M5 problem

[SPADGE]

Hi folks
My M5 is refusing to start today
Its always been slightly tempramental and if it didn't start the first time it fired you would sometimes have to wait a couple of minutes and it would start the next time.
Well today it's not firing at all
I havn't investigated much yet as its too cold out there but i do know there is fuel in the tank before anyone asks!
I did pull the plugs out earlier and although they definatly need changing these wouldn't cause it to suddenly not start at all.
Not much fuel evident on them either.
Cheers Spadge...

[johnl320]

Ecu thinks the engine is warm??

Battery starting to lose the battle abainst the cold.??

just a thought mate

john

[SPADGE]

Ecu thinks the engine is warm??

Battery starting to lose the battle abainst the cold.??

just a thought mate

john

The ecu could indeed think the engine is warm mate and the wires going to the plug on the temp sensor have gone 'brittle' as i was warned they have a habit of doing on these cars. I'm wondering if this could be the problem and if one or both of these wires are knackered if the car would fail to fire?
I could put a meter into the terminals in the plug but havn't got a clue what i'dd be looking for to be honest

The battery isn't great but i've had my starter charger on there and it makes no difference.

Cheers for your thoughts mate!

[c76jon]

Hi

id check simple things first

spark??
fuel??

eliminate those first then look deeper if needed

jon

[Brianmoooore]

Same procedure as for any car, Spadge.
Check for the fuel pump running when cranking, then check for a good healthy spark at a plug.
If the above are present, then it could be cold start enrichment isn't happening, but an open circuit wire to the temp sensor will make the ECU think that the engine is well below zero degrees, and give full enrichment.

[SPADGE]

Thanks for advice fella's.
This morning i managed to get it running so all is well again although i haven't established exactly why it refused to start in the first place
I checked the wiring to the blue temp sensor with a meter and all seems well there.
I took the plugs out to find they were/are totally fecked and will order a new set on Monday. But for now i just re-gapped them and cleaned them up.
There was very little fuel on the plugs despite a lot of cranking and so i checked the fuel pump was running which it was.
In the end i got the ump with it and resorted to my trusty can of Ether and it fired up almost immediatly
I suspect a fuel blockage was the problem and will investigate this more during next week and change the filter etc...
I havn't entirely ruled-out the pump itself as having had a look at the top of it under the metal plate it would appear it is the original which has done over 200k.
For now i'm happy its not an immobile object
Thanks again!
Jules...

[Andyboy]

Plug voltage is important on these and a set of shagged plugs would cause it not to start. I had a 525e yesterday that would NOT start. The plugs were firing (and a good healthy spark) and there was fuel because they were wet with petrol. The plugs were very well worn and it was having none of it although EasyStart gave it a nasty cough. A set of part worns and off it went.
As it happens the starter was a bit sluggish and taking a lot of power (had massive resistance), and not leaving enough for the plugs. With the plugs out the starter had an easier time and left enough power for the poor coil to do it's thang.

Still. I had the last laugh. Shorn of it's engine and other valuable morsels it was despatched to the metal yard this morning.

[DanThe]

I took the plugs out to find they were/are totally fecked But for now i just re-gapped them and cleaned them up.

ala pinto stylee!

[Brianmoooore]

As it happens the starter was a bit sluggish and taking a lot of power (had massive resistance), and not leaving enough for the plugs.

Can also not leave enough for the fuel pump, if it's on its way out. Car will cough a few times, or might just catch for half a second and then die.

[78dude]

My E32 735ia is starting fine these days, even if its -17,5 and snow its starts easly and it get warm after a 10 minute journey on the road.

[SPADGE]

I took the plugs out to find they were/are totally fecked But for now i just re-gapped them and cleaned them up.

ala pinto stylee!

Not quite Dan
With the pinto you would just pull a set from any other motor you had lying around and they would do the job
I did try and buy a new set of plugs yesterday buy my usual factors that have 'everything' on the shelf didn't have the correct plugs for an M5.
I'll get a new set @ 50 odd quid from zimmerbimmer tomorrow.

[rwikky]

I guess even the big boys have car trouble! Jules is a legend!!

[Andyboy]

With the pinto you would just pull a set from any other motor you had lying around and they would do the job

Only if it shared the Pinto's weird fat taper seat plugs. What a bastard they could be. How many of those have broken off in cylinder heads over the years?

Whilst you're getting the plugs, I'd be getting a DME relay too. On M50 cars they can fail in a weird way where the engine will only fire when the key is released. I had an E36 with this problem and also it would never start first time. Spin it over, nothing. Second attempt, fired up perfectly. The DME relay was the culprit.

[SPADGE]

With the pinto you would just pull a set from any other motor you had lying around and they would do the job

Only if it shared the Pinto's weird fat taper seat plugs. What a bastard they could be. How many of those have broken off in cylinder heads over the years?

Whilst you're getting the plugs, I'd be getting a DME relay too. On M50 cars they can fail in a weird way where the engine will only fire when the key is released. I had an E36 with this problem and also it would never start first time. Spin it over, nothing. Second attempt, fired up perfectly. The DME relay was the culprit.

Cheers Andy
I'll get the DME whilst i'm at it