924Board.org

[Roger Hall]

My 1981 924 has a loss of power and surges under exceleration at low RPM's. I have replaced injectors, air filter, fuel filter, spark plugs, cold start valve, and most of the vacum lines. I have also tested the aux air regulator, thermo time switch. It has improved but I cant get rid of the problem. Everything is fine when cold the problem seems to occur when the A/C is turned on. Also small backfires. It seems that the fuel mixture is rich. The problem is intermitent and I need some help please!!!!!

[JvGinPDX]

I had the same problem with my car. The mechanic I took it to adjusted the mixture. Get this: in was too LEAN. That made the car surge and miss, resulting in emissions. Once he made the mixture a little richer, the car ran better, no surging.

[Roger Hall]

The mixture has been checked 3 times in the last 8 months, but its worth a try. That would be a cheap fix. If I didn't think that the backfires indicate a rich fuel mixture I would suspect the electric supply to the fuel pump. When the A/C is on the fuel pump may not be getting enough current. Or the fuel pump may be going bad. The idle can fluctuate a couple of hundred RPM's. I thought it was due the the cold start circut, but maybe its due to the fuel pressure. Thanks for the info at least you gave me some new ideas. I was running out of my own.