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 Post subject: Porsche 944S2 wont start
PostPosted: Sat Jul 02, 2011 5:26 pm 
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Hi to everyone, I've psoted on this subject many moons ago but here is an update:

Worked on the car on July 1at - see below for details:

Hi to all and thanks for all the suggestions so far - Unfortunately I'm still pulling my hair out.

Spent some time on the car yesterday, here is what we tried:

1 - Drained petrol from tank incase of water contamination - filled with fresh fuel.

2 - Fitted a brand new DME relay ( the first was a spare from the glovebox that the previous owner said was good, so just to be sure ! )

Attemprted to start - Turning over no attempt to fire up.

3 - Removed fuel rail nut for testing fuel pressure, there was a little fuel in the rail that drained out after a minute or so ( NOTE: My dad thought the fuel smelt old )

4 - Tried it without the fuel pressure guage first, rags at the ready - turned ignition on: - No fuel, not a drop, nothing. ( knowing the DME was new, am I right in saying there was no need to remove DME and put a bypass wire on for this test ? )

5 - Tried it again with engine turning over - Again nothing, no fuel.

6 - Start to feel optomistic that we are getting somewhere, maybe a fuel pump ! - Shouldn't have been so optomistic.

7 - Using a spark tester, tested al plugs and the coil for a signal - Nothing, zero, no sparks, no power from coil.

8 - Checked all the earth points we could find and cleaned them.


Guys, I'm desperate now, what if anything can cause these 2 faults, is there anything else or can this only be an imobiliser / alarm fault ?

The only other thing I will mention is while we were doing this stuff, there was a random clicking noise throughout, like a relay switch, coming from the fuse box where the DME relay goes, even with ignition off and key removed, no set pattern to the clicking ( it sounded like it was coming from the fuse box, but couldn't be sure )

Please guys, what should the next step be ?

A low Paul


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PostPosted: Sat Jul 02, 2011 7:07 pm 
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OK plenty of non-start stuff here but; when it turns over does the rev counter bounce? If it does the the flywheel sensor & DME are probably OK. If not then you have no flywheel trigger & you'll get no sparks. See if you have 12V on one leg of the coil.
The clicking is probably the alarm module down by the ECU, & it maybe immobilised. You need to find out if the DME (in the passenger footwell screwed to a piece of plywood) has power on it. Download the manual from either Rick Cannell or Promax site & get busy with a voltmeter. Keep us posted.

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PostPosted: Sat Jul 02, 2011 8:03 pm 
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240zpaul wrote:
4 - Tried it without the fuel pressure guage first, rags at the ready - turned ignition on: - No fuel, not a drop, nothing. ( knowing the DME was new, am I right in saying there was no need to remove DME and put a bypass wire on for this test ? )

If it works like the 968, the DME doesn't activate the pump until you start turning the engine over, so you won't get anything at the fuel rail when you first turn the ignition on.

240zpaul wrote:
is there anything else or can this only be an imobiliser / alarm fault ?

Aagin, if it's like the 968, the imobiliser disables the starter as well; so, if you engine's turning over it probably isn't the imobiliser (unless the starter isn't imobilised on S2s...)

I would start with the no power at DME theory. Have you checked all the fuses...? Next step is get in there with a multimeter...

Good luck!

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PostPosted: Sat Jul 02, 2011 8:30 pm 
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Nope 944 immobiliser doesn't disable the starter (unless it is some weird one!) Pump will only run if DME sees cranking engine e.g. from flywheel sensor, hence the bouncing tacho question.

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PostPosted: Sun Jul 03, 2011 9:16 am 
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Just to clarify - the 944 will not crank if it has a h&p immobiliser. Thats not to say it has one of the many aftermarket ones fitted which will allow it to crank over.

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PostPosted: Sun Jul 03, 2011 10:01 am 
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Hi Jim

Can you just clarify, re the rev counter bounce - the engine is to be cranked over or just ignition switched on ?

The reason I ask, I did check for bounce with ignition turned on,which there was (very slight though ) but I didn't check when engine was cranking.

Thanks Paul.


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PostPosted: Sun Jul 03, 2011 10:38 am 
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240zpaul wrote:
Hi Jim

Can you just clarify, re the rev counter bounce - the engine is to be cranked over or just ignition switched on ?

The reason I ask, I did check for bounce with ignition turned on,which there was (very slight though ) but I didn't check when engine was cranking.

Thanks Paul.

When engine is cranking, this is fundamental diagnosis for non-start.

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PostPosted: Sun Jul 03, 2011 10:52 am 
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Re the imobiliser on this car - when purchased, the car had the original porsche imobiliser fitted. ( the small metal male slot )
This was replaced when it developed an intermitant fault.

Now I can't for the life of me remeber if the original porsche imobiliser stopped the engine from cranking over, I know Jim mentioned it didn't imobilise the starter motor, but is this definately correct ? I want to be 100% certain before I kil the auto electrician that fitted the new imobiliser.

The new one (A laser brand) does stop the starter motor and seems to be functioning as it should, so before I commit murder, any s2 owners still running original imobiliser, or with a better memory than me, does it disable the starter motor ?

Seems highly unlikely he didn't disable the original imobiliser though, don't you think ?

Paul.


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PostPosted: Sun Jul 03, 2011 11:47 am 
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My S2 cab has the original H & P immobilizer and yes it does stop the starter motor turning over.
Toby


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PostPosted: Sun Jul 03, 2011 5:57 pm 
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Hi Jim

I just checked for tacho bounce with engine turning over and there is no bounce at all.

Please advise next step.

Paul.


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PostPosted: Mon Jul 04, 2011 2:16 pm 
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I think this is usually to do with the Speed and Reference sensors.
Try going to http://www.clarks-garage.com/ and in the Garage Shop Manual area locate the link to Speed and reference sensors.

I expect someone who knows more will be on here soon and be of more practical help.

Richard


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PostPosted: Mon Jul 04, 2011 3:01 pm 
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I had a similar problem on my 924 turbo (I know it has a different engine) Try a direct live from the battery to the coil. I had wiring problems but it would fire and run this way.

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PostPosted: Mon Jul 04, 2011 7:43 pm 
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The s2 only has one crank sensor & a failure will cause the described fault. There are 3 wires on the sensor, an earth & 2 signal wires. I 'think' the signal wires are the 2 outer ones. You need to connect a voltmeter to the signal wires, set to ac volts & check for an output whilst cranking. The sensor connector can be found right at the back of the engine next to the fuel rail (under the long black cover, if fitted). It is the rectangular connector. If it has an output check the wiring for continuity all the way back to the ecu - download a wiring diagram from cannell. Let us know how you get on.

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PostPosted: Thu Jul 07, 2011 12:45 am 
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A BREAKTHROUGH - But still not fixed ( For my no fuel, no spark long term fault )

Went ape with a multimetre today - I've listed the readings below but the big finding was:

*** CONNECTION 86 FEED FOR DME RELAY (WHICH IS FOR THE IGNITION SWITCH ACCORDING TO CLARKS DIAGRAM ) SHOULD HAVE A READING OF 12 VOLT WITH IGNITION ON - WE GOT A READING OF ZERO ***( So the big / huge / massive / question is - What needs fixing when you have no voltage feed to pin 86 on DME relay ? ( feed from ignition )

After this find we decided to take a 12volt direct feed to pin 86 ( with DME relay in position ) we did this and turned the key -

Firstly noticed tacho bounce

Secondly a strong smell of fuel - A bit too strong actually, turned out the fuel was leaking about 3/4 way towards the rear of the car, couldnt get under to see exactly but could see and smell the leaking fuel.

We then tested for a spark with the 12 volt feed in place, WE GOT A SPARK !

So although the engine didn't fire, we presume the leaking fuel pipe / lack of sufficient fuel pressure was the reason for this.

I do feel a huge sense of relief today, but of course the problem still remains, so I'm waiting with baited breath, what is the fix for a no 12 volt feed to connection 86 ?


Other readings taken today just in case they are of relevance:
pin 87 - 2.5 - 3 volt
pin 30 - 12 volt constant


12 volt feed both sides of coil ( when igninition is on )

Many thanks

Paul


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PostPosted: Thu Jul 07, 2011 1:34 am 
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> what is the fix for a no 12 volt feed to connection 86 ?

Pin 86 goes to the ignition switch. So you may need to replace the electrical part to the ignition switch or look for faulty wiring in between.

If you have a factory alarm, have you tried to bypass it?

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