Adjusted screws, Great idle, Drove smooth, got back & idled too high

[Redsquall]

It was doing great after I reset the two adjustment screws (idle and microswitch) and the CO mix–I drove it and I was very surprised how smooth it sounded and much quieter... and just worked great –when I got back after going about 3 miles it went from idling before I left at around 800 to idling around 1200. What would cause that?

I then proceeded to adjust the CO and idle screw, and it did not nearly Idle as good on the second test run– Very jumpy and low, louder exhaust sounds. I'm tired of messing with it and giving it a break. I plan to reset the idle screw again and try to get the CO back to where it was when it was smooth. Suggest anything different?
Also, has anyone put together a clear and detailed tuning procedure?

[Bitsyncmaster]

If your adjusting the mixture for best idle you will never get things running right. Do you know if your Lambda system is even working? A dwell meter reading the FV duty cycle will tell you if it's working and let you adjust mixture to specification.

[Michael]

Chances are almost everything is out of whack at this point. If a DeLorean is running great and then all of a sudden it's not, the LAST thing you do is start turning screws, especially the mixture adjustment. Doing it without a Dwell meter will guarantee you 42 miles off base whether you count turns or not.

Something other than a screw turning by itself caused your car to run poorly.

[kings1527]

Echoing what's already been said but also you may want to double check that the microswitch screw is indeed adjusted correctly and activating the microswitch each and every time with that little "click" as it engages. I've had mine adjusted just a bit too high before where sometimes the microswitch would engage and sometimes not. Needed to be lowered just a tad.

[sdg3205]

Yes, you can't just start tweaking the idle and mixtures screws and hope for the best - thats just not going to happen.

Chances are you may need to actually adjust the length of the throttle arm between the butterfly assembly and the spool. Engine vacuum can hold open the butterfly just enough to prevent the idle micro switch from being engaged, and you wont know it until you blip the throttle for the first time.