Megasquirt Support Forum (MSEXTRA)

Hi all,

I've got a problem that is causing me all major of headaches. Engine is:
Nissan RB26
Custom 36-2 trigger on the crank
Honeywell 1gt101dc hall effect sensor with a 1.3mm air gap, wired to 12v
1230cc low-z injectors
Splitfire coilpacks (wired in wasted spark)
MS3 v3.57 with ms3x.

The jumpers and pots are set up according to this:
http://msextra.com/doc/ms3/ignition.html#geartooth

Basically, during cranking I get perfect rpm. As soon as the engine fires it starts getting sync losses. Changing the pots and/or the jumpers around makes it only worse. With boths pots fully counter clockwise i get no rpm signal at all.

I've scoped the signal coming from the sensor and its great. The signal at the cpu isn't so great though. The only thing i can think of is that the injectors are creating terrible noise????? Any thoughts?

Attached is an msq and a log of it trying to idle.

Any help is greatly appreciated. It's driving me nuts!!!!

Could you capture a tooth log of the problem? That will give us more to go on about sync loss.

Hope these help. I couldn't get it to idle this time. just cranks fires skips and repeats the process.

also, sometimes the fuel pump primes for 3sec or so, others it primes for about half a second. does this mean anything?

Unfortunately, neither log captured enough continuous data for me to see clearly what's happening. Was it synced up while cranking?

If I do something to stop it firing, like disconnect the coils, the fuel pump, or injectors, it cranks and syncs up fine. Cranks at about 180 rpm. As soon as it fires and the rpm goes up to say 3-500 it starts loosing sync. Very hard to get it to run at all, so its a total fluke to get a decent log of anything.

I'm starting to think megasquirt doesn't like these sensors. Seen a few threads where people give up and fit a vr.

I'm wondering if it's noise from the ignition. Are you using non-resistor spark plugs by any chance? How old are the plug wires?

No they are resistor type plugs. It doesn't have leads. They are individual cop coils with built in ignitors running straight off the ms3x spark outputs. I was thinking it was the injectors.