Help No Spark.

[RITS944]

Help No SPARK.
tHE car has been dead for almost 4 weeks. I replaced the DME
relay still no spark from the coil. I have had the car for over a
year and it has always ran like a champ. Four weeks ago i went
to get my son at work the car started fine, went in to get him
came out started right uppulled up to the door shut it off he
came out and no start, cranks over all day,checked timing belt
also ok what do I check next

RITS944

[SoCal Driver]

Quick checks are for voltage at the coil and at the injectors with the key on.

If no voltage at the coil then it's the ignition switch.

If no voltage at the injectors but voltage at the coil it's the DME/fuel pump relay.

If voltage at both but no spark it's the reference sensor.

[RITS944]

I have voltage at the coil how do i check the voltage at the injectors
and what should it be, also i have already put in a new DME/fuel pump
relay i bought at a porsche dealer. How do i check the reference sensor
thanks for your help RIT

[SoCal Driver]

Pull a plug off of one of the injectors, turn the key on and check at one of the pins. One will be battery voltage the other a little less as it goes through the other injectors.

Voltage at the injectors means the DME relay is working on the first set of contacts. These send power to the injectors and the DME. Second set closes to run the fuel pump during cranking and when the engine is running. You can override the fuel pump side of the relay by using a jumper between fuse #2 and #3 on the eight fuse buss. Count from the drivers door.

Another suggestion is to get a test light for the injectors. It will blink as the engine is cranked IF the reference sensor is good.

Check the connections at the sensors and wiggle the wires about. If you get spark then the sensor wiring is bad.

[DannoXYZ]

Actually the injectors are powered directly from the relay. The DME grounds the other side. So to really test the injector connectors, this lets you track which one, or more is bad. The 1st set of tests checks for proper operation of the +12v power line to the injectors and the 2nd continuity tests check for the condition of the ground (activation) wires on the injector harness.

1. disconnect DME
2. disconnect idle-stabilizer, CV-cycling valve
3. disconnect all injector connectors, be careful to remove the spring-clip first, then pull on the connector, don't pull on loop of wire.

POWER-LINE TEST

4. using battery-ground as ground, use a voltmeter to check for +12v on each pin of injector connector
5. all rearward pins should have +12v
6. all forward pins should have ZERO volts
7. if you have ANY voltage on the forward pin, then you've got a short in that connector.

GROUND LINE TEST

8. Also check ground pairs (forward pin)
9. set voltmeter to ohms and check continuity between forward pins of injector #1 & #2: should read zero ohms (connected)
10. check between forward pins of injector #3 & #4: should read zero ohms (connected)
11. check between forward pins of injector #1 & #3: should read infinite ohm s (not connected)
12 check between forward pins of injector #2 & #4:should read infinite ohms (not connected)

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if the injector power and connectors check out OK, then test the injectors and fuel-pump themselves. Pull the fuel-rail and put litlte clear plastic cups under the injectors. Crank he car and if you have fuel dumping into the cups. Crank for 30-seconds and the volume sprayed should be even as well.

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Next up, test for spark. If you've got power at the coil, that doesn't necessarily mean the DME is dumping the coil to make spark though. Unplug the center wire from the distributor and stick a plug in there. lay it on top of the cam-gear cover and crank, do you see spark? If so, the coil is good. Hook that center wire back in and pull each of hte plug wires. Stick a plug into each one and lay on top of the intake-manifold. Crank and you should see the plugs fire in the proper sequence: 1-3-4-2. IF you get spark coming from the coil, but it's not making it to the plugs, then you've go ta distributor and/or rotor problem.