MSefi.com read only forum (Jan.15,2018)

I have it running very well now with one other issue. My RPM oscillates along with dwell and other things, take a look at the log file. It does make the engine a little rough. I was thinking that the dwell prediction was going unstable so I changed it to next interval with no improvement. I think it has to do with RPM and I am not sure if it is real or noise. So if RPM oscillates then does everything else respond to it in the calculations or is there some other software path that can go unstable? How do I find out which input is the cause?
MSII
2.888
Thanks

def. if your rpm's are wavering, then the fuel calculation will follow. It would not affect the 2 temperature sensors, nor the tps sensor. It will affect the map, because map will vary with rpm. In turn, the map varies the injector PW, as well as the ignition timing. This will in turn vary the AFR, and any corrections based on AFR.

RPM typically wavers around 50 rpms in my setup, which is, I believe, a true representation of the what the engine is doing rather than an error in the signal.

I have no clue about your RPM oscillation problem, but I want to know : does this datalog was taken while runing on the battery on the car or on a kind of powersupply? Because the battery voltage is really clean (14.0-14.2v). Simply want ti know!

Good luck with your problem.

Sam

You can troubleshoot this by disabling things in the software. First of all, you should verify that there are no vacuum leaks. Then make sure that O2 correction is disabled until above your idle rpm. Then look for acceleration or x-tau enrichment kicking in. Those can also be easily disabled to see if it makes a difference. If you have acceleration or x-tau doing something at idle you probably have noise in one of the key signals (TPS, IAT, etc.) triggering a change in fuel.

You may need to adjust the VE or advance tables to stabilize the idle. I have heard of choosing rpm bins so that one is below your desired idle, one about at it and one above it. Then you can adjust the spark and fuel to "encourage" the engine towards the desired idle speed.