Hello All. I swear I've posted here before, but can't find or retrieve my login to save my life so I've registered again.

Got an '01 V6 Tribute that had a pretty significant accident about a week ago. Bashed in the front left corner hard enough to need a fender, bumper, headlight and radiator. Saved the hood. Insurance company totaled it out and I'm buying it back as a salvaged vehicle.

Spent this weekend pulling and hammering the metal back into shape sufficient to put on new aftermarket parts. Not going to win any shows but it looks better than I'd hoped.

Even right after the accident (I drove it home about a half mile) I noticed the idle was rough. It seemed to seek a little as well (idle lumps up, then down, etc).

Now that it's back together and I'm driving it the problem is pronounced. It idles fine for thirty seconds or so. Then I hear some vacuum-type servo cycle (kind of a whoosh-thump sound like a diaphragm closing, possibly somewhere under the air cleaner?), and the idle jumps for a second. Or, idling at a light, it bogs down for a second and then recovers. It hasn't stalled yet, but after an hour of highway driving I did finally get a check engine light. Plugged in the OBDII and got DTC's P1131 and P1151. If I understand correctly these essentially mean cylinder #1 misfired for some reason probably related to a lean mix, and that in an engine where nothing else had changed I should probably check the O2 sensor(s). I also see "check for vacuum leaks" listed: this seems likely to be my problem, frankly, and I haven't spotted any obvious culprit (like a hose hanging loose), but MAN that answer bugs me. Worse than "Have you tried rebooting?" But I digress.

I should also note that the air cleaner took a good whack. There was a tube leading from the radiator bracket to the cleaner intake, that included what appeared to be some kind of resonator champer. The tube and chamber got smashed pretty flat, and the sheet metal where they mount is, uh, no longer stock. I didn't put them back in. Is the fresh air side of that air intake critical enough that removing those might cause this?

So I'll keep staring at it and wiggling hoses. But for here I have two questions. Anyone know enough about the air intake system to know if that tube/chamber is critical? And anyone know what device that whoosh/thump might be coming from?

Hope to hear from you...

Randy in Sunny Seattle

 

I'm leaning away from a vacuum leak for a couple of reasons.

The problem doesn't occur when the engine is cold.

And the gas gauge now always reads full.

I'm guessing something electrical got whacked in the accident.

Is there some electrical/vacuum servo that might have an iffy connection, that would cause the idle to change if it lost signal?

Tried disconnecting the air flow sensor for a hoot, while it was idling and rough. The idle definitely changed.

Anyone got any thoughts on this?