The biggest problem continues to be very rough running anywhere

under 18”MAP.  It really won’t run any lower because of and bucks

and surges (but it runs really great above that MAP).   I am thinking

that the problem is the injector transition.  

 

Yes, pretty clearly that’s it.  I had problems at low MAP as well during the 20B dyno testing.  I noted the following in the test report:

 

“The other difficulty was that the mixture was much too rich at low MAP values.  Setting the correction at steady state conditions did not get the MAP values as low as occur when throttle is pulled back from higher power; resulting in a very rich condition which causes the engine to stall.

(How do you set the mixture correction at very low MAP?).

 

In order to get it to run well below the transition point, I had to put in large mixture corrections (lean).  I concluded that my problem was aggravated by two factors, my fuel pressure regulator was not MAP referenced, and my primary injectors have about 12% higher flow rating than the secondary.  I assume that since you are turbocharged  you using a MAP referenced fuel pressure regulator (FPR).

 

I finally got it running OK  below transition; at steady state, but reducing throttle from higher loads would take the MAP values below where I could get the big correction in, and the engine would flood out and stall.  I have since replaced the FPR with a MAP referenced version and we’ll see if that matches the default settings well enough.  I figure once airborn, and I can put it into a decent and have a chance to set mixture corrections for very low MAP.

 

Best of luck,

 

Al