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Dad's 89 Buick LeSabre unable to pull codes rough idle

6K views 13 replies 7 participants last post by  66dream 
#1 ·
I made it to Ia. with my 66, Now Dad's car (89 Buick Lesabre 3800) is down, runs rough at idle and will intermitantly chug cruising down the road ocassionaly.
I tried jumping the serial port with a jumper wire, but can not get the check engine light to flash 12.
Any sugestions?
Thanks in advance!
p.s. I'm displaying proudly my TC stickers on my rear quarter window and have had several people ask about TC. Good site!:hurray:
 
#2 ·
1. Does the bulb light during bulb test with the key?

2. Jumping the correct terminals?

3. Defective ECM
 
#3 ·
1. Does the bulb light during bulb test with the key?

2. Jumping the correct terminals?

3. Defective ECM


Check engine light comes on with key
I think I'm jumping correct teminals, I tried sevral (suppose to be outside right top two)
Not sure how to check the ECM
 
#4 ·
Does it have an EGR valve? It could be clogged up with carbon. If it has one, I'd suggest trying to clean the original as the replacements you'll get at auto parts stores won't work properly and a new one from GM will cost you a ton. Just get a new gasket, take it off and gently clean out the carbon and reinstall.

Since it is intermittant, you also might try getting a new gas cap. A good way to check this as a possible problem is to try driving it with the cap just loosly installed, not screwed down all the way and see if the problem goes away. Costs nothing to check it.
 
#5 ·
My parents 88 Bonneville did this as well, even acted up when they traded it in. It didn't show any codes at all, just would run rough and then run fine, like someone flipped a switch. Odd thing was if you unplugged a sensor, it would run fine in limp home mode, but go to acting up randomly once the sensor was plugged back in. Ended up being a bad ECM, according to the Pontiac dealer.
 
#12 ·
That code also refers to the circuit to the cam sensor so your trouble could be in the wiring and not just the sensor.
As you've tried 2 sensors ,I'd look at the wiring.
You can get the free wiring diagram by signing up to Autozone.
Add your vehicle ,then select Vehicle Repair Guides ,then select Chassis Electrical ,then Wiring Diagrams.
Your cam sensor wiring is on fig 5.
 
#13 ·
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