M52 starting problem after conversion

[etouring]

Hi all, Iv got a strange starting issue with my m52 conv. It cranks a few times then pops and bangs seems to fire backwards. I can hear the starter hitting the flywheel. When pluged into the comp says cam sensor, Iv tried a 2nd hand one but no change. Iv pluged the ecu into my mates car and all ok. Thanks for any tips

[daimlerman]

What is your chosen spec?

Flywheel/starter?

[etouring]

I'm using the e30(m20) had the flywheel lightened.

[daimlerman]

So you need an M20 spec starter...

M50/52 uses a different pitch starter,

[etouring]

Thanks for your suggestion. I'm using the m20 starter, I don't think the problem is the starter... It's misfiring before starting