Pesky misfire.

[STRAN]

I am down to just a few items for the rebuild on my Merc.

Have the P0356 misfire code. Put a meter on the plug for the coil. 20 ohms as opposed to 5 for its neighbors. The wire also shows 20 ohms.

I am thinking the wire is bad, damaged.

Plan on leaving most of it in place an run a new one. Buy a replacement or something.

Thoughts anyone?

Wait, looks like I need to focus on the 'driver' for the number 6 coil. Sound familiar?


D

[RF Overlord]

The drivers for the coils are built into the PCM. Disconnect the PCM connector and try to ohm out the wiring...sounds more like corrosion in the harness or a connector.

[STRAN]

I cleaned the contacts on the coil and the plug already, the wire looks a little jacked up.
I cleaned the fuel injectors with no effect.
Looking like I am going to have to run a new wire. First more research to make sure I have not missed anything, like double checking the spark plug.
Going to do a compression test on that cylinder, Oh dear. I hope it is good. I assumed the compression issues were all in the valve train which I had rebuilt.

[Zack]

For a definitive answer, swap that coil to a neighbor cylinder and see if the code moves with it.
Did you wash your engine bay when the engine was out?
Funny stuff happened to another member after water/soap got on the exposed pins of a connector

[STRAN]

For a definitive answer, swap that coil to a neighbor cylinder and see if the code moves with it.
Did you wash your engine bay when the engine was out?
Funny stuff happened to another member after water/soap got on the exposed pins of a connector

I did. I am planning on cleaning the connectors and pins again. I have to face the fact that the wire is showing 20 ohm's and the others only 5. Just don't feel like chasing down s short. I am certain this problem existed before the accident.

[Tnbigbody]

start the car goto the tailpipes put your hand just back of the tips to where you can feel the exhaust hitting your hand (but not close enough to burn yourself) and wait for the miss.. the hand that you feel it on is the side you goto under the hood shut the car off, take a new coil (preferable) or new boot and spring (cheaper) and start with the first cyl on that side and replace.. start back up and repeat stop when the miss goes away.. sounds stupid but it works.. atleast in my case I was getting a miss but no codes the boots are bad for breaking down on ALL FORD MOD MOTORS.. 2V 3V 4V it doesn't matter which one it is and this includes aftermarket coils the rubber is subject to heat soak like all other parts in the engine and as we all know heat destroys everything... hope this helps
p.s. put dielectric grease the connector and the spring from top to bottom it keeps moisture out of it

[STRAN]

Thanks guys, I appreciate the advice. The coils, boots and springs are all new. I looked at #6 and the plug ( all the plugs are new with stock plugs) has not been getting spark, it is very clean. The code is for number 6 as well.

[Marauderjack]

Is the low voltage plug LOCKING onto the coil??:confused:

I had a locking tab break a long time ago causing intermittent spark!!:argue:

The replacement pigtails are expensive and wire ties are cheap....just in case!!:beer:

[STRAN]

The tab was not broken but I zip tied it away along with the two tabs that were broken. I also pushed the contacts inside the tab just in case I had pushed them out of position with a prob.

I am going out in a few minutes to stare at it.

[STRAN]

Bump.
Well, I was not expecting my wife to file for divorce but she did. Right now my life is in total disarray. I am at an all time low on all fronts.

Having said that. After a discussion with an programming engineer I bought a used PCM. The only thing I did not do was pull the harness apart to look for a damaged wire. Now my new problem is the PATS (security system) and the new PCM do not communicate. That is the car will not start. Everything I have read says the PCM has to be re-programmed by a dealer or possibly a locksmith, has to be done on the car. I tried a re flash of the old PCM hoping that would solve the missfire but seems to have made it worse. Any comments, suggestions?

[Zack]

If you we're close I could bypass PATS for you.
Good luck!

[Motorhead350]

Sorry about life taking an expected turn.

Keep moving and never stop.

[STRAN]

Thanks Zack, I am actually considering it. I have seen some DIY ON YouTube.

[STRAN]

Sorry about life taking an expected turn.

Keep moving and never stop.

It has been utterly awful, almost unbearable. Good word MH.

[STRAN]

I had a locksmith take care of the key. On to the next issue, the battery won't hold a charge. The only a virus symptom is both post have the white powdery acid on them. Taking it to autozone to have it checked and go from there.

[RF Overlord]

Make a paste of baking soda and water to neutralise the acid and use a toothbrush to clean both terminals. Check for tightness with a 5/16".

Use a voltmeter and check for approx 14V with the engine running, to confirm the alternator is good.

[STRAN]

Thanks OL. Knew about the paste, didn't know what the alternator should be putting out. Unfortunately my voltmeter stopped working. Gotta have one of those so I will be picking one up today. I have not had time todo anything since my last post so I need to get this baby running to let the new PCM learn the engine. Pin and needles about that misfire.

[STRAN]

I put a charge on the battery again. Inspected the ground cable and cleaned up the connector, straightened it for better contact. Cleaned post which were not that bad. Started right up, alternator seems to be fine, tested it and the gauge in the car shows 14 volts. Let it idle a long time.the new PCM learned and the engine is running smooth. No missfire. Now for the air ride and the pesky drivers air bag.