i put in a new battery and autonator on a 1990 chevrolet lumina. the car ran fine before, now runs ruff. computer need to be rest and i need to no how to do this?i have been told to disconnect thepcm for 10seconds, i do not no what the pcm is? and can the battery be disconnected to do this same thing?. is the pcm located on the computer box? if so which wire is to be disconnected?
2007-01-12 06:52:55 · 10 answers · asked by ztar1462 1 in Cars & Transportation ➔ Car Makes ➔ Chevrolet
I doubt your car is running rough because of that,although disconnecting the battery for 60 seconds will do to reset the computer.Check your connections to make sure everything is where it should be and tight.If you still have a problem check to see that you didn't accidently pull off a vaccume hose.And check the spark plug wires and make sure you didn't knock one of those loose.If it ran good before then you shouldn't need to give it a tune up.But If you are going to have the car for awhile then you may want to give it a tune up anyway.
2007-01-12 06:57:34 · answer #1 · answered by JACK OF TRADES 3 · 1⤊ 0⤋
The PCM is the computer that runs your car. Powertrain control module is what it stands for. These PCM's for this type of car run on a speed densisty calculation as there is no mass air flow sensor and this has to be learned by idling. The PCM is located under that big piece of plastic in the front corner of the right front fender well under the hood. Yes, if you don't know what or where to find this power connection unhook your negative battery connection for about ten seconds. This powers down everything and clears all memory. Make sure all power is off to the car, that is no headlights, interior lights, and especially the ignition is off. Then reconnect the negative battery cable. Turn the ignition to the on position only, do not start yet as this sets the IAC motor and the computer is reading sensor data. Give it about 5 seconds. Then continue the ignition cycle by cranking the motor until the motor starts but without touching the throttle. This is important as the computer needs to start at the base idle position. The motor might stall, if it does just restart it again. Once running the motor will rev a bit and then settle down. Run the motor without touching the throttle until operating temp. is reached. This completes the relearn so you are done. Good luck.
2007-01-13 04:57:07 · answer #2 · answered by Deano 7 · 0⤊ 0⤋
When replacing the alt did you have the battery hooked up ?? If you did you could have blown the injection driver in the PCM .Unlikely that a idle relearn (unplugging the PCM fuse will fix the rough running unless its only at idle.To relearn idle disconnect the battery for 1 minute then drive the car try to get to the highway cause you need to go to wide open throttle for a couple of seconds.Then return to normal driving . This should relearn the idle . If your not able to do this go to the repair shop they can relearn it with their scan tool. Good luck hope I helped.
GM tech for 20 years
2007-01-12 07:07:13 · answer #3 · answered by Rudedude 4 · 0⤊ 0⤋
You already reset the computer when you disconnected the battery. Now the computer needs to relearn the best settings for your engine as you go through the next dozen drive cycles or so. However the rough idle may be a vaccuum hose or other air leak you've introduced possibly when you changed the alternator and battery.
2007-01-12 07:03:09 · answer #4 · answered by bobweb 7 · 0⤊ 0⤋
Just disconnect the negative battery cable for bout a minute.
But it ran ok before and now it runs rough? Makes no sense at all unless you knocked off a vacuum hose or a plug wire while you were changing the alternator. recheck everything the plug wires on a lumina run close to the alternator area for the rear plugs.
Check all your vacuum hoses
2007-01-12 14:09:48 · answer #5 · answered by Anonymous · 0⤊ 0⤋
I had the same problem. I was told to start, the car like 6 times, and the car will relearn the idle itself. Just start and drive the car for a little bit, to give the car time to do this. It should take care of itself, mine did.
2007-01-12 16:07:44 · answer #6 · answered by Speedbuggy43 4 · 0⤊ 0⤋
unhook battery for 1 minute then reconnect this might do it, if still runs rough, do tune up and change fuel filter as well, the running well before was what might have caused the alt and battery to go bad before
2007-01-12 06:58:12 · answer #7 · answered by Mr D 3 · 0⤊ 0⤋
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2016-10-19 21:26:35 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Autonator
2016-11-01 09:32:09 · answer #9 · answered by bidatsch 4 · 0⤊ 0⤋
check the spark plugs and spark plug wiring
2007-01-12 07:57:39 · answer #10 · answered by tparolini2000 1 · 0⤊ 0⤋