Mangonesailor
I'm Awesome
Hey guys.
I'm all about trying to spread out info of my personal experiences on things, and trying to help the masses that may end up having a problem that I (or they) can't rely on the good ole' Google to help them solve. This left me scratching my head for a little over a month, and tied up quite a few weekends trying to figure out what's going on. So I thought I'd share what I found, how I did it, and my end result.
So gentlemen. I've been fighting a P0300 (random multiple misfire) check engine light for the past month.
So here's some past info: Plugs (.050" gap), wires, cap & rotor (MSD), coil (Accel), intake gaskets, FPR, 19lb Bosch injectors, EGR & TB gaskets, all installed 1yr ago. The truck idled with a little roughness, and I could feel a miss every once in a while, but I didn't have any codes and got 13mpg. About 2mo ago I replaced the fuel pump and fuel filter. In the beginning of July I did a 0411 install... and that's when I received my P0300. I did not perform a crank relearn as every dealership I went to was unable to perform it, however I have since gotten it taught. Just drive up to the dealer (Shop) and tell them to program their Tech 2 (Scanner of whatever flavor) for an '02 Chevy Express van with a 5.7 or 8.1 motor and it'll be able to perform the crank relearn.
So, using an OBDLink MX dongle with Torque pro and Dash Command I decided to try to figure out what in the hell is causing all of this. Here's my counts:
I also have no comms with my ABS module.
Here's when they happen: Engine warm, idling in P or D, A/c on or off, with NO accelerator applied. If I accelerate the engine, they stop. Any bit of gas I give it and the engine runs flawless and will not miss. I do not have any lifters ticking and the engine internals sound fine (Via stethoscope).
Here's what I've done:
1. TPS sensor had read (way in the past) .4% open when the throttle was shut. So with Torque Pro running and the engine off I set the throttle closed position to 0% using the slop in the screw holes. After I started having my miss at idle I suspected it was the TPS or IAC valve. With the 0411 and Dash command I was able to see the TPS was showing -2.1* with the throttle shut, so I set it to 0* with the throttle shut. This did not help.
2.Then I looked at IAC counts and they were "0," so I replaced the IAC. They were still at 0, so I played (and counted turns of) the idle stop screw to see if I could get counts in the 25-75 range. They did not increase. I have verified the IAC is receiving a signal from the PCM by unplugging the IAC in the engine and plugging the old IAC external to the TB. i can feel and see it moving.
3. I then suspected a vacuum leak, so I unplugged the IAC and sprayed everywhere I could with starting fluid and used propane under the intake. Nothing.
4. I then started looking for loose vacuum hose connections, because why not anyways? I replaced the PCV's hoses and put a clamp on the breather tube's hose.
5. Cleaned the EGR valve. Lots of carbon fouling. No change.
6. Replaced the oil fill cap, and dipstick O-rings.
7. I checked fuel pressure: 58PSI KOEO, 54PSI KOER, then clamped the return line and jogged the pump. I stopped when I saw 68PSI, so I have pressure and volume.
8. I pulled cyl 4's plug to see what it looked like:
Gap was still at .050", regapped to .045", no change.
9. I pulled the upper plenum and had a look around. The intake runners all look evenly "washed" from fuel from the injectors. I wiped their tips clean, jumped the fuel pump for 15min, and checked for leaks with a paper towel. No leaks.
10. I pulled the dizzy cap and found this:
So i replaced them with a new Accel set, and used locktite on the rotor screws. I also found the old screw in the housing. I checked backlash in the rotor and it was fairly tight, so I left it there.
11. Replaced the FPR for the hell of it.
12. After sealing everything back up and test driving, I still got a p0300, with the same set of cylinders missing, and only doing it at idle. So, I fabricated a blockoff plate to verify the EGR wasn't leaking. Nope.
13. Changed #3 and 4 spark plugs, gapped to .050", nothing.
14. Put 8oz of marvel mystery oil in crankcase to rule out sticky lifters. No change.
15. 8oz of MMO in gas, no change.
16. Ran that tank out and swapped from 87 to 89 for two tanks. IT GOT WORSE.
17. Changed crankshaft sensor and cleaned pickup wheel to verify that was working properly. NOPE.
18. I had thought about the cylinders in relation to the firing order, and they are all next to each other. Yesterday I decided to pull the dizzy and check the gear. Good thing I did:
Camshaft looks OK too, and I checked the whole thing.
I replaced the dizzy with an entire unit from summit. It came with everything from the Gear to the Cap. I had to index the oil pump drive so that the rotor and it's pickup wheel would be properly aligned when I slipped it in. I used the old dizzy shaft, sans gear, in the old housing for that.
So, After all of that, I have no more misfires. Zero. None. Nada. The engine still kinda has a funky idle when cold, and it feels like it has a light miss when warm. However, I'm content with that.
I did get the P1336 code (Which is crankshaft angle variation not learned) after installing the new dizzy. I got that taught and no I have no more issues. I also unblocked the EGR valve, and all seems to be operating normal.
Hopefully this will help out someone in the future whenever they try to use their McGoogle skills.
I'm all about trying to spread out info of my personal experiences on things, and trying to help the masses that may end up having a problem that I (or they) can't rely on the good ole' Google to help them solve. This left me scratching my head for a little over a month, and tied up quite a few weekends trying to figure out what's going on. So I thought I'd share what I found, how I did it, and my end result.
So gentlemen. I've been fighting a P0300 (random multiple misfire) check engine light for the past month.
So here's some past info: Plugs (.050" gap), wires, cap & rotor (MSD), coil (Accel), intake gaskets, FPR, 19lb Bosch injectors, EGR & TB gaskets, all installed 1yr ago. The truck idled with a little roughness, and I could feel a miss every once in a while, but I didn't have any codes and got 13mpg. About 2mo ago I replaced the fuel pump and fuel filter. In the beginning of July I did a 0411 install... and that's when I received my P0300. I did not perform a crank relearn as every dealership I went to was unable to perform it, however I have since gotten it taught. Just drive up to the dealer (Shop) and tell them to program their Tech 2 (Scanner of whatever flavor) for an '02 Chevy Express van with a 5.7 or 8.1 motor and it'll be able to perform the crank relearn.
So, using an OBDLink MX dongle with Torque pro and Dash Command I decided to try to figure out what in the hell is causing all of this. Here's my counts:
You must be registered for see images attach
I also have no comms with my ABS module.
You must be registered for see images attach
Here's when they happen: Engine warm, idling in P or D, A/c on or off, with NO accelerator applied. If I accelerate the engine, they stop. Any bit of gas I give it and the engine runs flawless and will not miss. I do not have any lifters ticking and the engine internals sound fine (Via stethoscope).
Here's what I've done:
1. TPS sensor had read (way in the past) .4% open when the throttle was shut. So with Torque Pro running and the engine off I set the throttle closed position to 0% using the slop in the screw holes. After I started having my miss at idle I suspected it was the TPS or IAC valve. With the 0411 and Dash command I was able to see the TPS was showing -2.1* with the throttle shut, so I set it to 0* with the throttle shut. This did not help.
2.Then I looked at IAC counts and they were "0," so I replaced the IAC. They were still at 0, so I played (and counted turns of) the idle stop screw to see if I could get counts in the 25-75 range. They did not increase. I have verified the IAC is receiving a signal from the PCM by unplugging the IAC in the engine and plugging the old IAC external to the TB. i can feel and see it moving.
3. I then suspected a vacuum leak, so I unplugged the IAC and sprayed everywhere I could with starting fluid and used propane under the intake. Nothing.
4. I then started looking for loose vacuum hose connections, because why not anyways? I replaced the PCV's hoses and put a clamp on the breather tube's hose.
5. Cleaned the EGR valve. Lots of carbon fouling. No change.
6. Replaced the oil fill cap, and dipstick O-rings.
7. I checked fuel pressure: 58PSI KOEO, 54PSI KOER, then clamped the return line and jogged the pump. I stopped when I saw 68PSI, so I have pressure and volume.
8. I pulled cyl 4's plug to see what it looked like:
You must be registered for see images attach
Gap was still at .050", regapped to .045", no change.
9. I pulled the upper plenum and had a look around. The intake runners all look evenly "washed" from fuel from the injectors. I wiped their tips clean, jumped the fuel pump for 15min, and checked for leaks with a paper towel. No leaks.
10. I pulled the dizzy cap and found this:
You must be registered for see images attach
You must be registered for see images attach
So i replaced them with a new Accel set, and used locktite on the rotor screws. I also found the old screw in the housing. I checked backlash in the rotor and it was fairly tight, so I left it there.
11. Replaced the FPR for the hell of it.
12. After sealing everything back up and test driving, I still got a p0300, with the same set of cylinders missing, and only doing it at idle. So, I fabricated a blockoff plate to verify the EGR wasn't leaking. Nope.
13. Changed #3 and 4 spark plugs, gapped to .050", nothing.
14. Put 8oz of marvel mystery oil in crankcase to rule out sticky lifters. No change.
15. 8oz of MMO in gas, no change.
16. Ran that tank out and swapped from 87 to 89 for two tanks. IT GOT WORSE.
17. Changed crankshaft sensor and cleaned pickup wheel to verify that was working properly. NOPE.
18. I had thought about the cylinders in relation to the firing order, and they are all next to each other. Yesterday I decided to pull the dizzy and check the gear. Good thing I did:
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
Camshaft looks OK too, and I checked the whole thing.
You must be registered for see images attach
I replaced the dizzy with an entire unit from summit. It came with everything from the Gear to the Cap. I had to index the oil pump drive so that the rotor and it's pickup wheel would be properly aligned when I slipped it in. I used the old dizzy shaft, sans gear, in the old housing for that.
You must be registered for see images attach
So, After all of that, I have no more misfires. Zero. None. Nada. The engine still kinda has a funky idle when cold, and it feels like it has a light miss when warm. However, I'm content with that.
I did get the P1336 code (Which is crankshaft angle variation not learned) after installing the new dizzy. I got that taught and no I have no more issues. I also unblocked the EGR valve, and all seems to be operating normal.
Hopefully this will help out someone in the future whenever they try to use their McGoogle skills.