Starting problems

[Poppers19]

Hello all;

I am new to both the forum and the club so whilst I would have wanted my first posting to be about something other than a problem. However, the issue I have is that whilst the cars starts from cold everytime first time, once it has been started it then becomes hit and miss as to whether it will start again. If the car is left for about 20 mins it will definately start otherwise it depends what mood she is in, so to speak. For the record my pride and joy is a 944 S2 (circa 1990) but if anyone has any useful tips or advice it would be greatly appreciated. On a positive note, when she is going it's great and puts a smile of my face with every mile - but I guess you will all know this already.

 

[Tommys86]

Hi Peter, I don't know the answer but I'm definitely interested as I've experienced a similar issue on my S2! All be it mine is a track car, first thing she starts everytime, after a session, on a hot day it refused to start shortly after cut off. Now another driver mentioned about the heat being the issue and fuel delivery being poor if she's red hot?? How much truth is in that I don't know nor do I have a cure, except leave it 10 / 15 mins and she fires up like nothing happen? So sorry I can't help but advice welcomed!

 

[simdel1]

You hear about this a lot on older classics. The magazines seem to refer to 'fuel vaporisation' and recommend doing things like ceramic-coating the exhausts to bring under-bonnet temps down. I have a similar 'trait' with mine that it needs to crank for longer when it's hot than first thing in the morning.

 

[Copperman05]

DME relay is known to cause hot/cold start issues, change to much more reliable later version from 993, not an expensive part and v easy to fit, its where I would start... Edd

 

[pauljmcnulty]

DME relay

Definitely the first place to look given the symptoms. It's a while since this has come up, a few years ago it was almost a daily question. I guess that most 944s now have a new relay as it's such a common failure. The advice always used to be to carry a spare DME relay in the glovebox. If it didn't get you out of a scrape you'd probably find another owner needed one at an event! []

 

[Poppers19]

Thanks to all for the advice, have ordered relay from internet and will let you know how I get on.

 

[Tommys86]

thanks for input, where did you order the relay from? Think its another item for my shopping list!

 

[Poppers19]

I got the relay from ebay - Frazer Part Porsche Parts Specialist £22.00 - I think tthere are some which are cheaper but this is the later revised part which is apparently more reliable (part no. 993 615 227 01).

 

[simdel1]

This forum (myself included) is starting to get sloppy. We all forgot to ask for pics of the car! Any pics Peter?

 

[Poppers19]

Hi Simon, Will get pics organised and post as soon as. Peter

 

[peanut]

this topic has been covered a squillion times [] I think there was a thread about hot start problems only last week . There are several things you need to check.here is some suggestions I made on another forum recently.First thing you should check the next time it happens is to replace the DME relay with a 3x way bypass and see if it then starts. If it doesn't then your DME relay is probably not the cause Could be a vapour lock or a leaking injector , leaking FPR valve or leaking pump non return valve but most likely the DME relay Next time that it happens try removing the DME relay and fitting a 3xway bypass cable in its place. Basically linking terminals 30, 87 & 87b If the car starts immediately the problem was the DME relay if it doesn't then you'll need to do a fuel pressure and leakdown test to see if you are losing fuel pressure . last possibility is high resistance in speed sensor cable (try wiggling the cable when cranking) or maybe the ECU has a dry joint (try smacking it gently with your hand whilst cranking. I have read that the AFM can stick when hot . One last possibility.... check that you have a spark when you next have a hot start problem. It could be that your ignition amplifier is playing up when hot.

 

[Mike_Pollock]

Peanuts back!

 

[Poppers19]

Thanks again for everyones comments, especially Peanut for the detail provided. I have to say though that it is proving a bit of a weird one; # car will always atart if left for more than an hour. # when she does not start, if I get out of the car lock her and get in again she will 9/10 times start. # on the 1/10 she doesn't the I have to leave her for said hour then everything fine. As a consequence I am inclined to think the problem is with the alarm/immobiliser but because the problem is so intermittent it's proving hard to nail. Hopefully will meet you some of you at the Cambridge meet on the 11th and will be able to demonstrate whilst sipping on a shandy. Peter