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Help - breakdown yesterday - engine cutting out!

cuffn

PCGB Member
Member
I'm in need of some wisdom from anyone who may be able to suggest a fix to my current problem!

Car had just returned from the garage on Saturday morning following a re-con nerside caliper and new indicator/headlight column switch to pass the MOT. On my way down the outside lane of the M3 southbound near Eastleigh yesterday doing approx. 75 ish when the engine just suddenly died. Managed to get over to the hard shoulder and she wouldn't start again (turned over fine though). Had a quick look under the bonnet to check for anything obvious but no signs of any issue so attempted a restart to no avail and rang the AA. They said the current wait was 90 mins but they would put me on priority as I was on the motorway! They called back to say they would have someone with me in approx 1 hour! After I had waited a while I tried restarting and she fired and ticked over okay for about 5 mins. I was in a queue waiting for the AA to pickup the phone to tell them I was okay when the temp guage reached a point where the fan normally cuts in which I think I heard and it cut out again and wouldn't restart. I put the phone down thinking perhaps I will let them come after all and waited another 5 mins before trying a restart again. She started fine and was running for about ten minutes and this time I lifted the bonnet and increased the revs and let the fan cut in and out twice (with no cutting out of the engine) whilst in the phone queue to the AA again whn the guy with a low loader turned up. First thing he said was 'I have just come from another one of these - a white one with an alternator problem, followed by 'I wouldn't trust an old car like this on a long journey'! - Very helpful. Anyway, I explained the symptoms and he checked the fan cut in and out without the engine cutting out before he escorted me back onto the motorway at which point I came off the slip road to head back home. A couple of miles down the road it cut out again - temp gauge at same position as before and fan on. She started about a minute or so later and I managed to get her home again (approx. 20 miles) by keeping the temp down below the fan cut in point. Jumped in this morning to go to work thinking I would keep the temp down but she wouldn't start at all.

Do these sound like symptoms of a dodgy DME relay or something more sinister or heat related? Any help gratefully received as I had to use my wifes VW Sharan this morning which is an issue as it's now half term.
 
DME relay is always worth a try. I can't help thinking the temp issue is coincidental rather than part of the problem.
 
Thanks Fen - you may well be right, but it is the only thing that I can relate to the problem and by not revving too high and keeping the temp down I was able to get home without any problem. Doesn't explain the fact it wouldn't start this morningn though when cold.
 
Indeed. I'd change the DME relay as I said before, as it's only £20 and not exactly wasted even if it doesn't fix it. Next thing that springs to my mind is crank sensor, but it could be a number of things I guess.
 
For what its worth...didnt I read somewhere that that the fan/water temp sensor fools the ecu into running rich if it fails??
 
Yep, there is a temp sensor that tells the ECU what's happening, but it wouldn't make it fail to strart when cold.
 
Yep, there is a temp sensor that tells the ECU what's happening, but it wouldn't make it fail to strart when cold.

Missed that one [8|]

Must pay more attention.............

Must pay more attention.............

Must pay mor.............
 
hi nathan, before spending any of your hard earned cash on your car intermitent faults are the hardest and most costly to resolve if approached badly. remember the fire trinagle (fuel , ingnition , oxygen) remove any of the formentioned and your car dont run. the best approach is to look at 1 thing at a time dont change this then that you will be all over the place and get to a point where you cant remember what you have done. i sudgest you take the eaisest of the triangle first. oxygen

1, check there is not a blockage in the air filter leaves or other debris in the intake box, insure all vacume hoses are attached and are in good order ensure all related induction components are sound.

if all appears ok, fuel

2, ensure you got sum, dont rely on your fuel guage they too do go wrong, a gallon from a can is adeqate for the test, fuel pump/ fuel filter non delivery or insuffecient supply will break the triangle ( i think this is where your problem lies) a loose conection on the pump is a good one to start with, then a blockage in the fuel filer is next as you will be amazed what crap you get from the garage petrol stations. the fuel pump relay is most common for your symptoms as they do cut out when warm and fail to connect when cold.

so on to ignition

3, dont look too deep into the electronics at this point, stay with ELECTRICAL as they are more likely to be the problem. check the battery terminals are clean and of good connection and the earth strap is sound, ensure the wiring to the coil is ok and the high tension leads are securely fastend and are showing no signs of damage or wear as a lead arching to earth can overheat the coil, the conections on the dme relay or the fuel pump relay can be a culprit............there is another thing as you have an auto i am if unfamiliar terrirtory here but you may want to consider he park sensor wich stops the car being started in drive.....

see how you get on mate ps if none of the above help you let me know where you brake down next i am after a couple of body pannels pps what colour is your car, if you have walk dont look back "just joking" good luck Rob944s

 
Thanks for the reply Rob - all good advice. I am pleased to say however that as I didn't have a spare DME relay I rang Porsche Reading late yesterday afternoon and they had one in stock so headed over there from work and picked it up for the grand total of £22.78. I took it home hoping it would work but if not I would have a spare. Just for reference for others they seem to have superceded the part number which is now 993.615.227.00. Anyway to cut a long story short I got home and tried restarting the car twice just to check it still wasn't working. I then whipped out the old relay and put the new one in and it started instantaneously- result! Not wanting to get too excited I took her out for a spirited drive around and all was well and I have driven her to work this morning with no problems! Thanks very much for the pointers everyone. Intersetingly the engine seems to be running cooler since the relay change and the fan appears to be cutting in earlier - not sure why as I thought the DME relay was just for the fuel pump. The relay I took out was dated 27 Nov.1991 so hasn't done bad, but isn't the original. I am well chuffed at getting this sorted with so little hassle and without involving a garage and it just goes to show one of the benefits of this forum with those experienced owners sharing their knowledge with others - thanks again.
 
I agree with Tony. It's called the DME relay because it also powers the DME as well as the fuel pump though...
 
Weird thing was there was no signs of it running lean - no hesitation or stuttering or anything just cut out completely! Strange.
 

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