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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Mon Sep 25, 2017 3:25 pm    Post subject: Strange starting issue. Help required please! Reply with quote

Hi Guys and girls

Very long time no post. I hope everyone is well. I'm still living abroad, and my brother who is looking after my 993 is stumped on a starting issue the car has developed. He and I rebuilt the top of the engine ourselves, and have had most of the car apart at one time or another so are not total noobs with it. It was also mapped by Wayne a while back.

We also have the durametric, but no help there.

The problem goes like this.....

Car starts immediately, on the button from cold and runs well. Not perfectly but well. Turn off the car when its warm or even after a few minutes and no start. Can smell fuel. If it does start it will rev to 2,000 and stay there blip throttle and it comes down a bit but not drivable.

Leave it a while, the hotter the longer, then its ok again.

We know its not the DME. Changed it and jumping the terminals does not help.

O2 sensor is new and it passed the MOT afterwards, so its not that.

Fuel pump is running seemingly fine. Plus can smell fuel.

MAF has been cleaned, but could be faulty. Car runs well if you do not switch it off though. Have not pulled the MAF plug yet when its in a non start state but will try that next time.

Battery is good plus earths. The engine spins very fast when not starting, so its not the 200 rpm no start limit or whatever it is.

Have not checked starter motor earths yet.

Have not checked CHT sensor, but Motronic on the durametric shows no faults. And believe me when the car wants to throw faults then they do appear. Usually cryptic ones.

So any help much appreciated. The answer is out there somewhere.

If he gets stuck in another petrol station I think that will be it. Plus more importantly I am back in the UK next week and want to drive it without having to keep the engine running all the time.

Failing that the car is in SE London (Beckenham) and may have to go to a specialist (suggestions please). We hate to admit defeat though, and specialists love to fix things via an expensive just replace everything strategy. The car has done 200k miles and its just not that sort of situation/relationship.

Thanks again in advance

Berni
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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guards red
Hockenheim


Joined: 10 Jan 2008
Posts: 654



PostPosted: Mon Sep 25, 2017 7:00 pm    Post subject: Reply with quote

Hi,

I'd put my money on the crank position sensor as you have already guessed. Breaking down with heat and metal expansion. The gap needs to be a specific value.

Regards
GR
 
  
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ChrisT70
Barcelona


Joined: 26 Mar 2015
Posts: 1441
Location: The Sea


PostPosted: Mon Sep 25, 2017 7:13 pm    Post subject: Reply with quote

Also check for vacuum leaks etc.
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AMS
Newbie


Joined: 23 Sep 2017
Posts: 5
Location: Kimpton, Hertfordshire


PostPosted: Mon Sep 25, 2017 8:13 pm    Post subject: Reply with quote

Had very similar issue with 993 C2 race car last year and it was as has been said already faulty crank position sensor. Air gap set up is important, crank sensor faults dont always show up on durametric. Definitely first port of call.
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1972 2.7 Carrera RS (Rep)
2001 Boxster S (Racer)
2007 997 C2
 
  
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9torsion
Newbie


Joined: 18 Aug 2008
Posts: 32
Location: Lewes East Sussex


PostPosted: Mon Sep 25, 2017 8:14 pm    Post subject: Reply with quote

Hi I hope I can help, my car would sometimes struggle to restart at a petrol station when it was hot. This usually happened after I had done some miles and the engine was really hot, this also included a smell of petrol. I had my Injectors tested and cleaned which made the running of the engine so much better. It's a stab in the dark, but it may help?

good luck

A
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stuttgartmetal
Indianapolis


Joined: 23 Feb 2009
Posts: 2335
Location: Caterham. Surrey


PostPosted: Mon Sep 25, 2017 8:56 pm    Post subject: Reply with quote

When are you back ?
 
  
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Endoman
Imola


Joined: 11 Apr 2011
Posts: 874
Location: Bolton U.K.


PostPosted: Mon Sep 25, 2017 9:47 pm    Post subject: Reply with quote

+1 Crank sensor. Works by electro-magnetic induction if the coil has a break in the wire it will work until warmed and expanded then fail 'til it cools down.
Seems to be age related they only last 20yrs or so.
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gunner
Montreal


Joined: 04 Jul 2014
Posts: 608
Location: Kent


PostPosted: Tue Sep 26, 2017 8:17 am    Post subject: Reply with quote

Brooklands in Swanley is not too far from you. Sorted the misfire on my car when the distributor caps/rotor arms needed replacing.
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Cameltoe & Heel
Suzuka


Joined: 26 Jan 2009
Posts: 1026
Location: Preston - Lancs


PostPosted: Tue Sep 26, 2017 9:13 am    Post subject: Reply with quote

Chaps,
does anyone have details of the CPS?, location on the engine and replacement item costs etc?, is this a 'whilst you're in there' item that you should replace if the engine is out of the car?.

Trev
 
  
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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Tue Sep 26, 2017 9:49 am    Post subject: Reply with quote

Hello Guys!

Thank you so much for taking the time to reply and for the guidance. Will order a CPS today, and hopefully my brother can do the swap ASAP. He's knackered his back and I think this one will require some bending/keyhole surgery so he may not want to.

Will report back.

If my engine was out I would at the the very least remove the sensor, clean up any corrosion and debris, and check wire condition. Careful with the retaining bolt they love to snap.

Thanks again.
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Mon Oct 02, 2017 9:50 am    Post subject: Reply with quote

Hi Guys

We changed the crank position impulse sensor and it’s not that.

The car starts on the button, then switch off and will not start. You can smell fuel and there is a spark.

Any further ideas welcome!

All the best
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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Tobesetc
Barcelona


Joined: 02 Jun 2014
Posts: 1269
Location: West London, UK


PostPosted: Mon Oct 02, 2017 10:34 am    Post subject: Reply with quote

I seem to remember reading an article, I think in Porsche & 911 World this summer, where an older 911 (not 993) had what sounded like a very similar problem. In that case it was down to - I think - the fuel regulator where a membrane had failed. It stops hot fuel being forced through somewhere as the heat increases the pressure.

Anyway, I don't even know if there is such a component on a 993. Just thought I'd mention it.
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T8
General
General


Joined: 29 Jun 2010
Posts: 12961
Location: Kent


PostPosted: Mon Oct 02, 2017 10:48 am    Post subject: Re: Strange starting issue. Help required please! Reply with quote

berni29 wrote:


Failing that the car is in SE London (Beckenham) and may have to go to a specialist (suggestions please).



Clifford Lowe at Project Nine knows these cars inside out and would be my recommendation.

=> http://www.projectnineengineering.co.uk/
_________________
2007 Guards Red 997 Turbo Tiptronic
ex 2004 Polar Silver 996T Tiptronic
ex 2002 Seal Grey 996.2 C4 Tiptronic
ex 1978 Silver 924 Manual
 
  
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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Mon Oct 02, 2017 12:34 pm    Post subject: Reply with quote

Hi

Thanks will give him a ring.

A spot more information, sometimes the car will start and Rev to 2k rpm, whereupon if you touch the throttle it dies.

Tsk again

Berni
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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guards red
Hockenheim


Joined: 10 Jan 2008
Posts: 654



PostPosted: Mon Oct 02, 2017 5:04 pm    Post subject: Reply with quote

Sounds like a tough one. I'd be inclined to thoroughly check the ignition side of things. Suddenly cutting out sounds like ignition to me.

If you can borrow items the coils and ignition amps would be a check point. Do you have a Durametric or the like to read live info before the engine cuts out?

Regards
GR
 
  
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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Tue Oct 03, 2017 7:27 pm    Post subject: Reply with quote

Hi Guys

It's not fixed, but we now know the culprit is the CHT. It's reporting wildly differing temperatures, plus if you pull the plug the car behaves as you would expect (i.e thinks it is warm).

Basically when the car is warm and will not start the CHT says it is -23 deg C or thereabouts, so it's over fuelling. At least that is my belief. So it's a call to Matt at Type 911 in Bromley in the morning.

It's a bit annoying as I have just changed the crank sensor which is literally next to the CHT.

Another unrelated issue is that the car appears to have a faulty oil cooler temperature sensor. When hot the fan only comes on for a few seconds then cuts out. I know that the fan works at both speeds when jumped, and I swapped the relay with no charge in behaviour.

I have booked the car in with myself to fix both issues on Friday.

Thanks again

Berni
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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berni29
Watkins Glen


Joined: 24 Oct 2009
Posts: 2175
Location: Kent


PostPosted: Sun Oct 08, 2017 11:45 am    Post subject: Reply with quote

Hi guys

Just to bring this episode to a close.

The car is now fixed, although things were less straightforward than they could have been. Of course.

The CHT itself was a little awkward to remove partly because the camshaft end cap was 90 deg out and was fouling things up a bit. So we dropped the engine an inch or so and rotated that (fiddly). You can cut the old CHT lead and get a socket on, but the ratchet end will need to be quite small.

Getting the new CHT lined up so that it threads back in was a bit challenging given that the cable is quite stiff at the sensor end. Most people cut a 14mm socket to tighten it up, but I just ground down an old spanner and nipped it up with that. Probably not tight enough, but with this sensor I'm not sure it matters.

On my travels apart from discovering the incorrectly fitted cam seal cap, I noticed one of the engine mounts was coming undone. So I tightened that up and will get a tourque wrench on it soon. That could have been quite nasty actually.

Also I changed the front oil cooler sensor (had one already) because the fan would cut in for 3 seconds and then go off. It's a common fail. It's a 10 minute change through the headlight if you have a short 19mm spanner or crows foot. Now the car temp stays roughly around 9pm when hot, and the fan operates correctly.

For some reason the screen demist will not work at full boost now though. I was fiddling with relays so will have to investigate further.

Thanks again

Berni
_________________
993 C2 Tip 1994 187k miles. Black and Grey. M029 & Bilstein HD's, Elephant Racing RS bushes F&R, RS mounts, strengthened engine carrier, 100 cell cat inserts, HID's. Solid steering arms mod, top of the engine rebuilt, mapped by Wayne, suspension set up by Chris.
 
  
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