Hi guys.

New poster. 2008 BMW X3 - N52B30 3.0si M Sport 150000km and running fine up until recently. Which has intermittent problem. When it’s running it runs perfect. However a few times now and always either JUST after start or the instant I press accelerator pedal it coughs and dies. As soon as it dies I get same symptoms.

1) Engine coolant temp on dash goes to max hot regardless of temp.

2) No fuel (have pulled whole rail off, injectors are not pulsing and no fuel being sprayed)

3) No Spark (have tested every cylinder with proper tool while cranking.

4) 4x4 light comes on however no check engine or EML Light.

5) After cranking for 2-3 seconds the speedometer needle erratically jumps between 50-100kph and after I stop cranking settles back down.

I have tried replacing DME/EWS/KEY combo and still just cranks no fuel no spark. Just cranked and cranked on both sets.

After messing around for a few days I connected the battery and turned the ignition to position 2 and noticed the temp gauge stayed on cold (accurate position) so my heart skipped a beat and sure enough fires into life runs totally normally no issues no dash lights no codes.

Until of course it stopped again when I put it into drive and touched the accelerator (after a few days of normal driving). Exact same symptoms as above. I know that if the temp gauge is reading max hot that it Will crank but won’t start. The few times it has come right I have first noticed because the temp gauge stays in cold position when key turned on, and surely enough I temporarily have a normal X3 again.

Got a local mechanic to come out to plug computer in - nothing showing up.

I tried disconnecting the battery and unplugging DME and the junction box that sits on top of the DME that three multipin plugs insert into (integrated supply module?) And then trying to start again. After 3 tries of this it started again (temp gauge suddenly normal again when key turned on) - until a couple days later it stopped again (after running for a couple mins and the second I touched the accelerator in drive......

The last nugget of info I have was that a couple times after I have got It going I have held the RPM at 3000 In park and after 10 seconds or so the engine loses partial power and rpm drops (accelerator pedal still at position which was just maintaining 3000rpm) AND the EML Comes on... as SOON as I take foot off accelerator the EML light disappears and car behaves normally again. I can repeat this problem over and over by holding RPM at 3000 ish.

Anyone have any ideas what to try next? I’m thinking a faulty sensor that’s intermittent I’m the EML system? TPS?

Thanks for any help.