Restarting problems.......

[wolfie308]

I thought I'd cured my starting problems after recently fitting a new battery. Car starts perfectly from cold even if not used for a few days on first or second turn of the engine. Most days I drive about a mile to town and park up for 10-15 minutes to get a few bits of shopping. Three times in the last week, when I've returned, the car has started fine, but within a few hundred yards it's just died one me, twice on mini roundabouts and the third, coming up to traffic lights. All very embarrassing and potentially dangerous. From previous experience I've found that if you wait a few minutes, it'll start fine and I can get home without further problem.

Yesterday, I went to the post office but the queue was 15 long so I gave up and returned to the car. Thought it was going to start, but wouldn't quite catch and then just kept turning over. So, I just sat there for 5 minutes, tried again and started on second turn of the engine. As you can imagine this is becoming a right royal PITA, so any suggestions would be welcome.

 

[Waylander]

check the usual suspects

FPR
Vac lines
non return valve in the fuel pump (the normal for hot starts issues)

 

[Cater_Racer]

I'd suspect sparks before fuel, try multipoint plugs, or just different plugs.

 

[Eldavo]

With other components now coming up to the age where they're showing failures the standard answer from 5 years ago seems to haven forgotten - DME.

These are the exact symptoms my 2.7 had when the DME gave up the ghost!

 

[wolfie308]

Thanks for the input chaps, much appreciated. Thought I'd try something today, so before going to post, I went for a 10 mile blast to make sure it was properly warmed up. Parked up for 15 mins and on return, car starts perfectly. Drive half a mile, park up and spend 20 mins shopping at the weekly market, return to car which starts on the first turn and drive a mile or so home, no problem. So, it doesn't appear to be the typical hot starting problem.

FPR and fuel pump non return valve aren't things I am able to check, but the spark plugs were changed at 12k service by Promax earlier this year.

DME.......Hmmm....this was something I'd been meaning to change since these problems first appeared ages ago. I've got full service history back to 1994 and since there's no record of it being changed, I reckon that's the cheapest and easiest thing I can change myself, if nothing else, I can rule that out if doesn't sort it. Fingers crossed it does.

Found an old thread here which describes the symptoms I've been experiencing.....

http://www.tipec.net/_for...c.php?f=25&t=13732

 

[zcacogp]

Bar the cutting out while hot, the symptoms are pretty much the same as I have with my S2, and which I've posted about on here before; starts fine from cold, but struggles to catch when hot. However this isn't reliable; sometimes it will work fine from hot. My top suspect is the fuel pressure, and possibly the non-return fuel pump valve. Is there any solution to this other than a new fuel pump?

(FPR is about 3 years old, plugs are changed regularly. DME is about 8 years old but shows no other signs of causing problems.)


Oli.

 

[pauljmcnulty]

Hi Richard,
I haven't forgotten you, I have been laid up with a cold that's really knocked me out but will catch up before Christmas.

The cutting out does sound FPR-related, but if the DME is that old then change it anyway as a first option, or just a precaution. Do buy a genuine one though, as I've seen brand new ones fail and I'm not sure all are equal quality.

 

[Waylander]

Bar the cutting out while hot, the symptoms are pretty much the same as I have with my S2, and which I've posted about on here before; starts fine from cold, but struggles to catch when hot. However this isn't reliable; sometimes it will work fine from hot. My top suspect is the fuel pressure, and possibly the non-return fuel pump valve. Is there any solution to this other than a new fuel pump?

(FPR is about 3 years old, plugs are changed regularly. DME is about 8 years old but shows no other signs of causing problems.)


Oli.

the return valve is available as a separate part. 944 608 951 01

http://www.design911.co.u...eck-Valve-94460895101/

 

[wolfie308]

Hi Richard,
I haven't forgotten you, I have been laid up with a cold that's really knocked me out but will catch up before Christmas.

The cutting out does sound FPR-related, but if the DME is that old then change it anyway as a first option, or just a precaution. Do buy a genuine one though, as I've seen brand new ones fail and I'm not sure all are equal quality.

Hiya Paul,

I forgive you, give me a shout when you're better/available - look forward to a catch up.

Bought a DME from Promax for just under £25 inc post. Had a look at original, but Design911 are quoting £71 inc post for 'genuine Porsche part'. Didn't bother to check with OPC given the difference.

After reading other threads and comparing symptoms, I'm starting to think it could the FPR, but at least this should rule out one of the possibilities.

 

[zcacogp]

the return valve is available as a separate part. 944 608 951 01

http://www.design911.co.u...eck-Valve-94460895101/

Oooooh, now that IS helpful - thank you very much Martin! []


Oli.

 

[wolfie308]

At the risk of tempting fate, I think sufficient time has passed for me to be pretty sure that the new DME relay has cured the problems I was experiencing. The car has started every time on the button, hot or cold and hasn't cut out once since. Hopefully, that was a nice cheap fix.

 

[Eldavo]

What do I win?

(Just send me good vibes as mine is in the garage so I'm praying for a small bill)

 

[wolfie308]

10/10 David, best wishes, but sadly 'turbo' and 'small bill' are rarely synonymous.....waits for comment from Oli []

 

[zcacogp]

10/10 David, best wishes, but sadly 'turbo' and 'small bill' are rarely synonymous.....waits for comment from Oli []

Serious comment (which is very rare from me): it does strike me that Turbo's cost a fair chunk more to run than S2's. If nothing else, due to the extra complexity of stuff under the bonnet meaning that work to do a similar job takes a lot longer. Having said that, no garage these days seems able to produce a small bill for anything, let alone a 1980's car with a 'Porsche' badge on the front.


Oli.

 

[Eldavo]

I'm not sure that I agree with that entirely - my car has had plenty of time and money spent on it but a fair proport of that has been modifications or upgrades that I've chosen to make.

It also comes down to your usage of the car, mine is setup for track work which means everything gets upgraded in turn and I have lots of preventative maintenance done. Living in the North East of England means a fair hike to most tracks and my car needs to be able to get me there, lap all day and get me home.

Its currently in the garage to chase an oil leak which has turned out to be power steering related. So I've spent the evening taking the best bits from my two spare pumps to make one nice clean one to be swapped over tomorrow.

It's also getting a service and some oil lines are being changed over too. I run twin factory oil coolers and have remade all the lines as one of them was attached to the factory line with an adaptor and I wasn't happy about how it had to be routed.

The power steering hoses are being changed too based on age and they're getting quite brittle - again 50% of the total work being done would be "unnecessary" to most people but the car is a keeper and the peace of mind factor comes into play too.

 

[pauljmcnulty]

I agree with Oli and David, you're almost making the same point.

Most 944 Luxes, S or S2 models are pretty much unmodified. Obviously some are, but most are pretty standard.

A basic turbo has a few more difficult jobs, as I understand, so there are extra costs sometimes. But a far higher proportion of turbos are modified than any other model so that's where the costs start to become a grey area.

I'd chuck a figure in as a starting point and say that 90% of the extra costs of running a turbo are down to modifications, not the original design?

I'd say show me a standard turbo and it's costs over it's lifetime and I'd think it would be comparable to an S2, and a bit above a Lux. Show me the spreadsheets for the modified turbos and it's in to far more silly numbers, but usually still pretty reasonable for the price/performance/reliability/fun compared with modifying other similar cars?

 

[Waylander]

Spot on Paul

 

[Monkeythree]

I have one of each so when I get them both working I will gather some back to back data!

 

[Eldavo]

Yup - once you push the envelope away from manufacturers specs then you need an understanding of what you're doing and how it fits into the general scheme of things PLUS the finances to do it properly.

It it was always said that £1k got you a Promax/Lindsey stage 2 kit and an extra 50-60bhp. But then; do you want to stop, go round corners, keep the handling balance, put the power down as well? The 944 is a fantastic platform and package, you can't "improve" one element alone or else you lose that intrinsic feel of the car.