80 3.0 cis surging missing
 

My 3.0 is surging when I start it cold (for about 30 seconds), and when its warm (after sitting for a few minutes.) Also misses at a constant speed ie. Any ideas? Ive replaced: cap, rotor, plugs, wires, coil, injectors. Messed with: timing, air/fuel, idle. What do you all think? Warm Up Regulator? Cold Start Valve?
Any help would be much appreciated.

I have a very similar problem with my 2.7L. On cold start my idle searches (surges) until car is completely warmed about 20 minutes or 190 degrees. Idle searching will begin to taper off then. I have replaced accumulator, fuel filter, thermo switch, fuel injectors, adjusted co.

:confused:

Have you tried unplugging the O2 sensor? This won't explain your cold start problem (O2 sensor does not function until warm), but has been known to cure warm idle "hunting". On K-Lambda CIS you do no harm by disconnecting...the O2 sensor system was an add-on auxillary system. Reset the mixture once disconnected.
Worth a try.
Nick.

My 78 3.0 would surge on cold start if it was set too rich. Setting the mixture correctly seemed to help constant rpm surging too.

Cheers,

Joe

I had a similar problem with my 83 last year. Turned out to be intermittent relay (under pass seat) that operates the frequency valve.

OK. got the "surging". (a little air fuel, alot timing, 1/2 turn on the idle.)
So what about the miss?
Thanks guys!

Sorry..........its doing it at a constant rpm. ie 2nd gear at 30 mph 3100 rpm you can really feel it.
Thanks again