P0303

[MellowedZX2]

Ok guys so here is the deal, I have been getting this rough, missing, stalling that comes and goes, (I think I could have a wire grounding out) Brand new plugs, wires and 4 different coil packs, one brand new, one MSD had for a couple years, and two stock that worked perfect when originally installed.
So I read in another post that some one replaced their PCM and this fixed thier problem. Another side note, it has a new fuel pump and filter.

Lemme know what you guys think...

Joel

[j0hnZ]

I hate to be a broken record, but an engine needs 3 things to operate. You seem to have 2 of the 3 locked down. Just for shits and giggles why don't you check for vacuum leaks...start with the pcv valve hose. I'm not saying it is the problem, but it's something to check before blowing 200-300 dollars on a new pcm. You need to check the hose all the way to the bottom of the intake manifold.

[MellowedZX2]

No I know what you are saying, I really didn't think about checking for vacuum leaks simply because it is Intermittent, plus would a vacuum leak throw a P0303 code ("A P0303 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #3." quoted from obd-codes.com) . I will take a peek at it, heck at this point it couldn't hurt.
Thanks John

Joel

[j0hnZ]

Actually yes, my car was showing misfire cylinder 2 and 3. The PCV valve hose being broken will allow unmetered air into the intake manifold forcing the pcm to add more fuel causing spark plugs to foul out. You may have to replace the plugs again...just check them before you go off spending money. Still my car was acting like it was missing, would stall and die at every stop light/sign. I checked the pcv hose and sure enough I stuck my finger in a hole in the elbow at the bottom of the intake manifold.

Replaced the pcv valve hose and it runs perfect.

[MellowedZX2]

Hmm... see she runs, doesn't die, just misses you know... still i will check it out...

Joel

[iceracer]

P0303 says cyl. misfire on cyl no 3. So that is where you start. First thing would be to check the spark plug connector to see if it seated properly.

[mechtech]

Those plug wires have to be on right. This tripped me up once. I thought it was on OK, and it wasn't [also #3 seems o be the one people screw up on].
Does damp or humid weather have any connection? Wiring will respond to this.

[j0hnZ]

It could be not seated down all the way. Other then that he's changed them I don't know how many times it seems.

[MellowedZX2]

Guys I appreciate the insight, but yeah I have went through 4 coils and two sets of plugs, I have swapped the #2 and #3 wires and it still seems to be the same thing... I know they have to be seated all the way and I know you have to be careful, I have bent a plug wire in the past from trying to get them to seat the best way is to pull the clip back down on the wire seat the boot and then clip it.

Much thanks, I think there are some wires I am going to look at, and some connections I am going to upgrade to solder instead of butt connectors.

Keep the Ideas coming, they are all welcome...

Joel

[j0hnZ]

Well if you want to go the route of changing the PCM hopefully there is a zx2 guy down there who can let you borrow it for a test or something. I still say check for vacuum leaks.

[MellowedZX2]

Hey John, I did check for vacuum leaks I forgot to add that to the other post, I found none... I will continue the search.

Joel

[Tygen1]

So what plugs are you using. You gotta run the Motorcraft plugs, this caused the same misfire on mine as well when I tried some Bosch plats. Oil Leaking into the gallery has also caused a misfire.

[ZX2Fast]

This issue can also be caused by a bad injector. The last time my wifes car misfired it was just a bad plug wire. I misted them with water in a dark parking lot and I was treated to a fireworks show.

[MellowedZX2]

The Car has the motorcraft platinums, So i found the culprit, the wire or the plug on the #3 injector is the cause. I don't know exactly what the problem is but I adjusted the wire and it is fine no problems at all... So when I get some spare time at home I will look at it more in depth.

Joel

[mechtech]

Like I mentioned before - it's odd that it usually turns out to be #3.

[MellowedZX2]

Not the spark plug wire, the actual injector wire... I wish it was the spark plug/wire that would be much easier...

Joel

[ZX2Fast]

Guess I was right. The wire could have corrosion inside.