Help please re starting problems

[Guest]

Can anyone tell me where the thermo switch is for cold start injector.
At the moment there is no positive feed to the cold start injector just 2 negatives - can't be right can it?

Also can anyone confirm if the fuel pump relay has anything to do with the cold start injector?

Awful starting problems just now. Cold start it's like a cylinder is missing, then warm start it turn over and over without actually firing - hopefully the same problem will fix both!

All help much appreciated.

Andy

And please note, I am a registered member despite it saying otherwise. Membership no. 43818.

Gold/champagne 924, A183 HWD, if anyone has any history on the car, be great to hear from you.

Replaced rear seal, that went on fine, but the sunroof seal, while it fitted fine, the roof doesn't seem to settle completely flush now, is that going to cause me problems or is it just because the seal is new?

 

[PaulHere]

Hello Andy

Don't panic, there are quite a few things to check like replacing the fuel injector seals/checking the injectors aren't leaking - checking the cold start unit is in good condition - checking the air sensor unit (looks like a metal disc under the rubber housing) is clean and in good order.

I'm very much a beginner when it comes to the technical stuff but we have some very knowledgeable people here who can help.

Have you replied to the e-mail sent to you when you signed up forum? That will get you fully confirmed as a forum member.

You are also on record with the 924 Register although you havn't sent back your Register form yet (hint hint [])

 

[924nutter]

As you are a member you will have the September issue of the Post. In the 924 Turbo head gasket article that I submitted there is a lead picture of the back of the 924 head showing the housing that the thermo-time-switch screws into from below. you can just see the end of the brown plug.

Two earths are correct, as the switch acts as an earth return blocker when the coolant is above a certain temperature.

The fifth injector is supplied by the red/black wire from terminal 50 on the ignition switch, which means it is live only when the key is turned to the start position, and earths through the thermo-time-switch.

If the coolant is warm, or when cranking the engine for longer than the preset time (which can vary from 5 to 10 seconds) the fifth injector ceases to operate.

 

[Guest]

Cleaned out the disk in the plenum chamber, was all guey, but if anything, things are even worse now.

Given I am not the most mechanically gifted can you give me any idea how long it will take to get the cold start regulator out and check it over?

What parts would you suggest I get in to replace regardless ? It is worth replacing once removed, or is that likely to be expensive?

Given it's position, am I going to lose knuckle skin while I attempt this little operation?

Andy

 

[924nutter]

I have a 5mm Allen key brazed into a 5mm 1/4 inch drive socket, which is absolutely ideal for undoing the regulator, which I have had for about 10 years but these days there are a plethora of ratcher driven hex driver sets on the market for under a tenner. (in real money)

Hold on though. When did you last check the spark-plugs? The plug gap erodes at about 250 microns( 0.25mm) per thousand miles, and a gap that started out at 0.7mm will be nearer to 1mm after a year. The ingnition module is fairly tolerant of a big gap but there comes a point when the mixture is rich, with a gap that big she aint gonna fire, or if it does it will pop and bang until the engine warms up and the mixture leans out.

I though I had all sorts of horrerndous electrical problems with the hall sender and amplifier module on my mk1 Golf gti ( Bosch K Jetronic cis, the same as the 924) which used to bang and pop, till I put in a new set of plugs.

If you have to remove the regulator (and in fifteen years ownership of the same car I never had it fail on my 924) then;

Disconnect the battery.
Remove the plug.
Undo the two fuel unions and disconnect the pipes from the regulator
Undo the two socket cap head bolts and remove.
I have never tested one but when cold, say after an hour in the fridge, it should be possible to get some kind of flow into one, and out of the other port.

Bear in mind that blowing may not prove to be a conclusive test as it's only supposed to let by at 4 bar.

 

[Guest]

The weather has been too bad to work on the car, so in desperation I took it to those awfully nice people at Porsche Solihull (not even being sarcastic, they are so friendly and helpful - even washed and vacuumed the car and there was a nice tub of sweeties in it for the kids when I got it back.).

Anyway, they did some investigation and have said they are pretty sure it is the warm-up regulator.

Had a really good chat with the engineer about all the things they tried to gauge how confident he was that it really is the problem too and he was only too happy to talk/help which was excellent.

Only thing I can say against them is that they wanted over £500 to supply and fit ... called Porsche Shop in Halesowen and got one for under a ton, though, like Porsche, it is not a stock item, so awaiting it's arrival now: looks like I will have to risk those knuckles after all!

Can't say I am looking forward to it, but I am sure it will be a learning experience.

924Nutter - I changed the distributer cap and rotor arm, plugs, leads etc. etc. to at least discount the possibility of all the "easy" stuff ... just gutted it has to be what must be the most difficult part in the whole equation to fix.

The engineer said that the fuel pump on my car does not have the lock off valve (or something like that) to retain the fuel pressure when the car is swithced off. He thought they were fitted to the later cars, so can anyone shed any light? What should keep the fuel pressure from leaking when switched off, as this will help me fix the warm start problem I am having too! Will the warm-up regulator perform that task too?

Thanks all in advance.

Andy

 

[924nutter]

Underneath the fuel metering unit on my 924 (Nov '83) there was a solenioid in the return line to the fuel tank which is what I think they refer to as the fuel lock off valve. Yes, it could stick open, but the latest (i.e. when I bought mine 2 years ago) replacement pump from porsche shop comes with at least one new check valve. You could unscrew the lock off valve and check that for operation.
The regulator will be unlikely to cure the warm start, as it will be shut, and non operational
One last thing before committing to the regulator, what about the injector O rings? The engine can suck in air there until you get enough revs up to suck them into the recesses.

You pays your money.........

 

[Guest]

Mine is a 1984 A plate, so must be very similar I'd have thought to your Nov 83 model.

I confess, I haven't checked the "O" rings, but I have ordered the regulator from Porsche Shop as I am too depressed to put into words that my favourite new toy doesn't work "properly".

The leaks too are just such a headache - I cannot wait till I have them sorted, the back seat is soaked, the rear hatch is soaked, and drying it in this weather is nigh on impossible.

Where are the sunroof drainage pipes and where do they run? Would leaks from them be visible (i.e. would I actually be able to see dripping) or would water be coming from under the trim/carpet?

The main leak I am convinced is through the wiper mechanism, you can watch it dripping through from behind the plastic box as you look back, but there seems to be another major water feature in the back much further forward (just behind where the seat top hinges) without any evidence of dripping from above. Does the sunroof, or another, drainage pipe run anywhere through this area? or is it most likely a result of the "stream" of water that forms form the leak by the wiper assembly?

On one of the many attempts to find the rear leak (I think there were actually several) I did find a pool had gathered in the recess behind the off side rear wheel in the rear hatch. There seems to be a plastic/rubber plug which had completely clogged up with grime, and cleaning that seems to have at least prevented a recurrence for now.

I really love the car, but these problems take so much time to diagnose let alone fix, and it worries me that long term problems might (will) start arising if I can;t get them found and sorted. Arrgghh!!!!

 

[924nutter]

You have elec sun roof right? The front drains run down the windscreen pillar underneath the side trim. From memory there are two at the back too, that drain through the bottom of the cubby hole underneath the boot liner, each side. The felt seals let by a bit and the idea is that any seepage drains away.

Try going to a model shop that sells radio control accessories for models, and get two peices of 'golden rod' and a peice of 10 ba studding to join the inners together and try easing the rod into the drain hole with a view to poking it clear. Dont push too hard, or the drain pipe might come off the outlet hole.
Failing that, use a suitable length of net cutain spring, the plastic coated stuff. That is about the same diamenter but a bit more flexible.