Hi everyone, I have a 1998 gmc jimmy with a 4.3, automatic trans, and 4x4.It has been misfiring under acceleration. I have pulled up two check engine codes, p0339 and p0441. the crank and cam sensors. I have replaced the crank sensor with a new one. put in a new set of plugs. put ina used distributor with the cam sensor. Put in a new computer and had it reflashed by gm. Cleaned the maf. Replaced the tps. New distributor cap.STILL NOT RUNNING RIGHT! I dont know what to do next and the truck misfires so bad that it is undriveable. It misses very badly and cuts out really bad usually above 2200 rpm but every once in a while it does it all the time. If anyone can help that would be great, thanks alot, Matt.

 

I just dealt with the same exact problem. I replaced everything from the spider fuel injection to the plugs and wires and was still misfiring. Look at your rotor cap and make sure that the inside doesnt have any scratches where the fire can ark. The other thing is, check your rotor button point and make sure you dont have carbon build up or just replace the rotor button. I just wish I had someone to tell me the same thing before I spent a grand. This should definitely fix your problem.

 

You may want to remove your ICM (ignition control module) and take it to your local advanced auto or autozone as I believe they can run a test on the module to see if it is faulty. If the ICM is faulty, it will not be controlling the spark curve properly for the operating conditions of the engine.

*EDIT* Also, P0441 is an evap code. More specifically, Evaporative Emission Control System Incorrect Purge Flow. This could have been from a loose gas cap.

Also, on the P0339 code, you may want to inspect the wiring harness that runs down to the CKP sensor. As always, with replacing a CKP sensor on newer vehicles, it is a very good idea to have a CKP sensor variation learn procedure performed so that the PCM can fine tune the readings from the CKP sensor to the actual operating characteristics of the engine.

 

I replaced the dist. from a salvage yard and the rotor was used from that dist. the cam sensor was also inside the dist and whatever else is inside the dist. Where is the ignition control module. I thought it was inside the dist but i also thought the cam sensor was inside the dist but i only saw one sensor inside the dist. I still dont have any ideas on what to do. thanks everyone, Matt.

 

SlimshagE,
You spent a grand and it turned out to be the ignition rotor?

Holy spider injector Batman!!!!! Who told you to change your spider injector?

Let me guess....hmmmmmmmmmmmmmmmmmmm

THE BLAZER FORUM????????????????????????????

 

Nope, the friendly local technicians at Napa. With friends like them, who needs enemies to take your lunch money?

 

That's too bad about shelling out the big money and finding out it wasn't the problem. It seems like you can't change the ignition tune up parts enough on these Blazers. I'm just at the point that I do the plugs about every 30K miles anyway.

I have been looking around and keeping my eyes open for a ZR2 to replace my Blazer eventually. Every time a new Ford Explorer pulls up next to me and I have to "look up" to see it, I tend to lean more and more towards one of them. It is really a nice looking SUV now. I don't think I care to go through the same old problems again. I like my Blazer but I am pretty sure that I have had enough. There's no doubt that Explorers must have their own quirks but the one thing I always remember about my Ford Van from the 80's was that after 200K miles, every door opened and closed like the day I bought it new. Very well constructed vehicle.

 

Where are the cam position sensor and the icm. As soon as I find out where the icm is I am gonna take it in to get tested. Thanks, Matt.

 

ICM

^Click for larger view^

CMP sensor is in the distributor under the rotor. I have seen where the lower distributor gear has worn or cracked and caused all kinds of timing related problems. I'm sure that lastcoupe and/or Kordog can elaborate more, but here's a link to some information on the CMP sensor that I posted a while back: Where is the cam positioning sencor?

But your code was for the CKP (crank position) sensor... The CKP sensor is located on the timing cover at about the 7 o'clock position when looking at the crank pulley from the front.

 

I took the icm over to AAP and it tested bad so i bought a new one and installed it but I still have the same exact problem. If anyone has any other ideas that would be very helpfull. Thanks, Matt.