Reluctant to start

[zcacogp]

Chaps,

OK, one that isn't a problem ... yet ...

The S2 is getting sulky to start. Symptoms: it will turn over as briskly as ever, but not fire enthusiastically into life. It semi-catches, and sometimes will idle at a very low revs (not more than 3-400rpm) before dying. If it does this, it will always die - tickling the throttle doesn't make it pick up.

Sometimes, pumping the throttle when starting it helps, and it will start as normal. Sometimes it will start as normal anyway, without hassle. On each occasion, it has started at the second attempt. (I think it once waited until the third attempt.)

I'm not sure whether it is associated with hot starting only. I haven't tried it enough times to know.

The problem started very suddenly - this morning. It was fine yesterday. It has been driven long and hard in the last few days, and the ambient temperatures are high - mid to high 20's. However, it was as hot yesterday and didn't do it then.

It is almost the symptoms of fuel vapourisation, with the fuel lines near the engine getting too warm and the fuel evaporating. However, I haven't changed anything, removed any insulation nor removed any heat-insulating gaskets from the engine recently, so I doubt it is this. Other thoughts would be possibly some temperature sensor on the ECU has failed (common on VWs of the same age, but I don't know if it happens with Porsches?), or possibly the fuel pressure regulator (although I don't fully understand what this does, or what the precise symptoms of it failing are.)

I do have a spare DME relay, which I should probably try swapping. Any suggestions other than this - I'd be happy to hear them.

(The concerning thing is that this is being written from mid-France, half-way along the Loire Valley. Which is where the car is currently, on holiday! I don't mind it being reluctant to start as long as it does start, every time. If it packs up then I will be in the poo ... although I guess this is what you get breakdown cover for. Access to spare parts is limited as Porsche is a little-known brand in France, although I do have access to a local VW garage in the next day or so, if any parts happen to be common with VW or Audi.)

Thanks for any useful suggestions.


Oli.

 

[pauljmcnulty]

I do have a spare DME relay, which I should probably try swapping. Any suggestions other than this - I'd be happy to hear them.

First thing to check, as always, is the relay.

I'm no technical expert, but there has been a really noticeable number of people tracing faults to the fuel pressure regulator over the last few months. I'd known it come up a few times over the last 6 years, but whether it's the weather or another reason, they seem to be causing problems now.

 

[ghost]

It's that rubbish French air! []

 

[zcacogp]

ORIGINAL: pauljmcnulty
First thing to check, as always, is the relay.

I'm no technical expert, but there has been a really noticeable number of people tracing faults to the fuel pressure regulator over the last few months. I'd known it come up a few times over the last 6 years, but whether it's the weather or another reason, they seem to be causing problems now.

Paul,

As always, thanks. I've now swapped the relay, and tried to start it a couple more times. first time: it coughed a little and caught, as normal. No problems. Second time: it coughed a little and almost caught, then died. I tried it again and it wouldn't even cough. Third time, with pumping the throttle, it caught and started fine, roaring into life.

When trying it it was noticeable that there was a strong smell of petrol around. I wonder whether this is relevant, or coincidental? If it was starting too richly, this would explain both the symptoms and the smell of petrol (but I could well be guessing at straws here.)

I'm leaving it for this evening (going to concern myself more with wine consumption than petrol consumption), and keep my fingers crossed that all is well with it tomorrow!

Out of interest, is the fuel pressure regulator common with any VW parts?

Ghost: it just might be. That or French petrol, perhaps. (Which is expensive rubbish!)


Oli.

 

[dirtydirtyharry]

The king lead could be on its way out. Mine was damaged and it resulted in the engine not firing.

 

[xenon]

Sounds like an ignition problem to mel. Hope you get it sorted and enjoy your holiday.

 

[zcacogp]

Chaps,

Thanks for your answers.

As it is, the thing has behaved itself perfectly all day today. And that involves one stone-cold start, about 7 or 8 (maybe more) hot starts, and a couple of semi-warm starts (sitting for 1-2 hours in sunshine.)

The only thing that has changed has been that I have fitted the spare DME (which I did last night, and it didn't seem to make any difference then), and removed the black plastic cover from the fuel rail. I did this to see whether there were any leaks (there didn't seem to be any), and didn't re-attach it.

So, I can't understand it. I have the part number of the (Bosch) FPR, and if I see a Bosch Service Centre I will stop and buy a replacement (if they have one in stock) and fit it. However, fingers crossed, it may prove to be fine for the rest of the holiday.

I'll keep you all posted. (If you care!)


Oli.

 

[pauljmcnulty]

I'll keep you all posted. (If you care!)

Ahhh, of course we do! Hope it keeps going and the holiday is great. []

 

[Diver944]

Intermittent speed and reference sensors?

 

[zcacogp]

Paul, thanks! I am hoping it makes it back to blighty as well ... the holiday may turn a bit too adventurous for my (or more accurately, Mrs zcacogp's) tastes if it packs up ... All is awful otherwise. France is a ghastly place (see my other thread.) And not getting any better with time. (Some or all of this may not be true ... ) []

Paul (S), Thanks. It could be, but the tacho bounces as it should every time. When I get home I'll certainly take the sensors out and have a look (as well as attaching a fuel pressure meter to the fuel line to test the FPR), but as it is working for now then I will be happy if it makes it home.

Sc0tty - sorry, haven't seen any Sancerre. But, continuing the tradition of photos of 944's by alcohol production places, how about this:

(You can't see the dead flies all over the front from that distance ... )


Oli.

 

[JamesO]

A crap tank of fuel? I do know from experience that on the continent, petrol stations are happy to buy back petrol that has been pumped out of mis-fuelled diesel cars.

 

[peanut]

Hi Oli
sorry to hear you're having problems with the S2 Only just seen this thread.

Mine recently had similar symptoms to yours which happened when I let the tank run empty and left it unused for a week or so.

I checked everything . tested the fuel pressure ,FPR , DME, ECU AFN Injectors and sensors with no improvement.

Mine finally started when i did the following.

Cleaned the injectors by flashing them with a 9v PP3 battery and a couple of wires to simulate pulsing.

Filed the edge of the rotor arm and filed each of the distributor cap terminals basically removed the deposits and made the edges nice and sharp to promote sparks. I also filed the spark plug tips

I don't know if my problem was due to a weak spark or stick injectors or both but it got my car going again.

Hope by the time you see this itws all sorted .

 

[zcacogp]

Nick,

Thanks. As it is, all seems to be well again. I can't explain it, and will be looking into it in some detail when I get home, but after a day's worth of oddness it has behaved itself perfectly for the last two days.

I still suspect the FPR, and it will be the focal point of my investigations, but if it works to get us home on Sunday then I'll be happy.

Glad to hear that yours was cured by those things. I'll try them. (All!)


Oli.

 

[peanut]

safe trip home Oli.

 

[zcacogp]

Cheers dude.

I'll keep this thread updated as and when I arrive back in blighty, and find out the cause of the problem.


Oli.