Dedicated LVC Member
Jun 15, 2007
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So, last Saturday the car started idling rough, and frequently missing unless I drove it like I stole it. No biggie, I thought. Coil or 2 on the way out, I'll just buy a couple and change one by one to find it. I found 2 coils in the garage today after work, so started in. Changed cyl 4, seemed to run a tad better. Took it for a test drive, and the cel came on.

Pulled into a liquor store, scanned the codes with the xcal. P0102, and P0304. Changed the coil back out in the parking lot, cleared the codes, and picked up a bottle of vodka.

Drove back home. Still the low idle like it wants to die, but doesn't. Cleaned the MAF, no difference.

Wondering if I should try a different MAF, or something else. I will add that every couple/few seconds, their is a different noise coming from the air intake. Almost like the amount of vacuum is changing. Just for a split second. Cannot remember if that was there before.

All were changed a few months ago. Visteon coils, ngk plugs.
Well what are the codes reading? If plugs and could are ok then maybe your throttle body. I would replace maf first. It's cheaper
not sure if you checked for easy stuff: loose clamps, dirty filter, etc., leaks around the MAF. just curious, what did you use to clean the MAF? cleaning the throttle body wouldnt hurt, make sure you use the teflon-safe variety (CRC makes some) since the throttle body has a teflon coating.

people here will disagree, but if it was mine, i would disconnect the battery to clear the old specs and run a proper breakin for the battery and a drive cycle. it wont kil ya either way. it may just be that it was never properly calibrated with the new/cleaner sensor/coils/plugs and its just slightly throwing off the idle.
what is 0304, i did a casual search and got nothin..
0102 says maf issue..
0304 is just for misfire on cylinder 4. the coil i found in the garage must've been a bad one. i used maf cleaner on the maf. i think i have a spare one around, actually. probably swap that out tomorrow.
Changed MAF with the used one I had. No difference. I'm going to try disconnecting the battery overnight and see what that does.

Really not expectng anything to happen then, but it's free.

Forgot to mention, I can smell fuel when I start it up. Seems to be running rich.

I may clean the TB this weekend. Can't hurt. But I'm not sure a TB problem would cause it to smell like it's running rich.
Check for a vacuum leak.

Not a bad idea. The hard plastic vacuum lines become brittle and break. Had that happen on my '06 when I removed the TB for cleaning. There are no replacement parts so you will need to make your own harness using vacuum line and connectors.
yeah vaccuum check would prolly be my next stop.
i had a mis on one cylinder last yr and had to re-do all the coils. mine was going into limp and throwing throttle codes. I dunno, i would run the stress test on the coils. they sound new but they could be bad. i highly doubt battery disconnect is going to cure it. but i would def. do one after new coils are installed.
Vacuum check revealed no issue there. Brought it to the shop. Bank 1 is giving a lean code, which is why it's dumping more fuel into all 4 cylinders on that side. Going to pick up a new o2 sensor (bank 1, sensor 1) in the morning and try that.

I'm not convinced that's the issue. I'm worried about PCM wiring for some reason.

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