Need 924 help

[Mudd]

I posted this on the 924 site but got no response.
My 1978 924 revs to 2000 rpm after it warms up. What is the first thing to check. The car has 18,200 miles and other than the fast idle and no heat it runs pretty good.
because of the low miles do you guys think some Seafoam in the gas tank is a good idea.

[Dave Colangelo]

If the car has that few miles than it was most likely sitting for a very long time. This leads to the rubber parts degrading. Take a look at your vacuum lines, you may just want to replace them, they are cheap and easy to swap. Your fuel lines may also have some hair line crack, dont know if this would contribute to a faster idle but its worth checking out. I had some issues with the idle on my 924S a while back. New spark plugs, rotor and distro cap and a fresh air filter did wonders to flatten things out. I also pulled the throttle body off and cleaned it out really well. Im not sure about the 924 but the 944 throttle body had a little hole that goes around the main plate (mine was clogged and cleaning it out made a big difference). Also check out idle set screw.

Regards
Dave

[redstrosekNic]

+1 on running seafoam in the gas. Check for those pesky vacuum leaks too!

[Rasta Monsta]

For any CIS car, the first steps are to eliminate vacuum leaks, and then obtain the proper tester to check system and control fuel pressures (link explaining fuel system is HERE.)

If pressures are within spec, I would then check ignition timing and AAV. If those are within spec, I would check whether someone messed with the throttle stop, but this is a last resort.