I have a 97 2500 with 5.9. The problem started out with two surges the check engine light flashing very fast. Truck backfires (sounds like a machine gun). Pulled cades P300,P301,P302,P303,P304,P305,P306,P308. Already did tune up minus fuel filter. Cleared codes, truck still misses and smells rich but now no codes. Finally light came on again got code P1391 (cam and or crank sensor). Hayes book only goes to P804, talked to dealer and was told PCM. Replaced PCM with no change. Now I got code P320 (no distributor reference) but Hayes book shows for diesel engine. Any ideas what this could be?

 

1391 would point me toward the crank or cam sensor. crank sensor is in the top of the bell housing, passenger side. cam sensor is under the dist cap and is listed as pickup coil or secondary pickup coil in parts stores.

320 would point me towards the cam position sensor.

smelling rich would point me to the front O2 sensor. but i'd try the cam sensor first. the computer is usually right.

edit - by the way, did the dealer hook up his $10,000 scanner to your truck before telling you the pcm was bad or did he just guess. and did you buy it from him? if so tell him to remove it since it didn't fix the problem...

 

No, the book I have doesn't show the P1391 for my truck. The book also shows the P320 as for a diesel engine. The dealer showed me the codes don't match the years. I pulled the codes with an autoxray scanner.

 

If I'm not mistaken, the Haynes Manuel give you only 2 digit codes. Are you talking about the Haynes Dodge Manuel or the Haynes OBDII book?

 

Never heard of this before....

Your having 7 cylinder misfires, thats alot of misfires. Something is causing it to do that. The only cylinder that is not misfiring is number 7. And yes, The Haynes repair manual on dodge pickups only goes to P0804...

I agree with dhvaughan. It would make sense that a bad crank or cam sensor is the root cause for your cylinder misfires. Change those first and see if it affects the cylinder misfires...

 

Last night, I pulled codes and ect. with an OTC code reader. Now I still get the P1391,P320, but now I also got P42 the ASD circuit. I guess I should describe what happened to the truck. I drove the truck about 15 miles ran fine. Shut the truck off for about 10 mins. Refired the truck started down the road when it bucked twice then the Check engine light started flashing very quickly. The ABS light was on and so was the brake light. Couldn't get over 25 mph at 3k rpm. It just seems like everytime I get the CEL to come on I get different codes. Thanks for all the suggestions, I'll be testing all of them.

 

Checked cam and crank sensors, both (by the book) work as they should. Replaced fuel pump (low pressure). Still no change. Can't see timing mark at the tab. Starting to think this thing jumped time. Any ideas. By the way, how the HELL do you get the Damn heat shields off?

 

I would fine a PCM at the local junkyard. Sounds like the PCM likes to play games. However, when I smell rich fuel on my truck. I replaced the O2 sensors.

 

New PCM already installed. O2 sensors reading and changing.