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NJ924 · Joined: 13 Jun 2004 Posts: 20 Location: New Jersey

Hi all,
I have had my 1988 924s for the past 11 years. A few months ago, it would die on me while driving. We replaced the 2 timing/ position sensors and it seemed to be running fine.
Lately I have had trouble starting it. Here is what I am seeing:
- Sometimes it won’t start. This can be after it had been sitting or after I just finished driving it.
- Sometimes it will start, but stutters on acceleration from any speed and I can smell gas in the exhaust (acts like a stuck choke would on a carbureted vehicle). It maintains speed at any RPM with no problem
- Sometimes it runs fine with no problems.. easy start, smooth acceleration
Work that has been done:
- Realigned the Bosch Motronic Air Flow Meter as shown here http://www.youtube.com/watch?v=-11J8XawQtc
- Replaced the 2 timing/ position sensors
- Replaced the DME relay
- Replaced the fuel pump relay
Does anyone have a suggestion where I should look next? As it is, I can’t take the car anywhere for fear of getting stranded.
Thanks

larchie · Joined: 19 Jun 2003 Posts: 297

You might try looking for a leaky fuel injector, faulty fuel pressure regulator, or obstructed ERG valve.

NJ924 · Joined: 13 Jun 2004 Posts: 20 Location: New Jersey

Thank you very much for the advice. I will check those out... Anyone else?

NJ924 · Joined: 13 Jun 2004 Posts: 20 Location: New Jersey

Hi all,

I replaced the injectors. One had a crack. The car runs great,... when it runs.

I noticed that, when it won’t start, the tach does not move. I saw a post indicating that a bad sensor showed that symptom (it should bounce when starting if all is well). The other symptom is, on rare occasion, the engine will die and the tack goes to zero (even though it is still turning). So far, it starts running again without me pulling over.

I have replaced both sensors and the DME. Could one of those be bad? Bad wiring? Is there elsewhere I can look?

Thanks,
Frank
p.s. I'm desperate. My wife wants me to get rid of the car

Ozzie · Posted: Sun Oct 13, 2013 6:36 am Post subject:

On the NA the tach gets its pulse from the coil. Don't know about the S but probably the same.
_________________
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Engineer of Electro/Mechanical Systems Maintenance

larchie · Joined: 19 Jun 2003 Posts: 297

NJ924 · Joined: 13 Jun 2004 Posts: 20 Location: New Jersey

Thanks Guys.

The last time it died while driving was on a smooth road.Most often, I will be driving it one day and then it wont start the next time I try (as you said, it does crank).

When I got the car, 11 years ago, it wasn't running. It had been sitting for a few years with a bad interior leak, The mechanic had to reoplace the fuse blokdue to corrosion.

The connection problem sound like a possible issue. I guess the DME plug should be the first place to check?

Thanks
Frank

larchie · Joined: 19 Jun 2003 Posts: 297

Personally, given the flaky tachometer readings, I'd start by checking the brown wire from the tachometer to the T3 terminal in the engine compartment and from the T3 terminal check the connection and the green wire from there to the #1 terminal at the ignition coil. Check connections, but also check for resistance variation as you wiggle the the green wires as you inspect for wire degradation. While you are there, try resistance tests on the coil itself -- I think resistance between the terminals should be less than 0.1 ohms, but check Hanes to be sure.

Ian89C4 · Joined: 01 Apr 2011 Posts: 561 Location: North Carolina

Try replacing your negative battery cable. I had similar issues on my 911. After tearing down most everything I found that the negative cable had corrosion on the inside which did not allow the battery to ground enough which created a whole slew of problems.

Hope its a simple fix.

Cheers
_________________
Ian Edgerly
North Carolina

Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala")