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All started with Code 51 about 2 weeks ago, so replaced with new GM stock EPROM - 2 days later another code 51 and it dies (but both times does restart) so replace ECM - and relocated new EPROM - runs fine for a week , then tonight.

at stoplite - temp 210, idle drops from 5 to 4 and "Check Engine Lite" comes on and stays, she continues to run, place in neutral and up the idle, make it to parking lot stop sign, she dies with "Check Engine Lite" & "Battery" symbols lit. Place in park, restart, dash lites don't come on right away, but in about 5 sec they do, both symbols flicker on/off for about 10-15 sec then go away... Park and we have dinner, startup , not a problem, drive home , check codes: just 12's...

Any ideas, Maybe sensor(s)? or Bad ECM? any help would be appreciated.... thanks vinnie
 

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84 GRANDSPORT said:
Mass Air Flow Sensor?:huh:
Though maybe some sensor,,, got new AutoXRay and no error codes, replaced TBSensor, and order new MAF BurnOff Relay, MAP, IAC, due in this week... so we'll see, from the looks of them, i doubt they were every replaced... so now they will be...

Have data from recent scan if that might help diag the system... I appreciate the help... thanks.
 

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i would say it's a bad ground.have you looked closely at the battery and terminals.my 89 would act up sometimes,i replaced everything,turned out the last thing i replaced was the problem.the positive cable going to the starter.looked great on the outside of the wire,inside the wire was green and many strands broken.
one other note,if a problem is intermittent,it's usually electrical.
MAS codes are 33 and 34.
you gave it a good shot-code 51 mem-cal error,then you replaced the ECM,however code 55 is replace ECM.your battery and cables and grounds,is probably were your little demon is hiding.good luck.......:smokin:
 

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hawaii-5-lo said:
i would say it's a bad ground.have you looked closely at the battery and terminals.my 89 would act up sometimes,i replaced everything,turned out the last thing i replaced was the problem.the positive cable going to the starter.looked great on the outside of the wire,inside the wire was green and many strands broken.
one other note,if a problem is intermittent,it's usually electrical.
MAS codes are 33 and 34.
you gave it a good shot-code 51 mem-cal error,then you replaced the ECM,however code 55 is replace ECM.your battery and cables and grounds,is probably were your little demon is hiding.good luck.......:smokin:
Thanks: yea, i'm sure the deamon is hiding somewhere,,, cable(s) look good from the outside, maybe just replace pos & neg just to be sure... rechecked EPROM seating, good, and reset connectors to ECM... AGAIN... Yea, codes, I know, and the surprising thing is only code 51 comes up, but like i said in the post, funny part is that NO CODES were there after the last "die"... now its been running for maybe 5 days with no problems... COULD BE THE ELECTRICAL.... Heck, the cables are the cheap part of the fix, if it works... thanks again...
 

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vinnies87 said:
Thanks: yea, i'm sure the deamon is hiding somewhere,,, cable(s) look good from the outside, maybe just replace pos & neg just to be sure... rechecked EPROM seating, good, and reset connectors to ECM... AGAIN... Yea, codes, I know, and the surprising thing is only code 51 comes up, but like i said in the post, funny part is that NO CODES were there after the last "die"... now its been running for maybe 5 days with no problems... COULD BE THE ELECTRICAL.... Heck, the cables are the cheap part of the fix, if it works... thanks again...
I hate computer/sensor BS! That is another reason why I like my carbed setup over fuel injection! I havent seen a check engine lite in a long time & I know I never will again!:) Maybe you should just throw a carb on it & be done!:rolling: Seriously though good luck.:thumbsup:
 

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i forgot to mention,the first set of cables i replaced,came from checker auto,i new something was still not right.sure enough,there cheap replacement was a smaller cable than the stock one.to much resistance.thats what i get for trying to save 20 bucks.:laughing: i had minor problems with my battery terminals the whole time i had the car.i would have to clean them,tighten them real good and coat them with the battery spray,the car ran fine,if i jerked one of the cables,there was the demon again.
a side note,if you install all those parts you listed,you don't have to worry about them...:smokin:
the code 51 is still a little strange though,if you have a tech manual for the car,look for the computer grounds,and clean and retighten....sucks,i know.you will fiqure it out... :smokin:
 

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Also look at the firewall block where the underdash harness connects with the engine harness that is behind the battery. Those are known to get bad with corrosion, etc..

Still sounds like a bad ground.
 
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