1997 2.8 roadster (auto) keeps stalling at roundabouts and will not restart until engine has cooled down after 30 minutes

[stackwadd]

Help Please. My 2.8 Auto Roadster (89,000 miles) keeps letting me down, usually at busy traffic intersections! It has the M52 B28 engine.

I have been towed home by the AA three times in the last week. There are no fault codes showing, and no dashboard lights on at all. I have had a professional mechanic change the fuel pump with a quality replacement pump along with a new fuel pump relay. Car starts and runs beautifully. Then once it has warmed up, it stalls and will not restart. The battery is healthy. Cranking strongly. Sometimes, once cooled down, it will start again and seems to run fine for a while, only to repeat the previous behaviour - usually at busy roundabouts. I am now in a position that I cannot trust the car at all, as I know it will let me down sooner or later usually in a dangerous spot.

The last AA man suggested maybe the ECU box could be suspect as the fault manifests itself when warm and then reinstates once cooled down. He suggested (maybe) a solder weakness on printed circuit board inside the unit. Please can anybody suggest what I could do next to resolve this? I am totally out of ideas and have already spent quite a lot trying to get this fixed. There were no fault codes whatsoever showing when I had a diagnostic done on professional equipment. I cannot use the car anymore until I get this sorted.

 

[jaguartvr]

Triumph Thunderbird motorcycles suffer a similar symptom but it is a known problem. The sensor on the end of the crank that sends the spark signal is the culprit, Works fine when cold and fails when hot, as soon as it cools down it will restart until it gets hot again. I would think that the nearest part on the Z3 would be the camshaft sensor and these do fail quite often.

Well, you did say you were desperate for ideas! Good luck

 

[MRH1966]

Yes I would agree........camshaft senor or Crankshaft sensor..........just changed both on my 2.8 auto 1997.......made it a different car!! Get senors from BMW

 

[stackwadd]

jaguartvr and MRH1966. Thank you both for your comments. I will change both these sensors and hope that does the trick. How much were the BMW dealer sourced parts?

 

[jaguartvr]

I used a delpi sensor from ebay, cost £32

 

[MRH1966]

They were about £100 each from the dealer in Brighton........I always put BMW sensors on our Zeds as I know they will work

 

[stackwadd]

I changed the crank position sensor and joyfully it worked!

Many thanks indeed to @jaguartvr and @MRH1966 !!

This club, its members and the forums are marvelous.

I have just bought a delphi scanner off Amazon. I think it will pay for itself soon enough.

 

[Robert Hill]

Look up ECU testing on YouTube

 

[stackwadd]

Thanks @Robert Hill. I shall do.

Just an update on the long saga of my 2.8 roadster.

After spending some £600 on mechanics' time, £170 on a replacement fuel pump from Germany, £70 on a crank sensor, £40 on a cam sensor, and £260 on a cloned Delphi diagnostic set up with windows tablet, my roadster still kept stalling and dying on me. I was getting ready to send the ECU for testing and bracing myself for another £350 or so.

I broke down yesterday at 18:30 hrs. The AA intially said 3 hours, but that kept moving back. Around 03:00 hrs this morning I gave up and abandoned my roaster where it broke down. On a busy 70 mph road in Milton Keynes. I had been trying to get through on the phone for 4 hours. They just put you on hold. Even when you use their app it reverts to telling you to phone them . Then you cannot get through: just put on hold for hours and hours and hours.

I dread to think what could happen if a young unaccompanied vulnerable person was stranded on the dark shoulder of the M6 at night for all night, form dusk to well past dawn.

In the end, I gave up and phoned for a cab to take me home.

Just as was falling asleep at 05:00 am , I got a call from the AA, apologising for the delay and saying that a patrol would be with me at 08:00 hrs. So I had tp get up and get back to my car. The patrol finally arrived at 08:30, at the peak of the rush hour.

As it turned out, the patrolman was the real thing: The full shilling. He set about doing the diagnostics with a Delphi unit. Multiple error codes... fuel pump not priming etc. Then he hit the jackpot! All along it had been a loose positive terminal on the battery in the boot. All the credit and thanks to the AA mechanic, James. Thumbs down to the AA though. Surely waiting 14.5 hours for a breakdown patrol to arrive must be a world record!

 

[JimS]

Probably not a record, I have waited 10hours for an AA patrol previously.
What your experience demonstrates though, is that even though modern cars are more complex than ever it is often the simple things you would have checked first in the 60's that let you down. Battery, contacts and earth straps for example.

 

[jaguartvr]

AA are awful but RAC even worse, last time I used the RAC I waited for 7 hours.
I am now with GEM, they consistently get rave reviews. The last 2 times I called them out 5 minutes and 15 minutes.
They call back checking that you have been attended to and that you are happy.
No more expensive than RAC or AA

 

[t-tony]

I'm sure that was a fault someone found a little while ago on a car with very similar symptoms.

Tony.

 

[andyglym]

Thanks @Robert Hill. I shall do.

Just an update on the long saga of my 2.8 roadster.

After spending some £600 on mechanics' time, £170 on a replacement fuel pump from Germany, £70 on a crank sensor, £40 on a cam sensor, and £260 on a cloned Delphi diagnostic set up with windows tablet, my roadster still kept stalling and dying on me. I was getting ready to send the ECU for testing and bracing myself for another £350 or so.

I broke down yesterday at 18:30 hrs. The AA intially said 3 hours, but that kept moving back. Around 03:00 hrs this morning I gave up and abandoned my roaster where it broke down. On a busy 70 mph road in Milton Keynes. I had been trying to get through on the phone for 4 hours. They just put you on hold. Even when you use their app it reverts to telling you to phone them . Then you cannot get through: just put on hold for hours and hours and hours.

I dread to think what could happen if a young unaccompanied vulnerable person was stranded on the dark shoulder of the M6 at night for all night, form dusk to well past dawn.

In the end, I gave up and phoned for a cab to take me home.

Just as was falling asleep at 05:00 am , I got a call from the AA, apologising for the delay and saying that a patrol would be with me at 08:00 hrs. So I had tp get up and get back to my car. The patrol finally arrived at 08:30, at the peak of the rush hour.

As it turned out, the patrolman was the real thing: The full shilling. He set about doing the diagnostics with a Delphi unit. Multiple error codes... fuel pump not priming etc. Then he hit the jackpot! All along it had been a loose positive terminal on the battery in the boot. All the credit and thanks to the AA mechanic, James. Thumbs down to the AA though. Surely waiting 14.5 hours for a breakdown patrol to arrive must be a world record!

When my slave cylinder went the AA sub contractor arrived with 30 mins to tell me what I already assumed, called recovery and left, fortunately my Zed was in my garage. The flatbed arrived about 20 hours later to take it to the garage. Good and bad in one shout.