Helpful ReplyHot stalling - won't start - coil breaking down?

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Sandspider
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2018/02/22 11:25:57 (permalink)

Hot stalling - won't start - coil breaking down?

Hi all
 
Bit of a problem with the 944 yesterday. I will go through the Clark's garage test procedures when I have time, but want to check a few thoughts here too first...
 
So. Car had been standing for a fortnight or so, thought I'd take it for a spin yesterday. It was a bit lazy to start, but got there and idled happily. I left it idling while I topped up the tyres, and it stalled after about 3 minutes - not usual. I restarted it (it took a bit of accelerator to get it to fire, but then it ran happily) and finished the tyres, and set off. Got about a mile (out of phone signal, of course) and opened it up a bit, whereupon the engine died. Revs dropped to zero and it would turn over but not start on the key. Still rolling, so popped it into gear and it started, ran for a second or two then conked out again. I managed to roll to a pull over place, opened the bonnet, wiggled the distributor leads and fuel lines etc. but it wouldn't start. It would turn over happily and almost catch, but not quite. Walked into phone signal, got someone out to recover it, which took about an hour. Thought I'd try starting it one more time, and it fired as normal and ran happily! I drove home without any problems and left it idling for a bit - still no problems.
 
It sounded like a fuel problem, but I can't understand why it comes and goes in that case. I was thinking it might be the coil breaking down when hot, then working when cold. But it worked OK on the way home, and the engine was warm again then eventually. I'm not keen to take it for a longer drive in case it lets me down again! As I said, I'll look at Clark's garage, but would the coil give these symptoms?
 
I don't have a spare DME relay to test with (some scrot stole my spare).
Fuel filter was replaced two or three years ago - it's not original!
HT leads were replaced 6 or 7 years ago - and I doubt they're the issue as it runs fine when it runs.
 
Finally, if it makes a difference, I live in a Welsh valley with a stream and not much sun so it's a fairly damp environment over winter! But it was a pretty nice dry day yesterday...
 
Any thoughts appreciated, thanks.

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
BlackMagic
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 11:42:34 (permalink)
I have been told that the cause is easy to diagnose, but finding exactly what to change is more tricky.
 
I have had this for several years with my S2 and I still have to finally track it down.
 
The thought is that some damp/water has got into the electrics....somewhere. The engine starts fine but as it warms up the water turns to steam/vapour and causes a poor connection and the car cuts out. Leave the wiring next to a warm engine for 20 or 30 minutes and it dries out and the car starts again and runs fine. Its very annoying and difficult to track down.
 
Please do post if you find the offending article.
 
Good luck

William
white944
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 12:03:25 (permalink)
DME relay is easy to eliminate. do the 3 wire bypass trick. Could be a crank reference sensor going kaputt.

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sweetcorne
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 12:07:17 (permalink)
Fuel damper???
Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 12:50:47 (permalink)
BlackMagic
I have been told that the cause is easy to diagnose, but finding exactly what to change is more tricky.
 
I have had this for several years with my S2 and I still have to finally track it down.
 
The thought is that some damp/water has got into the electrics....somewhere. The engine starts fine but as it warms up the water turns to steam/vapour and causes a poor connection and the car cuts out. Leave the wiring next to a warm engine for 20 or 30 minutes and it dries out and the car starts again and runs fine. Its very annoying and difficult to track down.
 
Please do post if you find the offending article.
 
Good luck

William


 
Thanks William. Unfortunately, that does sound like a likely cause! I'll do some fault finding when I get a chance, and let you know if I find anything.

white944
DME relay is easy to eliminate. do the 3 wire bypass trick. Could be a crank reference sensor going kaputt.


 
Cheers, will try that - but I'd have to take for a drive with the bypass in place to be sure, and wait to breakdown!

sweetcorne
Fuel damper???



Hadn't thought of that, and had to google it to check what it does! Will hopefully eliminate it when I have some time to test bits and pieces.



No one thinking the coil is likely to be the problem then?
 
Cheers.

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
Eldavo
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 17:34:02 (permalink)
Sounds like a DME relay issue to me too. 

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Frenchy
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 20:40:40 (permalink)
Either DME or I suspect temp sensor as if the car is okay when cold and stalls when warm the ecu is being fooled into thinking it is cold and is over fuelling (choke) had it on one of my cars, buy an original if it turns out to be the sensor.

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robwright
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 21:18:54 (permalink)
I am with fuel damper.

Rob Wright
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Tony Maddocks
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Re: Hot stalling - won't start - coil breaking down? 2018/02/22 23:10:42 (permalink)
Hi There, i am trying to identify the interior colour of my Grand Prix White 968. I had mentioned previously on the site that I only needed 1 square metre of leather and someone suggested Southdown , which I know of thanks, or maybe straight from Germany. I am now back in New Zealand. I think the colour is Marine Blue as a mate turned up on Sunday with his '91 964 with what I thought was the same colours as mine( mines NZ new '92) His is also Grand Prix White. Not possible at the moment to get the 2 cars together as mine is currently in storage which seems the obvious thing to do. I was just thinking that maybe the GP White cars had a certain shade of Blue as standard. 
Remembering that mine was optioned with Leather inserts.
 
Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/02/23 11:40:50 (permalink)
Thanks gents, will investigate further. I can't see a way on Clark's garage to test the fuel damper? But I'll cross that bridge when I come to it!
Annoyingly I bought a spare DME relay years ago when I got the car, and never used it. And some scrote stole it when they went through my car on the drive one night - can't imagine it did them much good.

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
edh
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Re: Hot stalling - won't start - coil breaking down? 2018/02/27 17:33:05 (permalink)
Check your plugs - if it's the DME temp sensor they will be black.

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Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/02/28 10:51:45 (permalink)
Thanks EDH. I was going to have a look at her today, but since I can't see her for the snow I'll leave it!
 
New DME relay inbound anyway...

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
Jenko944
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Re: Hot stalling - won't start - coil breaking down? 2018/03/06 17:14:51 (permalink)
Mine used to cut out but only when hot and then would refuse to start for a good 20-30minutes... 
 
Replaced both ref sensors and now fine....
blade7
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Re: Hot stalling - won't start - coil breaking down? 2018/03/06 18:26:27 (permalink)
Test the fuel pressure regulator by removing the electrical connector from  one injector. If the car will run on 3 cylinders you've found an issue.
Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/03/07 12:42:51 (permalink)
Thanks for the further thoughts one and all.
 
Pulled a couple of plugs this morning, and they weren't black - the usual light brown deposits, but also a hint of bright green which I've not seen before. Car wouldn't start even from cold. New DME relay arrived today so I put that in, and eventually it started! Let it idle for a bit and took it for a short and cautious drive. I didn't take it too far, so can't be certain - but car was warmed through and didn't hesitate at all. I didn't rev it particularly hard however as that caused the final stall last time. Looking much improved anyway.
 
It's a bit drier here today but still cold, and still plenty of moisture around. So it seems that it might not be a moisture / steam issue, and probably was just DME relay. I'll try a few cautious longer drives and see how things go. Fingers crossed.

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
sweetcorne
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Re: Hot stalling - won't start - coil breaking down? 2018/03/08 13:51:32 (permalink)
???
Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/03/08 14:27:36 (permalink)
sweetcorne
???




???

Giles
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GlennS
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Re: Hot stalling - won't start - coil breaking down? 2018/03/11 09:48:22 (permalink)
If it suddenly cuts out, with no spluttering or coughing, and the revs just drop to zero then my money is on the speed/reference sensors.  I had all sorts of fun with mine.  Random cut outs when driving along, occasionally reluctant starts...  sometimes it would start and idle for a couple of minutes and then just stop dead.

Glenn
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Sandspider
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Re: Hot stalling - won't start - coil breaking down? 2018/03/13 10:18:53 (permalink)
GlennS
If it suddenly cuts out, with no spluttering or coughing, and the revs just drop to zero then my money is on the speed/reference sensors.  I had all sorts of fun with mine.  Random cut outs when driving along, occasionally reluctant starts...  sometimes it would start and idle for a couple of minutes and then just stop dead.




Thanks Glenn. That does sound like what happened to me. Not had a chance to go for another drive yet. Are the sensors expensive / hard to get to?
 
Cheers.

Giles
1986 944 Lux. Black. 17" Cup 1(?) alloys.
vitesse
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Re: Hot stalling - won't start - coil breaking down? 2018/03/13 10:45:26 (permalink) ☄ Helpfulby Sandspider 2018/03/13 10:59:08
My replacements for 924S were £80 approx inc VAT for the 2 from GSF-can often just be the breakdown of the leads due to the heat at rear of engine although the cans that fit in the bellhousing bracket can corrode/burst.
 
These were generic items fitted to various cars but made in Europe.OPC are twice the price at least.

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