Megasquirt Support Forum (MSEXTRA)

Ok - so I was not getting readings from my coolant temp sensor, IAT or TPS. I started checking grounds and found that the sensor ground was connected to pin 43 on the 88-pin BMW harness. Is this unusual? After connecting this pin to ground, all my sensors started working.

that's normal, that's why I don't trust those online wiring diagrams. all 3 sensor share the same ground. it's pin 44 on the later harness, btw.

It runs! I was pretty relieved to hear it come to life. I still have a lot to do but I should be able to start tuning tonight.

One thing I still don't know for certain is the "Tooth #1 Angle(deb BTDC)". I have heard various values between 80 and 90 degrees. I can anyone confirm if that is correct or not?

it's 84 degrees on the M20, I think the M50NV is the same.

However, you should check it with a timing light. Set it to fixed timing, say 10 degrees, and see if your timing light agrees.

I'll try but I am not sure I can get a timing light into the tight area I need to take the measurement.

you should be able to, but it can be hard to see. I suggest using some white out or white paint on the crank sensor mark and wherever the TDC mark is on the engine.

I think I can do it with a mirror. I was about to start patching together a spark plug wire so I can get a lead for the timing light and though I should see if you have any useful advice to keep me from electrocuting myself.

Congratulations on getting your car started. Its kinda nice being a few steps behind you, that way i can see how you work out the issues.lol. I dropped my engine in a couple weeks ago and wasnt getting any power to the ecu, then i returned here to see how your ignition relay mod. Thanks!

i also cant get a straight answer on the #1 tooth settings btdc for my m52. I also have to swap in my cam sensor for a honeywell i ordered.

m52 is a different angle, I think somewhere around 60 degrees.

I got it measured - for the non-vanos m50, 80 degrees appears correct.

I still have a few problems to work on however. The tach signal is not getting to my dash, neither is engine temp.

Also, cycle to get decent afr's seems really high. I only drove it for a mile or two but I am sure I saw over 80% duty cycle at ~3 to 4000 rpm and normal air-fuel ratio. I will do some more driving tomorrow and take some logs then.

dave.a.cote wrote:The tach signal is not getting to my dash

JP3 is not jumped, right?

dave.a.cote wrote:I got it measured - for the non-vanos m50, 80 degrees appears correct.

I still have a few problems to work on however. The tach signal is not getting to my dash, neither is engine temp.

Also, cycle to get decent afr's seems really high. I only drove it for a mile or two but I am sure I saw over 80% duty cycle at ~3 to 4000 rpm and normal air-fuel ratio. I will do some more driving tomorrow and take some logs then.

I think you may have a loose connector under your dash somewhere - I'm pretty sure the engine temperature gauge has its own sending unit.

dave.a.cote wrote:I got it measured - for the non-vanos m50, 80 degrees appears correct.

I still have a few problems to work on however. The tach signal is not getting to my dash, neither is engine temp.

Also, cycle to get decent afr's seems really high. I only drove it for a mile or two but I am sure I saw over 80% duty cycle at ~3 to 4000 rpm and normal air-fuel ratio. I will do some more driving tomorrow and take some logs then.

you sure it's 80? I'm pretty sure the NV uses the same crank angle as the M20 (84). 14 teeth to the VR sensor at 6 degrees = 84 degrees.

as far as the coolant temp, that's driven by a seperate sensor unrelated to MS. it might not be hooked up. For the tach all you need is an output from the MS CPU (I use JS11) straight to the tach. the E30 cluster works fine with a logic level signal.

80 is as accurate as I could see. Would it make a difference if I am using a S50 crank?

no it doesn't matter what crank you use, what matters is the toothed wheel.

you could set the engine to TDC, and count the # of teeth to the sensor. it should be 14 on a NV motor (counting 12 + "2" for the missing teeth)

Alright, I fixed a couple non-ms related things that were bugging me and finally got the car back on the road. It is driving a little better now but there are a few things that bug me.

One problem is my duty cycle. It often goes above 100%. This morning I hit 100% duty cycle at 95kPa map and 3100 rpm. That just does not make any sense. After goes over 100%, the engine does not start to go lean or anything so I think there is something wrong with how duty cycle is measured. Any suggestions where to look?

I think there is a setting in the output channel for duty cycle that might need to be corrected, it's calculating based off an alternating (batched) fire pattern but you're running sequential. At least I remember seeing something related to that a while back.

For a correct duty cycle reading when running sequential, set your engine parameters to 1 squirt simultaneous.

These settings aren't used with sequential as it is always one squirt per engine cycle, but the duty cycle calculation uses them for display purposes.

James

jsmcortina wrote:For a correct duty cycle reading when running sequential, set your engine parameters to 1 squirt simultaneous.

These settings aren't used with sequential as it is always one squirt per engine cycle, but the duty cycle calculation uses them for display purposes.

James

ah, that was what I saw. thanks - haven't ran my engine with it yet, but I'll make sure to change my MSQ.

That fixed my duty cycle reading. Thanks.

As for the tach, JP3 on MS3X was not jumpered. I jumpered it, still no tach.