3.4L V6 with High idle
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Joined: Sep 2017
Posts: 18
From: Oklahoma
3.4L V6 with High idle
From what I'm to understand from talking to friends and a couple local mechanics, this is a common problem with the 3.4L? Getting it second (or third or fourth, haha) hand makes pin-pointing the issue annoying as hell.
Replaced the IAC valve, the TP sensor, PCV is still good (and wasn't even hooked up, but plugging the hose back onto it didn't solve the high idle issue). Nothing I've tried has! I want to say there's a vacuum link somewhere, but I can't find it. Is there something back behind the plenum that's notorious for this issue? I've already got a new plenum gasket on the way as one mechanic suggested replacing it as the probable source of the vacuum leak (that's also hard to check for/hunt down with carb cleaner).
Any additional input, or requests for more details, are more than welcome!
Replaced the IAC valve, the TP sensor, PCV is still good (and wasn't even hooked up, but plugging the hose back onto it didn't solve the high idle issue). Nothing I've tried has! I want to say there's a vacuum link somewhere, but I can't find it. Is there something back behind the plenum that's notorious for this issue? I've already got a new plenum gasket on the way as one mechanic suggested replacing it as the probable source of the vacuum leak (that's also hard to check for/hunt down with carb cleaner).
Any additional input, or requests for more details, are more than welcome!
Thread Starter
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Newbie
Joined: Sep 2017
Posts: 18
From: Oklahoma
Okay, here's an update for everyone. I replaced the plenum gasket (did my valve cover gaskets while I was in there) and got everything put back together. Engine seems to run a lot better, but it did not solve the high idle issue. Still wants to idle at 2k in park and neutral. Drops down to about 1.2k in drive.
The prior ownder(s) removed the catalytic converter and bypassed it with some pretty sorry looking welds that have blown out in places. I went to town on them with muffler tape to rule out an exhaust leak for the increase in RPMs. Sounds a lot better, but it didn't make a difference on the idle.
A tertiary note. The heater core has been bypassed at some point and I think I'm missing a couple of coolant lines/hoses. The throttle body has one single hose closing the loop on the throttle body coolant line. It's not connected to anything! I see in other pictures that the 3.4L TB has two coolant hoses running off of it, but I can't see where they are meant to be going in the pics I find on the internet.
The prior ownder(s) removed the catalytic converter and bypassed it with some pretty sorry looking welds that have blown out in places. I went to town on them with muffler tape to rule out an exhaust leak for the increase in RPMs. Sounds a lot better, but it didn't make a difference on the idle.
A tertiary note. The heater core has been bypassed at some point and I think I'm missing a couple of coolant lines/hoses. The throttle body has one single hose closing the loop on the throttle body coolant line. It's not connected to anything! I see in other pictures that the 3.4L TB has two coolant hoses running off of it, but I can't see where they are meant to be going in the pics I find on the internet.
Thread Starter
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Newbie
Joined: Sep 2017
Posts: 18
From: Oklahoma
Buddy borrowed the OBD scanner and never managed to return it!
Either way, I got the issue fixed. Turns out it was the IAC valve. Thought I had the bindle out far enough, but apparently not. Took it off, pulled it up a few more millimeters, and now my idle is back to where it should be. Stupid IAC valves.
Either way, I got the issue fixed. Turns out it was the IAC valve. Thought I had the bindle out far enough, but apparently not. Took it off, pulled it up a few more millimeters, and now my idle is back to where it should be. Stupid IAC valves.
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