[solved] Engine & electrics cut out [no OBD fault codes] when warm never when cold

R

richyrich

Member
 Cambridge
2004 Z4 E85 3.0i RWD Petrol Convertible 120,000 miles [18 years and 110,000 miles with me!]

My engine and electrics are simultaneously cutting out whilst driving.

I got the car to a garage and left it on their forecourt overnight and explained the symptoms to them in the morning. It took them over a week before they could get the car into their schedule to look at, and over that time, each evening they drove the car into the garage and each morning they drove the car out onto the forecourt - the car started and drove perfectly every time!

When they checked the OBD it didn't show any fault codes so they took it for a drive and, after a while, the engine and electrics simultaneously cut out again. They got it back, no fault codes, cleaned out the idle air control valve and checked the ECU’s wiring, which seemed intact.

At this point the mechanics thought the fault to be with my ECU.

As I was struggling to find someone to test my ECU I asked the garage to check, and if faulty, replace the following so we could discount them causes;
  • MAF Sensor
  • Inlet Camshaft Sensor
  • Crank Sensor
  • Fuel Pressure Regulator
  • Fuel Pump
After all they'd done so they took it for a run [and gave it a bit of a blast!] over a number of miles [I think they said around half an hour which would be about 5 miles in those hills of B-roads] and they didn't experience the fault.

I then took it out and drove perhaps 5 or 6 miles up hill and down dale with various levels of acceleration and braking that I doubt the mechanic would have done. I drove for various distances with stops of various lengths of time. The car started and drove perfectly after each stop and start and I didn't experience the cut out fault either. After a few short drives over the next few days I felt confident enough to [aka ran out of time and needed to risk!] driving 150 miles south....

I got 14 miles before I experienced the cut out fault again - luckily, 1 mile before getting on the M1.
  • Turning the key to the ACC position would turn the electrics on.
  • It would take a while until turning the key to the ON position would try and start the car.
  • After a while longer, turning the key to the ON position would start the engine yet it wouldn't hold its revs for more than a or 4 seconds.
  • A while longer and I might be able to get the car started to move it 10 yards or so.
  • After anything from 20 to 40 mins or waiting I'd be able to start the car and move it a few miles before it cut out again.
    • I was able to get it back [via b roads] to the garage in 4 stages of doing this.
    • Of course, as soon as mechanics got to the garage the next day, the car started up and ran perfectly!
My garage has arranged for an auto-electrician to look at the car yet I thought I'd also turn to your expertise to see if there's any guidance I can share with the auto-electrician to help their investigation.

I first got my car to the garage on Easter Saturday, now 85 days ago, so any help with this will be massively appreciated, with many many thanks in advance, Rich

ps - Luckily my friend has recently put me on the insurance for her Alpha...
pps - she has a Stelvio Quadrifoglio ;o)
 
I had similar with a previous m54 3.0

The issue was the DME (ecu) which was failing

Solution was to buy a new DME, install it and bypass the EWS security to allow the car to start

I did get codes relating to the DME when it happened so to 100% confirm that same issue you should try to get a reader in the car and read the codes when it occurs

👍🏻
 
Do check your battery connections. They may seem tight, but they may not be. Any slight looseness will cause the symptoms you describe.
 
thank you all.

@bigwinn I've contacted 8 businesses in England who advertise ECU services.

7 say that my car's ECU is too old for them to test.

Only 1 www.ecuexpress.co.uk have replied positively, saying;
Unfortunately because there is no test rig set-up available for that module test & repair is not possible. The good news is that we can easily replace and recode the unit for you at a great price. Please let us know when you are posting it in. The cost of a plug n play replacement is only £ 225
Click to expand...

I emailed to ask them if they could tell me more about how the re-coding works and if the new ECU would work with my keys, central locking and alarm and the radio and drivers seat presets... unfortunately they didn't reply!

Is their re-coding what you went through and would you have any answers to my questions?

Many thanks again, Rich
 
richyrich said:
thank you all.

@bigwinn I've contacted 8 businesses in England who advertise ECU services.

7 say that my car's ECU is too old for them to test.

Only 1 www.ecuexpress.co.uk have replied positively, saying;


I emailed to ask them if they could tell me more about how the re-coding works and if the new ECU would work with my keys, central locking and alarm and the radio and drivers seat presets... unfortunately they didn't reply!

Is their re-coding what you went through and would you have any answers to my questions?

Many thanks again, Rich
Click to expand...
Hi Rich

Hard to know what they are using without asking.

I use Bimmertools MS54 to l recode when installing a new ecu and I use the standard bmw tools like ncs to flash software

When flashing I’ve never had other modules lose memory or presets

Cheers
 
hi everyone, the 2nd auto-electrician to look at it found it to be a faulty oil level sensor in the sump. £95 to replace the part. £14 for a new oil filter while they were at it, £52 to refill the oil and labour at £57.50 per hour. Here's hoping for some trouble free mileage! Cheers, Rich
 
richyrich said:
hi everyone, the 2nd auto-electrician to look at it found it to be a faulty oil level sensor in the sump. £95 to replace the part. £14 for a new oil filter while they were at it, £52 to refill the oil and labour at £57.50 per hour. Here's hoping for some trouble free mileage! Cheers, Rich
Click to expand...
That sounds unlikely. I had a dodgy oil level sensor (throwing codes) for a year in a previous car and it never gave me a problem with starting or cutting out. Good luck though.
 
Zedebee said:
That sounds unlikely. I had a dodgy oil level sensor (throwing codes) for a year in a previous car and it never gave me a problem with starting or cutting out. Good luck though.
Click to expand...
Have to say, I was thinking the same. Unless there was some kind of weird earth issue with it?
 
@richyrich - just read back through the thread and it may have well been my 3.0i that @bigwinn was referring to?
Since then I too have purchased and used the software to enable a compatible DME to be fitted.
If your issue does come back then you have two options, Lincoln or Attleborough, to help out with a DME swap
 
I have to say I think you may be disappointed

I hope I’m wrong but I still think your issue is dme related

Mine only happened when the weather was warmer- making me think it was solder related issues in the brain of the car

But I’d be happily proven wrong!
 
richyrich said:
hi everyone, the 2nd auto-electrician to look at it found it to be a faulty oil level sensor in the sump. £95 to replace the part. £14 for a new oil filter while they were at it, £52 to refill the oil and labour at £57.50 per hour. Here's hoping for some trouble free mileage! Cheers, Rich
Click to expand...
Hey all, from what I, an automobile layman [!!], understand the faulty oil sensor was shorting out the rest of the electrics causing the car to cut out.
 
Mine has that same error for the past four years I'm afraid. I've not read the thread in detail but cutting out when warm and running fine when cold is a classic crank position sensor failure symptom.
 
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