VEMS Startup
 

Just reaching out to anyone who might have gone down this road I'm currently on with initial startup issues after installing VEMS ECU. I have been working closely with Peeps and he has tried his best to help me diagnose a no spark no fuel condition during cranking. My car is an 86' 951 with a new 3.1l which was running with M-Tune, but had a few issues with WOT hesitation and a sharp idle drop an deceleration so I decided to go another direction. With all the options stand alone offered I decided to go with VEMS to have more versatility when it came to tuning. This is my first exposure to tuning/operating a stand alone ecu and Peeps has showed a lot of patience with me. So where we're at today is, Verified 500-1000 ohms from speed and reference sensors at the sensor and at the VEMS ecu connector. Verified the wasted spark setup thru a test mode within VEMS to each spark plug and its correct location. Fuel pump is priming when key is on. Made a trigger log and sent it off to Peeps for evaluation, but have not heard back yet on the results. I've been talking with another RL on here about my situation and he had asked if I was running a light weight FW. I have a Spec 3 push clutch with the steel FW that has the 3 scallops to reduce the rotating mass. I know from reading other threads on here that it has caused some screwy things to happen with the speed and reference sensors with a no spark and no fuel issues or just not running correctly. If anyone has had experience with this please pipe in, it will be greatly appreciated. Other items I've replaced last year are, injector wiring harness, DME relay and during the install of VEMS replaced all the pos & neg battery cables and terminals throughout.

Not sure where you are at in trouble shooting, but here is a video showing a static & dynamic test of the flywheel sensors.
I realize that your wiring is going to be different now, but if you've got VEMS installed then you should have some knowledge of the ignition system.

Thanks Paul, I recall viewing this video a year ago when I was having troubles getting the 3.1l running for the first time.

Oh man sorry to hear of your trouble David

My vems is currently in route should probably have it in the next week or so.

I have virtually the same setup as you. I was running M tune with basically the same run issues that you outlined. I also decided better to go vems.

My car is alusil 3L. I have a fully lightened stock steel flywheel with the BMW speed and reference sensors.

I assume you've tried the simple stuff like swapping the plugs on the speed and reference sensor?

when you turn the key to "on" do you hear the fuel pump priming?

Do you have factory alarm?

Link to the above mentioned bulletin https://www.lindseyracing.com/LR/Parts/SP44S-FIX.html

Yeah, you really need to scope the speed/reference mark signals and compare them to the waveforms in the factory DME Test Plan manual (available online here recently) before going any further. This is the most fundamental part of your engine management system, and if that is off, nothing is going to be right . . . . .at least check the air gap between the studs and sensors!

i had some issues on the EMU setup, what type of sensors have you choosen?
Faling, Hall sensor?

Yes

No Alarm

OEM Senors. Could be the original ones.

Yes, I've been through all of that extensively when starting up the 3.1l for the first time. The problems with startup was not related to the setscrew or the scalloped flywheel. Mainly I discovered shorted out original injector wiring harness plugs.
Peep has messaged me back and has evaluated my trigger log and said it was identical to one he saw previously with a no spark no fuel issue and this case had a spec push clutch with scalloped fw. Peep did not have a solution at the time so the individual installed a separate trigger wheel which fixed his issue. Peep will be looking into it to see if he can find a solution around using a scalloped fw with VEMS.