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993 Misfire now won''t start.

Mike_993

Well-known member
Joined
14 Mar 2017
Messages
178
Any ideas as to what this could be. Washed the 993 today planning to put it into hibernation. Started ok then when went to put it away and a terrible misfire. Seemed to smooth out at slightly higher revs. I have changed the DME relay with a spare but no difference. Left it for a while whilst studying distributor faults and now it won't start at all. Any thoughts appreciated.
 
Mike_993 said:
Any ideas as to what this could be. Washed the 993 today planning to put it into hibernation. Started ok then when went to put it away and a terrible misfire. Seemed to smooth out at slightly higher revs. I have changed the DME relay with a spare but no difference. Left it for a while whilst studying distributor faults and now it won't start at all. Any thoughts appreciated.

Did you powerwash the engine bay?
 
Just a very light wash of the exterior. I am always careful not to get any water in the engine bay.
 
May sound daft but check the battery earth strap.
 
Endoman said:
May sound daft but check the battery earth strap.

Will do. It turns over a treat on the starter motor and has a fairly new battery.
I just checked another DME relay and same result. I can smell petrol when working it's turning over on the starter.
Reckon I will need to have it collected, usually serviced by OPC but concerned with a fault like this it could be expensive!!
 
I had a very similar problem with non starting and it was cured by changing the Engine Temp sensor and the Crank speed sensors. Not sure which was at fault but had PARR change both for me. No problem since.
 
Ditto crank sensor failed 200yds from OPC Bolton the showroom guys pushed me in. Had exactly the same misfire, bad hot start on the 944, crank sensor again.
 
Sounds the same, Thank you for the advice. Presume they can diagnose it with an OBD reader and is this remotely a diy job?
 
Mike_993 said:
Sounds the same, Thank you for the advice. Presume they can diagnose it with an OBD reader and is this remotely a diy job?

My crank sensor failure did not show up on the OBD
:bandit:
 
Mine was checked and set with an oscilloscope. I have a LWF so the setting is differerent. The sensor is usually fused to the holder so that was replaced as well, easy diy on the 944.
 

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