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

Well I have been playing with this for some time now.
I am running MS-I spark and fuel, MSnS-E, MT v2.2.5 029q2 on v3 of the MS board

At around 1700 and 3000 rpm I get bucking or bogging of the engine. I have re-read the tunning guide and have adjusted my fuel and spark tables with no luck. I get this under load and if I just rev in netural. I do not experience this issue on WOT from a dead stop (very little if any)

So far I have also checked my base timing, ground connections (have added more). I am also playing with dwelt and considerating the DAVE cap option, but need to do some additional review to see if this will address my issue. I am getting great spark. I have searched this board about my issue and have applied some ideas that have been suggested with no change (increasing injector open time, dotTBS adjustments, overrun). The car runs great at idle. PW, MAP, spark angle, AF are good. I thinking it could be as simple of line noise, but I have no access to a scope to check this.

I just have narrowband O2s for now, but will be investing in some WB shortly. My setup consists of using coilpacks, using MS map, and I am using my oem distruptor (VR sensor) for crank position.

I have attached my latest log file, a pic of the spikes as well as my msq file.

Any suggestions would be great.

bump... anyone??

Joeyjoe,

What sort of ignition are you running (HEI, EDIS, direct coil control, etc.)?

To me it looks like resonance, because it seems to occur at the same rpm, and it seems to double the rpm. However, it could also be noise from the coil or spark plug wires, or a bad ground(s) - but I see you have fixed those already.

What you do to fix it depends to a large degree on which ignition you are running.

I don't know if MSnS-E has any 'smoothing' functions for the tach input, perhaps someone more knowledgable can comment.

Lance.

Thanks for the reply Lance.

Im running direct coil control, using the MS internal ingitor. I have put on brand new performance spark plug wires (just in case). One thing I notice is that my connection to my OEM VR sensor (in my distr) is running underneath my coil pack, I think I should move this or provide some additional shielding?

My ground connections consists of:
Ground coming from MS spark and connecting to my coilpack grounding strip. From there I have the coilpack grounding strip bolted to my block and also I have a 12 guage wire connecting from my coilpack grounding strip to a location on my firewall. I am woundering if my ground coming from my MS spark should go to another location instead of the coilpack grounding strip?.

Joe

I am going to search more on shielding the tach connection