ggrecian

What all components/sensors send info to the dme to tell injectors to pulse? DME bench tested "good " at ECU doctors. I have been chasing a crank no start for 3 mos. I have spark. I have tach bounce. I have 36 psi to the fuel rail at crank. I also have voltage to each fuel injector connection. However, injectors not firings. I have installed brand new fuel injectors. Please Help!

ggrecian

Also how many volts should reach the injectors with the ignition switch turned on? I am receiving a few volts to each of the two wires connecting to fuel injectors.is this correct? I have read i should receive 12 volts to one side? Is this accurate?

Adker

With just the ignition on, you should see battery voltage on both side of the injectors. When cranking, one side should pulse within a volt or two of ground and the other side should be at battery voltage. The voltage for the injectors comes from the DME relay, Try bypassing the relay.
http://www.clarks-garage.com/shop-manual/fuel-05.htm

The timing for firing the injectors/spark plugs comes from the speed and reference sensors.

ggrecian

thank you

Adker

Anytime. Hope you get it running.

ggrecian

tried bypassing the relay.fuel pump kicked on...still crank no start

Adker

Do you have battery voltage at the injectors with the relay bypassed?

blown 944

Take a look at the injector harness. I have experienced a short that changes the circuit to disable itself and it required me to short them to get it back in sync. Typically they become brittle under the boot. You can also check the pins at the DME to see if they are grounding. Iirc they are pins 12&14 but it's been a few years.

My money is on an exposed wire or more. I replaced my harness with a Lindsey piece.

konakat

If you have tach bounce then that should indicate that all necessary inputs are there. It is strange that none of the injectors are working, that makes me think it is a DME issue. Do you know someone that could loan you a known-good DME to plug in and test?

ggrecian

no.do not know of anyone with a known good dme..i sent my dme to ecu doctors for a bench test.it bench tested "good" do you have faith it that?

konakat

I have no idea how they test them, so tough to say. Given that they work on many different models, I doubt they actually test them in a car.

ggrecian

no factory or stock alarm that i can find.i am going to have it towed to the porsche mechanic tom...exhausted and beyond frustrated with it

konakat

That sucks. Please come back and update the thread once it is sorted out. You aren't the first or last with a similar problem, but all too often once the answer is found it never gets recorded.

konakat

If there was a factory alarm you would have a key lock mounted just aft of the drivers side door that was used to arm it.

ggrecian

u will definately update as i appreciate all of your guidance