An inexplicable fast idle - 230SL

[[CatchMe]]

Hi all

My 230SL has me flummoxed and my maiden post here is in desperate need of some troubleshooting advice.

Today I performed some basic maintenance on the 230; a compression test, cleaned up the plugs, inspection of the ignition leads and greased the suspension.

Once done the car instantly fired up but idled at 2500 rpm, yet it was fine as recently as last night. Half an hour later and it's still a problem.

The ignition leads all tested fine and i haven't disturbed the vacuum line to the distributor when taking the cap off and back on.

Where should I start? Is it possible in doing the  compression test (with fuel pump and coil disconnected) Ive upset the cold start system?

[Tyler S]

Did you adjust your ignition timing or inadvertently bump the distributer during your work?

[ja17]

Yes, as Tyler suggested, take a look at the timing.  Make sure the vacuum mech. in the distributor is hooked-up and working properly especially if you have a vacuum retard distributor. Next check the engine linkages to make sure the intake venturi valve is closing all the way.

[[CatchMe]]

Thanks both, I disconnected the injection pump linkage to give better access to the plugs. I'll start there tonight.

[[CatchMe]]

And all fixed. Sure enough I had ever so slightly misaligned the tube that holds the ignition leads, and supports the control linkage. 2 or so mm was all it took to raise my cold idle by more than 1000rpm.

Lesson learned - being take a breath, slow down and pay attention! Thanks all.