: Still getting Missfire-New AC Delco Plugs and new coil packs
06-15-11, 01:58 PM
My 02 Deville was getting a steady stumble and Check Engine Light flashing, checked the codes, the only one that didn't deal with the Torque Converter Clutch Solenoid was the PCM 0300 code (engine missfire). I changed the spark plugs (used new AC Delcos) and new coil pack cassettes with the new ignition modules included. On the rear side, I did see a little oil residue. Do you guys think it could be the boots needing replacing also? One other thing, the stumble/missfire started very distinctly about 3 weeks ago. I'm a teacher and out for the summer, so I don't have to drive the car very much, but what do you guys think. Would driving it very much ruin the Catalytic converter?
06-15-11, 05:38 PM
There are a lot of possible causes, but I would suspect a Fuel Injector, Fuel Regulator or Fuel Pump as the most likely suspect..
Do you guys think it could be the boots needing replacing also?
Only if they where carbon tracked. IF they where, the track would soon transfer to the new plug and misfire. Whenever carbon tracking is involved, you must replace both the plug and boot (or wire). Otherwise it will just keep transferring back and forth.
06-16-11, 12:00 AM
06-16-11, 11:28 AM
How did the plugs you yanked look? Any dirtier or more fouled than the others?
06-16-11, 11:52 AM
The plugs didn't look especially fouled, but the car has 129k miles, and and I sorta think they were the original because when I bought the car at 80k miles, I think the previous owner wasn't the most meticulous. At any rate, when I drive it seems perfectly normal, but the CEL flashes, so I know there is a missfire. At idle, I feel the slight vibration, but the CEL doesn't flash. It did seem that putting on new coil pack cassettes and plugs improved the idle, but there is obviously still a problem with no code being thrown other than P0300. It does sort of seem like there is a gas smell coming from the exhaust on startup, but it goes away after a while, so I'm guessing the unburned fuel is getting dumped in the cylinder and through the Catalytic coverter (which really makes me nervous). Does the PCM shut off the fuel to that injector?
Does the PCM shut off the fuel to that injector?
It does sort of seem like there is a gas smell coming from the exhaust on startup, but it goes away after a while, so I'm guessing the unburned fuel is getting dumped in the cylinder and through the Catalytic coverter (which really makes me nervous).
Have you checked for a leaky FPR?
06-17-11, 09:31 AM
Yes, I checked the FPR, and there is no leak coming out of the nipple. I tend to think it isn't fuel pump because the car is getting up to speed pretty well, though not as well as before this issue started. Luckily I don't drive it much right now because it's summer. Once again, I didn't change the boots, I'm thinking that might be the next step, though I know taking a blind stab at these things rarely leads to rectifying the issue.
06-17-11, 09:46 AM
OK, I just ran the codes again, I'm getting P0036 (oxygen sensor), P0300 (random missfire), P1571 (torque converter clutch solenoid) and PCM U1040 (not sure on this one, I can't get the OBDII codes window to open up on my computer). Do you think the oxygen sensor might be suspect?
Have you checked for a ripped plenum? Pretty common on the 2000+ engines and will cause a misfire/rough idle, might even affect the O2 sensor, but I'm not positive.
06-17-11, 10:48 AM
yes, the plenum is about 7 months old, I doubt its already ripped again. The way the car acted when that happened (when the plenum ripped) was much worse that whats happening now.
06-18-11, 11:12 AM
I'm pretty sure that the p0036 is for the heater circuit on the O2 sensor. This code is for bank 1 position 1, and if I'm not mistaken, position 1 is one of the forward-most O2 sensors critical to fuel trim. I'd begin by resolving that (most likely O2 replacement) as poor fuel trim control will definitely cause misfiring.
06-19-11, 10:18 AM
I've been trying to get that 02 sensor off the car, but I can't get it to budge. One more thing, when I touch the coil pack cassette ( the one against the fire wall), is give me a steady shock. I can touch the front one fine, it doesn't shock me. Do you think the electrical connector might be at fault. I don't see any fraying.
when I touch the coil pack cassette ( the one against the fire wall), is give me a steady shock.
That ain't right.
06-19-11, 11:47 AM
Disconnect the negative battery cable and continue your inspection, safety first
Sent from my Northstar powered phone
06-19-11, 12:08 PM
One more thing, when I touch the coil pack cassette ( the one against the fire wall), is give me a steady shock. I can touch the front one fine, it doesn't shock me.
That's a problem.
06-20-11, 11:32 PM
I can tell you that I experienced the same issue on both my 95 Concours and on my 02 Explorer. Check all of the wires for soft spongy boots and cracks in the boots. I replaced the wires on the Concours and the boots on the Explorer as it has coil-over-plugs system. Problem cured.
06-25-11, 10:15 AM
Hey Soccer, Hit that o2 sensor with some pb blaster and then the next day try to turn it while the exhaust is hot..If you are trying to take it out with the exhaust cold you are gonna have a hard time..They come out so much easier with a hot exhaust.. Did all of mine that way..