D-Jet Problems, Stalls when hot, misses at med. rpms Options

[john_g]

I'm having problems that I'm pretty sure come from somewhere in the D-jet system. I have a '74 914, bored to 2056. Here are my symptoms:

It idles okay. It's a bit rough when cold, but it doesn't cut out on me and warms up to a steady idle quickly (1200 when cool, 800-900 when warm), but when it's been run for a longer time and is good and hot, the idle drops well below 800 and it stalls. It'll start back up right away but only if I treat it as if it's flooded - I have to put the accelerator to the floor as I restart it. Secondly, at mid rpm's, between 2200 and 2800, it hesitates, sputters, misses, and occasionally backfires - this happens whether it's cold or warm.

What I've done or have had done:
usual tuning routine
replaced the CHT sensor
replaced the MPS
replaced the distributor
cleaned the PVC valve
checked for vacuum leaks
checked the TPS, it seems good

Two air-cooled mechanics with good reputations have worked on it and haven't been able to solve the problem fully. All the above helped a bit, but the situation is still there. There has to be some sensor that isn't reading the situation correctly. Any ideas, or ... has anyone had a similar problem? (IMG:style_emoticons/default/confused24.gif)

[Java2570]

I would absolutely make sure that your wiring harnesses are in good shape....sometimes they can have breaks or bad spots in wires and can cause all sorts of gremlins. It would be a great idea to get ohm readings with a multimeter on your CHT for cold and hot values....that way you know for sure if the CHT is working correctly for cold and warm conditions. The webpage that Boxsterfan mentioned has a ton of great D Jet info and lots of tips and tests you can use to diagnose these sorts of issues.

[john_g]

I would absolutely make sure that your wiring harnesses are in good shape....sometimes they can have breaks or bad spots in wires and can cause all sorts of gremlins. It would be a great idea to get ohm readings with a multimeter on your CHT for cold and hot values....that way you know for sure if the CHT is working correctly for cold and warm conditions. The webpage that Boxsterfan mentioned has a ton of great D Jet info and lots of tips and tests you can use to diagnose these sorts of issues.

Thanks. I"ve used Paul's D-jet site before and it has helped smooth things out to some degree.

Another thought - would a mild performance cam (ground for EFI) cause some hesitation under light throttle?

[Millerwelds]

[quote name='john_g' date='Mar 28 2015, 04:19 PM' post='2166699']
[quote name='Java2570' post='2166659' date='Mar 28 2015, 02:15 PM']

Another thought - would a mild performance cam (ground for EFI) cause some hesitation under light throttle?
[/quote]

Webcam 73? Mine acts the same way. The bucking was cured by redoing the TPS. The low idle/stall when hot I still have to deal with.