help....ECM ?
zbo2
10-26-2004, 08:05 PM
hi there.........
i have a 94 convertable with a 3.4 auto........it just started to act up, when crusing at a steady speed after the engine is up to temp it acts just like somebody is turning the key off and on, when cold it runs fine, it only acts up when up to temp....if you step on it when it is acting up it pulls smooth as glass up to a 100, but as soon as you settle to a steady speed it starts bobbling all over again. i changed the ign module, the crank sensor, the cam sensor all to no avail. i put a scanner on it and drove it, the TPS was reading steady while it was bobbling in fact the only reading that was moving around was the O2 sensors, which is understandable when it seems like the ign is being turned off and on.....make no mistake it's not a miss like a plug wire.
the other things that are happining at the same time are the tach starts to flutter mostly down at the same time the bobble starts, up the 1500 rpm, and i've seen the speedometer drop as much as 20 mph on a couple of occasions even though the vehicle speed was the same.
when cold it drives perfect.....i'd like to throw a ECM in it......but it's not one of the cheap ones, it has to be programed......any ideas??????
i have a 94 convertable with a 3.4 auto........it just started to act up, when crusing at a steady speed after the engine is up to temp it acts just like somebody is turning the key off and on, when cold it runs fine, it only acts up when up to temp....if you step on it when it is acting up it pulls smooth as glass up to a 100, but as soon as you settle to a steady speed it starts bobbling all over again. i changed the ign module, the crank sensor, the cam sensor all to no avail. i put a scanner on it and drove it, the TPS was reading steady while it was bobbling in fact the only reading that was moving around was the O2 sensors, which is understandable when it seems like the ign is being turned off and on.....make no mistake it's not a miss like a plug wire.
the other things that are happining at the same time are the tach starts to flutter mostly down at the same time the bobble starts, up the 1500 rpm, and i've seen the speedometer drop as much as 20 mph on a couple of occasions even though the vehicle speed was the same.
when cold it drives perfect.....i'd like to throw a ECM in it......but it's not one of the cheap ones, it has to be programed......any ideas??????
89IROC&RS
10-26-2004, 09:28 PM
perhaps an IAC valve????
zbo2
10-26-2004, 10:24 PM
anybody know how to check it........or what the values should be
4onFloor
10-26-2004, 10:50 PM
it's never the ecm, atleast usually so hold off on that. i guess the only way to see if the IAC is working at all is to pull it out and start the engine. the pintle should move a little bit, then move all the way out.
does your car have a MAF sensor? ya might wanna have that checked, or try cleaning it with carb cleaner.
does your car have a MAF sensor? ya might wanna have that checked, or try cleaning it with carb cleaner.
zbo2
10-28-2004, 07:39 PM
yooooooo....
well thanks for the help...............i did try the ECM..........got one used for 60 bucks so i tried it...........it worked fine.....but didn't fix the problem............as a last resort i put a vehicle speed sensor in and that fixed it..........i guess it was randomly telling the computer that it was exceeding the preset over MPH limit and shutting the motor down.go figure...
thanks :naughty:
well thanks for the help...............i did try the ECM..........got one used for 60 bucks so i tried it...........it worked fine.....but didn't fix the problem............as a last resort i put a vehicle speed sensor in and that fixed it..........i guess it was randomly telling the computer that it was exceeding the preset over MPH limit and shutting the motor down.go figure...
thanks :naughty:
89IROC&RS
10-28-2004, 08:41 PM
didnt think of that one.... *scratches head* good call on that.
Chevyracincamaro
10-28-2004, 10:56 PM
have to put that in the memory banks for next time. never would have thought of it...
4onFloor
10-29-2004, 12:17 AM
it's never the ecm
nobody ever listens to me :disappoin
nobody ever listens to me :disappoin
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