Wont start - No spark - utterly frustrated.

[paul240z]

Hello to everyone

This is my first post on the forum ( I'd always thought I had to be a paying member - Doh ! )

I've a 1990 Porsche 944S2 that has been sat idle for 18 months now, the car turns over but won't fire up.

Firstly I am not a mechanic by any stretch of the imagination and have very limited mechanical skills, but I have been told the car has power to the coil but has no spark. We also did the 12V at the terminals test on the DME relay and the test for the crank speed sensor both of which seemed to check out ok. The after market imobiliser only disarms the starter motor so that's not to blame.

I've seen all the walk through guides on the Clarkes site but to be honest it's beyond my mechanical means, anyway after another trawl through the postings on this forum I've decided it's time to get an expert to take a look.

I'm based in Chesterfield, Derbyshire 5 mins from J29 of the M1 motorway, can anyone recommend:

A - A 944 guru that would be willing to come and take a look ( For a fee obviously plus as many bacon sandwiches and mugs of tea you can stomach ) or -

B - A specialist in the Derbyshire area or surrounding areas of Notts or South Yorkshire that's got a good reputation. I just worry that by taking it to just any garage the **** might get taken and costs spiral out of control.

P.S. I want to put a fresh dizzy cap and rotor arm on the car, did I read somewhere a volvo cap fits ? Can someone recommend the best place to buy these items.

All advice very much appreciated.

Paul

 

[zcacogp]

Paul,

Sorry to hear of your frustration.

A non-starting S2 has a pretty standard (and easy) set of checks to run. Any half-decent mechanic should be able to do them, so take it to a good reliable local garage (or auto electrician) and see what they say. Or (better) a local indie. DON'T pay over the odds because of the badge on the nose of the car - it's not specialist or complex, and any premium charged is purely a money-making exercise on behalf of the garage.

Volvo cap does fit. Alternate parts fitment thread is here;

http://www.porscheclubgbforum.com/tm.asp?m=467365


oLI.

 

[Hilux]

I have been told the car has power to the coil but has no spark.

The coil has high and low voltage windings.

Check the main lead from the coil to the dizzy is working by pulling it off the dizzy and earthing it and turning the car over. If there is a power supply in to the coil and no spark from it then there`s your problem.

If it has a decent spark fine so then check a plug in the same way (with the other three leads off the plugs) If they have a spark but a weak one it may still be the coil windings but you`ll also get an idea of what the plugs look like . Also check the rotor arm tip isnt burnt back.

I am not sure on the 944T but if the ECU doesnt see a trigger via the crank sensor it might not fire up the coil.

 

[robwright]

You are absolutelt correct. If the DME (ECU) doesn't see 200 rpm at cranking it will not ground the coil and therefore will not complete the circuit for spark generation. This is generally a symptom of speed & reference sensors. I would check all the HT side first though as short of changing them or checking the gap from the flywheel the flywheel sensors can be difficult to test. You actually need an oscilloscope to do it with any certainty.

 

[Hilux]

ORIGINAL: robwright

You are absolutelt correct.  If the DME (ECU) doesn't see 200 rpm at cranking it will not ground the coil and therefore will not complete the circuit for spark generation.  This is generally a symptom of speed & reference sensors.  I would check all the HT side first though as short of changing them or checking the gap from the flywheel the flywheel sensors can be difficult to test.  You actually need an oscilloscope to do it with any certainty.

In that case carry on with what I said and see if it sparks onto the HT lead however a simple test is to borrow a coil first and see if that makes a difference if you`ve no spark.

 

[pauljmcnulty]

This is my first post on the forum ( I'd always thought I had to be a paying member - Doh ! )

Lol, welcome!

Hope you get it sorted here, plenty of owners with far too much experience of the cars. []

 

[peanut]

I think I have replied to your posts in another forum Paul ? I seem to remember the 240z handle.
Sorry to hear that you still have issues. I'll assume that I haven't told you this already .

If you are absolutely certain that
1. you have at least 3bar fuel pressure in the fuel rail whilst cranking
2. That all your injectors are pumping fuel into the inlet ,
3. Your cold start injector is also working
then we can assume that the fuel delivery system, ECU , DME relay , Ignition switch , FPR, Engine coolant temp switch, 02 sensor , AFM etc are probably working ok and we can dismiss the fuel delivery system and concentrate on the ignition system.

The late cars like the S2 and 968 from 1988 onwards use a seperate ignition amplifier module which on our S2 is situated on the pass side inner front wing. (see pic)

The Ignition amplifier module takes the 1.5to 3v from the crank sensor and amplifies it up to 12v to supply the coil low tension circuit.

The ECU then controls the spark that the ignition module generates in the coil by pulsing the amplifier and adjusting the advance and retard

First check needs to be the crank sensor.
1. Check that it has the correct resistance and the coil in the sensor hasn't gone open circuit or been damaged by something whizzing round on the flywheel.
2. Check the cable from the sensor to the connector block which is on a bracket above the rear cam cover. Make sure there are no cuts or damage and that it isn't hard and brittle .Pop the connector and clean the contacts. Measure the resistance of the sensor .
3. Check that there is a tiny bounce of the tach needle when you crank the engine as the tach is connected to the ignition circuit.

Next I would check that you have a 12v supply and ground to the ignition amplifier module. If you are not sure about how to check the ignition amplifier modules other terminals then try to get a spare to substitute .

The coil is very unlikely to be faulty. They either work or they do not. An easy check for your coil is to fit it to another car to test it.

The last essential job is to clean all the main earthing points . The earths are vital but are nearly always overlooked . If your earth points are corroded you will not get full 12v at any of vital ignition componants .
The important earth points are
1. rear valance (under carpet) which is the earth for the fuel pump.
2. MPll and MPlll both of which are under the bonnet in front of the fuse/relay box. These earth the ECU and DME relay and other vital stuff.
Lastly the earth strap from the rear of the engine to the firewall. Make sure you cover the inspection hole in the clutch housing before doing this job to prevent bolts etc falling into the clutch.

If everytrhing checks out you should have a nice strong HT spark at the coil ie 1/2 " inch +
Lastly check all your HT leads and clean the edge of the rotar and the terminals inside the distributor cap . File the electodes of the spark plugs to a nice sharp edge to promote a good spark and check that your rotar hasn't come loose on the shaft.

I shouldn't bother to buy a replacement dizzy cap and rotar just yet. There is nothing on either compnent that will suddenly break down and stop working.
The dizzy cap may have developed a crack and be arching inside the cap but it won't stop working completly. All it is is a piece of plastic with 4x brass terminals connected to a single socket on the outside for the coil lead. Ditto the rotar. Its a bit of moulded plastic with a small piece of brass attached . Nothing to fail there either. All you need to do is check its tight and file the brass strip to a nice sharp edge to encourage a strong spark between the rotar and the dizzy terminals.

 

[Diver944]

ORIGINAL: paul240z

I'm based in Chesterfield, Derbyshire 5 mins from J29 of the M1 motorway, can anyone recommend:

The closest Specialist to you that I have heard good things about is Zentrum in Calverton just north of Nottingham

http://www.zentrum.co.uk/

 

[944 man]

You could consider Simon at PHSportscars / Kirkman's too (in Shardlow J24a).


Simon

 

[peanut]

another one-post -never -return member I fear

 

[doctor924]

Are you absolutely certain the immobiliser is not wired into other parts of the ignition system?
I had a similar problem - that required a careful removal of all aspects of the failed immobiliser from within the fusebox?