924Board.org

[legoist]

Hi all,

I just bought an 87 924s that wasn't running and I am currently trying to piece it back together. The car currently turns over and just as it catches, dies. Here's what I have learned and tried so far:

All the vacuum lines were disconnected so I pieced them back together from diagrams as best I could. I have a question about a l pipe that has a small nipple in the bend that goes off to the fuel regulator(?) in the driver side back section of the engine bay. What does the other part of the L connect into?

I also pulled and replaced the rotor and distributor, they were pretty fried. I have spark to each plug.

I pulled the plugs which ere black from poorly burnt fuel and cleaned them. they were correct Bosch plugs as spec-ed by the manual.

I replaced the reference sensor because the wire was cracked and the plug had no way to lock to the other fitting. It didn't help but I learned to cover the timing hole before unscrewing that bolt the hard way. Both Ref and speed sensors have proper resistance.

I checked the timing marks to make sure the rear and fronts showed at the same time.

I removed an aftermarket ignition cut out relay from an aftermarket alarm.

The wiring harness had suffered a little corrosion and the PO had re wired it to get both spark and fuel. I have pulled all the tape off and looked for bad connections. I'm not 100% sure the fuel injectors are wired correctly, but I have 2 separate diagrams that show them wired differently. Any one have the correct wiring for the injectors available?


The fuel pump is running and I am getting fuel but I haven't pressure tested it. However since the fuel is unburnt on the plugs, I figure it isn't the main issue.

I've unplugged and plunged the maf in to see if anything changed while starting, but nothing did.

I'm open to suggestions, and I'd really love to drive it?

Thoughts anyone????

Thanks in advance,
-Chris
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924s - 1987 Not running

[fiat22turbo]

Well, you've got to figure out why you're not getting spark.

You need, Air, Fuel and Spark in order to have a running engine. You've got two out of the three.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[legoist]

I have spark when I crank the engine. Something is telling it to stop, or the fuel and spark are out of synch.

Are the injectors supposed to have continuity across all the wires? there may be something wrong with the wiring of the injectors so that they squirt on the wrong part of the cycle.

-C
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924s - 1987 Not running

[legoist]

I just verified that speed and ref signals are making it to the DME.

Both sides of the fuel injector wires contact the pins on the DME. Totaly open circuit Is this correct? I can't figure out how they are properly triggered individually in this set up.

Sigh


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924s - 1987 Not running

[Smoothie]

Possible ignition switch problem? Does it die right after releasing the key?
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[legoist]

yes it does, but if I try and hold the key on and grind the starter it also dies. Does that help rule that out or should I try hot wiring it?
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924s - 1987 Not running

[ideola]

No, you should remove and inspect the ignition switch. It's about a 20 minute job and a $5 part. I'll bet a dollar-to-a-donut (as the saying goes) that the little white switch is cracked like every other one I've seen, and is causing some if not all of your grief.
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erstwhile owner of just about every 924 variant ever made

[gohim]

Before you go any further, I suggest that you spring for the Porsche 944 Factory Workshop Manual Set. I spotted an Authorized Porsche dealer who was selling new ones for $175 (half of suggested retail) last year). I posted a message on this site with the information (use Search Function to find it).

Are you sure that you set the clearance on the reference sensor properly when you replaced it? Did you install a new one, or a used one of questionable heritage?

You will find the complete vacuum and wiring diagrams in Factory Workshop Manual, along with the answers to every question you can think of. Improper vacuum line connection could cause the problem that you are having.

In the meantime, unless you can verify how old/long the timing and balance belts are/have been used, you should stop cranking the engine till you can complete a FOES (front of engine service).

Have you checked the condition of the timing and balance shaft belts? Is it possible that the timing belt has skipped?

Another common failure item is the DME Relay (most educated/experienced owners carry a known good spare in the glove box).

You should also check the connections at the brain bo for corrosion, and open the box up to check the solder connections the brain boxes suffer from poor/cracking/bad solder connections.

I took a quick look at my 924S, and the vacuum line that comes off the rear of the Pressure Regulator on the Fuel Rail at the rear of the engine turns forward towards the front of the engine, passing under the Intake Manifold turning back towards the Brake Vacuum Booster under the Air Flow Meter connecting to a Control Valve mounted by the Brake Vacuum Booster on the rear of the left inner fender.

[legoist]

I just got back from a weekend away. When I got home I re-wired the ignition with 2 toggle and a push button for the starter. All the same symptoms. The little switch was cracked though....

I have factory 944 manuals that I got from some site. They are pretty comprehensive.

My biggest issue is there never seems to be a very good vacuum diagram. I get a few lines and I have followed those, but it doesn't seem to be the issue.

Anyone know a good Bosch fuel injection site. I still think the wires on the FI are all crossed up.

-C
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924s - 1987 Not running

[legoist]

I did check the timing marks and the belts are OK and on my list of things t do once I get it to run more than a second. Sigh.
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924s - 1987 Not running

[gohim]

If you had a Genuine Factory Service Manual, you would have good vacuum diagrams.

The illegal bootleg copy of the Factory Service Manual that you have is probably a copy of a copy that was illegally scanned, and probably was not a copy of the current (6) volume service manual which has complete vacuum diagrams for the 924S. Porsche does not sell electronic versions of the Service Manual and has not authorized anybody sell to sell them or put them on the Internet.

The Ford Taurus Performance website that I visit is currently soliciting donations for a Website Owner who was foolish enough to place the Ford Service Cds on his Server for free downloading. The Judgement against him will keep in in debt for the rest of his life. This should be a warning to other Website Owners who think the the Car Manufacturers don't care about their illegal activities.

[legoist]

Hmmm. I got a 6 volume manual from a freedom of information act site that I saw on another board. It has good wiring diagrams for the 924s but I have yet to get a great vacuum diagram, esp. since there were some hoses missing. My hanes manual has the l pip I was talking about going to nowhere, but that's the hanes manual for you.

I am really leaning towards the "rewired" fuel injectors. I'm going to attempt to re-wire them to the diagram tonight.
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924s - 1987 Not running

[legoist]

this is the diagram I have for the Fuel injector wiring. You can see 2 injectors are controlled by port 14 and 2 by port 15 on the DME. Currently I can run a continuity test on any given injector and both sides are open to both ports.

I imagine that to control any given injector the ecu would pulse to them. Since they are apparently in a gang fire configuration the ECu would pulse 2 one bank then the other.

The blue red ( marked bl/rt) runs down to the fuel pump relay in the diagram. Should these be separate circuits? or does the elay entering on pin 35 of the DME stay open to both 14 and 15?

Anyway.... that's all I have until I can actually go work on the car.
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924s - 1987 Not running

[ic932]

You've probably checked it out but...www.clarks-garage.com

I would'nt be suprised if the previous owner suspected a fuel delivery problem and wrongly blamed the injector wiring.

Your symptoms are quite common especially when one of these engines has been left sitting for a long time.

In my experience it takes a massive vaccum leak to prevent starting. Yes, if one of those small black vacuum lines is disconnected it will probably not idle...but you would be able to feather the throttle to keep it alive...you will hear hissing and the exhaust manifold will be very hot very quickly!

First thing I would do is remove the air filter box, dump a shit load of fuel direct into the inlet manifold...just dont stand in front of the AFM lol. You aim is to see if you can get her to run for 5-10 seconds. Don't expect it to start without lots of throttle. That will eliminate the wiring issue.

next step would be to remove the fuel rail and injectors...

[legoist]