '94 with a 350. Plugged it in, hit the key and she fired right up and idled. But I still have a few things to get done to the engine to work ouut the bugs. EGR valve, some vacuum routing, timing. But mainly I want to say thanks for the info.

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