m52 backfiring and wont idle

[E3irty]

Finished the last few jobs on the car today after the engine conversion and went to start it. It fired, idled nicley for a few miniutes, then as I blipped the throttle, it revved up and then died. Now when I come to start it it will fire for about a second or so, then cut out again. If I start it with the throttle open slightly itl fire and run but backfire through the throttle body violenly. Suspected idle contol vavle at first but since disproved that. Cam sensor? Now im stuck booked onto a trackday on monday! Help!!!!!

[E3irty]

Something which may be relevant, my cam cover breather is vented straight into the inlet bellows. Im sure this is how the guides for the m50 manifold tells you to do it, surley my crankase will just be ambient now? Arnt these engines designed to work with a partial crankcase vacum? I know with the m20, a good test for breather system health is to remove the oil cap and see if the revs fall. Obviosly this wont happen with my current breather setup on the m52 :s

[heathy325]

Has similar issues with my m52 conversion and ended up to be a crank sensor

[Motorhole]

Perhaps not the best person to advise on this seeing as I've still not sorted my own issues! But you could try the MAF - see if it runs with the MAF unplugged. If it does, then that's potentially an issue. Crank sensor is another as heathy 325 has pointed out. If you want to check the cam sensor, the car WILL start and run with the cam sensor unplugged, but the injectors will be loud (they will batch fire rather than fire sequentially). At least it will give you a chance to see whether or not that is the issue.

I don't think the breather is the prob. Lots of people are running this setup, myself included. Ran fine until I dicked things up.

[heathy325]

Ye the breather into the intake elbow is fine that's how mine is running too so don't worry about that it's defo an electrical fault I would say and like my previous post says I had similar issues when I completed mine ie it conked out after revving, idled lumpy and struggled to start every now and again

[E30BeemerLad]

The fact it idled alright to start with is what is confusing me

Are the ICV plug and MAF plugs the right way around?

Also, they will run like crap if the lambda sensors are plugged in wrong. The wires from the lambda for the rear exhaust manifold plug into the plug on top of the engine nearest the front of the engine and the front branch plugs into the plug nearest the rear of the engine.

[E3irty]

Sorted it! Massive air leak on the ICV hose! Runs beaut now, SO revvy with a lightend fly! Cheers guys