'79 930 backfire then rough running
 

I've been battling an intermittant starting problem over the last
3-4 weeks. Would start sometimes. Other times would only hint of starting. PO insatlled a Perma-Tune. After replacing the stock coil with a conventional one, (Perma-Tune said this was OK), it has been starting regularly.

This morning the car backfired then ran rough. Has very little power. Idles roughly at 500 RPM. I pulled each plug wire from the cap. No signifigant change on any cylinder. Seems like an air/fuel issue. I looked for vacuum leak with no luck.

Oh yea, now it is not starting again......

Any help would be appreciated.

I've had other 911s...this is first turbo.....

Check for spark when it doesn't start. Check fuel pressures

Big Bang Theory
 

Your Turbo probably has CIS injection. The big bang you heard was likely a backfire thru the air box. The good new is apparently nothing burned up. The bad news is that you probably cracked the air box. Sounds like its time for an engine drop!

Good Luck!

Fred Cook
'80 911SC coupe (w/CIS and a popoff valve)

turbos don't blow airboxes. try bypassing the delayed ignition cutoff relay. that could be the no start problem. it's the smaller silver relay behind the rear defrost relay, on the engine elec board. bridge the red wire that gets hot with the key on to the red/white wire.