DJet Problems, 3000-4000 RPM Stumble Options

[yeahmag]

I'm helping a friend with a DJet issue and I use to consider myself pretty good with this system, but I'm running out of ideas with this one. There is a considerable stumble at steady-state, 3000-4000 RPM. So far I've done the following:

* Replaced his dizzy with one of my good ones - re-timed.
* Replace his spark plug cables, rotor, and cap known good ones.
* Disabled the TPS to rule that out.

He's running a Petronix Ignitor that we swapped over to my dizzy. I'm starting to suspect it, but what keeps me from changing that out is that it runs well at WOT. It really feels like a spark/timing issue...

What am I missing here???

-Aaron

[76-914]

Ign on and pushing the throttle will activate inj's. Hey Chris, wouldn't pulling temp sensor II do the same thing; i.e enriches the mix?

[ChrisFoley]

... wouldn't pulling temp sensor II do the same thing; i.e enriches the mix?

I'm not sure how much enrichment occurs with the IAT sensor unplugged.
I noticed a small difference on my N/B AFM when I moved the sensor from laying on top of the engine to inside the cold air intake on my dual TB setup.

I recently had a symptom of low CHT on one cylinder. At idle I could pull the injector plug and the rpm wouldn't change, although the engine seemed ok when driving, and the cht only lagged by 40 degrees or so. With the injector disconnected the engine clearly was only running on 3 cylinders and the cht stayed cold. When I bench flow tested the injector it seemed to spray just fine, but I didn't measure the flow rate.
Since I replaced the injector with another used one the engine runs much better with all chts close together.