CEL code 41 problem with 91 Bonneville

Friends, we have a trusty 1991 Bonneville with 192k miles on it. A month ago, it started hesitating and losing power as I was driving down the interstate. The CEL came on. I was able to drive it home later that day, but within a day or two it was running very poorly. I got the code which said 41, camshaft position sensor signal not received. I replaced the camshaft position sensor and thought I had it fixed, as it seemed to run fine. Then about 4 days later, the same thing happened, the CEL came on and it was running real rough. I took the sensor out and put it back in, thinking maybe I didn't have it seated properly or something. It ran okay for a week or two, and then acted up again (same code, 41). It will start up and run, but it very consistently hestitates at low RPMS (right now I have the sensor unplugged), so the CEL is staying on. At 30 or 40 MPH, it seems to run smoothly as normal, but I do not feel the car is trustworthy since there is no telling when it may suddenly act up and lose power like it did last week.

Any guidance you can provide would be so greatly appreciated! I saw a post last night that said that if the problem recurs after replacing the sensor, then the camshaft position magnet inside the timing come has come apart. Does this sound like the likely cause? If so, I'm not sure how to proceed. I would be tempted to try fixing it myself, though I haven't done a job of that magnitude in over 20 years. Could it perhaps be a fault in the computer?

Thank you for any help/advice!
Dave

This is up my alley. Been there. :banghead:

Had the same problem on a 3.8L.. Turned out to be the CRANKSHAFT POSITION sensor. Comes up with those same codes for some reason and I also swapped the camshaft sensor with no help.. Hard to troubleshoot. Eventually for me it got more violent and sometimes engine stoped at bad times. It still could be wires to that area from the Ignition Module but my $ is on the sensor.

Buick Lesabre, Park Avenues have same problem . same engine.

Requires a puller for the harmonic balancer and a good impact wrench.. actually its not a balancer but a wheel on this engine.

Good luck.. :grinyes:

Thanks so much for your reply. This is very encouraging to have some specific possibilities as to what may be wrong. After looking at some other posts from May of 06, it does also look like it could be a missing cam magnet. Apparently it is possible with a little mirror to look and see through the cam position sensor hole to see whether the magnet is missing or not. I think maybe I should check that first. Sound reasonable?? P.S. Go Huskers, I grew up in Kearney.



[quote=Bassasasin]This is up my alley. Been there. :banghead:

Had the same problem on a 3.8L.. Turned out to be the CRANKSHAFT POSITION sensor.

Bassasasin, I was just looking through some records and I see that the cam magnet was replaced about 15k miles ago, along with the timing chain and so forth. So I suppose the cam magnet is there as it should be. To my mind this lends support to your proposed diagnosis as the crank sensor. Thanks again so much.
Dave

No Problem Dave.. Just to add my car had a violent stall at any speed a jerk or even added a complete stall after a jerk or two.

The Camshaft sensor controls fuel pulses.. the CRANKsensor sends firing timing pulses to the IModule. Its also good to know that THE BOOK says pull off the CAMshaft sensor connector on "fail to run" car and if the car runs its the camshaft sensor..i guess it defaults.

. Just saw a post on allingning that crankshaft sensor.. By putting a rubber band on the hub and turning it around feeling for a good position on the allignment of the sensor.. Sounds good if you can turn it easily.. But .. 4 me I would shop swap it.. $200 including parts.

Bass