1991 964 Hard to start then dies...

[Costelles]

The car turns over well......tries to catch.....finally catches after some time.......runs.....then dies.

If I push the accelerator it dies....

There is a spark, the plugs, dizzys and rotor arms are fairly new.

Ive tried a different DME relay..

Any ideas?

 

[Gordon Attar]

One suspects water ingression somewhere

Unfortunately they all point to point to a DME relay fault, which youve already checked and youve also checked the obvious ones

Is there any dampness in the fuse box from all the recent rain if maybe/yes maybe worth using a hair dryer on the contact points.

Check under the seats for dampness which may also have got into the electrics

 

[colin129]

I'd be surprised if it's water ingress, my front boot has got very wet with all the rain we've been having & probably points to a new sealing rubber required, but the car started first time after 3 weeks without use, no problem & no fuss. I should point out that the battery was disconnected during the period of inactivity.

 

[Gordon Attar]

ORIGINAL: colin129

I'd be surprised if it's water ingress,

Depends where the water is!!


Oh one more suggestion the symptoms could also be the distributor drive belt has gone

 

[MrMoots]

I had a similar problem on another car (not a 964, but similar engine management) a few years back which was an air leak after the airflow meter from a split vacuum pipe leading to the fuel pressure regulator.

 

[RSGulp]

It starts and idles rough then when you try to give it some throttle the engine dies? Sounds like a classic intake air leak to me.

First check all the vacuum tubes are still connected and not perished or split.

Now, with a screwdriver or suitable socket carefully tighten every jubilee clip holding the rubber boots/seals to the inlet manifold half a turn - look all around the engine bay and if you see a jubilee clip or hose clamp tighten it to take up any slack. Not too tight - just half a turn to stop any leaks.

Pay particular attention to the rubber seals between the intake manifold and the tops of the heads - 3 on each side just above the spark plugs - they're hard to reach so often get overlooked.

Whereabouts are you based Costelles?

 

[carreraboy]

RS Flywheel? sensor?

 

[Costelles]

Hi RS Gulp

Im just East of Southampton at the top of the river Hamble, why do you ask?

I cleaned the ISV back in the summer and tightened all the hoses at the same time but I did do a few miles over summer so I will check again on Sunday

Scott

 

[RSGulp]

I was going to say if you were anywhere near me I'd pop over to give you a hand. But you're a bit far from Glos. []

 

[Steve Brookes]

Have you disconnected the battery recently. If so, you might need to get a Porsche specialist to put a Bosch Hammer on it and do a system adaption.

 

[colin129]

ORIGINAL: Steve Brookes

Have you disconnected the battery recently. If so, you might need to get a Porsche specialist to put a Bosch Hammer on it and do a system adaption.

I see quite a lot of posts about trouble from disconnecting the battery. Before I fitted a cut out switch, my battery completely drained on several occasions & I was able to bring it back to life with the car running fine afterwards.

Now I always disconnect the battery via the cut off (Discarnect) when I am leaving it for more than a few days without driving & I have never experienced any problems.

I can't believe I'm just lucky as I have disconnected & reconnected so many times & never had any problems.

 

[Steve Brookes]

Colin I don't have problem with battery disconnect either. Both you and me have similar models. However, those with C4s often have problems caused by battery disconnect and need a Hammer reset to sort them out. As the OP has a tiptronic, it too might suffer battery disconnect problems (as it has more complex electronics than our manual C2s). It was only a suggestion of something to check in response to the OP was asking for suggestions. However, I suspect the real solution will be to get the car to a specialist.....which will involve them doing a system test with a Hammer anyway. []

 

[Costelles]

Thanks all for your suggestions..

I disconnect and remove the battery regularly (Trickle charged in between drives) as the car isnt/wasnt used as much as I would like. It's odd as I had the car MOT'd in the Spring this year and did a number of small fixes and used the car for 3 months 2/3 days per week doing perhaps 1000 miles in the process.

The car performed perfectly and stared on the button every morning then all of a sudden I had this issue.

I will check all the suggested areas this weekend and let you guys know if I find the cause.

Otherwise, I will have to get it to a specialist thats close by....JM in Christchurch isnt too far or the guy in Wiltshire but I can remember his name.

We have an engine specialist in the family so I may get him down to look before just in case its something obvious.

Cheers All
Scott

 

[Dekker]

I've disconnected battery many times and in the early days had it die on me from lack of use until I learnt about how long it took to drain it, 7 days.
Never had to use a Hammer, just take it for a blast to reset the electronics. Mine's a C4.

David

 

[Melv]

the guy in Wiltshire but I can remember his name

Steve Bull, Devizes.

http://www.stevebullspecialistcars.co.uk/

PS -I'm delivering a Range Rover to the New Forest this Monday if you need it trailered there!! www.flyingbluedog.co.uk...... []

 

[Gimme Shelter]

I have to get my C4 system adapted after each time the battery has been disconnected. It runs, but won't tick over, until the system adaption has been done.

 

[RLambert]

Have you checked the micro switch on the throttle is working correctly? It should click open when the throttle opens.

I had this on my 90 C2, the car would tick over but would die if you tried to rev it up. Bu99er to find what the problem was but when I did it was a simple fix with some WD40.

 

[topcats993]

Problem .My car had started to be hard to start from cold ,you could get it to fire up after a while but it would not tick over from cold ,I cleaned the ISV then I found if I fired it up and if I kept my revs around 1800/2000 for five mins by just sitting in the car it would be fine

Cure . I suggested to OPC Byfleet that it might be my clyinder head temp sensor giving up the ghost ,so I put the car in for a minor service a couple of weeks ago and asked them to check it out and keep the car for a few weeks if need be
They found it a pig to start and went with my suggestion after not finding any fault codes registered and she fires up first time every time now with a new Head temp sensor (£160 ish part)

Happy Days

 

[Laurence Gibbs]

Worth getting a hammer on it to see if it throws a code. Otherwise your playing guessing games rather than trying to find the fault. Having said that. NTC 11(cylinder head temp sensor) can give hard starting and worth checking if you have a meter with a ohm's setting. Simply unplug it and read the resistance. I can't remeber what it should be now, hopefully someone else might chime in( likely to be very low ohms cold and about 1k hot at a guess). You will find the plug for it in the bank of three that sit behind the engine blower motor it will be the one that heads off to the rear of the engine, as the sensor is screwed into the cylinder head , simply follow the cabling. Worth also CONFIRMING you have good spark/ fuel and that both rotors are turning on the dizzy. If the dizzy belt has snapped one rotor will turn quite freely the other wont .
apologies for not reading above post first, anyhow i do at least tell you where it is and how to check it[]