Hi. I'm at Thompson Speedway this weekend and my car had died twice on the track in the same spot during a tight right handed bowl. I get stealing and sputtering and then it just dies. It only happens on the track. I can't reproduce in the parking lot. I tried changing dme relay to a new non Porsche model but no luck. I checked all grounds, coil and spark wires and ref sensor wires. All fine. I'm jumpering the relay for the next run. But I'm out of ideas.

What else should I check before my weekend is ruined?

 

Did you check the fuel pump connections & then the fuel filter?

 

Fuel starvation, did you replaced your fuel lines recently?

 

More info from searches...

I would check you fuel pressure regulator, located on the fuel rail, toward the rear of the engine compartment. When this regulator fails it cuase some wierd running problems! Pull off the vacumm line to the valve sniff it for leaking fuel, if so replace the regulator. Also, if it has been on the car for awhile I would replace it any way, they go bad all the time, $80 for the part. When my unit went bad, my engine would run rough, sputtering and running mega rich at times, lots of black smoke out the tail pipe! Then it would be ok for a while! When the reg would act up the fuel pump would make strange whirring noises becuase the reg would restrict the fuel returning to the fuel tank inturn starving the fuel pump bearings (the fuel pump uses exsess fuel to cool it) and hence the noises! When this regulator fails it will either leak fuel onto your hot engine! Or fail internally and keep the fuel rail pressure sky high the engine will start up, run for a second then flood out! If you pull off one fuel injector connector, the engine will start up and run fine abeit only on three cylinders! Dave Jalali

 

Some more...

When a 944 engine either won't start or dies when running (maybe it will restart, maybe it won't), the first thing to check is to see if the injectors are clicking when cranking (evidenced by using a NOID, a stethoscope, a screwdriver to your ear or whatever). If there is no
"clicking"...you have no injector fire either because of no voltage or no pulsing ground from the DME.

Easy test...disconnect one wire clip from one injector and crank the engine over...if it starts...you have found the problem .... WHAT IS THE PROBLEM??? ...The fuel pressure regulator is bad. Yes, the fuel pressure regulator. See, the fuel pressure jumps from around 2.0bar to 7bar or more when the regulator closes. The increased fuel pressure on the injectors causes them to draw
more current. All 4 injectors get a constant 12 v from the DME RELAY. Injectors 1&2 are paired and get their pulsing ground from DME CONTROL UNIT wire # 15, and 3&4 get their pulsing ground from DME CONTROL UNIT wire #14. This means that injectors 1&2 always fire at the same time, and injectors 3&4 fire together.
It is not sequential.

When the fuel pressure goes too high, too much electrical load (I can not be specific here on the milliamp draw) overcomes the ability of the DME CONTROL UNIT and it shuts that function down, causing you to lose injector fire...the engine dies. If one fuel injector is unplugged, that reduces by 25% the load on the
CONTROL UNIT, and it can produce the current necessary to fire three injectors, the engine will run.

Try it yourself. Run your engine and clamp off the return line from the pressure regulator . The engine will die. Disconnect one injector (won't hurt the catalytic converter), clamp the line...the engine will be running a little rough on three cylinders...but it won't die. If you have a NOID and a duplicate harness connector, you can easily see the electrical results.

Many, many people have purchased fuel pumps, DME's, you name it because of so called electrical problems, when it is a simple fuel pressure regulator problem. courtesy of "istook"

 

The filter was changed very recently. I have not inspected the pump wiring yet. The fuel pressure gauge has been fine and no issues under wot for several laps. Lines have not been changed. But I should think that a flow issue like that would affect me always under wot. Not just random stalling.

 

Can't test for injector clicking because it runs like a dream in the parking lot. It's only stalling when hot on the track. After a few minutes it starts and runs fine. Heat or sucking up something bad in the tank?

 

No bad smells at regulator. It either runs perfect or not at all.

 

I think I know this one. Check your ground/connection to the fuel pump. It could be corroded and be causing resistance when hot. This makes the fuel pump stop when the wire heats up. Once it cools off, it will start again. Take the 2 pin connector apart and check (looks like O2 sensor plug). It sits next to the fuel filter in the back.

 

Sounds like you need to replace the internal screen filter that is in series with the external canister fuel filter. If the screen filter is dirty you will have fuel starvation on tight turns.

 

Totally dead now. Tach just climbs to 6 now for some reason. Dead ecu? No bounce, it just climbs smoothly right.

 

Oh I may have hooked the coil wires backwards when I was debugging it. Could that have damaged something? The tach going nuts seems to have started when I made that mistake but not 100% sure. At least it's moving now. It hasn't been moving at all since the final death.

Anyways Thanks for help guys. Hard to search on crummy wireless phone.

 

I have run into similar problems with wiring issues mainly involving wiring going to the AFM.

 

You've had no tach or crazy tach readings due to afm wiring?

It's the tach issues that make me not think fuel.

 

Found it. Burned sensor wire. Some electrical tape and it's all better. For today anyway. http://imgur.com/zNchvou