MS42 - e39 - M52tub28 No rpm signal, no start

[etistl_e39]

Hello everyone,

I'm having an issue that I will describe below and am looking for pointers.

The car is a 1999 e39 528i. The only modification is a M50 manifold with the Seems Legit Garage (SLG) kit to adapt the throttle body, fuel rail, idle valve, etc. I also opted for their ECU flash so that the whole thing works together nicely. What they do is they send an ECU that is already flashed, you swap it out with your existing ECU and off you go.

That worked as expected, but I am not happy with the performance of some of the cold starts and low throttle drivability. I'm an experienced calibrator on other ECUs so of course I'll try fixing it myself.

I purchased Bytetuner, got it all licensed and up and running and downloaded a dme2 out of the ECU that was flashed by SLG. It turns out, the HW version from that downloaded dme2 is not supported by Bytetuner. That's no big deal, I should probably should have checked before, but whatever... I figured it would be a good exercise to start from scratch.

My starting point is this dme2: MS42_E39_528_M52_ZB7526759_HW0006753_SW7526760_US_Simplified_MAF_Scaling

Now for the actual problem: The engine doesn't start! When I log data, I can see that the engine speed signal is constantly at 0 while cranking. If I flash my original downloaded dme2 back to the DME, I see engine speed and it fires up no problem. I can't find a reason or calibration value that could affect the ability oft the DME to see engine speed... can someone help?

To add to the confusion, if I put the original untouched ECU in the car, it will also not start or see engine speed. If I flash that ECU with the SLG tune, it works.

I'm quite confident there is no wiring, sensor, fueling, etc issues on the car since I drive it every day on the SLG flash.

[Renovelo]

What HW variant is being used on the tune which works?

[etistl_e39]

It is 7500255

[etistl_e39]

I'm thinking I might be having an EWS issue. I will send over a .dme2 to get the delete applied and try that

[Renovelo]

This was exactly our thought too considering your last point.

[etistl_e39]

It was the EWS. Once the delete was applied to my tune, the car started. I'm still not sure why it didn't start with the untouched original ECU, but it's ok for now. Moving forward, I'm running the simplified maps and increased MAF range provided by Renovelo.

Thanks for the quick turnaround on the EWS delete!