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Stalling when stopping

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Old 12-22-2023, 12:18 PM
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pyramidimaging
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Default Stalling when stopping

Hope ya'll can offer some advice. My '91 964 3.6l baby is starting to stall when coming to a stop. I then have to wait at least 30 seconds before restarting. Seems to get worse as the engine warms up.

I'm thinking it may have something to do with a temperature sensor that helps control air intake. Any thoughts are greatly appreciated.

Last edited by pyramidimaging; 12-22-2023 at 02:13 PM.
Old 12-22-2023, 03:16 PM
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jreifler
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Any other symptoms? Stuttering? Misfires?
Old 12-22-2023, 04:24 PM
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No_snivelling
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Did you have the battery disconnected for any length of time?
Old 12-22-2023, 04:38 PM
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Earlydays
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My car would stall when the DME relay was going bad......
Old 12-22-2023, 04:46 PM
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misteralz
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Clean the ISV first. It's free.
Old 12-23-2023, 07:47 AM
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LM964
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Worse when the engine really hot (i.e. if yes, do you know that both the oil cooler fan low and high speeds operate)?

Cold running ok? DME fuel relay swapped over yet? Rough idling (ISV)?
Old 12-23-2023, 08:22 AM
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pyramidimaging
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Originally Posted by jreifler
Any other symptoms? Stuttering? Misfires?
No other symptoms noted.
Old 12-23-2023, 08:26 AM
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pyramidimaging
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Originally Posted by misteralz
Clean the ISV first. It's free.
Excuse my ignorance but what is an ISV and where can I find it on the car? I found a thread in the 928 forum about spraying WD40 into it but nothing to help me locate this ISV in my 964.

I'm hopeful this is the problem as the fellow in the 928 forum was stating the exact same symptoms that I'm experiencing.
Old 12-23-2023, 08:37 AM
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pyramidimaging
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Originally Posted by LM964
Worse when the engine really hot (i.e. if yes, do you know that both the oil cooler fan low and high speeds operate)?

Cold running ok? DME fuel relay swapped over yet? Rough idling (ISV)?
Not sure about really hot but may likely be the case since it seems to occasionally stall when first starting out but then stalls on every stop after more time has elapsed. Really scary when I'm on the interstate with stop and go traffic. People behind me get quite upset when it stalls and I have to sit for 30 sec or more. Plus, I have to be sure not to try and start it before it's ready or I just keep delaying when it will start.

Thanks for these suggestions. I'll research this more after I find out where the ISV is located and clean it, since that sounds quick and easy.
Old 12-23-2023, 08:38 AM
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Originally Posted by No_snivelling
Did you have the battery disconnected for any length of time?
Battery was not disconnected.
Old 12-23-2023, 09:19 AM
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Originally Posted by pyramidimaging
Excuse my ignorance but what is an ISV and where can I find it on the car? I found a thread in the 928 forum about spraying WD40 into it but nothing to help me locate this ISV in my 964.

I'm hopeful this is the problem as the fellow in the 928 forum was stating the exact same symptoms that I'm experiencing.
It sits on top of the engine. Silver cylinders with two hose connections and one electrical connection. It's easy to get to.

Search for a picture of the engine bay on this forum and download the service manual. That will help you.
Old 12-23-2023, 11:17 AM
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Vegas993
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I would check your Fuel Pressure Regulator.
Old 12-23-2023, 02:38 PM
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pyramidimaging
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Originally Posted by cjoenck
It sits on top of the engine. Silver cylinders with two hose connections and one electrical connection. It's easy to get to.

Search for a picture of the engine bay on this forum and download the service manual. That will help you.
Ok, found the ISV, thanks. Could not find, via search, a service manual, though. Do you have a link?

Also, the two hoses are attached with crimp on clamps. I'm going to try and pry them off with a screwdrivef and reclamp them but will probably have to cut them off. Then I'll have to figure out the diameter for a replacement clamp.

So, it was easy for me to find ISV but not so easy for me to remove it. I'm just a novice though.
Old 12-23-2023, 04:56 PM
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100% Fuel pressure regulator. I went through this exact same thing. Not anything easy to look at to determine if it’s working correctly. I replaced mine and it was exactly why after my car stalled and wouldn’t start again. The FPR is supposed to pull the fuel back when the car stops running and instead fuel was being dumped into the engine. It was like the car was flooded and it wouldn’t start. 30 seconds or so later it would start. Pretty annoying at a stop sign with cars behind me!
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Old 12-23-2023, 11:41 PM
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I had similar symptoms and my problem turned out to be the camshaft position sensor.


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