84 944-Restore Needs help!!! No Spark

[944-restore]

Forum -- I'm in the process of restoring my 84 944. Ive had the car for 20+yrs however its been sitting unused in the garage for 5yrs. Got a wild hair and decided to restore . I've replaced and/or rebuilt all the mechanical parts and actually started and drove the car to get it painted ..O happy day!

I brought the car home after the paint job and proceeded to restore the interior. After about of week of working carpet and upholstery I attempted to start the car. To my dismay the 944 would not start

I immediately went to Clark's garage, followed the trouble shooting section and determined that I did not have spark. I have replaced the sensors, coil and obtained a used DME from ebay. I have followed Clark's recommendations for ignition system check out. So far all systems passed check-out.

I'm at a loss as to what to do next...
I'd appreciate any assistance or recommendations
Thanks in advance for the help

[Truckin4life]

I am in the SAME BOAT. Drove my car one day. Came home, parked it ran like a champ. Went out 2 days later to start it, and no start. NO spark.

Did you check the grounds?
Does the fuel pump kick on?
The abs connector have a good connection?
What about the AFM connector
TPS connector?

Are you getting voltage to the coil?

[MrTibbs]

Do you know the DME is a good one, or do you know anyone with a car you can test it on? They're tricky to test - I had a no start and the only way to know whether the DME was good or bad was to test a known good one in the car.

And are you sure it's a no spark problem? How did you check this?

Mike

[944-restore]

Truckin4life and Mr Tibbs.. appreciate the reply.

These are the tests I have performed.

Removed and inspected cap and rotor – all in working order

Verified timing belt properly installed

Verified crank shaft turning

Installed a spark tester at plug 1 and verified “no spark”

Removed coil wire installed a spark tester in end of coil wire - verified “no spark”

Verified 12V at coil black wire with ignition switch to the "run" position

Verified 12V at coil green wire with ignition switch to the "run" position

Removed the fuel pump relay and jumpered the pins 30 and 87b –the fuel pump activated

With the fuel pump relay removed I have verified 12V at terminal 30

With the fuel pump relay removed I have turn the ignition switch to the "run" position, and verified 12 VDC at the relay primary coil terminal 86

Verified crank shaft position sensor wiring continuity from engine connector to DME connector

Performed speed sensor resistance check between terminals 8 and 27 on the sensor connector.(1040ohms) Verified for infinite resistance between terminals 27 and 23.

Verified DME connector terminal 18 to Ground and Terminal 35 to Ground.

Performed reference mark transmitor resistance check between terminals 25 and 26 on the transmitter connector.(1040ohms) Verified for infinite resistance between terminals 26 and 78.

With ignition switch in "ON" position have verified 12 VDC from the Fuel Pump / DME Relay to the DME computer electrical connector at terminal 1 (is terminal 1 correct ?)

With ignition switch OFF and DME computer plug discionnected. I connected a voltmeter from terminal 4 on the DME plug to ground. I cranked the 944 and obtained a 12 VDC reading.

I have not verified the DME’s are good. Of course the ebayer who sold me the DME stated that it worked when removed. Any recommendations as to where I can send this thing to be checked??

I’m skeptical of the grounds but am unsure of the process for verifying a short or broken ground. I did a lot of “messin around” under the dash to install new carpet, power antenna and stereo. However all systems seem to work properly (lights, ventilation, windows and such). Any recomendations?
Did not check the AFM (air flow sensor?) and the TPS (throttle position sensor) I’ll do that this evening

Not sure about the ABS acronym.

[img]

[MrTibbs]

Hi,

This sounds familiar from when I got my parts car up and running to see how good the engine was.

The only thing I think you've not done is check the resistance of the coil primary and secondary windings - can't remember off the top of my head what they are but Clarks' 'troubleshooting no spark' guide will tell you.

To me it sounds like the DME you've bought is bad, but that's only my hunch. The amount of stuff you've checked and verified sounds like it should be OK, but the DME isn't sending the spark signal.

The AFM would cause it to start initially then cut out (I discovered this when I removed it to check belt tension and forgot to connect it again when finished!).

Really the easiest way to check the DME would be to try it on another car that's running fine.

Only other thing I can suggest is making sure your lead from the coil to the cap isn't broken or anything - a long shot but it'd be a cheap fix if this was causing your no spark.

Good Luck - hope you find it soon.

Mike

[Guest765]

OP when you checked the cap and rotor did you verify the spring loaded center "button" is still present and not seized or binding in any way?

[Jrboulder]

I have the DME from my 84 that I took out of my car when I went to a late setup. I would like to keep it with the car (not sell it) but I could send it to you for diagnostic pourposes then you could send it back when you have an answer. PM me if you're interested.

Jackson

[944-restore]

Really appreciate the Forum input.
The mechanical work was enjoyable but this sparky stuff is driving me to drink !!

The coil is new from Pelican after I initially developed the “no spark” I have not checked the resistance - will do that this evening

I checked the coil wire resistance – no opens noted after I wiggled the wire around

I’ve checked the cap and the spring loaded center button… all is in working order

Jrboulder - really appreciate the offer to lend a DME – I’ve sent my contact info to your forum visitor site.


Is there any way a ground short could cause this problem? If so what type of checks should I perform?

[Jrboulder]

Okay- I will have to check my visitor messages when I get home because I can't figure out how to view them from the iPhone.

Jackson

[krystar]

are u sure the reference sensor is set at the correct height?

are u sure the timing stud on the flywheel is still there?

[944-restore]

Good call on the timing stud.. I have not checked the ref sensor height, its a real pain to get to but its worth a check.

[krystar]

yea that's not one of those common problems...but if it's not there, u'll never fix the problem heh

[Truckin4life]

I'm in the same boat and i will be monitoring this thread very closely. Ive done just about every test as the op and i have the same issue.

[Cocacolakidd]

Check to see if the Tachometer bounces, just 1/16" or so, when the ignition switch is turned on. If not it very well could either the DME it self or the timing and reference sensors may be bad...

[944-restore]

No tach bounce when i crank the car. The sensors are new as of 3/11. They both check out on ohms check. Ive also verified the timing stud is present.

[Cocacolakidd]

Something is loose or wrong with the sensors or DME - Check to see if one or both sensors are adjusted within limits and with complete connections. Can also be in the DME it's self - do you have a known good DME to switch out for a test ?

It's also possible to have a new sensor to go bad - rare but possible.

[944-restore]

Found the problem!

I obtained a DME diagnose procedure and ran a pin check on the 32PIN DME harness which led to a “no voltage” reading on harness pins 18 and 35 . Traced the circuit back to the DME relay power output. Pulled the panel and found the spade connector loose.
The car started immediately after I plugged the connector back into the panel slot and the car started immediately.
I now have a running 944, spare DME ,spare DME relay, and spare coil.
Life is good!

My thanks to members of the Forum for your recommendations and Jorge at ECUDOCTORS.com for the diagnostic procedure.


http://site.ecudoctors.com/tech-data/DME-Diagnose-Follow-up-Forms.pdf


Hoist the Jolly Roger and break out the rum!

[ERAU944]

Originally Posted by 944-restore

...After about of week of working carpet and upholstery I attempted to start the car. To my dismay the 944 would not start

I'm glad you found the problem!

I'm not sure if you were working in the area in which the fuse box resides or not but if so everyone should take a lesson: If you have a problem after you modify, replace, or even so much as rubbed your arm again something - CHECK THIS THOROUGHLY as problems are often created while we are in there fixing something else!

that's why it is said in the aviation industry: always beware of issues on an airplane that JUST came out of maintenance.

No matter how careful you are, things can happen! I'd be lying if I said that I hadn't created a problem or three for myself.