High idle, revving up at stoplights

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May 5, 2024 | 12:19 PM

bubbahtx

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5th Gear

Joined: Jan 2024

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High idle, revving up at stoplights

hey y’all. Got a few problems I was hoping yall could help me with. Currently driving the 95 5.8 351w. The issues is the truck is surging/revving up whenever I press down on clutch, and randomly the engine is revving up/red lining when stopped or when idling. Whenever I start the truck it always idles real low and the camber never evens out. Replacing the TPS and the IACV fixed it short term but the issue is persisting.

Last edited by bubbahtx; May 5, 2024 at 02:11 PM.

May 5, 2024 | 01:25 PM

xlt4wd90

Lead Driver

Joined: Sep 2003

Posts: 7,018

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From: SoCal

Look for a large intake vacuum leak.

May 7, 2024 | 05:05 PM

bubbahtx

Thread Starter

5th Gear

Joined: Jan 2024

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Quote:

Originally Posted by xlt4wd90

Look for a large intake vacuum leak.

i tried that. but for some reason the problem is still persisting. Do you have any other suggestions?

May 8, 2024 | 07:53 AM

Rusty Bucket Ohio

Mountain Pass

Joined: Jun 2016

Posts: 207

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From: West Tennessee

Could you have a broken motor mount that is pulling at the linkage ? Just a random thought that came to mind

May 8, 2024 | 01:50 PM

Conanski

FTE Legend

Joined: Jun 2006

Posts: 31,930

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From: Ottawa, Ontario

A vacuum or gasket leak will result in a wandering idle, but so would intermittent electrical connections. Any codes set in the PCM? Has the PCM been removed for inspection recently? Two things to look for, pins pushed back in the PCM connector and leaking electrolytic capacitors on the circuirt board, the corrosive fluid in the caps can damage other components and circuitry and result in all kinds of unusual behavour.

May 14, 2024 | 08:27 PM

bubbahtx

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5th Gear

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Quote:

Originally Posted by Rusty Bucket Ohio

Could you have a broken motor mount that is pulling at the linkage ? Just a random thought that came to mind

not going to lie, I had replaced a motor mount on this truck not too long ago… and I thought I did it right… but I still have quite a bit of wobble in the engine whenever she’s running. What linkage are you referring to?

May 14, 2024 | 08:30 PM

bubbahtx

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Quote:

Originally Posted by Conanski

PCM looks fine as far as pins go… it is loose in the firewall and does have a bit of back and forth play when I wiggle it after tightening it. I also checked the circuit boards and they’re good, no signs of corrosion or water in the connections… I replaced the TPS again and the problem seemed to correct itself for now… but I’m sure it will come back eventually like it did the last time I replaced the TPS… where would you suggest starting in the whole deal replacement? I currently have nothing connected to the intake except the air filter… took all the hoses off and plugged the lines in, which seemed to help the issue.