924Board.org

npszenica · Joined: 17 May 2010 Posts: 5 Location: Michigan, USA

Hi everyone, as you can see, I'm new here. I've been lurking for a while, and decided I should join.

I have an '87 924S which I bought a year ago for $1200. The car had been sitting for about a year and a half, but before that, the seller put over $3000 into the engine (water pump, timing belt, etc., I have all the receipts and can check if needed). I got the car last June, but did not actually start driving it until this February. It needed a new rack & pinion, as well as some other things to be roadworthy, and I needed a job first. All was lovely until I was driving it in mid-March, and it died while leaving my school parking lot. Thinking I might've stalled it, I tried restarting the engine, but to no avail. After about 2 minutes, and creating a large traffic jam, it started, and I drove home. About an hour later, I was driving my friend home, when it died again and would not start. I had it towed home, and it's been sitting outside ever since.

I'm not that great mechanically, but I'm privileged to know people that are. My coworker Peter and I have worked on the car a few times in the past weeks, and here's the current situation:

-battery voltage is ok, and it cranks ok
-engine ground is good
-chassis ground is good
-fuel pressure at the fuel rail is adequate (the fuel filter needs replacing, but sufficient fuel is getting to the engine)
-the ignition coil, distributor cap & rotor, and spark plugs are all new (bosch and autozone brand parts)
-the voltage of the new ignition coil is good
-the ignition coil wire is new
-I have the rest of the new spark plug wires, but they have not been installed yet
-I have a new DME relay
-there appears to be no spark

Any ideas? Peter and I are stumped, and I'm tired of not being able to drive it. Thanks in advance!
_________________
Black 1987 924S 5-speed
Broken odometer, unknown miles

I always wanted a Porsche, and now I've got one!

legoist · Joined: 03 Apr 2009 Posts: 30 Location: Eugene OR

I had a similar issue. I finally traced it to a faulty computer. try thumping it when it won't start. it is under the steering wheel. sometimes the traces get bad and connections get intermittent or break entirely.

Also if that isn't it my car sometimes has issues with the DME socket. It needs to be wiggled cause some of the plug is loose. I finally gave up on the DME and built a jumper that had a switch on it that I could just tun fuel off and on with.

Good luck.
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924s - 1987 Not running

TJC · Posted: Fri May 21, 2010 3:58 am Post subject:

You state that the fuel pressure appears to be adequate, but were you able to test it with a gauge?
The pressure should be about 29# at idle and 33# to 39# with the vacuum hose off of the pressure regulator. Mere visual prescence of fuel does not necessarily mean that the pressure is great enough for the engine to run.

Also, were you able to confirm that there is no spark?

Does the engine turn over normally, or faster than before?
_________________
'95 BMW 318i/5 ..."Pearl"
'87 Porsche 944 NA... "Liebchen"
'02 Porsche Boxster..."Sunbeam"
'04 BMW X3..."Xander"
Still on the Prowl!

www.ttrs1.com

John_AZ · Posted: Fri May 21, 2010 10:02 am Post subject:

npszenica & Peter,

When you turn the key and crank the engine----------Does the tach needle bounce 1/16 of an inch?

If no bounce, it means the reference sensors are not sending a signal to the DME (computer).
Clean the reference sensor connections at the rear top of the engine. Do not cross the 2 wires. If the cable cover is rotted and the plastic connector falling apart, you may need new sensors.

Try to start the engine--see any tach bounce?

If no tach bounce---check the resistance of the sensors:
http://www.clarks-garage.com/shop-manual/ign-02.htm

GL
John_AZ
1988 924S 61K + 1987 924S 115K

joecitizennn · Joined: 12 Sep 2005 Posts: 2096 Location: no mans land

joecitizennn · Joined: 12 Sep 2005 Posts: 2096 Location: no mans land

Also crack the fuel rail nut and see if there is any pressure at the rail after the car has sat. . Your FPR may be bad.

Druman · Joined: 19 Mar 2007 Posts: 419 Location: Middleport, Ohio

I also had a similar problem, it ended up being my crankshaft/cam sensor (there are 2). It's possible that it's just dirty. Take them out wipe them off and put them back. Or if yours are like mine, it just needs replaced. They're over $100 if you want to go the Auto Zone route.
Hope this helps.

7osh
_________________
87' 924S non-sunroof (Red) 45K miles
85' 944 "early" NA (Red) 130K miles

PORSCHE pisses excellence...

masterdave · Joined: 10 Dec 2008 Posts: 183 Location: Harrison NY

i had the same exact issue, i also traced it back to a bad computer the grounding transistor that pulses the coil apparently is not great and has a tendency to fry there are a few places that rebuild ECUs, it ususaly costs about 300 for every thing they will also just test ECUs to see if they have an issue i would have it checked it could save you alot of time and money replacing things that are not broken. May also be the coil.

npszenica · Joined: 17 May 2010 Posts: 5 Location: Michigan, USA

Alright, here's a status update on the car. Since I last posted, we towed it back to my friend Mike's house. He fiddled with the connection to the ECU and was able to get the car running. I drove it back to my house a few weeks ago, and it drove well (the fuel economy seemed to have improved vastly, and it felt strong); that was on a Monday evening. I drove it around on the Tuesday, and it ran fine. Tuesday afternoon, I was driving with my brother and sister in the car, when it died in exactly the same manner as last time and refused to start again. It sat there for 2 days until we came back with a tow rope and brought it back to my house, where it's been sitting for a few weeks now. Do you guys think I should have the ECU rebuilt? If so, where should I have it done? What else should I check before doing that?
_________________
Black 1987 924S 5-speed
Broken odometer, unknown miles

I always wanted a Porsche, and now I've got one!

npszenica · Joined: 17 May 2010 Posts: 5 Location: Michigan, USA

Alright, here's a status update on the car. Since I last posted, we towed it back to my friend Mike's house. He fiddled with the connection to the ECU and was able to get the car running. I drove it back to my house a few weeks ago, and it drove well (the fuel economy seemed to have improved vastly, and it felt strong); that was on a Monday evening. I drove it around on the Tuesday, and it ran fine. Tuesday afternoon, I was driving with my brother and sister in the car, when it died in exactly the same manner as last time and refused to start again. It sat there for 2 days until we came back with a tow rope and brought it back to my house, where it's been sitting for a few weeks now. Do you guys think I should have the ECU rebuilt? If so, where should I have it done? What else should I check before doing that?
_________________
Black 1987 924S 5-speed
Broken odometer, unknown miles

I always wanted a Porsche, and now I've got one!

John_AZ · Posted: Thu Jul 29, 2010 2:44 pm Post subject:

B4 you take the DME (ECU) to a shop or send it to an internet service shop, Disconnect the battery and remove the DME.

Got a solder iron?
http://forums.rennlist.com/rennforums/924-931-944-951-968-forum/310806-early-dme-repair-write-up-with-pics.html?referrerid=20449
OR
http://forums.rennlist.com/rennforums/924-931-944-951-968-forum/289396-dme-repaired-w-pics.html?referrerid=204

Simple EH?

OK, not a good idea,
eBay will usually have your DME for about $90 +sh at auction

Still not a good idea?
Send to an internet service shop:
http://www.ecudoctors.com/

First clean all your grounds----everywhere.
Clean the DME cable connection with electronic cleaner
Clean the reference sensor connections at the rear top of the engine.
Test the sensors for correct resistance
http://www.clarks-garage.com/shop-manual/ign-02.htm

Get a set of spare reference sensors and try another set.

Bad ignition switch?

GL
John

jrrhdmust · Joined: 19 Mar 2008 Posts: 180 Location: Middle Georgia

I would also check the Flywheel, and TDC sensors. They are at the back of the engine, where there are two identical connectors stacked. Don't get them mixed up! Take a multi-meter and check the resistance. Clarks Garage has it posted on what the resistance should be.

You don't want to break into the computer if you don't have too.
_________________
67 Mercury Cougar XR7 under Restoration
71 VW Superbeetle Completed Resto 11/07
73 Mustang Mach 1 10 Year old restoration

mehall · Joined: 15 Dec 2008 Posts: 191 Location: Richmond, MO

Try the fuel pump fuse.

joecitizennn posted his problem with it this morning.
_________________
Mark

'87 White 924s manual
'94 Lexus LS400

www.kcws.org

npszenica · Joined: 17 May 2010 Posts: 5 Location: Michigan, USA

Alright, here's the current status:

The Saturday before last (August 1), my friend and his father came over to work on the car with me. Some previous owner had installed a security system, and really cut up the wiring under the dash while doing so, so we took it all out, hoping that it might be preventing it from starting. Unfortunately, it wasn't the problem, but it certainly can't hurt to have all that crap out of there. The ignition coil is good; it's new and we tested it with a multimeter, but there's no power getting to it as of now, and there's no spark at all (this is confirmed). Tomorrow we'll try replacing all the fuses. Any other ideas?
_________________
Black 1987 924S 5-speed
Broken odometer, unknown miles

I always wanted a Porsche, and now I've got one!

masterdave · Joined: 10 Dec 2008 Posts: 183 Location: Harrison NY

It could be the SMS relay or a fuse how ever i had the same issue with my car initially, i had a good coil good wires but no spark. It turned out to be the ecu it's self I had to have it rebuilt. Apparently the transistor that actualy pulses the coil ground is not such good quality and c. Fry esialy. The place that rebuilt my ecu said it was a common problem. There are lots of places that do it I'll try and find the website that did it for me and post a link later. Check the grounds and maje sure they are all clean and clear.