prariedom Posted January 5, 2007 Report Posted January 5, 2007 So, I replaced the ECM on my Lumina, and she fired up...with different problems. I suppose that's what I get for going to the boneyard, but at least now I can get her under her own power to a scanner... She runs fine, as long as you don't accelerate too hard - then it'll go flat, not really stall, but no power either...and you have to shut it off and wait a few to get it to start. The other weird thing is the speedo now appears to be giving wrong info - I'm passing everyone in sight, even tho it says I'm doing the speed limit, keeping even with them in a 65 zone, mine said 53...and if you rev the motor out of gear while coasting the speedo jumps. I think I have a snafu'ed ECM. I don't know the stock size of tires, but it appeared to be correct speedwise with the old one. I did not change the PROM, but it came off of a Euro 3.1 that's only a year newer (1991) - I wouldn't think there'd be that big a difference. Any ideas? Quote
CNBZ34 Posted January 5, 2007 Report Posted January 5, 2007 I would suspect a couple things. Has the prom been altered in the replacement ECM? Or it could be bad. I went thru a nightmare with my 88 Trans Am GTA with that. When I had finally ruled out everything else and it was a TPI engine, I went to Napa and bought a replacement, snapped in my PROM and BAM! Ran like a champ. ECM's at Napa are around $100 give or take. With what you are describing, I would really suspect a bad ECM and/or PROM. Just my .02 Quote
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