Ron Doyle

Hello Friends!
my 75 914 1.8 f/I, misses out and backfires after it warms up ( only when driving, not idling) I’ve changed the plugs, wires and set timing, same problem. Thanks for any help.

ehokana

Forgive me as I have gone to carbs and cannot recall the name of the part off the top of my head. I had similar issues and it turned out to be a pin-hole split in one of the rubber diaphragms of the FI. Might be worth looking into

Maltese Falcon

On your '75 1.8L you have the Bosch Air Flow Meter (barn door) style efi system. Good idea to simply remove it, clean it out (usually short bursts of low-press air), cloth wipe, check for smooth operating of the swinging door. A common problem (with the symptoms you report) is the cold start AAR valve. These are not like the D-jet AAR valve (not interchangeable). It's also found on the 912e, Auto Atlanta may have some decent rebuilt units; I haven't seen these AAR valves at the dealer, nor the online catalogue sales lately.

Dr. 914

if the valves are in adjustment, the dwell set to 50 the timing to 27 degrees btdc, and you have NO exhaust leaks, then look at the air flow meter flap for sticking when hot, and the head temperature sensor for high hot resistance