XJ6 SIII, idle adjustment

[dvr]

I would like to turn the idle down a bit. Can't seem to get an allen wrench on the adjusting screw. What size is it? Best tool to use. Which direction to turn to lower idle?

Thanks Guys!

 

[jessebogan]

It is something weird like 5/32.You may have to trim a longer one to fit, I use a cutoff wheel, as they are made of well... tool steel. Turn the screw "in" to lower the idle. It is just an air passage. Look for vacuum leaks if the idle has changed....Once you find a size that fits, you can use an appropriate 1/4 drive flex socket to turn the screw.

 

[dvr]

Just a follow up... The adjustment screw appears to be loose in the hole and doesn't want to screw in. Plugging the hole does not change the idle. The engine still has a high idle. I have checked and replaced all vacuum lines. Could this be causedby an exhaust leak? Also, 02 sensor is new.

Thanks

 

[Deleted member 8987]

I would also want to inspect the throttle plate and bore. Look for wear on the shaft or bushings (moves up and down, in and out), and see if you have a bunch of buildup in the bore that needs to be cleaned.
Had a TR8 yesterday with that issue....not buildup, rather throttle plate not quite centered, rubbing on the bottom slightly, holding the idle up to 1200 or so until you manually pulled the throttle shut, then 750.
Dave

 

[DrEntropy]

Not likely an exhaust leak affecting idle. Check all the pivot points as Dave suggests, then get a spray-bottle with water in it and spritz all the joints in the intake plenum while listening for idle change. An open-ended stethoscope is useful to generally locate any vacuum leaks as well. The "idle screw" issue is odd. As Jesse stated, it is actually an air bypass. But it shouldn't be that loose. Has the bypass p'raps been plugged by a DPO (due to having wallowed out the set-screw)?

 

[Michael J.]

Check the condition of the rubber hose connecting the idle adjustment block to the base of the throttle body. Check the hose for the electric Auxillary Air Valve to the intake manifold.

There is a vacuum line that connects to the underside of the intake manafold.

Make sure that the two screws that mount the cold start injector are both tight.

Check the vacuum hose to the distributor.

 

[Michael J.]

One other thing to check, there is a cam and roller effect for the Kickdown cable where it hooks to the throttle. Spray some WD-40 to see if it is binding and work the throttle several times. I had several incidents of that cam binding that caused high idle.

 

[Exotexs]

the allen wrench is 7/32nds. and you need to bend it like an inverted "bow" to reach the hex set screw. Turn it clockwise to close the air flow.