Miraculix

So, winter has passed and my 993's issue is still not solved by either Porsche or independant mechanics in Sweden.

To give you more information of what I know now I can start out by saying:

The car wont start or it will start and die after a while if I let the engine warm up and then shut her off for a couple of minutes.

A very good example is going to refuel her at a gas station:

I fill her up with gas which aproximently takes 3-5 minutes depending on the pump speed. Then I go in and pay which takes like 1-3 minutes:

Wont start!

Say I drive and eat at a restaurant somewhere and keep the engine off for about 10-15 minutes:

Car will start but then die only a couple of minutes later.

And say I go for lunch and keep the engine shut off for 30-40 minutes:

Car is fine..!

I checked for a spark but when the car has stopped, there is none!


New Wiring harness
New DME Relay
New ECU by Porsche (2 years ago)
Carguard alarm system thrown away
New Distributor cap
New Fuel filter
Checked Tank transmittor
New Ignition Lock contact
OT-sender
New service
New Distributor incl. Hall-transmittor
New Ignition module? (Placed next to ECU in the car)

max911

when you say that the car will not start- does the engine turn over, but does not start?? or, does the engine not even turn over ??

Dbltime

Need more background but on the surface sounds like an immobilizer issue. Do you lock the car when you go to pay for the fuel? Just a wild guess. Do euro cars have the immobilizer?

GabiOsz

I have a similar problem, it happens with a similar time frame, (ie. filling up with fuel, etc.).

When i get the problem, the car will turn over, but not start first time. Giving it a little Gas and a couple more tries seems to get it going, and it never dies once started, but i would be interested in what others have to say about this.

I also live in a cold(ish) climate (UK). I have had the distributer caps and wiring harness changed, and it has been much better, but occasionally it will do this. I also get over run, and wonder if it can be related, (ie. I can get starting trouble after I have had over run when switching off).

austin944

When the car doesn't start you can disconnect the coil and measure the resistance across the terminals. If it's an open circuit (infinite resistance) then that's the problem. Or just take a heat gun and warm it up and then measure the resistance. Saves you the cost of having to replace it.

Speedraser

It's very likely you've already done this, but...

Did you change the DME relay? My car wouldn't start in the same situation -- when warmed up and then shut off for about 5 minutes, like after filling with gas. The starter would spin the engine, but it would not fire. If I then let it sit for a minute or two, it would start. The dealer found an error code indicating the mass air sensor -- several hundred dollars. Thanks to this board, I replaced the $26 DME relay instead, and completely cured the problem.

Steve Weiner-Rennsport Systems

Thomas:

You seem to have a stubborn one on your hands.

You've gotten several good suggestions here and assuming that you have already swapped the DME relay for a new one, I would:

1) Try different coil drivers and coils in a no-spark condition. Its not unusual for these to fail.

2) Given how difficult it is to test the Crank Position sensor when the car is acting up, I'd suggest that it be replaced. One needs an oscilloscope to see its ouput.

Lastly, wiring faults can be cause of major grief. It might be time to check the engine harness and all of its connectors.

Miraculix

It's a long list of components changed so far, I just can't seem to access my old thread about it from the search engine?

Anyone have some good suggestions where to translate English engine part names to Swedish?

I wouldn't know what a Crank Position senor is..

Miraculix

New Wiring harness
New DME Relay
New ECU by Porsche (2 years ago)
Carguard alarm system thrown away
New Distributor cap
New Fuel filter
Checked Tank transmittor
New Ignition Lock contact
OT-sender
New service
New Distributor incl. Hall-transmittor
New Ignition module? (Placed next to ECU in the car)

Laura

No start - does it try to turn over or is it totally dead?
Dash lights and gauges lit?

graham_mitchell

Laura, it turns, just doesn't fire up

Agro1

Hate to say it, but have you checked the plugs and ignition wires ?

Robert Collins - 96 993TT

Miraculix,
Not being a master mechanic, about the best I can do is call mine for you. I'll call him and see if he can think of some thing sfor you to check. He's been working on 911s for about 25-30 years, so he might have a few tricks up his sleeve, and he is always willing to help a Porsche lover.

Man, I just hate to see any 993 owner go through this much agony while the rest of us are in heaven, it's just not right. This should be the car that you're telling all your friends they need to get one instead of running from one....clearly not the experience you're having right now.

I'll post again soon...

Nemick42

hello,

If I may, I would suggest the following. it seems odd that you have no spark when the car will not start, but it also means that this is the most likely area to investigate. I do not see where the Crank Trigger (sensor) has been checked, but I think it was suggested in an earlier post. Basically, the Crank trigger is a component which identifies where the crank is in its cycle and then tells the ignition Coils to do their thing at the right time. If there is a faulty connection, or even a faulty gap with this component, you would have the symptoms you have described.

I do not know where the trigger is located on the Porsche engine, but your mechanic should be able to check it. It may be that the Crank trigger can be changed with the engine in place, if so, it would be wise to swap it with a new one. Since the problem is not consistent, it could be that it will check out fine when tested, but fail uunder temperature differences.

Hope this helps

Biovox

I had a similar problem on my 965 (R.I.P) where the engine would just cut out when it got hot. Leave it to cool down and it started just fine. The problem was traced to the crank position sensor. Evidently the bracket holding the sensor had corroded in such a way that when it got hot enough it moved the CPS (Hall effect) just enough for it to fail to pick up the rotation. The ECU fails to see the trigger from the sensor and inhibits fuel and ignition. If you can hear the fuel pump when you try to restart but get no spark then this may well be indicative of the problem. The garage replaced both sensor (~70GBP) and bracket (~11GBP) and this cured it. I think the CPS is mounted between engine and gearbox - they usually pick up the crank position off the flywheel I believe

Good luck