Car idles at 1500

[Roland69]

We have one of Theese at work and it's awsome for finding any kind of leak...but it was a few grand to buy. I just used it today to find a small exhaust leak that we couldn't find by ear or feel

 

[v8only]

soak every damn square inch of the motor with carb cleaner, and every square inch I do mean. if it doesn't effect the idle at all, you have no leak.

 

[leathernotch]

I just got done fixing a problem identical to this. I have a gt40p explorer motor, and I had to hog out the mounting bracket on the two holes to move the bracket up higher to clear the taller valve covers. hogging the holes caused the bracket to move backwards too toward the firewall when I tightened it. As a result I would turn the idle screw all the way out, but it wouldn't idle under 1500 or so because the screw wasn't touching the plate. I loosened up the two bracket bolts and slid the plate forward, which caused the plate to contact the adjustement screw, and fixed my problem. Not sure if yours is a similar deal, but worthy of throwing out there for sure.

I have an 1 inch spacer so I don't know if the last owner did anything like that but I will look into it.

What about the rockers if they where all too tight would it cause this??

 

[leathernotch]

UPDATE: w/ the IAC unpluged and the idle screw completely in all the way towards the firewall the car idles at 1400, I just dont get this at all

 

[v8only]

is the plate up against the backing screw when you back out the screw all the way?? try pushing backwards on the throttle plate toward the screw, toward the firewall and see if the idle comes down.

 

[leathernotch]

I am not sure but the car idles the same with the cable taken out or disconnected

also the car idles correctly when I start her cold w/ computer reset but only for a few min till she is warm

 

[HISSIN50]

How is the cold idle versus your hot idle? The IAC might not be doing anything or be stuck partially open. Your car would idle ok cold, but it hoses your hot idle.

My experience with it is that I've had to do roadside repairs on cars with bad IAC's and the solution was to introduce a slight vac leak at the TB. This kept the vehicle from stalling until the issue could be fixed.

If you want to check the hard parts for a vac leak: seal all vac ports (block them off) except for one, which you connect a vac gauge to. Disable the ignition and fuel system and crank the car. You should see 3-9" hg on your gauge. If the reading is near zero, chances are there is a leak between the plenum and lower intake, etc.

Good luck.

 

[leathernotch]

Got the idle to 1000rpms and the vac read 10 so I guess its a leak going to tear the topend apart and figure it out.
Thanks

 

[jrichker]

There have been several instances of lower intake manifold gaskets slipping out of place while the manifold is being installed. The result is a vacuum leak between the manifold flange and the valley between the heads.