[NeedPorscheSpeed]

Hello gentlemen.



Well, yesterday morning, it was 5 degrees outside when I went to crank up my 1990 Porsche 944 S2. (I know it's not my 968, but I feel that the S2 is similar enough for this type of discussion.) So, it fired the first time I cranked the engine, but then sputtered and died. So, naturally, I turned the key again, and while the battery seemed weakened a bit, the engine refused to fire. I hoped against hope that the battery was to blame, so when I returned home, I gave the battery a full charge. (My spirits were lifted when I saw that the battery charger was on the lowest mark when I began charging.)



Well, just now, in 35 degree weather, I put the battery back in and attempted to start the car. Just as I feared, the engine did not fire a bit, although she turned over just fine. I suspect that it is the DME; I mean, the car was running just fine less than 12 hours before I attempted to crank it in 5 degree weather. Is DME failure a common problem that occurs in cold weather? (I know that DMEs are more likely to fail in hot weather, as I suffered such a calamity a couple summers ago.) Some other things that spring to mind are the DME relay and the fuel pump fuse; the coil, of course, is another. I suppose I should check the Distributor Cap, too, although I don't really feel as though it would fail in cold weather. What do you guys think? What are some other possible culprits?



If it is the DME, I can't imagine the cost to replace it. The 968 DME is outrageously expensive, and there are a lot more of them around than the S2. What really stinks is that I had someone that wanted to buy it in the Spring... It looks like it is time to call the 968 up out of the bullpen; she was on winter break, but no more...



Thanks for reading!

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[S_Cal968]

Generally all electronics have a operating temperature range, [namely the IC's]. However at 35° it should start.

Do you have a spare [known good] DME relay? I would think they used one in the S2[?].

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[NeedPorscheSpeed]

Hi there, S_Cal. Thanks for responding. Come to think of it... Southern Cali's weather would be quite nice about now. <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />



I tried the 968's DME in the S2, to no avail (same part number, so no problem to swap it out); I also checked the fuel pump fuse, and it was fine. At this point, I am thinking coil (since it is the original coil from 1990) or, gasp..., the DME. <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" /> When it gets a bit warmer, I plan to try the 968's coil in the S2. The good news is that the 968 fired right up and is running great. It sure is nice to have a backup ready to come out of the bullpen!



Thanks again for taking the time to respond.



[quote name='S_Cal968' post='30707' date='Feb 7 2007, 04:06 PM']Generally all electronics have a operating temperature range, [namely the IC's]. However at 35° it should start.

Do you have a spare [known good] DME relay? I would think they used one in the S2[?].[/quote]

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[stian968]

Hi



I have used my 968 for 2 months in temperatures below 5 degrees. As far down as -15 degrees. And it works just fine. During summer the temp. is up to 30-35 degrees. But all seems fine... My guess would be the coil I guess...



Stian

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[NeedPorscheSpeed]

Thanks for your input, Stian! I am hoping that it is only the coil, as that would be a nice and easy fix...



[quote name='stian968' post='30726' date='Feb 8 2007, 09:03 AM']Hi



I have used my 968 for 2 months in temperatures below 5 degrees. As far down as -15 degrees. And it works just fine. During summer the temp. is up to 30-35 degrees. But all seems fine... My guess would be the coil I guess...



Stian[/quote]

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[stian968]

You`re welcome. I truly understand your need for driving your Porsche ! I`ve also seen

that the DME relay has been an issue, and in several discussions here it has been adviced to

always have an extra relay in your glove box. I spoke to my local dealer which is a good

friend of mine, and he told me that he had never heard of a blown DME. According to him, they are

"bullet proof".



Good luck ! Stian !

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[flash]

assuming htat the control components are intact and functioning, the coil has been my guess on this one - i've had this happen, but very rare, and not for a very long time - not terribly common



i've always used the bosch super blue coil, and never had an issue with it - i have one in my 968 too

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[sp4149]

[quote name='NeedPorscheSpeed' post='30705' date='Feb 7 2007, 12:47 PM']Hello gentlemen.



Well, yesterday morning, it was 5 degrees outside when I went to crank up my 1990 Porsche 944 S2. (I know it's not my 968, but I feel that the S2 is similar enough for this type of discussion.) So, it fired the first time I cranked the engine, but then sputtered and died. So, naturally, I turned the key again, and while the battery seemed weakened a bit, the engine refused to fire. I hoped against hope that the battery was to blame, so when I returned home, I gave the battery a full charge. (My spirits were lifted when I saw that the battery charger was on the lowest mark when I began charging.)



Well, just now, in 35 degree weather, I put the battery back in and attempted to start the car. Just as I feared, the engine did not fire a bit, although she turned over just fine. I suspect that it is the DME; I mean, the car was running just fine less than 12 hours before I attempted to crank it in 5 degree weather. Is DME failure a common problem that occurs in cold weather? (I know that DMEs are more likely to fail in hot weather, as I suffered such a calamity a couple summers ago.) Some other things that spring to mind are the DME relay and the fuel pump fuse; the coil, of course, is another. I suppose I should check the Distributor Cap, too, although I don't really feel as though it would fail in cold weather. What do you guys think? What are some other possible culprits?



If it is the DME, I can't imagine the cost to replace it. The 968 DME is outrageously expensive, and there are a lot more of them around than the S2. What really stinks is that I had someone that wanted to buy it in the Spring... It looks like it is time to call the 968 up out of the bullpen; she was on winter break, but no more...



Thanks for reading![/quote]

Given the symptoms, my guess is the Hall sensor at the rear of the engine. On our 1984 944 last year it wouldn't start altholugh it had been running fine the week before. The Early 944s had two, the 968 has just one but when it dies, the engine doesn't fire, but still cranks. There is a BMW replacement that is half the price but the lead is twice as long is you want to save some money. BTW the plug for these sensors is very brittle and disconnected is the same as a dead sensor. Clarks Garage has some info on checking the sensors on a 944, it's the same sensor in the rear on a 968, so you can quickly determine the cuplrit. Installed the BMW sensor and the 944 fired on the first crank.



good luck, sp4149

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[S_Cal968]

Jon,

Actually it's been fairly cold out here compared to what usually is. You may have heard in the news about all the crop damage out here - I live in one of the areas they're referring to. My heating bill has almost tripled... <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" />



Just for grins have you attempted to access the trouble-codes? Also in some cases if you have access to a known good coil, you can compare the resistance at the terminals. However if this is a temp related issue this won't help.

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[Renalicious]

I think my DME is dead, or dying. Thankfully I had a spare in my glove box, so I put it in and the engine has been running fine. To give you an idea, I started having ignition problems 3 weeks ago. Initially I thought it may have been fuel issues since the first time my engine died was when I was driving home from work with almost no fuel. I went to the gas station which is right across the street from my house, filled it up, and lo and behold, it wouldn't fire (kind of embarrassing hehe). I thought "Ok, maybe clogged filter", after a while, it fired up and I drove home. A week later I was driving around and all was well. Drove to the store to get some fuel cleaner, fired it up, got to an intersection and it died AGAIN. Doh! Took about 10 minutes this time.



Now, yesterday I was out for a long drive, went to visit the folks and stayed for dinner, on my way out, it died again just outside their place. This is when I remembered the DME issues. I poped in the new one, and everything seemed to work fine. Got home, put the old one back in. Did a quick fire up and it started up fine.



This morning I'm on my way to the store, and what happens? 2 minutes after I leave my place the car dies. So, I swap in the new DME, and all was well. At this point I'm thinking that the old DME is basically done. At least I'm hoping it's the DME, not some more obscure problem. However, I will set up an appointment to get my fuel filter and lines changed sometime next week. Just in case.



As for the weather thing, I did leave my car out in the cold-ish weather at work all day long for a few days at a time prior to when this started occurring. So I don't know. I will keep the old DME and have the shop test it if they can, unless someone here wants to do so <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



The moral of the story, carry a spare DME just in case. You never know!

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[S_Cal968]

Ren: From what you described it could be a variety of things - it may not be the DME. Have you tried checking the stored codes? Or you may have a flaky DME relay, hall sensor or other intermitent electrical connction [i.e. bad ground] or a questionable fuel pump. Unfortunately intermitent gremlins are hard to pin down. For example, it would be nice to have a fuel pressure gauge to monitor the fuel rail during a no-start or measure the 12v to the DME. In fact I was considering coming up with a LED pilot light for the DME...

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[Renalicious]

[quote name='S_Cal968' post='31163' date='Feb 18 2007, 06:22 PM']Ren: From what you described it could be a variety of things - it may not be the DME. Have you tried checking the stored codes? Or you may have a flaky DME relay, hall sensor or other intermitent electrical connction [i.e. bad ground] or a questionable fuel pump. Unfortunately intermitent gremlins are hard to pin down. For example, it would be nice to have a fuel pressure gauge to monitor the fuel rail during a no-start or measure the 12v to the DME. In fact I was considering coming up with a LED pilot light for the DME...[/quote]



I know, I'm really hoping it's just the DME. But I will have the shop check everything over the next time I take it in for servicing. I'm planning on getting the filter and lines replaced, but don't know about the fuel pump. How big of a job is that anyways? I heard horror stories about how with some cars you need to take the fuel tank apart just to get to the pump. Ugh. Of course my first car (83 ford escort, heh!), had a mechanical one right on the engine <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />



This next outing to the shop will be a big one. Planning on getting a lot of stuff done, but hopefully it'll make a few things right.

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[Darth Vadar]

The fuel pump is at the rear, near the tank, but, thankfully, not IN the tank. Under a cover plate, IIRC.



Since you said your car died with the "old" DME Relay in, and you swapped in a replacement, and it immediately started, one would think that is at least a significant part of your issue...

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[gryphon]

My DME relay gave me similar problems, namely more and more difficult starting, until I replaced it. It's apparently not your typical electronic device that fails instantaneously as one might think. Regardless, the new relay is supposedly more dependable than the previous one, so I'd leave it in...and it's a cheap part by Porsche standards.



Tom

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[S_Cal968]

Ren: I must have mis-understood, I thought you were referring to the electronic control box [dme], not the relay. [oops]



Anyway I've been able to revive the a flaky relay by cleaning up the contact points with a burnishing file. It's easy to do; the top of the relay comes off and the file is lightly swipped between the points. Despite my efforts I always carry a spare just in case...

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[NeedPorscheSpeed]

I thought that it would be courteous of me to report the fix for this problem. Hey, better late than never, aye? <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />



The problem was a weak battery. Last March, a month after I had posted here, I tried to start the car with the battery, now fully recharged, to no avail. Finally, after letting the car sit a while and having tried everything under the sun it seemed, last June I tried one of my 968 batteries, and the S2 sprang to life. Thankfully, she has been fine ever since!



My apologies for not having "completed" this thread before now.



Cheers!

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