Recovering from a low RPM kill... pure embarassment
08-25-2002, 09:11 PM
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Recovering from a low RPM kill... pure embarassment
Does this happen to anyone else?
My car starts great... cold or hot and doesn't die from a rapid drop in RPM as it did with poor gas and over-filled oil... however...
If I should ever kill my engine from a low RPM situation (backing into a parking space, etc), It usually takes over a minute for my car to recover and start again! I can either keep trying the starter, or just wait 60-90 seconds. Same result either way. Does this happen to you? Any ideas?
My car starts great... cold or hot and doesn't die from a rapid drop in RPM as it did with poor gas and over-filled oil... however...
If I should ever kill my engine from a low RPM situation (backing into a parking space, etc), It usually takes over a minute for my car to recover and start again! I can either keep trying the starter, or just wait 60-90 seconds. Same result either way. Does this happen to you? Any ideas?
08-26-2002, 12:32 AM
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Hi Bob,
If you haven't done it already, try replacing your DME relay. At around $15, worth a try.
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=3&t=000561" target="_blank">DME Relay Fixes Starting Problem</a>
The 964 uses the same part number as the 993.
If you haven't done it already, try replacing your DME relay. At around $15, worth a try.
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=3&t=000561" target="_blank">DME Relay Fixes Starting Problem</a>
The 964 uses the same part number as the 993.
08-26-2002, 05:29 AM
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Dear Randall,
You need to be more specific on the 993. Post model year 1995, DME relay 993 part number. The 1994 and 1995 model year 993s use the 944 part number DME relay that was installed in the 964.
Bob the part number you need to find is,
993 615 227 00
However I do not think you problem is the relay.
I would certainly check the voltage levels on the battery. It may be that the alternator or battery is tired.
Ciao,
Adrian
911C4
You need to be more specific on the 993. Post model year 1995, DME relay 993 part number. The 1994 and 1995 model year 993s use the 944 part number DME relay that was installed in the 964.
Bob the part number you need to find is,
993 615 227 00
However I do not think you problem is the relay.
I would certainly check the voltage levels on the battery. It may be that the alternator or battery is tired.
Ciao,
Adrian
911C4
08-26-2002, 06:27 AM
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Hey...I always chalk it up to "high performance sports car - high performance problems". 
Actually, this has happened to me a few times, I usually attribute it to the fact that I have a "Cup" lightweight flywheel/clutch and when the car does stall...the DME is apparently "confused" and what not.
...not to mention how confused the driver was!
A few weekends ago I spun my 964 pretty hard at CMP and the car stalled...it took quite a bit of cranking to get it started back up - that's the second time I've ever experienced a prolonged starting issue.
Your issue does seem to be more related to something that is technically "amuck" though, I have to agree.
I would be interested in finding out what it took to resolve the issue...of course, once it is in fact resolved.
Actually, this has happened to me a few times, I usually attribute it to the fact that I have a "Cup" lightweight flywheel/clutch and when the car does stall...the DME is apparently "confused" and what not.
...not to mention how confused the driver was!
A few weekends ago I spun my 964 pretty hard at CMP and the car stalled...it took quite a bit of cranking to get it started back up - that's the second time I've ever experienced a prolonged starting issue.
Your issue does seem to be more related to something that is technically "amuck" though, I have to agree.
I would be interested in finding out what it took to resolve the issue...of course, once it is in fact resolved.
08-26-2002, 06:43 AM
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Dear Bob,
I agree with what Jeff says. The fact that you stall says something might not be quite right. In fact the old leaking dipstick gasket can cause this.
Difficulty in starting easily after such a stall however is a nice little 964 thing. I have never driven in one that does not do this. They like to be given a little rest in between starts.
Ciao,
Adrian
911C4
PS: BTW we have similar limitations on our dry sumped jet engines. If you overheat the starter motor it will not start either. Minimum 30rpm is required to start.
I agree with what Jeff says. The fact that you stall says something might not be quite right. In fact the old leaking dipstick gasket can cause this.
Difficulty in starting easily after such a stall however is a nice little 964 thing. I have never driven in one that does not do this. They like to be given a little rest in between starts.
Ciao,
Adrian
911C4
PS: BTW we have similar limitations on our dry sumped jet engines. If you overheat the starter motor it will not start either. Minimum 30rpm is required to start.
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08-26-2002, 10:59 AM
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I'm going to show my mechanical ignorance and ask a couple of really basic questions here....
(1) What does the "DME" stand for anyway?
(2) What is the job of the DME relay?
In Bob's original post he said,
My car starts great... cold or hot and doesn't die from a rapid drop in RPM as it did with poor gas and over-filled oil...
(3) How is it possible for an oil overfill to hamper engine start or make it stall?
I think I may be experiencing this very problem. I recently changed the oil and it looks like I'm very close to full - perhaps slightly overfull. Lately, I've killed the motor when the car was cold and I jump off the throttle. I have a lightweight flywheel and this happens if I run the A/C when the motor is cold. (Just one of those quirks I've learned to live with.) When the engine is hot and the A/C is on, stalling isn't a problem. However, since my last oil change I've embarassed myself by stalling a cold motor (with the air off) when abruptly getting off the throtle.
Terry Riedel
'90 C4 Cabriolet
<a href="http://www.p-caronline.com/directory/c4_guy/" target="_blank">http://www.p-caronline.com/directory/c4_guy/</A>
(1) What does the "DME" stand for anyway?
(2) What is the job of the DME relay?
In Bob's original post he said,
My car starts great... cold or hot and doesn't die from a rapid drop in RPM as it did with poor gas and over-filled oil...
(3) How is it possible for an oil overfill to hamper engine start or make it stall?
I think I may be experiencing this very problem. I recently changed the oil and it looks like I'm very close to full - perhaps slightly overfull. Lately, I've killed the motor when the car was cold and I jump off the throttle. I have a lightweight flywheel and this happens if I run the A/C when the motor is cold. (Just one of those quirks I've learned to live with.) When the engine is hot and the A/C is on, stalling isn't a problem. However, since my last oil change I've embarassed myself by stalling a cold motor (with the air off) when abruptly getting off the throtle.
Terry Riedel
'90 C4 Cabriolet
<a href="http://www.p-caronline.com/directory/c4_guy/" target="_blank">http://www.p-caronline.com/directory/c4_guy/</A>
08-26-2002, 11:40 AM
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Dear Terry,
DME= Digital Motronics Electronics. It is the Bosch whole system trade name really and has become slang for the Engine Control Unit.
DME Relay=Switches power to the ECU. Switches power to the fuel pump and Switches power to the O2 sensor heater. Just a relay called the DME relay.
Oil and stall. When you overfill the oil the dry sumped system does not like this. It vents the excess oil. In the design of the 964 system, some vented oil finds its way into the airbox. In the airbox is the airflow sensor. Bascially a vane connected to a potentiometer. The vane position tells the ECU (DME as we call it) how much air is going in and the fuel schedule is adjusted in accordingly. If the vane is contaminated with oil it does not move properly. If it gets stuck shut the DME says hey I have no air you cannot have anymore fuel. Stall.
To find this problem is easy. Remove airbox cover, remove airfilter. Stick hand inside airbox and seeif you can feel the oil. If you can, remove airbox and throughly clean to remove all traces of oil.
Ciao,
Adrian
911C4
PS: However your problem is the LWF and the aircon. The C4 in particular does not like LWFs and Porsche recommend you do not install them.
DME= Digital Motronics Electronics. It is the Bosch whole system trade name really and has become slang for the Engine Control Unit.
DME Relay=Switches power to the ECU. Switches power to the fuel pump and Switches power to the O2 sensor heater. Just a relay called the DME relay.
Oil and stall. When you overfill the oil the dry sumped system does not like this. It vents the excess oil. In the design of the 964 system, some vented oil finds its way into the airbox. In the airbox is the airflow sensor. Bascially a vane connected to a potentiometer. The vane position tells the ECU (DME as we call it) how much air is going in and the fuel schedule is adjusted in accordingly. If the vane is contaminated with oil it does not move properly. If it gets stuck shut the DME says hey I have no air you cannot have anymore fuel. Stall.
To find this problem is easy. Remove airbox cover, remove airfilter. Stick hand inside airbox and seeif you can feel the oil. If you can, remove airbox and throughly clean to remove all traces of oil.
Ciao,
Adrian
911C4
PS: However your problem is the LWF and the aircon. The C4 in particular does not like LWFs and Porsche recommend you do not install them.
08-26-2002, 12:12 PM
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[quote]Originally posted by Adrian:
<strong>Dear Bob,
***snip***
Difficulty in starting easily after such a stall however is a nice little 964 thing. I have never driven in one that does not do this. They like to be given a little rest in between starts.
Ciao,
Adrian
911C4
****snip***</strong><hr></blockquote>
With all due respect, I have to disagree with you here, Adrian. Perhaps I've taken what you written out of context? A car that is difficult to restart--and requires a little rest--after stalling, is dangerous by design. I've never driven or come across a (properly running) 964 that has been difficult to start after (operator error) stalling. Likewise, this is analogous to saying that your (hot) 964 will be difficult to start if you shut it off for 10 seconds while switching drivers, running back into the house, etc.
Terry ... as others have suggested, as long as you have the LWF, it's very difficult to determine if anything else can be causing your car to stall. You might consider trying this idle stabilization valve adjustment that is working well for '95 993 owners. I don't know of any reason why it shouldn't work for 964 owners. That said, don't be surprised if you adjust your ISV, and still have stalling problems.
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=3&t=002968" target="_blank">Adjust ISV</a>
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
<strong>Dear Bob,
***snip***
Difficulty in starting easily after such a stall however is a nice little 964 thing. I have never driven in one that does not do this. They like to be given a little rest in between starts.
Ciao,
Adrian
911C4
****snip***</strong><hr></blockquote>
With all due respect, I have to disagree with you here, Adrian. Perhaps I've taken what you written out of context? A car that is difficult to restart--and requires a little rest--after stalling, is dangerous by design. I've never driven or come across a (properly running) 964 that has been difficult to start after (operator error) stalling. Likewise, this is analogous to saying that your (hot) 964 will be difficult to start if you shut it off for 10 seconds while switching drivers, running back into the house, etc.
Terry ... as others have suggested, as long as you have the LWF, it's very difficult to determine if anything else can be causing your car to stall. You might consider trying this idle stabilization valve adjustment that is working well for '95 993 owners. I don't know of any reason why it shouldn't work for 964 owners. That said, don't be surprised if you adjust your ISV, and still have stalling problems.
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=3&t=002968" target="_blank">Adjust ISV</a>
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
