Nichoms

Hi, My girlfriend has a bone stock 2005 Mustang GT with 85k on the clock. She had not had any problems with it since she got it with 500 miles on it. She had it serviced at the Ford dealership the whole time.

One morning she went to start it and it didnt want to start. Sort of seemed like a clogged fuel filter but we checked her records and it had been replaced recently. Feathering the gas we got it to start, so took it in to Autozone to get it scanned. Cylinder 6 misfire...

I looked at her records and they had not ever replaced the spark plugs, so I replaced those. That got rid of the rough start but the misfire was still there and you could hear some ticking.
We ran seafoam and several injector cleaners through there with no change.
I moved the coil to another cylinder and the code still came up with a cylinder 6 misfire.

I got a screw driver and listened to the injectors; cylinder 6 injector was not firing. So I ordered a new injector, replaced it and the misfire is still there. You could hear the new injector working but it did not fix the misfire.

I pulled the valve cover and was looking for a bad lash adjuster or lifter. I noticed the exhaust lifter was sticking so I replaced the lifter. You could tell the old lifter was stuck by pushing on it, sometimes it would go in all the way but 90% of the time it would get stuck half way down.

So a couple days after replacing the lifter the engine light came back on.... misfire cylinder 6.

There is still a little ticking sound and still the misfire. I'm not sure what do do next.

I have cleaned the MAF and IAC. I also checked for vacuum leaks and nothing. I cant find anything wrong with the harness and the coil boots look fine.

Crank sensor? ECU messed up? Any suggestions?


Sorry for the long post but there was a lot to explain. Any help is much appreciated!

Nick

tx_zstang

What code? A failing alternator can give misfire and cam sensor codes. The 'voltmeter' on the instrument cluster is just a dummy light and does not show actual voltage. If it's the stock alternator, that could cause all the problems.
Also, check the wiring from the injector and cop back to the pcm, make sure no rodent chewed through or a wire hasnt rubbed through somewhere.

S197_GTvert

check the following:

* coil packs just because the boot it fine the actual coil itself can be bad check for any water damage inside the coil ( remove the boot )
* alternator ( known for going bad early )
* hold a screw driver on the top of the coil pack or listen around it see if you hear any hissing or exhaust type leak sound coming from that plug its a long shot put the plug may be backed out

Nichoms

Thanks for the responses guys.

The Code is P0306

Alternator - We brought it in the Autozone and they did an alternator test with it under a load and the alternator showed to be good. I will check the output voltage with a multimeter to verify it is producing correct voltage.

COP - I'm pretty sure the COP is good because I have moved it to other cylinders then reset the computer and waited for the light to come back on and rescanned. It always says cylinder 6 misfire no matter which coil is on it.

Note: No matter what COP is on cylinder 6, when I pull the connector to the COP the engine does not temporarily slow down like it doesn when I disconnect any of the other COPs. This makes me believe its either the ECU/wiring/valve issue.

Spark plug - The problem started with the original spark plugs. I pulled the plugs and installed new ones to the proper torque specs so I couldnt imagine that #6 plug worked its way out. The old plug didnt have exhaust blackening on it so I don't think thats the issue.

Wiring - I have checked the wiring for the most part but have not followed it all the way to the ECU. Where is the ECU in these cars? Behind the glove box?

Thanks again for the suggestions, and keep them coming if anyone has any ideas. I'm tired of messing with her car, I want to get back to messing with mine!! lol

S197_GTvert

uce is in the passenger side kick panel and i know this is prob a worst case option but you could always compression check that hole

Nichoms

I followed the main harness and could not find anywhere that looked worn or any problems. I guess the ECU is on the passenger side up by the radiator.
I also put a multimeter on the COP connector and it was reading the same voltage and amperage as the other COP's.

I couldnt really find a good spot to measure directly off the alternator but I measured to where it connects to the battery and it was reading right over 12V. I know the battery is supposed to read 12V but an alternator should read around 14V right? Where should I measure the alternator besides the power cable that goes directly to the battery?

Thanks!

atomicpunk

Voltage should read around 12v engine off and around 14v engine running.
Another thing it could be is the crankshaft sensor. It's on the passenger side of the block by the harmonic balancer, under the air cond. compressor. I don't know of a way to test it but it's a cheap part.

Nichoms

The crank sensor is only like $25; I think your right, worth a shot! Thanks man

Also, my battery is reading 12v while running, should the actual battery ready 14v while running? If so then it might be the alternator, even though we got it load tested.

Derf00

You're getting to a point where you're throwing parts at it.

Go to the dealership, for $100 they can tell you what's wrong with it. They do a battery of tests on each cylinder to determine the EXACT cause. You say "but it's a 100 bucks!" Well, you can throw more parts at it if you like and still have the problem. Your time, your money, your choice.

Just my 2 cents having been in your shoes in the past. I prefer working on my own stuff but I know my limits and I have no shame in admitting I haven't always been able to figure out what's wrong with my cars.

Nichoms

I see your point but other than the spark plugs which were due anyways we only have $50 dollars in it right now. $35 for the lifter and follower and $15 for the injector. Almost everything has been just work and swapping parts around.

Its really odd but the injector was not working and the new injector is now working, and the lifter was stuck. So both of those items were required. Replacing the lifter got rid of all the chattering but not the SES light. So really we havent spent any money that wasnt required other than some fuel injector cleaner.

If I find out the alternator shows to be good and the crank sensor doesnt help then we might consider taking it to the dealer. But that would only be $25 thrown at a part that was not required.

Thanks for your input though.