98 Expy running rough
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From: Isanti, MN
98 Expy running rough
My friend has a '98 Expy with the 5.4(I think!) that recently started running rough. I haven't driven it, so I can't give specifics, but it's almost sounding like a misfire. He said the problem gets worse when the engine is under load, but can be heard clearly at idle.
I plugged my OBDII scan tool into it and found a P1506 code, which is an IAC fault.
I'm thinking it may be a vacuum leak, since a bad IAC wouldn't cause it to run badly under load...but I'm not sure if a vacuum leak would cause problems like that either. Any ideas?
And if it's a vacuum leak...are there any common problem areas?
I plugged my OBDII scan tool into it and found a P1506 code, which is an IAC fault.
I'm thinking it may be a vacuum leak, since a bad IAC wouldn't cause it to run badly under load...but I'm not sure if a vacuum leak would cause problems like that either. Any ideas?
And if it's a vacuum leak...are there any common problem areas?
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Joined: Jun 2004
Posts: 679
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From: Orlando, Fla
Well, I would check the line from the PVC valve to the IAC. It can collapse from age or the plastic elbows can crack. Its also fairly easy to remove the IAC and check for carbon build up. If that's what you have, some would say clean it, I say replace it, its not that expensive.
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NotMatt
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Jan 8, 2025 05:58 PM
