911SC stalls/bucks when hot

[nzaldivar]

Hey Guys,

I have a 79 911SC with stalling/bucking symptoms while driving.
The car starts fine and runs fine but bucks/stalls while driving, harder acceleration makes it happen faster.

Pressure test results @ 85 degress
cold control pressure 42 (a tad high)
system pressure 68 (within spec 65-75)
warm control pressure 51 (within spec 49-55)
rest pressure normal

Any thoughts on next step? Air/fuel mixture? How could DIY test this?

Thanks,
ned
nedzaldivar@yahoo.com
79 911SC Targa - 168K miles

[Paulporsche]

If you are getting surging under light load at constant speed you may be running too rich. Try leaning the mixture in small (about 1/32 or 1/16 turn) increments. Drive the car and see if that helps.

Can you smell the "richness" while the car is idling? Is your tailpipe very black?

Have you checked /unplugged your O2 sensor?

There are numerous threads for DIY CIS analysis, including O2 sensor
issues. Check them out.

Good luck.

Paul

[Paulporsche]

Also don't forget DME/relay and Fuel Pump/relay threads.

Paul

[vash]

what about the method of setting mixture using a dwell meter and the lambda info test port? i dont have my book, but i was just reading about that last night.