[NeedPorscheSpeed]

Well, today, I decided that I would drive my black 1992 968 to work. After driving it gingerly during the past two weeks after some major repairs, I felt she was ready for primetime. Around 2:00 p.m., I stopped at a restaurant to eat, and at 3:00 p.m., when I returned to her, she would not start.



At first, there was spark and it tried to start, but just could not quite turn the corner, so to speak. I immediately thought that it was probably the DME Relay, so I had my sister come pick me up and take me home. I grabbed a good 993 Relay, and went back, confident that I would be driving the 968 back home. It didn't happen. In fact, it was actually worse in that there was absolutely no spark.



Here are some factors that may help you guys to offer some pointive suggestions:



1) During the past three months, I replaced the camshafts, tensioner pads, tensioner chain, distributor cap, and distributor rotor.



2) About two weeks ago, I retimed the timing belts and tensioned the balance shaft belts.



3) After the repairs, the car would start right up every time without any fuss.



***Once in a while, when re-starting the car after she had run for a while, she would immediately die. However, for completely cold starts, it always cranked right up and remained running. This problem had not manifested itself lately, so I felt she was safe to drive daily again.***



4) Today was a scorcher, with the temperature at 100 degrees and the heat index at 110. The extreme heat really me me think it was the DME Relay, but, again, I tried a new relay, and it still would not start. In fact, there was no spark at all.



To summarize: here are the things I have tried so far:



a) Replacing the DME Relay

<img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> Inspecting everything under the hood

c) Holding the throttle open while cranking the engine



Right now, the car is parked at the restaurant, and I have cleared it with the owner to leave it there overnight if required. I would like to return to the car in a few minutes and attempt to get her running. Any and all suggestions and thoughts are appreciated. Thanks in advance! <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[flash]

while i tend to think coil, take a look at the hall sender - it's right above the exhaust immediately behind the distributor - known to fail from heat - without it, car no go

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[NeedPorscheSpeed]

[quote name='flash' date='Jul 25 2005, 07:38 PM']while i tend to think coil, take a look at the hall sender - it's right above the exhaust immediately behind the distributor - known to fail from heat - without it, car no go

[right][post="7886"]<{POST_SNAPBACK}>[/post][/right][/quote]



Flash, I have been leaning towards the coil, as well.



Regarding the Hall Sender, I have collected conflicting information about whether or not a car will run without it. Some say the car will run, but will be a bit rough. Others say it will not run at all... When I inspected the Hall Sender earlier today, it did not look good at all. The insulation, what is left of it at least, is dry and brittle. In fact, when I did all the major over the past few months, it didn't look great then, actually, but it certainly looks worse now. It is one of those things that I was planning to replace soon, but now, it appears it may have bitten me in the tail before I acted preventively. <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" />



Well, it appears it may be time to pump some more money into Black Beauty.



:::takes a deep breath, composes himself, and thinks... "don't be upset, Jonathan...this is a part of the deal for any car that is over ten years old... Long live water-cooled Porsches!":::

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[flash]

dan sandru just had to replace his as well not too long ago - same condition - i seem to remember him saying his car would not run without it, and i had heard that elsewhere as well - frankly, i haven't unpluged it to find out, but if it's crunchy, it needs replacing anyway



and yup - 10 years old means every rubber and plastic part is suspect



joining you now in that deep breath - care to join me for a beer too while we're at it?

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[Anchorman]

This could be very wrong - but I recall reading that the Hall sensor is only needed to get the car started - I think it confirms the relative position of the crankshaft and the camshafts. Once started, the Hall doesn't perform any ongoing function. If that's correct, the Hall sensor certainly could be the problem.

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[NeedPorscheSpeed]

UPDATE: I went back to the restaurant at 9:00 p.m. to attempt to start the 968. As it was dark, the only thing I did was just turn the key a couple times, after inserting a new DME Relay. My hope that was that with everything cooled down, especially a failing coil, it would crank. It didn't happen. So, tomorrow morning I will take off work, get my tools, and go try to fix her around 6:30 a.m. before the sun comes out and scorches me. I am going to exchange the coil, inspect the sparkplugs and wires, and do a few other things, and if all that fails, I will call for a tow truck. If she has to be towed, I'm just going to have her towed home so that I can work on her in my garage. I think I can get her running again, I just don't know if I can do it within 2 hours time in a parking lot... From 7 a.m. til 9 a.m., the heat index is forecasted to be from 80 to 89 degrees, but after that, it will be 95 to 101 until 5 p.m.



To add insult to injury, last week, I left my lights on and ran down the battery of my S2. Well, I went to charge it just now, and it won't take a charge... I think I've had enough for one day. Good night. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[Greimann]

[quote name='NeedPorscheSpeed' date='Jul 25 2005, 06:03 PM']Regarding the Hall Sender, I have collected conflicting information about whether or not a car will run without it.  Some say the car will run, but will be a bit rough.  Others say it will not run at all... 

[right][post="7887"]<{POST_SNAPBACK}>[/post][/right][/quote]

It will run without it. The timing will be retarded by 6 degrees. The diagnostic procedure in the manual has you disconnect the hall sender plug, connect up an oscilloscope and start the motor to check for a square wave signal.

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[Dean968]

Hi there



Deano here from over the pond.



My 1992 car exhibited EXACTLY the same symptoms.



I had the Flywheel sensor AND the Oxygen sensor replaced at the same time (my mechanic narrowed it down to these 2 and the costs wasn't bad).



I've done about 6000 trouble free miles now.



Hope that helps.



Cheers, Deano.

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[NeedPorscheSpeed]

Greimann,



Thanks for the confirmation. I had finally found that bit about the timing being retarded by 6 degrees at about 2:00 a.m. What I should have done is gotten a good night's sleep with the full expectation that you would come through for me. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> Thanks again for your help.



Dean968,



Hello there. I am going to check my flywheel sensor in just a few minutes. Thanks for the idea, and thanks for sharing your experience. If I have much more difficulty getting her going again, I may just replace the hall sender, flywheel sensor, TPS, O2 sensor, etc. Then watch it be the DME... <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />



Greimann,



Hello again. Along these lines, do you know if the tach is supposed to bounce in a 968? It does in my turbos and S2, but I never have noticed it in my 968. The idea in my other cars is that if it doesn't bounce, it is an indication of a failed speed or reference sensor. As the 968 only uses one sensor, it may not exhibit "bouncing" behavior while cranking. Can you clear that up? Thanks.



Well, guys, I'm off to the restaurant to try to get her moving. I had planned to go this morning early in order to avoid the heat, but it just wasn't possible. Now the heat index is 103, but a man has to do what he has to do. Wish me luck that I won't melt. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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[Greimann]

I have no idea about the tach bounce thing. Perhaps someone else does?

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[Brett968]

First thing I would verify is that your DME is actually coming on. With the ignition key in the ON position put before attempting to crank the engine, all of your dash lights should come on. Check that your Check Engine light is coming ON with the other lights.





Brett

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[NeedPorscheSpeed]

Okay, I spent a couple hours today working on the 968 right there in the middle of the restaurant parking lot. I know, I have no pride. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> It is still not running, and here is an update of what I have done so far. Causes for concern are in italics.



1) Inspected the Hall Sender. It has metal showing, and after having found out that the car will run with a failed Hall Sender, albeit with 6 degree ignition timing retardation, I am thinking about testing it with the Hall Sender disconnected. My thinking is that, because the connecters are bare, it could be shorting out the circuit.



2) Sniffed Fuel Injector and Fuel Rail for leaking fuel. No gaseous odor detected.



3) Removed the Vacuum Line from the FPR. Again, no gaseous odor detected.



4) Tapped the Speed and Reference Sensor.



5) Inspected Spark Plug Boots and Wires.



6) Checked all Spark Plugs for fouling. They all still look virtually brand new; I'm glad since they only have 100 miles on them.



7) Cleaned the battery posts and leads.



7b) Jumped off the bridge... (j/k) <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />



8) Jumpered the fuel pump. It works fine.



9) Exchanged the coil. No change.



10) Inspected the TPS and MAF wiring harnesses. The TPS harness boot has minute cracks in it, mainly due to its being at a 90 degree angle.



11) Inspected the fuel injector harnesses. All look fine.



12) Tested Spark Plug #2 and #3 for arcing. No spark.



13) Tested the Coil Wire for arcing. There was spark, and she went boom! <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />



14) Inspected the distributor cap and rotor. No visible problems. The distributor cap and rotor are both brand new, and have about 100 miles on them. Although I inspected them, it was already dark, so I was using a flashlight. Therefore, I could have missed a minute crack possibly. If I am getting spark from the coil to the distributor, and not to the spark plugs, in turn, then that leaves the distributor cap and rotor as the possible culprits, I would think.



15) Ensured that the timing was still fine, as a longshot, and it was.



So, this leaves #12 and #14 as the most salient leads. I have spark at the coil, but not at the plugs. (To complicate matters, both the distributor cap and rotor are brand new, with about 100 miles on them.) If spark is being sent to the distributor cap from the coil, then there must be something faulty about the distributor cap, right? If anyone has any other conclusion, please share it with me.



Two things that I also want to relay so as to provide a complete picture:



(1) The car is cranking perfectly. The battery and starter are both strong. However, there is no attempt at starting. At no point does the engine fire. When I first began cranking her after eating for about 40 minutes, the engine did fire a bit, but it never would quite start.



(2) Although the car had been running well for the past 100 miles after the freshening and repair work, when I timed the belts, my camshaft timing pulley mark was a bit to the right of the mark on the rear camshaft pulley cover, I would say by about a mm. The reason it was to the right, and not perfectly centered is because when it was perfectly aligned, it ran quite rough. When I re-timed the belt, I moved it over a tooth, and it ran great. It certainly appears to be as it was when I timed it.



My future course of action is to go back tomorrow morning with the distributor cap that I took off back in April. It was still functioning, but just looked a bit worn. Therefore, I put on the new one. If that doesn't work, I am having her towed home. Of course, my plans may change if any of you have some ideas.



Thanks for reading! <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[Dean968]

Just to note: When my tried to start my car after I'd left it after a long journey my rev counter needle flicked up and down too as the car was cranking (and, obviously, not starting). Not sure this was a clue to the aforementioned sensors but who knows!



Cheers, Deano.

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[Dean968]

<img src="/forum/images/smilies/968/unsure.gif" class="smilie" alt="" />



PS - I meant to also say I WASN'T getting a spark at the coil...

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[Greimann]

Here is my guess for today: <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



"She ain't got no gas in it"

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[jww968]

Try unplugging one fuel injector. A fairly common reason for non-start is a bad fuel pressure regulator. If the fuel pressure is too high, the injectors cannot open. Unplug the wiring to one injector and if the car runs on three cylinders, you need a new regulator.

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[zaga1]

Make sure the injectors fire. Even though the harness looks find, you might have stripped wire under the protective harness, specially where the harness bend near the injectors. If a cable is stripped it will shut down the DME and the injectors won't work. I don't remember if you still has spark from the plugs.



I figured this one out after months of looking. I almost when insane.

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[94SilverCab]

http://www.automotive.com/porsche/19/alabama/



No disrespect, but after 2 days of beating your head against a wall...maybe a dealer service shop would be the way to go...

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[flash]

i hate to say it, but i'm inclined to agree - at this point you are getting a lot of varying inputs - check out the simple stuff, without spending any money, and then call a tow truck and at least get it out of there and to some place safe



not sure about the dealership thing, but at least get it to a shop where they know this car - most of the dealerships here are really the last places i would take one, but that may just be a local thing - somebody in your area would be a much better judge of that one

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[NeedPorscheSpeed]

Thanks for your replies, guys.



Greimann,



Interesting you should say that. The last thing I did before parking the car was to get some fresh gas... I'm beginning to wonder if I got a bad tankful! <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" />



jww968 and zaga1,



Welcome to the board, and thanks for your input. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



94SilverCab,



No offense taken. However, the nearest authorized Porsche dealership is some two hours away (the one in Huntsville opens in a few months). Also, I would rather beat my head up against the wall another week or two in my garage rather than pay the going $98.00 per hour that Porsche dealerships charge. Because she is not my only mode of transportation, there is no rush. If the no start condition persists for a few months, of course, to the dealership she goes. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />



Flash,



Well, I've just about covered all the simple stuff... Just about time to get her towed home, I guess. If my last ditch effort today doesn't work, I guess we'll call it a defeat. But I and Black Beauty will rise again! <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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