Every time I take my car to the wash as soon as the front end gets wet it starts to get engine shakes and shows a check engine code p0304. Then I turn off the car once I get back to my house I turn it off and an hour later it's fine the engine lights goes off after I drive it for awhile

 

Something electrical is not liking getting wet. Wash the car then open the hood and look for water intrusion on an electrical connection or coil pack.

Could be a vac leak too.

 

Well I was changing the fuel filter and notice that the driver side fog light is melted out of the housing and the bulb is just sitting outside of it I'm thinking that might be it but I don't know why it would mess up the engine like that

 

That's probably a 2nd fault. Your first is as the other poster said.

 

What model vehicle?
Which engine?
What year?

 

Yup, water getting in.. It happens in different ways on different years... Please update your signature with "car information".

Circuits are shorting out from water intrusion... Better get it tidied up before a quirk becomes a failure...

 

LOL! Dueling posts!

 

Can you recreate this in your driveway with a water hose? You can pin point the area of the fault.

 

Great minds think alike??

It just so happened I had the faster fingie on the enter button today

 

It's a 2001 s- type 3.0.

 

Classic case of a cracked coil on cylinder 4.

It only takes a near invisible hairline fracture in the coil to become sensitive to humidity.

Let us know!

 

well if thats true then swap coils on 4 and 5(4 is the front cylinder on the drivers side for left hand drive) theyre right under the cover and 2 8mm bolts. Take it back again and see if it repeats but move to #5. Ide place a bets that the pollen filter box is clogged with leaves where water drains out and is the getting too wet on the ecu right underneath it. At least thats my first thing to look at. Take off the wipers, the wiper cowl and next to the pollen filter is a drain opening close to the fender. Make sure its cleaned out since it collects alot of leaves and debris over the years, esp a 10yr old car. Also make sure the wiper cowl snaps back down onto the base of the windshielf since its purpose also is to stop water from just running down into the engine compartment and directing over to each side drain.

 

I had a similar problem that was intermittent and aggravated by rain on my own 01 3.0. The wiring harness was frayed by contact with the fuel connection guard. Take a look there just in case.

 

Good point with the clogged box and with the coil swap on cyl 4/5. I just did the coil swap (for a p0304) a few days ago and the code followed the coil (became p0305) in about a minute of run time.

I was guessing the coil because the symptoms were mentioned only along with car wash bay's, not rain or hose and because I just had this senario on my father's 2000 3.0 last week. His symptoms (p0304) were only present after humid car washes as well. Niether rain or hose could duplicate the misfire.

As a side note, when we were testing for the misfire, I was using carb cleaner to test for vacuum leaks as a possibility. None were present, but the carb cleaner cleaned the residue from outer surface of the coil packs and as a result, the misfire increased from occasional to persistant. With the residue gone, we could see a nearly invisible hairline crack in the coil.

Anyway, hopefully all of our different ideas are a help to vega1 chasing down his misfire. I have become dependant on the info. in these forums for backyard diagnostics

 

Jumped on this morning to help.... But all I can say now is....
^^^^^^ What they said ^^^^^^^

 

I cleaned out the drain openings and still having the problem must be something else what about the light I was talking about in my other post

 

^^^uh. No
i thought you said the problem moved with the coil??

 

No that was someone else but I'm going to change the coil pack today I just need to know which one is 4

 

Brutal already told you

 

It moved to three now