MoTeC Global Forum

Working with a new build of a 3.2L air cooled porsche with an M800 set up for alpha N / TPS. Normally asp engine, twin lambda, after market I.T.B. stacks with a BMW sourced TPS on cylinder 6, Bosch green giant injectors 0280155968. Have been working with a tuner and completed a dyno tune. Upon finishing it and working on the road there is a noticeable stumble/stutter upon sharp acceleration. Smooth/slow acceleration is ok. We have been going in circles with various fuel enrichment settings and I'm not the expert but I believe that the sensitivity is maxed out etc. Basically running out of ideas. I'm attaching the M800 ECU file, also working on getting the logging set up so we should have that soon. Can anyone see anything we are missing or suggest an approach to improve the throttle response please?

Thank you
Jeff

Not really possible to debug without logging, which might be why you are struggling. is it going lean or rich when cracking the throttle?

Have you got the ITB linkage balanced for airflow at both idle, and 2000-2500 RPM? If not, that can make a Porsche stumble (carbs or injection).

If I had to guess, I would say sensitivity isn't the issue, it's the clamp values, they limit how much extra fuel can be applied. Sensitivity is just how much change is required to get this much fuel.

Looking for at your config, and comparing to other 911 engines, I think you are too rich and bogging on acceleration. By using a large IJPU, 17ms (your fuel table maxes at about 60%), then means your AE Clamps can be much smaller. Perhaps even 60% of the suggested values in the F1 Help. Alternately, change the IJPU (I suggest 10ms), and let the software re-scale the table, now the F1 defaults should be a good starting point.

I would also change the Fuel Accel Sensitivity table to the suggested values in the F1 Help. That is about 1/10th of the values you currently have.

Stumble upon sharp acceleration from what rpm? Bad everywhere, or bad at specific rpm? I'm assuming this is low injector, not shower?

Thanks guys for the replies
We appreciate the feedback
The posted file had extreme values on accel for testing.

Strange that Injector latency numbers @ equal pressures for the 968's vary greatly from Motec test data to Bosch supplied data to other privately tested data...

Cheers

In comparing data, be sure the fuel pressure values are comparable (proper Differential Pressure using MAP reference pressure regulator, vs Gauge Pressure with no MAP adjustment). Also, be sure those are the same injectors.