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I am working on a 1987 944. I dont have spark to the plugs.

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I am working on a...
I am working on a 1987 944. I don't have spark to the plugs. The engine turns over with the starter. I have heat to both sides of the coil with the key on. There is no spark from the coil wire to ground when cranking. I pulled the wire from the distributor cap and held it close to the block to check for spark.. The car has a Clifford theft alarm system. The valet button works properly when setting the system with the 5 digit code.
I believe that if the alarm system was the problem I would not have a starter or juice to the coil.
I am not familiar with the electronic pick-up system, Halls effect or what type of area to look for.
Could you send me that information? Thanks Mike
Submitted: 4 years ago.Category: Porsche
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Answered in 15 hours by:
5/4/2013
Porsche Mechanic: Josie-Mod,
 replied 4 years ago
Josie-Mod
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Satisfied Customers: 5
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Hi, I'm a Moderator for this topic. I've been working hard to find a professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.


I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, please let me know and I will cancel this question for you. Thank you!
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Customer reply replied 4 years ago
Thank you for letting me know. I will be patient and wait until you are successful. Thanks again Mike
Porsche Mechanic: Josie-Mod,
 replied 4 years ago
Thank you, XXXXX XXXXX your continued patience. We will continue the search for a professional for you.
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Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Marty
Marty, ASE Certified Technician
Category: Porsche
Satisfied Customers: 54,162
Experience: ASE & Bosch Certified Master Tech. Over 30 years experience.
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Hi Mike, my name isXXXXX common cause of a no start on the 944 is a bad DME relay. The relay powers the engine control module. The relay is at position G5 in the diagram below. I'd replace the DME relay and see if that solves the problem. Click here for the relay. The ignition system uses a crankshaft sensor and a tdc sensor to send signals to the DME to fire the coil. If your sensors are bad you will also have a no spark situation. The sensors are mounted in the bell housing above the flywheel. I've attached a wiring schematic of the system below. Also make sure that your timing belt didn't break. Let me know if you have any questions.

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Marty
Marty, ASE Certified Technician
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Customer reply replied 4 years ago
Marty You helped me earlier with a 1987 944. I replaced the DME relay and still have a no start situation. The timing belt is good. Is there a way to test the 2 sensors without replacing them? Thanks Mike
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, yes you can ohm out the sensors to see if they are open. You should measure between 600 - 1200 ohms resistance on the sensors.
Marty
Marty, ASE Certified Technician
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Customer reply replied 4 years ago

Hi again Marty I checked the ohms and both sensors are above 1000. 1018 and 1027. I've replaced the DME relay. Do you have any other suggestions where I mught look? Thanks Mike

I also checked the 7.5 fuse that works with the DMV it's good

Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago

Hi Mike, can you give me some background on the no spark problem?

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Customer reply replied 4 years ago
The car has a Clifford anti-theft system. I believe that is operating as it should. The engine cranks and there is heat on both sides of the coil. These are the two components that are disabled when the alarm is set. The engine cranks and the cam shaft is turning, compression sounds good, even thru the cycle. There is no spark to the plugs and no spark coming out of the coil when the wire is held close to a ground. There is no fuel pump action either. The DME relay is new and the two sensors are within the ohm range.
Customer reply replied 4 years ago
I am not sure if you received my answer. Did you get it? Thanks Mike
Customer reply replied 4 years ago
Hi Marty. I don't know if you have been getting my reply's. Could you please let me know. If you can't help me then I will another expert. Thanks Mike
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, sorry for the wait I have been away. The DME relay is also the fuel pump relay. I'd test for power to the relay on terminal 30 then jump terminal 30 to both of the terminal 87's and see if it starts. You need to remove the relay when you jump it. Let me know how you make out.

Marty
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Customer reply replied 4 years ago

Marty I jumped 30 and the 2 87's and the car starts and runs good. The fuel pump stays on when wired in this manner with the key off. I had just replaced the DME relay and the customer replaced it also in the not too distant past.

Is there anything that could be blowing these relays or is there a ground wire that is making a connection? I know you can't tell but I'm hoping that you could suggest a way to check the problem. Thanks again for your patience

Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, I need you to test for power on terminal 86 of the DME relay when cranking the motor.
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Customer reply replied 4 years ago
There is no power on # XXXXX when cranking.
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago

Ok, then we need to get to the back of the ignition switch and test for power at terminal 15 with the key on. It sounds like you have a bad ignition switch. I show terminal 15 going to the alarm control module (if equipped) and then out of the module to the DME relay. If you have no power at terminal 15 you need to replace the switch. If you do have power at terminal 15 you can solve this problem by running a direct feed from terminal 15 on the ignition switch to terminal 86 on the DME relay.

Marty
Marty, ASE Certified Technician
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Customer reply replied 4 years ago

Hi Marty. I keep coming up against another problem when I think it's solved. I went to check at the rear of the ign connector and when I remove the retaining cap all the wires came out tof the connector.

I have a solid red wire.

red and black wire(10gauge)

solid black wire

gray wire

black and yellow wire

black and red wire (16gauge)

There are number at the rear of the switch, you can see with the cover ca off. Can you tell me where the wires should plug into or send me a wiring diagram to show? Thanks Mike

Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, I've listed the wires and locations below.

Red - terminal 30
Red/black - terminal 50
Black - terminal 15
Gray - terminal P
Black/yellow - terminal X
Black/red - terminal R
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Customer reply replied 4 years ago

Marty

I put the wires back in as shown and now the car starts and runs. I don't know if it had a faulty connection or? I may have put the wires back on in different positions as there were 2 30's etc. Can you tell me which letter, P X R is the one for #86? This should wrap the questioning. Thank you for your help. Mike

Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, it's terminal 15 from the ignition switch that sends power to terminal 86 on the DME relay.
Marty
Marty, ASE Certified Technician
Category: Porsche
Satisfied Customers: 54,162
Experience: ASE & Bosch Certified Master Tech. Over 30 years experience.
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Customer reply replied 4 years ago

Marty I don't know if you will get this reply or not. If I don't hear from you tomorrow I will try to contact you again. I am having a problem with the same 87 944. I have replaced the dme relay and the electrical portion of the ignition switch. I was getting a signal from the ign switch,15, to term 86 on the relay board. Now I am not and the car will not start again. There is no fuel pump action when I connect 30 87 and 86 with a jumper and no spark. The crank sensors are good.

The car does have a Clifford alarm system. The starter does turn over and there is electricity to both sides of the ignition coil. The alarm if activated is supposed to cancel these two functions. I don't think there is a problem with the alarm. Do you have any suggestions as to what step to take at his point? Thanks Mike

Customer reply replied 4 years ago
I now have electricity when cranking to 86 on the relay. The fuel pump is working but there is no spark from the coil to the plug wires or from the coil wire to ground. Also there is no flash on either side of the coil wires when cranking. This car is driving me nuts. Thanks again Mike
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, if you jump from terminal 30 to both of the terminal 87's and the car has no spark I'd suspect one of the crank sensors is bad. I'd recheck the sensors and also make sure that the battery is fully charged. Low voltage can give you a no spark situation.
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Customer reply replied 4 years ago
I replaced the battery and rechecked the sensors crank and tdc. One reads 1050 ohms and the other 1043 ohms. I am testing them by putting one probe on the center electrode and get the readings when I check one of the outer electrodes. I am getting readings the same on both plugs. Should each outer electrode be giving a reading? The other electrode does not get any reading. Thanks Mike
Customer reply replied 4 years ago
Hi Marty I don't know if you got my last reply or not. I'll wait until tomorrow and try to contact you again.
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, sorry for not getting back to you I had a busy day yesterday. As I recall this car started and ran when you jumped the DME relay previously and then I think the wires came out of the back of the ignition switch. Has the car run since you put the switch back together?
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Customer reply replied 4 years ago
yes it ran for a couple of starts. I pulled it out and into my shop several times and then it wouldn't start again. I rechecked the sensors and installed a new battery to no avail. I also tried the jumping of the dme relay. This relay plug has a 30 a 87 and a 86b on the relay box. Am I testing the sensors properly? Any further steps I can take? Thanks Mike
Customer reply replied 4 years ago
Sorry mis-typed it's 87 and 87b
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Yes you are checking the sensors correctly. You should probably check the signal from the sensors to the DME and make sure you are getting a signal. You will need a lab scope for this test. I've attached some instructions. Also make sure that the DME is getting power.

Test Speed Sensor
Test Reference Sensor

Test DME Power Supply



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Customer reply replied 4 years ago
Thanks Marty I will do the checks and will see what I get. Mike
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Ok Mike, let me know how you make out.
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Customer reply replied 4 years ago
Marty I was able to check the DME power supply. That tested, both tests, good. The other tests which requires a ocilliscope the engine has to start in order to test the patterns which we are unable to do. I pulled both sensors out and inspected them. One was dirty and both are magnetized. Any suggestions. Mike
Porsche Mechanic: Marty, ASE Certified Technician replied 4 years ago
Hi Mike, did you try to get a reading while cranking the motor? You should be able to get a reading from the sensors while cranking.
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