My yellow '70 1.7 (stock D-jet) daily driver has been acting up lately. The problem is that it seems to run on only 3 cylinders some of the time. It seems to be completely random too. I will start out driving and it will run fine, then all of a sudden a cylinder stops working and the car exhibits a thump-in-your-back type of periodic missing. Then it might go away on acceleration or it might not for several minutes. Another thing.. During acceleration under the 3-cyl condition, there may be lots of little pops and backfires. Sometimes there are and sometimes not. The fact that it starts and stops so suddenly leads me to believe that it could be electrical.

I recently adjusted the valves and did the timing, put in new plugs, a new cap and rotor and also put in an electronic ignition module from my old 1.8 engine from my first 914. The wires are new and I gapped the plugs etc. Everything was working perfectly for a few days after I did this, and then slowly this problem started to creep up once in a while. Then more often.

What should I start checking? Bondo told me that I may have a leaking injector, any other thoughts?

-Tony

I had a similar problem with my car. I found by moving the wiring harness around I was able to make it come and go. My 30yr old wires were very brittle and had some bad connectors. After replacing the harness, it ran perfectly. Just a thought.

also, check the CHT and make sure it's not loose ...
check the grounds on the main block, the fuel injectors need those to work properly.

Andy

Interesting. I notice that once in a while if I get in there and jiggle the wires around it helps things. So maybe thats what is going on. I guess its time to build up a new wiring harness.

-Tony

I had the exact same problem...Found a broken wire inside one of the injector connectors...Fixed that and all is right in the world.

Gotta look real close but its an easy fix...

2-OH!

check the CHT and make sure it's not loose ...
Took me weeks before I check it.