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1987 944 N/A stopped running, now no start

New to the forum but see a wealth of knowledge here so thought I would reach out. I was driving my 1987 944 and it chugged at one point during acceleration but recovered just fine. 60 miles down the road later I was accelerating slowly to proceed from a stop sign and the car just simply stopped running. Turns over like a champ. I have changed the DME relay and the ignition coil .. no spark at plugs? Hope someone can help. Thank u all in advance
Old 03-22-2019, 05:24 AM
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Do you have oscilloscope? Multimeter?

Measure impedance of speed/reference sensors.
Plot output waveforms of speed/reference sensors.

These form very beginning of engine-start cycle. If DME doesn't see that engine is spinning, it will not turn on fuel-pump or fire spark-plugs. Don't replace perfectly-working parts with brand-new perfectly-working parts. Nothing will change. Test and measure and compare your numbers with what's listed in workshop manual to determine if a part is good or bad. Otherwise, you will be blindly throwing thou$sands blindly at hundreds of possible problem parts before luckily and accidentally stumbling upon the one part that's causing this issue. In many cases, after spending thou$and$, many people find that just a minor adjustment is necessary.
Old 03-22-2019, 02:00 PM
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Thank you. I will be looking at the reference sensors. I have heardof that being the cause. As a matter of fact.. I am not smelling fuel either..
Old 03-22-2019, 03:14 PM
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Had a very similar problem a few weeks ago.after I went through all the usual suspects and found nothing it ended up being my ecu. Btw I have the same year as you. If you have a buddy with another 944 swap ecu. Till I found another late model ecu I was able to use the one from my 83 . It didnít run great but it started right up. I only used it to test.
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Old 03-22-2019, 07:21 PM
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You should have a 1/16-1/8 in. bounce on the tach when the starter is engaged. If not, suspect the speed/ref sensors. Check the connections at the back of the engine. I had one disintegrate, one may also have disconnected for some reason ( not secured by the clip, etc). Then follow Danno's advise.
If you have tach bounce, then search the forum for no start checklist and start working it.

Good Luck
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Old 03-23-2019, 06:35 PM
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Going to look for tach bounce today and check ref sensors! Will let you all know what happens. Thanks!!
Old 03-25-2019, 05:50 AM
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I have tach bounce and ref/speed sensors are good... No spark and no fuel. Suspect DME. .. SHOULD I GET A NEW DME?
Old 04-10-2019, 07:10 PM
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Also, does anyone know what the silver box is located in the driver's leg area on the left side wall?
Old 04-11-2019, 11:28 AM
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In the Fires of Hell.....
 
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Your computer is under the passenger footwell, beneath a piece of plywood.

The shiny silver thing is your cruise control computer, which also likely doesn't work.
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Old 04-11-2019, 01:41 PM
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1987 ECU may be above drivers legs not under foot well. Don't forget the alarm module if installed.
Old 04-12-2019, 11:31 AM
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Thank you! I found and identified both. Cruise control doesn't work lol.. hoping the DME will get her running again. Miss driving it
Old 04-13-2019, 05:28 PM
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I don't have the factory alarm and have heard this might be an issue but so not understand if an aftermarket alarm could cause a no start if the alarm is working properly
Old 04-13-2019, 05:46 PM
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Anyone out there have good DME for sale?
Old 04-15-2019, 05:58 AM
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Where are you located?

I am in Washington State near Spokane.
ed
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Old 04-18-2019, 12:38 PM
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Sounds like the DME relay.....they can exhibit a host of problems when faulty. Get an OEM one...and then get a spare......also make sure the bracket the fuses and relays sits in is all snug up and not loose...with all the vibrations, mine made one little wire come loose.....at least you have tach bounce as that is a real PITA to fix......

Bon courage!

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Old 04-20-2019, 03:44 AM
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Actually if it was the DME relay you shouldn't get tach bounce. However it's always good to use the simple jumper wires to eliminate the DME relay if there is a no-start situation. Plus you can just drive home if it works.

clarks-garage.com has info on the jumper.
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Old 04-20-2019, 03:54 AM
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Tach is driven by DME. If you have tach bounce, then DME and DME relay are fine.

Did you measure impedance of both sensors? At sensor plugs AND at DME connector? 4 different measurements.
Even better to plot sensor signals with oscilloscope. This gives you peak-to-peak output voltages of sensors.

In majority of cases, after spending thou$ands in swapping perfectly-working parts with brand-new perfectly-working parts, they find out all that’s needed is sensor-spacing adjustment.
Old 04-20-2019, 09:33 PM
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Both sensors ohm good but cannot be removed without me pulling out the housing. I slaved in a new DME relay and no good. Both my old relay and new relay ohm good as well. I am not extremely skilled at all of this. I removed the DME just to try to test the sensors at the DME plug but not sure how to count off the pins in order to ohm at the correct locations for checking the sensors there . I am located in Sumter SC in case anyone is close by
Old 04-21-2019, 03:03 PM
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Quote:
Originally Posted by Sebscst View Post
Had a very similar problem a few weeks ago.after I went through all the usual suspects and found nothing it ended up being my ecu. Btw I have the same year as you. If you have a buddy with another 944 swap ecu. Till I found another late model ecu I was able to use the one from my 83 . It didnít run great but it started right up. I only used it to test.
Did you have tach bounce also?
Old 04-21-2019, 03:04 PM
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Quote:
Originally Posted by TibetanT View Post
Where are you located?

I am in Washington State near Spokane.
ed
I am in sc
Old 04-21-2019, 03:05 PM
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