Can't start my car!!

brian williams · Feb 8, 2015

Left starting up my car for far too long over December and January. It must be 2 months since I did, I must be stupid!! Tried changing the DME relay to no avail and a few fuses but no luck there. The battery has been on a CTEK conditioner so is up to power. Can anyone point me in the right direction please? The starter is trying hard but the engine hasn't tried to fire up at all. I suppose the next thing to check is that fuel is getting to the carb and that the distributor and rotor etc. are ok. Any help gratefully accepted!

bernard tester · Feb 8, 2015

Hi I would check for spark first pull the top ht lead off no 4 and put a spark plug in while you get someone to try to start it, earth the plug on something, you will see if there is a spark.You can check if there is fuel pressure in the system (not at the same time) it's injection not carbs.

brian williams · Feb 9, 2015

Thanks for the reply Berny. I looked for a spark as advised and after grounding the plug in a couple of places to be sure, couldn't see a spark. While I was in the engine bay I took off the easier to remove dizzy cap and just quickly wire brushed the contacts. So what is next, coils maybe?

vitesse · Feb 9, 2015

I'd also check the immobiliser/alarm if you have one of the Hamilton & Palmer type with a receptor in the steering wheel shroud-does it bleep when inserted etc?

Where the wiring is fitted into the main loom,normally under the dash near the steering column there is a double fuse holder-these can go funny ,slip off the lucar connectors etc.

Result -no spark but engine still turns over-worth a try.

brian williams · Feb 9, 2015

This shouldn't apply as I had the original alarm replaced because it no longer worked. The new alarm does have an immobiliser which works and so shouldn't be an issue. Thanks anyway.

tscaptain · Feb 9, 2015

Perhaps it read your forum signature and decided it was going to teach you a lesson.......[

]. Hope you get it sorted soon but afraid I can't add to previous suggestions.

38F3E1 · Feb 10, 2015

From what I read above it sounds likely to be electrical (I'll assume you did the spark plug test correctly). It could be either a lack of electricity getting to the system, the low tension circuit or the high tension circuit. Therefore I would either get hold of an electrical meter and wiring diagram if you feel confident enough to diagnose for yourself, or get a local motor electrician or better still your local Porsche indi to get their electrical man to help you out. With this approach you should be able to trace where the problem is easily enough.

If you start just replacing parts such as coils it can get expensive very quickly.

Ian.

Steve Brookes · Feb 10, 2015

Just in case the second DME relay was no good either, I would pull a spark plug to see if you were getting fuel.

Dekker · Feb 10, 2015

ORIGINAL: brian williams

This shouldn't apply as I had the original alarm replaced because it no longer worked. The new alarm does have an immobiliser which works and so shouldn't be an issue. Thanks anyway.

Just because your alarm is new, that doesn't mean it can't have a fault.

12v comes from the ignition switch but to find out why you don't have 12v at the coil, you need to be able to read a circuit diagram and use voltmeter to chase down the cause.

If that's not your competence then you'll need to call out some help.

brian williams · Feb 10, 2015

I'm just going to check as many connections etc. as I can just to discount any loose/corroded items before I call anyone in. It has to be something simple but important I hope!!!???

Fred Hindle · Feb 10, 2015

How well is the starter spinning over the engine? If you can connect another fully charged battery to the existing one that should get it cranking faster, also the electrics will be getting a good feed.

If you just start the car don't have the engine on the second car running.

Cheers,

bernard tester · Feb 12, 2015

Hi sorry I had not checked back on the fourm if there is no spark, check to see if there is voltage at the coils two on left hand side you should get about 12v with it turned on check with volt meter or use a 12 volt bulb and two wires one to earth one to the coil you should get voltage at both on one side don't worry about which side but I think it's normaly the two termanals closest that have the 12v feed if no voltage check from there if you had feed at one coil it should run if the dizzy belt was broken it should run on the top plugs. I suspect you have lost the feed to the coils. hope this helps Berny

brian williams · Feb 13, 2015

Had a quick look at the coils and they both had a plastic cover covering the contacts and wasn't sure how to remove them. There isn't much room to do much in that area anyway. I the meantime I have asked a local auto electrician to call to check it out, but will probably be Monday before he can fit me in. I will post up what he finds. Thanks for replying.

brian williams · Feb 17, 2015

The local auto electrician called this afternoon and found that there is power to the coils but no power to the distributors. He wasn't familiar with the electrics of the car and although he said that by checking everything he may be able to find out what's wrong, it would be a lot more cost effective to trailer the car to Bob Lewis at Broxton, where I get it serviced, or to get someone mobile in who knows the 964 electrics and would have a much better chance of diagnosing the problem. Anyone have any ideas?

Steve Brookes · Feb 18, 2015

There is no power to the distributors. The distributors are mechanically driven by the engine and just distribute the sparks supplied by the coils. There is an electrical plug on the side of the distributors which is for the hall sensor inside the distributor but that won't stop the engine firing if it's faulty (you can actually unplug it and the engine will still fire up and run).

Dekker · Feb 18, 2015

ORIGINAL: Steve Brookes

There is no power to the distributors. The distributors are mechanically driven by the engine and just distribute the sparks supplied by the coils. There is an electrical plug on the side of the distributors which is for the hall sensor inside the distributor but that won't stop the engine firing if it's faulty (you can actually unplug it and the engine will still fire up and run).

Good info Steve, I guess from personal experience of the problems you had with the hall sensor?

colin129 · Feb 18, 2015

ORIGINAL: brian williams

The local auto electrician called this afternoon and found that there is power to the coils but no power to the distributors. He wasn't familiar with the electrics of the car and although he said that by checking everything he may be able to find out what's wrong, it would be a lot more cost effective to trailer the car to Bob Lewis at Broxton, where I get it serviced, or to get someone mobile in who knows the 964 electrics and would have a much better chance of diagnosing the problem. Anyone have any ideas?

Brian, unfortunately this is a problem using AN Other auto electricians, you get the same with the RAC/AA. Have you tried calling RAC/AA, at least they will take the car to your local specialist if/when they can't fix it.

vitesse · Feb 18, 2015

So power at the coils-does that mean 12v at the primary terminal .when cranking the engine?If so ,the King lead from the coil(s) should be carrying HV to both distributor centre cap terminals.

No spark at a removed spark plug?=no HV from coil.

Are both king leads fully pushed home-are all plug leads properly pushed home?
Easy to check with one of those Neon plug cap adaptors or in line spark gap testers whether HT present .

After that it's back to the DME, even maybe the ignition switch which can switch the starter motor but miss out the ignition circuit-even connections under the front seat to the control unit-no damp under the carpets,I presume.

Just idle thoughts[&o]

ras62 · Feb 21, 2015

Hi Brian

I suspect the culprit is likely the fuel pump, it could be stuck after standing. To do these checks requires two people but its easy enough.

First check fuse 34 this is a 15A fuse that feeds the fuel pump. If ok then carefully take the plastic cover off the DME relay. Inside there are 2 relays, one should operate when the ignition is switched on. The second should operate when the engine is turning over, when it closes it sends power to the fuel pump (this also proves the the DME has received a signal from the crank position sensor). Don't attempt to start yet, with the ignition switched on you can manually press close the second relay and you should then hear the fuel pump run. It the pump doesn't run you could try removing the cover underneath the car and giving it a clout with a hammer. Double check fuse 34 to make sure it hasn't blown. If the pump does run then try starting the car and watch for the second relay to operate. If it doesn't then there is a problem with the crank position sensor, highly unlikely though. Hope this helps.

Best. Rob

brian williams · Feb 21, 2015

Rob, I have checked all the fuses there and all ok. Not sure if it is the DME relay as there is no spark at all. I was talking to Bob Lewis where I get it serviced and he mentioned about the flywheel sensor which sends signals to the DME which then sends signals to the ignition and fuel pump. Also I have done some searching on Rennlist and found a few instances of cars not starting because of this sensor and not having shown any other symptoms. Apparently with time the contacts get knackered up, so I'm going to take a look. It will add to my so far basic knowledge of 964's. P.S. Remember the Rennlist North Wales run outs organised by John Boggiano? I think we should resurrect them do you?