1999 4.2L - rough start, rough idle
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Member
Joined: Jul 2004
Posts: 10
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From: Mechanicsburg, PA
1999 4.2L - rough start, rough idle
Longtime reader, and I always appreciate the insight here, so I'm posting, hoping for some additional thoughts.
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!
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!
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
It's hard to tell how much trouble the blown belt caused.
Could have broken a sensor plug.
The idle is controlled by the Idle Air Controller.
If it sticks, it's connector is not seated etc an idle issue would be present.
Check that out next.
Good luck.
Could have broken a sensor plug.
The idle is controlled by the Idle Air Controller.
If it sticks, it's connector is not seated etc an idle issue would be present.
Check that out next.
Good luck.
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Member
Joined: Jul 2004
Posts: 10
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From: Mechanicsburg, PA
Thanks Bluegrass, I'll look at that when I get home tonight. I need to run it and listen / check the exhaust a bit more closely; Saturday it sounded like it was almost choking, like it was not getting enough air / fuel or that it could not get the exhaust out. Saw other posts pointing to the cat's (never had to mess with them, never changed them) and fuel filter (just changed it last summer). Curious to see if anything points toward either of them as well.
