ECU replacement???
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Instructor
Joined: Dec 2014
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ECU replacement???
Can anyone suggest a vendor or shop with a replacement ECU for 91 L-98?? Rock Auto has a rebuilt OE unit for $100 (plus core). Did not if any one had purchased one from Rock Auto. Other than using original PROM how difficult is reprograming (idle, theft) to do??? Thanks
Team Owner
Joined: Sep 2003
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You're quite convinced it's an ECM issue? Did it fail the "tap test"?
I'm an RA hater I guess- they market/resell so many different grades of the same product it seems ridiculous and people receive two or three different sparkplugs for a eight plug order. I just don't like and haven't ever purchased from.
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Instructor
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I'd maybe see if there was a local that could help you. If there were issues I believe I'd rather do it "toe to toe" rather than an Internet exchange. Some/most auto stores have relationships with suppliers. Hold on to your core until the job is done. There's minimal aggravation involved on a '91. The PROM to change and then just some basics.
You're quite convinced it's an ECM issue? Did it fail the "tap test"?
I'm an RA hater I guess- they market/resell so many different grades of the same product it seems ridiculous and people receive two or three different sparkplugs for a eight plug order. I just don't like and haven't ever purchased from.
You're quite convinced it's an ECM issue? Did it fail the "tap test"?
I'm an RA hater I guess- they market/resell so many different grades of the same product it seems ridiculous and people receive two or three different sparkplugs for a eight plug order. I just don't like and haven't ever purchased from.
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Instructor
Joined: Dec 2014
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Pro
Joined: Jan 2003
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From: Denver Colorado
Woody41,
Are you able to pull codes or is the ECU totally dead?? Have you checked for electrical basics: battery cables good, fuses good, connections to ECU clean and tight?? If you can get any codes that will tell you a lot.
Last ECU I bought, years ago, was from Checkers, now O'Reilly and was good for the life of the car (80K) while I had it.
Are you able to pull codes or is the ECU totally dead?? Have you checked for electrical basics: battery cables good, fuses good, connections to ECU clean and tight?? If you can get any codes that will tell you a lot.
Last ECU I bought, years ago, was from Checkers, now O'Reilly and was good for the life of the car (80K) while I had it.
Thread Starter
Instructor
Joined: Dec 2014
Posts: 144
Likes: 9
Woody41,
Are you able to pull codes or is the ECU totally dead?? Have you checked for electrical basics: battery cables good, fuses good, connections to ECU clean and tight?? If you can get any codes that will tell you a lot.
Last ECU I bought, years ago, was from Checkers, now O'Reilly and was good for the life of the car (80K) while I had it.
Are you able to pull codes or is the ECU totally dead?? Have you checked for electrical basics: battery cables good, fuses good, connections to ECU clean and tight?? If you can get any codes that will tell you a lot.
Last ECU I bought, years ago, was from Checkers, now O'Reilly and was good for the life of the car (80K) while I had it.
Pro
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From: Denver Colorado
OK, sounds like the situation is it cranks but won't start, right? So it is either no spark or no fuel. Check to see if you have fuel pressure at the Schrader valve on your fuel rail, that takes a gauge. Pull a plug wire and see if it has spark when it is cranked. Once you know if it is fuel or spark the problem is half solved.
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Thread Starter
Instructor
Joined: Dec 2014
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OK, sounds like the situation is it cranks but won't start, right? So it is either no spark or no fuel. Check to see if you have fuel pressure at the Schrader valve on your fuel rail, that takes a gauge. Pull a plug wire and see if it has spark when it is cranked. Once you know if it is fuel or spark the problem is half solved.
Pro
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From: Denver Colorado
I'm confused also, it "should" run if it has spark and fuel, does it only run when the starter is engaged, key in "start" position, and then fail to fire immediately when you release the key to the "run" position? Does it continue to fire at all after you release the key from "start" or die right away? If it only fires while the starter is going and then dies, the issue is likely with the switch or the wiring to the switch. I mean the actual switch assembly on the lower steering column, not the key/lock cylinder.
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I'm confused also, it "should" run if it has spark and fuel, does it only run when the starter is engaged, key in "start" position, and then fail to fire immediately when you release the key to the "run" position? Does it continue to fire at all after you release the key from "start" or die right away? If it only fires while the starter is going and then dies, the issue is likely with the switch or the wiring to the switch. I mean the actual switch assembly on the lower steering column, not the key/lock cylinder.
Pro
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From: Denver Colorado
Car will start and run for a few seconds after you release the key, it will idle until you open the throttle then engine dies immediately then when you put key in start position it will turn over and not restart. What you are saying makes sense when I was last driving it last time the car cut off like you turned off the switch. I will look at wiring diagram, I thought everything was in the key cylinder. I agree it should run....
I see why this is frustrating. If you just let it idle after starting will it keep running until you open the throttle or does it die after a short time?
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Instructor
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There is a rod that connects the key cylinder to the real switch mounted on the lower steering column. Be sure to disconnect the battery before you do anything with the switch... its a slide switch and could activate the starter if moved around. I see why this is frustrating. If you just let it idle after starting will it keep running until you open the throttle or does it die after a short time?
I see why this is frustrating. If you just let it idle after starting will it keep running until you open the throttle or does it die after a short time?
Racer
Joined: May 2004
Posts: 295
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From: Newton NJ
Thanks, when it starts it will idle, as soon as you touch throttle it dies and no restart. I was under the dash this afternoon, I did not notice a rod, I will check it out again. This is my first Corvette and I really like this car. I am in process of selling my Triumph Spitfire in order to buy a C4 convertible....BUt i need to get this one driving first.
Also keep the fuel pressure gauge connected and watch your pressures, be curious to see what happens during the starting and quitting sequence.
Hope this helps
Last edited by cmontel727; Jun 27, 2015 at 11:15 AM.
Thread Starter
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When the car starts then quits i would check for spark and fuel again. Sounds like one of them is giving out. My 87 has gone through some ignition modules in the distributor. Gave similar symptoms.
Also keep the fuel pressure gauge connected and watch your pressures, be curious to see what happens during the starting and quitting sequence.
Hope this helps
Also keep the fuel pressure gauge connected and watch your pressures, be curious to see what happens during the starting and quitting sequence.
Hope this helps