Hey all. Spent ALL DAY yesterday (finishing at 10:30pm) working on the car. Fixed a few minor interior things, installed a new dogbone, and replaced the valve cover gaskets. After the gasket replacement (also did all the plenum gaskets as well), we're having an idle issue.
On start, in park, car revs up to about 1500 and stays there (even when warm.) Driving around it seems fine, idle sounds the way it normally does. As soon as you park again, idle goes back up. I've read most of the posts here about vacuum leaks, the IAC and the EGR. I don't want to do an EGR delete, but the propane method for testing for leaks seems scary. Is there a way to test for a crack in the EGR without pulling everything back out?
Another post said that the computer won't reset until you get above 35 MPH, which explains why the car was <b>originally</b> idling around 2k rpm but then dropped after running around and doing some "test the car out" errands. It seems like the IAC reset after the higher MPH, but still isn't quite right. The threads say to plug the IAC hole with a finger to see if the car dies. Where's the hole? Inside the throttle body? I want to try this test to see if we have a vacuum leak -- evidently if it's a vacuum problem the car will stay running, even with the IAC hole plugged. If the vacuum system is solid, the car will die, correct?
On the bright side, acceleration now is freaking AWESOME. That dog bone swap was great, no more shudder as you speed up. =D
Unless you have leaking plug wires, you don't really have a problem using the propane test. You can unscrew the mixer tip on the end and slide a length of rubber hose over the tip. Lightly open the valve and pass the end of the hose around joints and lines. I would look at the EGR tube and the gaskets, again. This is assuming you took the upper intake off with the tube, throttle body and EGR tube attached. Check other hoses like brake booster for clamps that might be loose.
The idle air port is inside the throttle body. It's at the bottom of the venturii.
Thanks Fierofool! I'm going to spot check the EGR tube, we left it attached so we likely cracked the little bugger. Going to disconnect the upper plenum again anyway and make sure the lower is nice and tight. I'm getting a super high pitched whistle coming from the engine, it sounds like it's coming from under the plenum (which makes me thing EGR is a good possibility.) Want to make sure I tightened the lower up enough, though.