2004 Engine misfire and flashing check engine light

[fg1911a1]

Good Morning,
I am getting very frustrated with my 04 turbo cruiser. This vehicle has been back to the dealer four times for the same problem. The problem is a number four cylinder misfire. To date the dealer has told me the following:
1. Needs tune up. Dealer replaced plugs and wires.
2. Needs PCM. Replaced PCM.
3. Might need ignition coil.
The first time, the check engine light came on again after about 4 miles.
After the PCM was replaced (I had to wait two weeks for the part) the light
came back on after about 2 hours.
I have not change the ignition coil....should this be my next step.....I live in SC and it is very hot here.....could this be a "heat related" issue with the coil?
Thanks for your help.

[CREWZIN]

Welcome to the forum,

First, we've been told that you shouldn't run the car if the engine light is flashing. That's from a mechanic on the forum. To quote exactly what he said:

When the check engine light flashes, it means there is a severe drivability problem. For instance, say you leave your gas cap off or your cam sensor were to fail. The light would come on solid.
However, say you had a single or multiple misfire which could lead to engine damage if you were to continue driving. The light would come on and flash.
NEVER drive or allow the engine to run with a flashing check engine light!

The coil, to my knowledge is one of the last things to look at. 99% of the time, all the misfires and problems are something else. Has anyone looked at a vacuum leak around the No#4 cylinder? There have been cases where the upper manifold or other part has had a small leak and caused the code your getting.

Are you paying for the parts that the dealer is throwing at your cruiser? Hope not.

[fg1911a1]

Thanks for the information.
First, Yes.....paid for it all.....except for the PCM which was under warranty.
No, I do not believe they check for a vacuum leak. I paid $109.00 for their
troubleshooting and the only thing they told me was the PCM was bad. Is this leak something I can check with some soapy water or spraying wd40 in the area?
Thanks again.

[CREWZIN]

Yes, that's what some of the owners say to use. I've never tried it myself. Seems a bit messy and I'm a clean freak when it comes to keeping the engine clean.

[fg1911a1]

Yes, Understand.....I like things to look nice also....but right now, I just want to fix this stupid light and rough idle. You would think the dealership would know what they are doing.....and this is the foreman that is working on it.

[CREWZIN]

Before you go too far, here's some reading for you.....

Error Code P0304 Cylinder 4 Misfire Detected

05 PT Cruiser. 60,000+ miles. Cylinder #4 misf... - JustAnswer

PT Cruiser 2.4 Check Engine Light PO300-PO302

Error Code P0304 Cylinder 4 Misfire Detected

P304 misfire and loud noise

[fg1911a1]

Thanks for the reading. Seems like a common problem with no clear answer.
I will try the wd40 on the intake.
Thing is, the car runs great....just rough and idle and the CEL.
Also, sometimes the light is off, sometimes it is on solid and sometimes it blinks.
Seems to indicate an intermittent problem.....this is why I was thinking along the lines of a heat related issue in the electrics....coil, plug breaking down....
Maybe some electricians tape over the CEL.....??? LOL.

[quicksilverdon]

# 4 missfilre is quite common - spray WD-40 at lower intake joint - where it meets head - if idle smooths out, it's the lower gasket.
Coil impacts 2 cylinders at a time and is usually very reliable.
Since they did plugs & wires, that shoukd be okay - that's the usual cause.
Only other cause is a clogged injector - try some lucas fuel injection cleaner.

[fg1911a1]

Thanks for the input. I will try that. Question, wouldn't it run rough all the time with a leaking intake?

[quicksilverdon]

If you read the posts, those who had leaky gasket said it ran fine at speed - it was idle problems.