PCV issues

[brinx182]

1989 c1500 5.7 tbi
I’m fighting a high idle issue and I’ve sprayed carb cleaner all around the intake manifold, throttle body gasket, and all hoses under vacuum. I think the culprit is my PCV valve. I have a new one installed and it’s functioning properly. The stock hose has no leaks but at idle the right angle portion that connects to the throttle body collapses completely and partially pulls my pcv valve out of the cover. Would that cause an idle issue? Also is the PCV valve supposed to have a gasket between it and the valve cover? Thanks for any help you can give.

 

[RawbDidIt]

1989 c1500 5.7 tbi
I’m fighting a high idle issue and I’ve sprayed carb cleaner all around the intake manifold, throttle body gasket, and all hoses under vacuum. I think the culprit is my PCV valve. I have a new one installed and it’s functioning properly. The stock hose has no leaks but at idle the right angle portion that connects to the throttle body collapses completely and partially pulls my pcv valve out of the cover. Would that cause an idle issue? Also is the PCV valve supposed to have a gasket between it and the valve cover? Thanks for any help you can give.

It would cause it to run lean, especially at low rpms. Stands to reason more air = lean condition = more fuel sent from ECM = high idle. Even if that ain't the problem, it's a problem, and a cheap and easy one to fix. Auto zone has the PCV hose couplers available and they're so cheap, i don't remember how much they cost. $5 even sounds high to me.

Normally I'm a pretty big fan of looking at the data, but I think you can wait until after you fix the obvious problem before you look at the data here. The only thing you're going to do is confirm there's a vacuum leak until you get it fixed. After you've replaced the boot, attach vacuum gage and make sure that's the only issue.

On my 1997, I don't recall a gasket between head covers and PCV, not sure how it is on TBI

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[PlayingWithTBI]

On my 1997, I don't recall a gasket between head covers and PCV, not sure how it is on TBI

TBIs have a "D" shaped rubber grommet in the valve cover in which the PCV valve goes, on the passenger side. On the driver's side there's another grommet that has a tube which goes to the TB spacer to vent the crankcase too. The PVC is hooked to the bottom center plate of the TB and gets engine vacuum. The other vent tube is at atmospheric pressure since it's above the throttle blades of the TB. Older engines just used a vented air filter but, TBIs sucked it back into the intake to reduce emissions. You need to have both to properly breathe.

 

[RawbDidIt]

TBIs have a "D" shaped rubber grommet in the valve cover in which the PCV valve goes, on the passenger side. On the driver's side there's another grommet that has a tube which goes to the TB spacer to vent the crankcase too. The PVC is hooked to the bottom center plate of the TB and gets engine vacuum. The other vent tube is at atmospheric pressure since it's above the throttle blades of the TB. Older engines just used a vented air filter but, TBIs sucked it back into the intake to reduce emissions. You need to have both to properly breathe.

Good to know, thanks.

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