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944Thomas
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1986 944 No start
Aug 1st, 2019 at 2:24am
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Hi everyone, I'm new to the forum and have completely hit a wall in my project. I picked up an 86 na auto due to the fact the body and interior were in amazing condition. It did have many mechanical issues and I thought it would be nice to get it back on the road again.

I had sorted out most of my issues mechanically (which I wont go into) and was moving on to smaller issues. I was able to drive the car a few times with little issue. Problems began after I installed an aftermarket stereo since the stock was not working. I tested the stereo and it worked perfectly. Went to start the car and would only crank not start or run. Attempted to put the old stereo back in thinking it was a weird coincident with no luck.

What I have tried already.
-The shifter was moved while I pulled the stereo out, not sure this matters or not.
-My alarm was bypassed by the PO. and doesn't exist.
-Narrowed it down to fuel pump not getting power and replaced dme relay with 2 different ones. It would run with a jumper installed but not a relay. I do hear the replay click when the key is turned.
-Took out dme and checked it for cracked solder joints or damage. It was very corroded but no clear signs of damage.
-Hooked up dme again and tried to run car at least with the jumper again to move it. Now wont run even with a jumper(the jumper does get the fuel pump running) but wont start and I have no tach bounce, when I previously did before dme removal.
-Swapped Dme with another used one thinking maybe it was damaged when i took it out, and I'm having the same issue with the other dme. cranks but no start no tach.
-My speed sensor reads 1054 which is in spec and my ref sensor reads 1038 which is in spec.

I'm completely stuck and every-time i try something it gets worse, please any advice would be helpful thanks!
  
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Springgt
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Re: 1986 944 No start
Reply #1 - Aug 1st, 2019 at 5:52am
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Did you undo the battery cables when you installed the radio?  If so check to make sure that the cables at the battery are clean and tight, especially the small positive cable that powers the ECU.  It solved my no start problem once when the small positive cable was loose, but not visibly loose.
  

Original owner 1984 944 Guards Red
Just back on the road after a 7-8 year storage.  Yea!
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YIM  
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944Thomas
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Re: 1986 944 No start
Reply #2 - Aug 7th, 2019 at 5:10pm
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Thanks for the suggestion, but I checked at the battery and at the dme. I have my 12v at the two pins when the key is turned and checked all three grounds for the board and checked ok. I would assume I'm getting power to the board. At this point I assume either my sensors are somehow bad even though they have proper resistance or by some odd coincidence both dmes I have have the same issue which I just find very unlikely.
  
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Ky951
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Re: 1986 944 No start
Reply #3 - Aug 8th, 2019 at 5:43pm
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My understanding is if you are getting no tach bounce, the problem is the reference sensor.  Sounds like you have good resistance numbers, but the problem is likely the output.  Check out this info from Clarks Garage.

http://www.clarks-garage.com/shop-manual/ign-02.htm
  
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944Thomas
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Re: 1986 944 No start
Reply #4 - Aug 9th, 2019 at 2:38am
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Thanks, I ordered a new sensor should be here in a couple of days. Hopefully it takes care of it.
  
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Dave W
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Re: 1986 944 No start
Reply #5 - Aug 9th, 2019 at 12:05pm
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Agreed. Very likely a bad ref sensor.
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
... Let's go hit some twisty roads! ...
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944Thomas
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Re: 1986 944 No start
Reply #6 - Aug 13th, 2019 at 1:22am
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Replaced with brand new oem sensor today. Still have no tach bounce and no start. Would it be safe to assume the dme's I have tried are bad at this point or am I missing something else? I have resistance readings at the sensor and at the dme harness so wiring should be good.
  
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tony3911
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Re: 1986 944 No start
Reply #7 - Aug 13th, 2019 at 2:53pm
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Did you double check your gap when you replaced the sensors?  If everything else is testing good but you're still not getting tach bounce, it could be a possibility
  
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OhioTom
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Re: 1986 944 No start
Reply #8 - Aug 16th, 2019 at 8:48pm
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There are 2 sensors that could be bad.
They are right next to each other.
I always replace them as a pair.
  

Tom Simpson&&VW/Porsche freak.
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Dave W
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Re: 1986 944 No start
Reply #9 - Aug 19th, 2019 at 9:10pm
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And it is easy to connect them incorrectly since both sensors are the same.  Try swapping the connections to see if it resolves the issue.
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
... Let's go hit some twisty roads! ...
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Up On Ramps
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Re: 1986 944 No start
Reply #10 - Aug 30th, 2019 at 11:34pm
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Had a similar instance with my 87, even replaced the reference sensor wiring harness - no help.  Purchased a refurbished computer and it has worked well since (been about five years now).  I was beating my head against the wall, troubleshooting voltage at the coil, fuel injectors, dme, sensors, etc.
  

1981 931
1987 944 Base (Auto)

"A mind is like a parachute, it doesn't work if it is not open" - Frank Zappa
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