1994 Chevy Cavalier Check Engine light on, rough idling

Tiny
HYPER20KID
  • MEMBER
  • 1994 CHEVROLET CAVALIER
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 69,000 MILES
Hello! As of about a month ago, my check engine (CE) light would intermittently come on and off, without the car feeling any different. About last month till now the CE light comes on after about a minute of driving, and when dark, the headlight dim a little right before the CE light comes on.

I tried jumpering the two pins to make the computer flash the error code, however it doesn't even flash anything! Not even the standard 21 if there is nothing wrong.

The car has also started to really idle rough in drive and reverse since last month also. (I'm talking full out interior squeaking shakes that can only be stopped by pressing on the dash/center console!)

I have also noted in the last month that the cars temperature gauge does not move as it used to.
At normal operating temperature, it is usually 1/4 the way up, and when stopped and idling, would climb up to 1/2, and then the fan would kick on, and go back down to the 1/4 range. But as of lately, it will climb to normal temp. (1/4) and stay there even if I was sitting in stop and go traffic on a 90F day!
(It didn't do this staying at 1/4 temp thing before the CE light was on)

My ideas so far was that if the car has a sensor to turn on the fan, that it might be stuck in the on position, but I don't have any real clue.

Thank you!

Thomas
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Friday, October 3rd, 2008 AT 10:44 AM

3 Replies

Tiny
JACK42
  • MEMBER
Do you hear the fan running all of the time? If not it could have a thermostat that is stuck open, not allowing the engine to reach full temp. The shaking sounds like an engine misfire, has it been tuned up lately? No codes. Check all fuses with a test light. Might need to have a shop plug a scan tool into it to see if it is communicating with the ECM
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Friday, October 3rd, 2008 AT 12:45 PM
Tiny
HYPER20KID
  • MEMBER
It does sound like it is running all the time, but I can never tell. I used to be able to hear it turn on and off when it would heat up, and then cool the engine down, but I can never hear it do that anymore.

No, it hasn't been tuned up, but I did note today that it only shakes when idling in drive, but not reverse. (I wasn't sure last night)

Also, how would one check the fuses with a test light?

(I only know so much about cars)

Thanks!

Thomas
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Friday, October 3rd, 2008 AT 3:30 PM
Tiny
JACK42
  • MEMBER
To see if the fan is running, open the hood with car idling in park and look at the fan, When the engine is cold with the a/c off the fan shouldnt be running. Using a test light is fairly simple, you use the clamp end on a good ground (seat mounting bolt is a good one) thn turn key on, touching the pointed end of the tester to the small metal contacts in theend of the fuse, both sides of the fuse should make th etest light illuminate, if not the fuse is bad
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Friday, October 3rd, 2008 AT 6:27 PM

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