Hey guys,
New to the forum, but i already did a fairly lengthy search and came up with nothing of interest.

I recently purchased a 1998 Dodge Ram 1500 2 Wheel drive, 4 door, 360 Auto, for 400$. The only thing wrong with the truck is it has a slight hesistation.

It throws a P1931 code. I tested the crank sensor per spec of the book, and it checks out fine. So does the TPS. I swapped ecu's with a friend. Truck ran well for about 40miles, then right back into the same ole routine.

Ive replaced plugs, wires, cap, rotor, and airfilter, and threw in new oil/filter and injector cleaner for good measure.

The symptoms are: Truck runs fine accelerating.. Idle is somewhat lope-y (similar to that of a carb'd vehicle with a medium cam), low end power seems to be lacking. If 100% throttle is applied, the truck runs like a champ. On decelleration the truck backfires several times until RPM's drop to what i would guess would be under 2500rpm (no tach........ el-strippo model). If i drive the truck at 40mph, and use 15% throttle or so, it bucks and jerks, backfires, and misfires. As soon as i get agressive with the throttle, it pulls right out of it, and runs great. This makes it impossible to maintain a constant speed. If i clear the code with a scanner, it will come back within 10-15minutes of drivng.

Anyone have similar problems? I seen tons of similar posts, but they were all remidied by something i already tried/replaced.

Thanks I appreciate it,
Chris

 

I've had some problems as well. Every so often my CEL comes on with a cylinder 5 misfire. you can feel it missing, but it goes away after about 30 minutes or so. I also have a problem with my e-brake and abs lights every once in a while. I have tried pretty much everything as well. Any thoughts?

 

For what its worth.. my abs and brake light are on. From my understanding the previous owner had an issue with the left front caliper, and i think thats why mine are on... cant see any reason why they would be connected to the P1391 code for any reason.

 

Try another working sensor,
Then it may be in the distributor

 

i am having the same problems as you have described
i have replaced IAC, Cleaned my TB, Replaced Cap and Rotor,and checked all i have done at least 2 times to make sure it is correct and i am still having the same problem it idles alot better than it used too, but it bucks or surges while driving when i am going 10-30 mph if i hold steady on the gas. if i give it more throttle it goes away. so this must be a very common problem for dodge's or at least the rams

 

Guys, if you have a code for a crank reference signal, then throwing plugs, an IAC motor, etc at it is NOT going to fix it. Replace the sensor.

 

You could have dirty contacts at the cam sensor. Unplug it, remove it from the distrubutor, clean the connections, and put some dielectric grease on the contact. Do the same on the pigtail. That happened to me when I rebuilt my engine. Cleaned everything up and the code never returned.

 

Said items were 'while i was there' items...except the iac... it broke while i was cleaning it, so i just replaced it....

thanks for the tip. ill try that. Does anyone have a diagram of how its setup in the dizzy? Its a little difficult to see because of its location, so if i knew what i was going for before hand, id be way better off. Im gonna give it a shot tomorrow. thanks,
Chris

 

If your buddy is good enough to swap pcm's w/ you, maybe he'll let you take his map sensor for a test drive.

 

It will only go in one way as it has a notch for the routing of the pigtail, so reinstallation will not be an issue.