D-jet guys, never before encountered problem Options

[TheCabinetmaker]

Just reinstalled my new engine before musr12. Its a 2056 with Raby 9550 cam and djet. I reinstalled the original FI system complete. Components were bench tested before being reinstalled. Car runs beyond my expections.

Heres the only problem I have really have. Upon cold start (not cold-cold start) it idles very low and rough. A few minutes of throttle held to about 1400 rpms, and the aar kicks in and everything is normal from there. Or, if I start it and pull it out of the garage to the drive, everything is normal. Aar is working properly. Head temp sensor is the correct one and ohms are within specs both hot and cold. Ts-1 also shows 310 ohms at 60 degrees. Cold start valve is not hooked up. I have considered a leaky injector, but is seems that would cause problems only when there is adquate fuel pressure, not after setting all night. Ambient temp seems to make no difference.

Opinions please.

[r_towle]

MPS needs to be set under load...even with an O2 sensor.
Its a guess otherwise...and you would be shocked at how small of a turn makes such a huge difference.

I drive them while tuning...I dont have a bench setup, I use an A/F meter, O2 sensor and seat time.
It takes about 20-30 minutes to get it perfect.
Start cold...then as you drive you need to keep tuning.
After that, I start one more time the next morning to verify the "new" cold setting still works.

If you are all ok with how it runs everywhere else, put in a varialbe POT on the ambient air sensor and re-connect your cold start injector.
Turn the POT up till the injector flows when you have your specific problem....that might help.
From there you can measure the POT to see what value of resistor you need to trick it.

OR, use a VW 411 mps and your problems will go away.
Its a single diaphram and much easier to get right all across the range.

For me, I start it and get in and drive it to the store...any temps.
When I get there, it idles perfectly...a 10 minute drive.
Air cooled cars properly tuned for running temps tends to run like crap when cold...

Rich