Car wont start

ace_944 · 02-12-2008, 09:26 AM

My 87 944 wont start just wondering if this could be the problem. Drove it to a friends house the other day seemed fine then when i was leaving it didnt make a sound. Stero still works, though there seems to be no power going to my sub. Btw this is the main ground that goes to the block.

hpservertech · 02-12-2008, 12:37 PM

yea, that will definatly cause some problems.

I would replace it.

ace_944 · 02-12-2008, 03:12 PM

Could it be the only reason my car won't start though?

exitwound · exitwound's Garage

Fix that first (get a replacement cable) then reask the question. Mine wasn't that bad, but it was dropping mucho volts when I turned the key and the starter wasn't getting nearly enough juice to crank the engine.

hpservertech · 02-12-2008, 07:12 PM

No it wont be the only reason. but since we dont know any other systems or description of the problem we can't just guess. it could be a bad battery, bad fuses, no relays, no gas in the car. Lots of things. But we need more then a question about why it wont start.

DMRK · 02-12-2008, 07:51 PM

Do you mean the starter wont turn over the engine although there seems to be power?

ace_944 · 02-12-2008, 08:25 PM

battery tested fine, but a bit earlier today i was trying to figure it out had the key turned all they way on and was hearing buzzing sounds of the electricity kept it turned and was walking around the car to see if it would help me figure it out then everything went completly dead not even the ! was lit up. I'm thinkin its gonna be the alternator.

hpservertech · 02-13-2008, 09:24 AM

If you can't get it to even turn over then it wont be the alternator. That doesn't start until the engine is actually running.

Could be your ignition switch or starter. But could also be bad cables. Take a look at the positive side as well.

ace_944 · 02-14-2008, 01:23 PM

how does one know if the ignition switch bad? there a way to test it?

Razorback1980 · Razorback1980's Garage

Get a volt meter and a 4ft section of wire with alligator clips on each end. The starter motor needs 12+V on the large terminal of the solenoid. It also needs a good ground back to the negative post of the battery. When you turn the switch key, the small post on the solenoid should receive 12+V from the switch key. That's really all there is to it.

If you clip the 4 ft wire to the small post and then to the positive lead of the voltmeter and then the negative lead to a ground somewhere on the motor...when you turn the key to start, the voltmeter should read 12V. If it does the switch key is doing what it's suppose to. If not, then you need to check the large post of the solenoid to make sure it has 12+V. If it does then the starter is not receiving power back from the switch key to make the starter turn over and there is a connection break between the large post of the starter and the small wire coming back to the starter.

Razorback1980 · Razorback1980's Garage

This is a really rough diagram of how the starter works. For any electric motor to turn, it needs a positive connection from a power source (battery) and a negative connection from the same power source. In the diagram, you see the negative runs to the engine and the starter is part of the engine and grounds through that cable. The positive cable runs from the battery to the large post on the starter solenoid. This large post has power all the time. The solenoid's job is to take that power and when told to do so, forward that power on to the starter motor to make it turn. The way this is done is through the switch key. Hopefully you can tell from the drawing that power runs from the main solenoid post to the switch key and then when the switch key is turned to the start position, it forwards power to the small terminal on the solenoid which connects the large post of the solenoid to the power input of the starter motor. This makes the motor turn.

ace_944 · 02-14-2008, 02:51 PM

Thanks for all the info hopefully it'll help get this problem taken care of.

ace_944 · 02-15-2008, 01:25 PM

I did the tests earlier today, had power coming from the battery to the large post then when i had the jumper on the small terminal it didnt show any reading. Does this mean its the ignition switch is bad? Also i found out that the reason why my car went completly dead was the battery, put in charged one and it still doesnt turn.

Razorback1980 · Razorback1980's Garage

Probably means the ignition switch is the problem. Put a wire with an alligator clip on the small post and then touch it to the positive battery post....making sure the car is in neutral first and see if the starter turns....if so, then take the ignition swich out and check to make sure power goes through it with an ohm meter.

Jimbo7.1 · 02-16-2008, 02:32 AM

First time posting on this board. Hello everyone. Have an 85.5 Porsche 944 and had the same problem as JK. Let me tell you, I took it too a Porsche dealership and they never solved it. Took it to a private Porsche shop and they replaced the rotor and spark plug wires and that never solved it. Took it to a regular mechanic friend that works on domestic cars and he thought it was the fuel regulator and he wound up replacing that. Still didn't solve the problem. We both narrowed it to the ignition switch. Well, the switch was cracked in two places and pretty much was causing the problem, so I thought.

Naturally, I had the switch replaced. This was within the last week of August 2007. So I drove the car to work for the first week in September and on the second day of driving the to work car would not turnover. The car left me in the parking lot at work and of course I had the car towed to my home. Thinking the worst and becoming frustrated, I decided to leave the car parked until I was ready to have it fixed. Well, a week ago I decided to research the problem. Went to Clark's Gargage and narrowed the trouble shooting diagnosis to the ECM computer and fuel system areas and printed out all the technical data in order to give to the mechanic friend of mine. Drum roll please...the problem was just the fuel pump and nothing else. Here's the funny thing, I always told the Porsche mechanics and the mechanic friend of mine and they always said it was not the fuel pump. Purchased a Bosch fuel pump and fuel filter and car runs like a dream. Sometimes frustration and other emotions gets in the way of thinking logically.

konan · 02-16-2008, 07:06 AM

I had this problem when I forgot to connect the ground wire at the back of the engine right above the sensors that are such a pain to get to.

ace_944 · 02-16-2008, 03:51 PM

The starter didnt turn when i wired it directly from the battery. Does this mean my starters bad?

ace_944 · 02-19-2008, 05:28 AM

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Techno Duck · Techno Duck's Garage

Quote:

Originally Posted by konan

I had this problem when I forgot to connect the ground wire at the back of the engine right above the sensors that are such a pain to get to.

You need to be careful of doing this, as you can fry the DME by not having that ground connected. My friend went through this on his 944S...and finding a S DME was not easy (or cheap).

Quote:

Originally Posted by ace_944

The starter didnt turn when i wired it directly from the battery. Does this mean my starters bad?

If the starter does not turn over when jumped directly off the battery then its probably bad. Take it to a autoplace that can test it for you to verify. You did ground the body of the starter right?

And regarding your starting problem, if you turn the key and get nothing, no click, no anything..its surely those corroded cables. The starter draws some pretty serious current and those are probably not offering a sufficient ground.

I did have a similar problem last week. I would turn the key and get nothing, just a ominous hum sound. All gauges worked, battery was charged right and never had problems before. I smacked the hell out of the starter with a mallet thinking it was stuck, but did not help. I tested everything, battery cables, all wiring and the starter itself. Everything was fine. I ended up testing the ignition switch, tested out fine aswell. Replaced it 'while i was at it' and everything works again. Not exactly sure what the problem was, either the switch had intermittent failures or i must have 'jiggled' something in the right way. Replacing that ignition switch was NOT fun...i think it took me about 10 minutes to get those two screws out!

To test the ignition switch, use a multimeter and connect jumper leads to pins 50 and 30. You should have infinite resistance, turn the key and it should go down to approximately 0 ohms.

konan · 02-21-2008, 04:37 AM

quote:You need to be careful of doing this, as you can fry the DME by not having that ground connected. My friend went through this on his 944S...and finding a S DME was not easy (or cheap).
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I know it acted really weird, you would think that one ground wouldn't be that important but it is.