No Injector Pulse

[SShaw]

I have a 1986 944. I have spark and the fuel pump appears to be working but the car will not start. I do not hear the injectors firing when I listen with a stethoscope. Pulled the DME relay and did the 3 wire jumper and same issue. What to do next. PS. The guy I got the car from said he removed the security system. Is there something he might have messed up that would allow spark and fuel but no injector pluse ?

[Gordon Rankin]

Does the engine itself turn over?

[944jcb]

there's a procedure to bypass the alarm system on clarks-garage.com, you can try that to see if the removal by the p.o. is the problem. I unhooked mine and did the bypass and it worked fine good luck!!

[SShaw]

I am told that the alarm that was removed was an aftermarket alarm. There is no sign of a plug in the passanger foot well by the DME computer. The Car turns over with the switch as normal. Has fuel and spark but the injectors are not firing.

[S ECU Repair]

The Trigger to the Coil and Injectors are driven by the same signal that comes from the reference sensors , if you have checked both of this sensors and they tested good , the next thing you need to do is to verify if you have 12 V to one side of the injector harness .
If you do ,make 100% sure there is no alarm system connected to the harness .
Here is a chart for testing the Motronic 35 Pin units :

Make sure some points of testing will only affect drive-ability and not a starting issue ,most important points to check are 12v supply , grounds and resistance values from Crankshaft sensors.

If everything seems to be fine after the check up we can offer you a free testing for your DME.

Best Regards

ECU Doctors Team .

[John_AZ]

Thanks for the chart +1

John

[mikepellegrini]

Originally Posted by S ECU Repair

The Trigger to the Coil and Injectors are driven by the same signal that comes from the reference sensors ECU Doctors Team .

Which sensor powers which? I thought the reference sensor controls the spark and the speed sensor controls the injectors?

I vaguely recall something about the engine having to reach xx RPM for the injectors to fire? That the speed sensor?

[SShaw]

Ok, This is where i am. I have #1,2, & 3 injector now firing. The car runs on three cylinders. I have power With a test light to the # 4 injector but I do not hear it clicking as I clearly hear the other three when I listen with a stephoscope. The chart above says #4,5 & 6 fire from pin # 15 on the DME computer. I can't seem to find the # 5 & 6 injectors (just kidding). My next question is does #4 really fire on it's own from the # 14 connector. If not I would expect the injector is defective. If so the computer or wire could be the issue.

Thanks

[John_AZ]

Injectors fire in pairs. See post #4
Injector Spray

GL
John

[S ECU Repair]

Inside the DME Pins 14 and 15 are joined to a single component ,so i believe you have a defective injector or somehow a damaged harness .