Yet, ANOTHER phantom misfire issue
#11
#12
Hooking it up to a scanner, and checking fuel sync wouldn't be a bad idea......
Pickup in the distributor clues the PCM in as to what cylinder is firing, so it knows which injector to fire. Has nothing at all to do with ignition. Crank sensor deals with that. It has been demonstrated that a crank sensor can give a weak signal on individual cylinders, which leads to a weak spark on those cylinders..... I don't quite understand just how that happens, only that it does indeed happen.
Running a compression test also wouldn't be such a bad idea, to rule out any potential mechanical problems.
Pickup in the distributor clues the PCM in as to what cylinder is firing, so it knows which injector to fire. Has nothing at all to do with ignition. Crank sensor deals with that. It has been demonstrated that a crank sensor can give a weak signal on individual cylinders, which leads to a weak spark on those cylinders..... I don't quite understand just how that happens, only that it does indeed happen.
Running a compression test also wouldn't be such a bad idea, to rule out any potential mechanical problems.
#13
I changed the wires with moroso 8mm. Wrapped them in tubing and routed them away from one another until they teach the cap. Took truck for a ride. CEL came on. Codes P0300/0308 STORED, P0301/02 PENDING. I'M stumped. I have extra plugs. I'll put them in those cylinders and see what happens? I don't notice any drivability issues...purrs like a kitten at idle and moves pretty well for a near 20 year old truck.
I already replaced the distributor pick up....What is it's purpose? Could it be faulty? For some reason, cyls 1/8 seem to be pesky.
When fixing the plenum...I also replaced the oil switch pick up which is right next to the distributor. If I accidentally without knowing bumped the distributor, could I have thrown off the fuel/firing synchronization?
I already replaced the distributor pick up....What is it's purpose? Could it be faulty? For some reason, cyls 1/8 seem to be pesky.
When fixing the plenum...I also replaced the oil switch pick up which is right next to the distributor. If I accidentally without knowing bumped the distributor, could I have thrown off the fuel/firing synchronization?
#14
I found a couple of videos and instructions on doing a hard reset. Not really sure if it worked? When using the odbwiz software, when I click on freeze frame, it says that there was something, blah blah blah nothing stored....if I did the ecu reset correctly, there shouldn't be ANY type of freeze frame..correct?
#16
Every time someone posts about random misfires, after having performed a lot of parts replacements, it makes me think of when the same occurred to me with my Second Gen.
The Backstory: I had completed the rebuild of the engine and dropped it into the bay before proceeding to reconnect everything. During the reconnection process, I observed grease and dirt on some of the connectors but did not give them a second thought. The engine fired up fine and I continued with the break-in procedure to get the rings to seat. Shortly after, the CEL was flashing and I pulled codes for random misfires. Some searches yielded results such as a possible crack in the CKP (sensor in the distributor), while others indicated issues with the spark plug wires. After a careful inspection of the CKP sensor I noted zero cracks but a lot of grease and dirt on and inside the connector. I decided I had nothing to lose, so I used connector cleaner and Q-tips to clean the harness connector and the connector on the sensor.
The Verdict: The random/erratic misfires disappeared. The dirt and grease impedes resistance enough to wreak havoc with the sensitive voltage requirements of modern vehicles.
The Backstory: I had completed the rebuild of the engine and dropped it into the bay before proceeding to reconnect everything. During the reconnection process, I observed grease and dirt on some of the connectors but did not give them a second thought. The engine fired up fine and I continued with the break-in procedure to get the rings to seat. Shortly after, the CEL was flashing and I pulled codes for random misfires. Some searches yielded results such as a possible crack in the CKP (sensor in the distributor), while others indicated issues with the spark plug wires. After a careful inspection of the CKP sensor I noted zero cracks but a lot of grease and dirt on and inside the connector. I decided I had nothing to lose, so I used connector cleaner and Q-tips to clean the harness connector and the connector on the sensor.
The Verdict: The random/erratic misfires disappeared. The dirt and grease impedes resistance enough to wreak havoc with the sensitive voltage requirements of modern vehicles.
#17
Thanks to all who have replied and came to my aid.
Yesterday, since my beloved EAGLES weren't playing, I decided to dedicate more time into trying to solve this problem. I removed the air cleaner/snorkel and just gave the engine a thorough comb over (vacuum lines and electrical connectors). I also broke out the multimeter and made sure that all injectors were receiving voltage while the truck was running. All checked out OK. I hooked up my ODBII scanner just to double ckeck the codes I was getting. STORED were P0300/01/08. PENDING status showed every cylinder!! I was like WTF!!!! I'm no genius, but something isn't right here?!?! With the engine running, I decided to jiggle the ignition wires at the spark plug end to ensure the boots were properly seated. I then moved to the distributor cap side...here's were the fun begins! Pressing down on the individual wire boots..all checked fine. I then, decided to wiggle the coil wire at the boot end and WHAMO...HELLO...Daddy's F*#king awake now!!! After nearly Sh*ting my pants and collecting my composure, I turned off the truck and pulled the coil wire off the truck. At that time, I took advantage of Moparite's advise and performed a Hard memory dump (to be quite honest, never heard of this and the thought Never crossed my mind). with both battery cables off and the positive cable end grounded to the frame. I decided to rebuild the coil wire. The spark plug wire kit that I bought required you to make your own boot terminations. When I first made the coil wire, I didn't like how it turned out but I went with it anyway (should have listened to that little voice). I re-terminated the end with a different style boot/connector and reinstalled on the truck. I also decided to check the plugs and re-gap them to their proper spec .035. About 15 minutes had passed. I hooked up the battery cables, and followed the hard dump procedure outlined in another thread. Started truck up, took her for a quick spin (usual route, 2 miles) came home and patiently waited for CEL to come on while sitting in the driveway (10 minutes). She didn't. I took the truck to work today (35 miles). The CEL usually would usually come on about half way there. It didn't. Got to work, hooked up OBDII scanner...no codes in PENDING status, no codes STORED either. CEL is off....hmmmm! I'm not quite 100% ready to say she's fixed??? I'll know for sure later on today when I head for home. Keeping fingers crossed that the CEL stays off.
Yesterday, since my beloved EAGLES weren't playing, I decided to dedicate more time into trying to solve this problem. I removed the air cleaner/snorkel and just gave the engine a thorough comb over (vacuum lines and electrical connectors). I also broke out the multimeter and made sure that all injectors were receiving voltage while the truck was running. All checked out OK. I hooked up my ODBII scanner just to double ckeck the codes I was getting. STORED were P0300/01/08. PENDING status showed every cylinder!! I was like WTF!!!! I'm no genius, but something isn't right here?!?! With the engine running, I decided to jiggle the ignition wires at the spark plug end to ensure the boots were properly seated. I then moved to the distributor cap side...here's were the fun begins! Pressing down on the individual wire boots..all checked fine. I then, decided to wiggle the coil wire at the boot end and WHAMO...HELLO...Daddy's F*#king awake now!!! After nearly Sh*ting my pants and collecting my composure, I turned off the truck and pulled the coil wire off the truck. At that time, I took advantage of Moparite's advise and performed a Hard memory dump (to be quite honest, never heard of this and the thought Never crossed my mind). with both battery cables off and the positive cable end grounded to the frame. I decided to rebuild the coil wire. The spark plug wire kit that I bought required you to make your own boot terminations. When I first made the coil wire, I didn't like how it turned out but I went with it anyway (should have listened to that little voice). I re-terminated the end with a different style boot/connector and reinstalled on the truck. I also decided to check the plugs and re-gap them to their proper spec .035. About 15 minutes had passed. I hooked up the battery cables, and followed the hard dump procedure outlined in another thread. Started truck up, took her for a quick spin (usual route, 2 miles) came home and patiently waited for CEL to come on while sitting in the driveway (10 minutes). She didn't. I took the truck to work today (35 miles). The CEL usually would usually come on about half way there. It didn't. Got to work, hooked up OBDII scanner...no codes in PENDING status, no codes STORED either. CEL is off....hmmmm! I'm not quite 100% ready to say she's fixed??? I'll know for sure later on today when I head for home. Keeping fingers crossed that the CEL stays off.
Last edited by Brancajd; 10-19-2015 at 10:33 AM.
#20