High searching Idle

[jss06c6]

Ok, that's clearer..

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[jss06c6]

Old one on the bottom, new one on the top..[ATTACH]

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[jss06c6]

Put the new PCV connector on. Guarantee no leaks there! It's darned tight! Fired up the engine. High idle 1300 rpm, until closed loop kicked in. Dramatic swings in AFR as fueling was dithered. Finally settled down at full coolant temp (193F). Idle still sits at 1175 versus commanded 750. IAC locked at 0 trying to adjust idle to commanded. Verified IAC working. Stepper motor kicked in at 1325 room (4), then rises with increase in rpm. Now suspect something went wrong in the TB. I'll put a borescope under the plenum just to make sure no other vacuum connections are off. Then I'll pull the bellows off and use the borescope to look closely at the TB blades during idle and increasing rpm.

Steve

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[A26B]

Sounds alot like the MAP hose. Off, broken connector, or plain rubber line with low point oil collection in low point. The rubber connectors on each end of the hard plastic pipe are prone to tear due to age. If you can reach, remove the MAP hose from the plenum barb & put your finger over the barb to see if the high idle is due to the MAP hose.

The lower dual PCV hose in mine (94 w/57k) was rock hard on the side towards the firewall & completely rotten on engine side.

[XfireZ51]

Originally Posted by jss06c6

Old one on the bottom, new one on the top..[ATTACH]

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U can easily see how out of shape the old one is v the new one.

[jss06c6]

Originally Posted by A26B

Sounds alot like the MAP hose. Off, broken connector, or plain rubber line with low point oil collection in low point. The rubber connectors on each end of the hard plastic pipe are prone to tear due to age. If you can reach, remove the MAP hose from the plenum barb & put your finger over the barb to see if the high idle is due to the MAP hose.

The lower dual PCV hose in mine (94 w/57k) was rock hard on the side towards the firewall & completely rotten on engine side.

Jerry,

The MAP hose is not off, nor broken. Checked that again this morning. The connections are tight, including the 90 degree fitting on the bottom of the MAP sensor. I'll pull it to make sure it's clean however.

I also checked the PCV hose while replacing the top fitting. Pliable and tight. No issues that I see there.

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[jss06c6]

Originally Posted by XfireZ51

U can easily see how out of shape the old one is v the new one.

Yes, agreed, but replacing it had no effect on the problem. Going to check under plenum with borescope for all the usual suspects and check the TB as well.

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[Ccmano]

At the risk of stating the obvious. You checked both MAP sensors, right?
H

[XfireZ51]

Originally Posted by jss06c6

Yes, agreed, but replacing it had no effect on the problem. Going to check under plenum with borescope for all the usual suspects and check the TB as well.

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Have u done the ole 3ring binder in front of the TB trick yet?
Could point to either vacuum leak, or TB issue.

[jss06c6]

Not yet but definitely part of the diagnosis..

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