junkrider

Hi-

This is just an FYI, I see alot of questions but few resolutions to codes.

I know its not a mustang, but this info will apply to any EFI vehicle.

Vehicle:
Working on my friends 1997 Jeep GC, 4.0L., 150K.

Problem:
Multiple misfires. Check Engine Light. Throws a 43 (coil current error) from the key-on-off-on diag method.

Scanner shows P300, P304, P305, P306. THis is multiple random misfires, cylinders 4,5,6.

O2 voltages bounce, but seem good range.

Timing bounces (due to misfire) at idle.

Idle rough, but not terrible.

Vacuum reading about 17 +/- 1 inch when engine misfires.

MPG not bad, getting about 20mpg.

Checked electrical tests, all good. Checked fuel pressure, okay. New tune up about 10K ago, including plugs, wires, coil, cap, and rotor.

Crank pos sensor is new, as I broke the old one when we rebuilt the trans.

O2 sensors new.

We recently replaced the exhaust manifold as the old one was cracked, so I suspected possible vac leak at the intake (cyl 4,5,6 are adjacent). While idling vehicle cold, I doused the intake gasket area with starting fluid. Slight rise in idle momentarily, but not bad. (yes, that is not a good thing).

Once warmed up, I did it again. Put a direct hit on the injector where it inserts in the manifold, and WOW! The misfire was very noticable. Did it again on all injectors, one at a time, and found that the only one that did not matter was cyl 2. #6 just about stalled the vehicle.

The O2 sensors read about .8v (very rich) when I sprayed the injector holes.

Final diagnosis: bad injector seals.

Cost:
Code scanner: $200 (CP9185 from advanced auto)
Injector seals: $9 (advanced auto)
Time about an hour to diagnose and change out.

(Actually this the 10th time I used the scanner in the past 2 weeks).

Peace of mind not getting a$$ raped by the dealer:
PRICELESS!!!

So, for anyone getting those codes, do your research, and check those seals.

Things to watch out for:
The new seals are tight. Use some dish soap to lubricate before putting injectors in. I use electrical connection grease (very light coating).

Use caution with the starting fluid (fire risk). Have an extinguisher in your garage. You do have one, right????

Hope this helps someone out there.

-mike

Forgr8ness

To add to what has already been said. I was getting error code s P340, P305, P306, and P0*** (cant remember but is was a system too rich bank #2). My symptoms were significant loss of power in all gears. Sometimes it would run okay and other times not. No matter when (hot or cold) i would hear a clunking around 2500-4000 RPM's then it would stop. On these forums i learned this was most likely the Cat.

Not wanting to spend the money to replace one cat, i bought new plugs, wires, and a fuel filter to chase the misfire problem. It got worse. Then i replaced the coil pack, no change. At this point i was rather upset and took the coil pack back and got my money back. Then i had an epiphiny (sp?). i looked at the plug packages (2 per pack) and somehow managed to get three different types of plugs. So i went and made sure to get the right plugs, gapped them and replaced them again. No noticable change and now the rattle was starting to happen at 2k rpm.

Ended up ordering Pypes "The Beast" dual exhaust system from Blue Oval Industries. After i did this i found several horror stories about Blue Oval. Not good for me. My order was fine and although i had to make an additional cut or two more than what they said i got the system completely hooked up in a day. I am sure some could do it much quicker than the 15 hours is took me, but i am a rookie and did it with no knowledge of how to do it so i was still happy. at this point it was 11pm so i didn't test drive.

I took it out the next morning and it sounded GREAT. Actully sounds like a mustang should. It's not a GT but at least i am still getting 30mpg on the highway. Did a WOT run and got it to 90 with power to spare. i would have kept going but it was 10am and being the father i am all i could think about was going to jail for 45mph over the speed limit. through out the entire range of gears the car sounded awesome and lacked no power at all. At this point everything seems to be fixed.

Just wanted to put it out there that these codes can also be caused by a clogged cat. Granted it isn't the most likely source, but if you have tried everything else this may be something to try. I still have cats, but now they are high flow Pypes cats as opposed to the clogged stock ones.

Hope this Helps someone.