'HELP' Car completely cuts out??

[M3petHEAD]

Hi peeps,

i have a strange one going on, has anybody else had it??

Drive along not honing about 30mph and for a split second the whole car dies...lights/dash/stereo/steering.... i mean everything, then fires back up.

I have checked the obvious (in my head obvious) battery, engine oil, so before i take to a specialist wondered if anybody's had this???

Car is E46 convertible M3 (54 plate)

Edited by M3petHEAD on Thursday 31st October 20:01

[rassi]

Battery connections? Cam position sensor?

[M3petHEAD]

rassi said:

Battery connections? Cam position sensor?

checked battery....but i wouldn't know where to start for cam piston sensor, ill google it and check that. thanks
(im not that mechanically minded as you might of guessed)

[AHUX]

I had this happen to me when I owned a E46 M3, although mine was coupe. It was really weird and everything reset itself Mpg, clock etc.

All i did was tighten the connections to the battery, they weren't particularly lose at the time but it did seem to do the trick, the car didn't do it again for the remaining 2 years that I owned it. I have heard that it can occur as a result of a dodgy earth connection?

[VinceFox]

That does sound like a bad earth, somewhere.

[M3petHEAD]

AHUX said:

I had this happen to me when I owned a E46 M3, although mine was coupe. It was really weird and everything reset itself Mpg, clock etc.

All i did was tighten the connections to the battery, they weren't particularly lose at the time but it did seem to do the trick, the car didn't do it again for the remaining 2 years that I owned it. I have heard that it can occur as a result of a dodgy earth connection?

ok mate sound, did check battery, but ill tighten it see if that does it.

[M3petHEAD]

VinceFox said:

That does sound like a bad earth, somewhere.

if it is a earth issue, guessing thats more for a specialist to find. but buy sounds of it it nothing to worry about too much?

[VinceFox]

M3petHEAD said:

VinceFox said:

That does sound like a bad earth, somewhere.

if it is a earth issue, guessing thats more for a specialist to find. but buy sounds of it it nothing to worry about too much?

I'm a bit of a duffer when it comes to lectrics, but based on past experiences if it's erratic and intermittent, it's usually an earth. Can anyone ohere suggest a decent sparky near you?

[With these feet]

Do you get any warning lights up prior to the car cutting out?
Do the ignition lights come on when it cuts or do you lose all electrics completely?
Has the car got a hidden kill switch / alarm system / immobiliser??

Suggestions would be..

faulty ignition switch, wiggle the key and barrel with the engine running. If the switch drops the feed to the ecu it will stop the car.

Fault in power from fusebox to ecu - corrosion or loose connection.

Main power problem, check main fuse between battery and fusebox for corrosion / tightness.

If you have an alarm, see if it can be switched off and see if the fault occurs. Could be alarm cutting in/out.

[M3petHEAD]

With these feet said:

Do you get any warning lights up prior to the car cutting out?
Do the ignition lights come on when it cuts or do you lose all electrics completely?
Has the car got a hidden kill switch / alarm system / immobiliser??

Suggestions would be..

faulty ignition switch, wiggle the key and barrel with the engine running. If the switch drops the feed to the ecu it will stop the car.

Fault in power from fusebox to ecu - corrosion or loose connection.

Main power problem, check main fuse between battery and fusebox for corrosion / tightness.

If you have an alarm, see if it can be switched off and see if the fault occurs. Could be alarm cutting in/out.

thanks, gives me a few things to check. ill let you know the outcome

[Captainawesome]

Had the same with mine but was only when starting her. Tightened the battery connections up and the problem disappeared.

[phelix]

Had something similar years ago on a Fiat Coupe turbo (don't laugh!). Was at speed going down the motorway and flashed my main beams to let a car pull out in front of me and all the electrics died for a second. Turned out to be a slightly loose battery connection. Start with the simple stuff - don't just make sure the battery connection is tight - make sure it's both clean and tight. Look for a frayed/corroded earth strap between the chassis and engine or the alternator and the engine. What work has been done on the car in the last 12 months?

[M3petHEAD]

Just though i would let you know, still no problems since sorting the battery terminals