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Motor cutting off.
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TOPIC: Motor cutting off.

Motor cutting off. 10 years, 8 months ago #16390

I have had the 944 for two years, 12 track days no issues. This year we put slicks on the car and in hard right hand turns on the same track I have run on with no issues with street tires the motor cuts off until the car comes out of the hard right hand turn. Did the fuel thing switching everything, no difference. Put rain tires on and it goes away. I believe it is electrical as when the car is in a hard right hand turn the tach drops to zero rpms and comes back when the motor comes back. Checked groung wires, gas tank full, but does not do it every lap. Any advice whould help.

Re: Motor cutting off. 10 years, 8 months ago #16394

  • joeblow
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  • Seasoned Racer
  • Old Racer
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Try swapping out DME relays, computers, flywheel triggers.

Check connections at the coil especially the wiring that might shift around on the track for possible shorts. That should also lead you to check the connections at the computer as well. Sounds like it is computer related to me.

Last thing, make sure the battery POS TERM is not touching the hood or firewall under cornering.
Old Racer!

Re: Motor cutting off. 10 years, 8 months ago #16396

  • Big Dog
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I had a similar issue when I changed the fuel tank in my car. It turned out that the new tank would allow fuel to go up into the other side of the tank on hard right hand turns.

I added 5 gals of gas and it still did the same thing, added another 5 gals and it was solved. I switched the tank back to the first one and no problems. The car would not bobble with only 1.5 gals in the tank. The other one needed 12/15 gals. Go figure.
Jim Foxx

Re: Motor cutting off. 10 years, 8 months ago #16409

If the tach goes to zero, but everything else still look fine, you probably have an ignition issue. If it was a fuel problem your tach will still work.

I would start with the crank position sensor. This is the sensor that tells the DME when to fire. On the 944 NA it is located in the back if the engine and on the 944 16V it is located in the front.

These sensors are prone to connector issues, specially the 16V. The connector gets brittle due to the engine heat and eventually disintegrate. If the connector is in bad shape I would replace it. You can buy just the connector from any AMP supplier.
Zeca Pires
Miami FL

Re: Motor cutting off. 10 years, 8 months ago #16425

One thing I'd do before doing all of the more complicated stuff that has been suggested is to check out the fuel pump suction strainer, which most of us call the sock. It filters the fuel through mesh panels that can tear, which often causes fuel starvation during hard cornering. Your motor will cut out during hard cornering and while accelerating out of the turn, but then will smooth out and run normally the rest of the time. The procedure to check and/or change the sock is pretty simple and the part is cheap. There is a pretty good description of the process in Clark's Garage at www.clarks-garage.com/shop-manual/fuel-19.htm
Steve Marlow
944 Spec #47x
NASA Certified Instructor
NASA AZ Licensing Director
2012 AZ Region 944 Spec Champion
Last Edit: 10 years, 8 months ago by spec944#74.
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