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97 C1500 350 Erattic Misfire and Detenation


dusty3
07-18-2013, 07:08 AM
I am having problems with my truck going dead while at highway speed, not cranking when I go into a conveince store for a few minutes, and sometimes it will diesel and pop at idle after driving a few miles. Most all times the truck will start after a few minutes and run fine till the next episode. I definitley had a cap, rotor and plug wire problem, so I replaced them all with premium Carquest Gold products, no cheap stuff. After replacing cap, rotor and wires, the shutting down at highway speds and intermittent non-start issues stopped for now. This morning while pulling in to work at idle my truck went dead, I put it in park and restarted, it restarted immediately and was dieseling terribly, I shut it off and restarted again and it idled great:banghead:. Fuel pressure is strong at 62 psi. The truck has 298,000 and runs great other than the above mentioned problems, which I believe have all been addresed except for the dieseling. What else should I check?

MT-2500
07-18-2013, 07:42 AM
Explain dieseling while running.
A engine diesels after shut off at high idle.
Have you checked for any code?
Have you checked for good spark when it does it?
Old style dist. or new flat top dist.?

j cAT
07-18-2013, 10:28 AM
I am having problems with my truck going dead while at highway speed, not cranking when I go into a conveince store for a few minutes, and sometimes it will diesel and pop at idle after driving a few miles. Most all times the truck will start after a few minutes and run fine till the next episode. I definitley had a cap, rotor and plug wire problem, so I replaced them all with premium Carquest Gold products, no cheap stuff. After replacing cap, rotor and wires, the shutting down at highway speds and intermittent non-start issues stopped for now. This morning while pulling in to work at idle my truck went dead, I put it in park and restarted, it restarted immediately and was dieseling terribly, I shut it off and restarted again and it idled great:banghead:. Fuel pressure is strong at 62 psi. The truck has 298,000 and runs great other than the above mentioned problems, which I believe have all been addresed except for the dieseling. What else should I check?

you do not mention the distributor ! these are well known to fail around 175-225,oooMILES.......

what occurs is the distibutor bearing and or gear wears out. check for any wobble of the distibutor shaft/rotor .

replace the ignition module also. any arcing will damage the electric components....

dusty3
07-18-2013, 10:37 AM
I don't know any other way to describe dieseling other than erractic low to high engine RPM and detenation knock. Like I said in my first post truck went dead while pulling into my parking spot, upon re-start it knocked, skipped, popped, idle was exceptionally low and would get faster and slower along with the pop and knock. I turned the ignition off, waited a few seconds and re-started and it cranked and ran perfectly. I don't have a way to check codes, but will try to get it on a scanner asap.

dusty3
07-19-2013, 07:00 AM
OK, so disregard my first post where the intermittent engine shut off at highway speed got better, yesterday and this morning the problem has gotten worse.

Let's start with yesterday afternoon. Left work went home and truck sat for 2.5 hours, I started truck to drive to town and about 3 miles down the road the engine quit at 55 mph, I put it neutral and re-started and continued without stopping. When I got to town about 2 more miles, it shut off again and would not re-start. I called Carquest and they brought me an ignition module, I installed it and it still would not start. I had my son with me so I had him roll the engine over and it had no spark, I pulled the coil wire off and held it close to the coil tower and it sparked and fired right up. We then went to the football park about .25 miles down the road and while driving through the parking lot at 15 mph the truck started knocking and popping again, I put it in neutral and it cleared up and we proceeded about 100 ft, before I could put the truck in park the engine quit again. We spent about 30 minutes there and when we got back into truck it would not start, after several attempts it started and we proceeded home. The first red light we came to it stalled, I re-fired and held RPM at 3,000 til the light turned green and took off. We made it down the road about 2 miles, while running 60 mph the truck quit again, sarted popping, knocking, spitting and sputtering until it climaxed with a huge backfire that disentigrated my muffler:crying:. All I could do at that point was laugh because it scared the hell ot of my son:lol:. I pulled to the side of the road and re-started, now it sounds like my old dirt track car and we made it home. While pulling into my driveway it started dieseling, I put it in neutral coasted down the hill parked, popped the hood while it was still dieseling and I swear the engine was spinning BACKWARDS, when I saw this I immediately shut it off for a few minutes and re-started it ran fine:banghead:. This morning it fired right up and went dead 30 seconds later, it quit on me 2 times before I got out of my driveway each time re-starting, I drove 6 miles to work with one more episode. I still have not gotten to a scanner yet, but will try today, I want to go fishing this weekend so it has to be fixed. Let me add one other tidbit, it has rained daily for the past 2.5 weeks, some of the worst flooding that I have ever seen down here including HURRICANES. Parts that I have replaced; Distributor Cap Flat Style, Rotor, Plug Wires, Ignition Module, all Carquest Gold Premium parts.

MT-2500
07-19-2013, 07:12 AM
OK, so disregard my first post where the intermittent engine shut off at highway speed got better, yesterday and this morning the problem has gotten worse.

Let's start with yesterday afternoon. Left work went home and truck sat for 2.5 hours, I started truck to drive to town and about 3 miles down the road the engine quit at 55 mph, I put it neutral and re-started and continued without stopping. When I got to town about 2 more miles, it shut off again and would not re-start. I called Carquest and they brought me an ignition module, I installed it and it still would not start. I had my son with me so I had him roll the engine over and it had no spark, I pulled the coil wire off and held it close to the coil tower and it sparked and fired right up. We then went to the football park about .25 miles down the road and while driving through the parking lot at 15 mph the truck started knocking and popping again, I put it in neutral and it cleared up and we proceeded about 100 ft, before I could put the truck in park the engine quit again. We spent about 30 minutes there and when we got back into truck it would not start, after several attempts it started and we proceeded home. The first red light we came to it stalled, I re-fired and held RPM at 3,000 til the light turned green and took off. We made it down the road about 2 miles, while running 60 mph the truck quit again, sarted popping, knocking, spitting and sputtering until it climaxed with a huge backfire that disentigrated my muffler:crying:. All I could do at that point was laugh because it scared the hell ot of my son:lol:. I pulled to the side of the road and re-started, now it sounds like my old dirt track car and we made it home. While pulling into my driveway it started dieseling, I put it in neutral coasted down the hill parked, popped the hood while it was still dieseling and I swear the engine was spinning BACKWARDS, when I saw this I immediately shut it off for a few minutes and re-started it ran fine:banghead:. This morning it fired right up and went dead 30 seconds later, it quit on me 2 times before I got out of my driveway each time re-starting, I drove 6 miles to work with one more episode. I still have not gotten to a scanner yet, but will try today, I want to go fishing this weekend so it has to be fixed. Let me add one other tidbit, it has rained daily for the past 2.5 weeks, some of the worst flooding that I have ever seen down here including HURRICANES. Parts that I have replaced; Distributor Cap Flat Style, Rotor, Plug Wires, Ignition Module, all Carquest Gold Premium parts.

Find out if it is losing spark or fuel or a sensor is droping out.
Where you have a lot of rain check fuel and fuel filter for moisture.
You need to get it on a engine capable scanner and watch data when it quits and get codes.
And also hook up a fuel pressure gauge while driving when it quits.
Make sure it is not going below specs.

Tech II
07-19-2013, 08:04 AM
I agree, that it may be fuel related......easiest thing to do is replace the fuel filter and see if that fixes problem....otherwise, you will have to drive with a fuel pressure gauge attached to monitor pressure when problem occurs.....

Also if you have a MAF, make sure there is no air leak between it and the throttle body....

And get any codes read.....

j cAT
07-19-2013, 09:21 AM
you could have bad fuel. with the rainstorms the fuel at the suppliers may have had water enter the tank.

I guess your not interested in the distributor check .

the other item could be the ECT or the connector to it. electrical is what I think is the problem since it is not always screwing up.

dusty3
07-19-2013, 10:38 AM
Thanks for the help guys, I really appreciate it. I went down to Carquest to return the tools that their mechanic loaned me to change out the module yesterday and spoke with their head mechanic and the store owner. The mechanic said he still believes that the cap, even though is new, still has moisture in it. The owner of the store agreed to sell me a brand new, not remanufactured, distributor with cap and rotor installed for 100 bucks. I will change the distributor during my lunch break and report back, if it is not raining, it rains everyday.

dusty3
07-22-2013, 07:13 AM
My update. I installed the distributor during my lunch break, it ran great fired right up and ran for 10 minutes. I left work 2 hours later and was headed to the auto parts store 2 miles down the road when it went dead 100 yards from the store, I coasted into the parking lot and it would not re-start. I talked with the owner and he gave me a coil and installed it, it cranked and I went to the shop area in the back of store. On the way to the shop it started spitting and sputtering. We stuck a fuel pressure gauge to it and saw that it only had 43 psi at idle (97.350). Mechanic hooked up scanner and it spit out a MAP sensor code, it turns out that when I changed the intake gaskets last year, I forgot to plug it in. No other codes. Pulled the MAF sensor and cleaned with MAF cleaner, cleaned all mating surfaces and installed, still having problems, it would run for 2 minutes and shut down. It finally stopped restarting and the mechanic said that the new coil was bad, so I put the old one back on and it re-started. After 3 hours of head scratching the truck ran long enough that I could make it home, it quit 200 yards down the road, a good samaritan towed me back to the shop. At this point we all agreed to change the fuel pump, so I did the next morning. It still would not start and fuel pressure remained the same. It had no spark, so I pulled the coil wire and let it rest on top of the coil tower and it started right up. I plugged the coil wire in drove it home. I drove it a little saturday and sunday it started going dead again. I got it back to the house and started messing around with the electrical connection to the coil, if i wiggled it a certain way the truck would die, so I pulled the pin connectors out of the plug housing and installed each pin to its connector in coil. I found that 2 of the connector pins fit loosely, used a pair of pliers and squenched the connectors a little, re-installed each pin back to coil and truck cranked and ran good. I also drove it to work this morning with no troubles. Iwill let you know if I have any other problems.

dusty3
07-23-2013, 02:17 PM
Update; Sunday the truck started shutting off and running like crap again. I was determined to fix this sob if it took me all day. It only took 10 minutes to fix, after all of the parts changing and hours of checking stuff, all that was wrong with it was a loose pin connector in the electrical connector to the coil. The way I found it was by wiggling the connector while the truck was running and it would cut off, then I could wiggle it opposite way and it would start running again. I seperated the pins from connectors and tightened each one up with pliers before putting back together and installing, been running great since sunday.:grinno:

j cAT
07-23-2013, 03:04 PM
Update; Sunday the truck started shutting off and running like crap again. I was determined to fix this sob if it took me all day. It only took 10 minutes to fix, after all of the parts changing and hours of checking stuff, all that was wrong with it was a loose pin connector in the electrical connector to the coil. The way I found it was by wiggling the connector while the truck was running and it would cut off, then I could wiggle it opposite way and it would start running again. I seperated the pins from connectors and tightened each one up with pliers before putting back together and installing, been running great since sunday.:grinno:

That's great you got all this going. hard to help when you have poor electrical connections/intermittent failures like you had I figured it was electrical.

having post all your troubles with resolving this I found this a valuable post to those with old vehicles that have these type problems. parts most times fix the problem but when things get this old you must look at the wiring/connectors ,and grounds.

since the ignition parts are all changed it should run and start much better. maybe save some on MPG.

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