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Join Date: Aug 2003
Location: Florida
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Car wont start.

My 1985.5 944 has been sitting for a while. It used to start but hasnt for about 6 months. Ive been meaning to get on it but havent really since I just havent made time for it.

Ive been told that it can be the DME relay or the Crank Position Sensor.

All I know is that the car is not getting spark. There is none coming from the coil to the distributor and none from the distributor to the spark plugs. The engine will turn, but not turn over. Hence I know the starter is working.

I am having the battery charged as I speak. I have been told that if the tach jumps when trying to start the car that the CPS is ok. I will test this theory when I try to start it after reinstalling it.

I do not know how to check the DME relay.

All I know is that I need to get the car started and soon. Taking it to the local mechanic is out of the question, as I can not afford it, and I also know I can fix it myself if I put my mind to it.

Any advice and ideas would be greatly appreciated.

I am also selling the car, so if anyone is interested just PM, email, or AIM me. Email and AIM will get faster replies though.

Old 10-19-2003, 12:44 PM
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Not being able to afford a traditional mechanic is why most of us are here. There are a few that just like to beat on themselves too.

Let's clear a few phrases up. Turning over and cranking are pretty much the same thing. That is the starter will engage the flywheel and spin the engine over. "Starting" is where everything comes together and the engine comes to life and sits there purring.

When a 944 sits with out being run for a months it's found that the electrical connections at the battery and from the battery to the chassis and then to the engine -- the grounds -- will corrode. These need to be cleaned.

Next is the DME/fuel pump relay. There are two stages to this relay. The first is when you turn on the key. This closes the first set of contacts powering the DME and injectors but not the coil. The coil gets it's power from the ignition switch. So with the key on you should see 12 VDC (battery voltage) at the coil (opposite the green wire connection) and the injectors.

The tach is connected to the DME (green wire) side of the coil. So if you see the tach jumping when you crank it then the reference sensor would be seeing the pin on the flywheel and telling the DME to fire the coil. If you want to check that it's getting spark take a spare spark plug, pull one of the spark plug leads, insert the spare plug and lay this on the intake. You should see a spark when you crank the car. If you do then it's time to look at the fuel pump.

The fuel pump is powered from the second set of contacts in the DME relay. These can not close until the first set does. When you crank the car the same current that goes to the starter solenoid also goes to the DME. The DME then runs the fuel pump for a set time to charge the fuel system. This is independent of the speed sensor which, as part of it's logic, will keep the fuel pump running above a cut off of 200 rpm.

So what this boils down to is turn the key on and use a test light or volt meter to check for 12 vdc at the coil and at one of the plugs to the injectors. If this is good then lean out of the driver seat, crank the car, turn the key back to on and listen for the fuel pump to run about a half second. Check for spark with the spare plug.

You have just checked the ignition switch, the first and second contacts in the DME and the fuel pump. You have not checked that fuel is getting to the injectors or that the speed sensor is working.
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Hugh - So Cal 83 944 Driver Person
NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts and/or cam chain and tensioner?
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Old 10-19-2003, 03:42 PM
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Originally posted by SoCal Driver
So what this boils down to is turn the key on and use a test light or volt meter to check for 12 vdc at the coil and at one of the plugs to the injectors.
I guess I forgot to mention that this has already been done.

I will try the spark plug on the intake bit, but after I get a new battery as the old one I had was bad. But I know that the battery is not the whole problem because I also tried it with the battery from my Honda which is good and it still didnt work. Ill also check into those grounds you mentioned, as it grounding out was another idea that my father, my brother and myself had.
Old 10-19-2003, 03:56 PM
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The grounds are on the back of the engine block. Kind of a pain to get too. Also check the connectors to the battery especially if they are not stock like the chinzy clamp on the cabe kind.

Better check to see if your fuel pump works.
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Hugh - So Cal 83 944 Driver Person
NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts and/or cam chain and tensioner?
New Users please add your car's year and model to your signature line!
Never break more than you fix!
Old 10-19-2003, 04:02 PM
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Where are you located? Any pics of the car?
Old 10-20-2003, 04:02 AM
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Im located in NW Florida, AIM me at S13Sil80. I have pics as well.

Old 10-20-2003, 01:20 PM
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