New member, but longtime reader... looking for some thoughts / help.
I have a 99 4.2L automatic, all stock, with 215k miles. My oldest daughter was driving it (mistake #1) and said it started running rough out of nowhere and sounded like it had a huge air leak under the hood. I had her bring it home and park it; turns out the Serpentine belt had broken longways - there was still a thin belt on keeping things running, but probably about 1/3 of it was gone, and I found some shreds of it under the hood. I also found the PCV valve popped free from its rubber grommet, but still attached to the hose.
I cleaned up the grommet and PCV and reinserted it back, replaced the belt, and it ran terrible. It revved real high and low and struggled to stay running; I also noticed the alternator was squealing and very loud. I replaced the alternator which quieted that, but the idle was still up and down, revving high then low, and the exhaust had a putt-putt sound like a golf cart.
I drove it to get some gas and drove it around for 5-10 miles; it never threw a code, but it still does not sound right and does not accelerate well or idle well. I do not hear any hissing that sounds like an obvious vacuum leak (and I had just spent $250 a few months back replacing some hoses and 2 sensors).
Looking for the inexpensive tests / solutions, or a series of things to try before I head to the mechanic again. I'll try to answer any additional questions if it will help narrow the focus. Thanks!
Your 99 with the PCV valve and grommet is completely different than my 02. That being said, I would continue to inspect for intake leaks, the surging idle warrants that, plus the PCV valve being dislodged by the shredding belt parts is the area to concentrate on. Follow the line routing from valve to intake, don't assume or overlook anything. The IAC is trying to compensate for the presumed leak. Could the belt have dislodged any plug wires? Keep us informed.
Thanks for the thoughts Bill. I'm not sure if the belt and the PCV have a physical relationship or not - that is, I don't think the belt pieces knocked it off. I wondered if because the belt was compromised, if it would cause the engine to not be able to operate correctly and that created a pressure buildup, like a backfire, that popped the PCV out of its hole.
When I first started it after she brought it home, you could hear it sucking loudly with that vacuum leak; once I reinserted the PCV, I did not hear any other air leaks. I looked at the plug wires and they all appeared to be fine. When running, it sounded like it was almost choking, like it was not getting enough air / fuel or that it could not get the exhaust out. I have read other posts pointing to the cat's (never had to mess with them, never changed them) and fuel filter (just changed it last summer), so I am curious to see if anything points toward either of them as well.
"I'm not sure if the belt and the PCV have a physical relationship or not - that is, I don't think the belt pieces knocked it off. I wondered if because the belt was compromised, if it would cause the engine to not be able to operate correctly and that created a pressure buildup, like a backfire, that popped the PCV out of its hole".
The belt drives the accessories, AC, PS, Alt. and water pump, I 'm leaning toward the debris causing the issue, not an engine burp or backfire.
Okay... after I got home last night, I started the truck. It turns over fine, but the initial idle is real low, to the point of stalling out, which it did the first time. I refired, low idle, then fast idle, then low-fast-low-fast, like it was riding a roller coaster. There seems to be a good flow of exhaust from putting my hand back there while it was running. I couldn't get a good look under the hood because it was getting dark and I did not have good light outside.
As I think about it more, I'm wondering now if the debris from the belt did other damage - like wiring / connectors for the IAC or TPS?