1980 Porsche 924 2.0 Lux - Shonky Rocket [update 13/7/22]

Cor! Why did I not see this thread before? Incompetence on my part I expect.
I've been forced to read it all instead of doing what Mrs Sweetpea wants ("Would you come to bed, I want to go to sleep!") and I've book marked it for future reading pleasure.

Keep up the good work

James

The mild feeling of achievement gained from my recent progress has been somewhat shortlived. Yes, I could have mentioned this earlier but I wanted to keep some linearity to the thread. Anyway after the (partially) successful test drive the electrical Gremlins decided to feed again...

Before getting into that though, when I was filling up at Asda on the 'test run' this was getting air...



Shortly after I filled up and was 'test driving' this thing pops up again and we end up doing a little ring out to the motorway, down a couple of junctions and back into Leeds together which was cool. That rotary sounded sweet and could leave me for dust. So back to the Gremlins...

This problem has appeared and gone away several times now over the last year. Not always exactly the same but probably related.

Back when I was recommissioning the car it had a bout of failing to start (not even trying) which kind of went away by unplugging re-plugging 'stuff' back in. Later shortly after fixing a problem in the indicator stork it would start but when the key went to normal on position it would cut out, again fiddling made it go away. These problems have happened and cleared a couple of times since but on the whole its been OK.

A few weeks ago the car cut out while driving (while in a queue at traffic lights typically) and did the same thing, start but not stay running as above. It just decided to work after a couple of minutes (and missing the lights) and has been OK for a few weeks after.

And now the latest recurrence after doing the steering column bearings. I think I need to fix this for good before I get left stranded somewhere.

To recap there are two symptoms:

1) Ignition on - Electrics come on but the battery light on the dash stays lit, Moving it to the Start position nothing happens. You can hear the mechanical click in the ignition barrel but nothing else.

2) As above but when moving the key to the start position the engine starts. It stops when the key springs back to the normal ON position. (this can occur during driving, not only when trying to start).

My thoughts are wiring or ignition switch. Apparently the ignition switches are known to be troublesome on these so I'll start there I think.

So that's where it's up to at the moment, broken, again!

-Steve-

PS. I found this useful link about changing the Ignition Switch which might come in handy.

www.clarks-garage.com/shop-manual/elect-25.htm

it DOES sound like an ignition switch problem...can you test it with a continuity tester?...I know it only happens once in a while, but maybe you could "make it happen" with the switch on the workbench...

JP

nas80 - That Asda is my nearest petrol station, are you local too? It would be cool to meet up, I would love get a closer look at the RX7.

07lilredwagon - Getting it out to bench test it is the painful bit. It seems to be the same ignition switch as the Golf/Scirroco/T2/T4's use although the sites I checked don't list it under 924. I have ordered THIS so fingers crossed. It's cheap enough anyway. This way I can plug the new one in without fitting it to test it first.

bstardchild - Thanks, It's grown into rather a long thread over the years, I hope I didn't bore you too much . I have my RRG camping tickets for next year so come and say hello. (That applies to anyone going, we like random strangers gatecrashing our camp to talk about cars. After all that's why we go.)

The 'Original Equipment Quality' YANG MING switch arrived...



Plugged it in, it fits. So I jabbed a screw driver in and gave it a try...



Well the switch works a treat, but the car still doesn't.

It was still being a pain to start, then it did start, then ran happily for 5min and then just cut out. When it was running it sounded like it was running fine but I heard a couple of 'Cracks' that sounded like arcing. It was dark so I turned my work light off but I couldn't see any sparks from the HT stuff anywhere. It only did it a few of times and I couldn't pinpoint where the sound came from. If it was something wrong with the HT side of things I would expect it to be lumpy and hesitant ect. while running but it isn't. I did decide to look at the distributor cap though and that looks bad and like it might have been sparking...





Clearly that needs changing but it doesn't seem to fit with the symptoms I'm getting. I'm puzzled.

-Steve-

Yeah sure here's a pic, though for the well being of the interwebz I had to censor my fingernails...



The rotor seems a firm fit and not damaged although there was some movement in the rotational direction.

-Steve- (off for a manicure)

PS, What'd confusing me most is why it will often (although not always) start so readily in the ignition 'start' position but then go off when the key springs back the normal on position. Surely this cant be anything to do with that?

Nice nail polish! Got to get me some of that.

Your problems are probably nothing to do with this... But I'll say it anyway... How's the earth to the engine block?
When I put the MR2 back together I missed it off and there was not so much as a click when I tried to start it. I could imagine if yours is a bit duff it could stop the engine or only allow it to run with the coil ballast resistor shorted (as it would be with the key in the start position).

James

In your video, when you revved it with the key still on start (poor car!) it looked to me as if the rev counter dropped to zero 'instantly' when you let go of the key.

What I'm driving at (badly) is this...

The rev counter is normally driven by the low tension side of the coil - it takes a stream of pulses off the contacts or igniter. If the engine dies because of fuel starvation (for example) the rev counter will accurately read the speed of the engine as it stops. If the ignition's low tension fails the rev counter will drop like a stone 'cos it's not getting pulses to read.
It's not obvious but it looked like that's what happened. It's easier to see if it happens while you are driving because the momentum of the car keeps the engine turning while the rev counter drops to zero.

Anyway, if that observation is right then I'd agree with your 924 forum chappy that you should be looking at the ignition feeds. That wouldn't explain the starter not turning though - which a dodgy earth might.
You could possibly have two faults though.

James

A little later I refitted the heater blower cover to stop rain water running off the windscreen straight into the motor/heater box/inside the car. A little job easily sorted.

Then I noticed we hadn't put the fuse box back in its mount earlier on. This rang warning bells so I started the car up and left it idling while I moved the fuse box back into its mounts. Before I got half way it cut out, bummer. Que lots of starting the engine and cutting it out, fiddling with various wires/connectors trying to find the culprit. Disturbing connector 'A' seemed to cause the issues. Connector 'A' also happens to be the one I cleaned up last year with a burnt pin.

Back then I had been cleaning up loads of connections, relays and earth points etc though, so when the starting problem cleared it could have been any number of things that cured it. I had never known the function of this pin. It could have been for the rear wiper or heated screen or any number of unimportant things so I had never been that bothered. So what does pin A12 actually do?...



Ahh it goes to the Bosch ignition unit, and just like that all became clear. I better fix it properly this time then. I cut out a piece of beer can and rolled it round a little jewelers screwdriver to make a little pin release tool. I removed a redundant good pin (I think it was the interior light or something) and the charred pin...



Then I soldered the ignition wire to it...



I heat shrinked it and refitted it, and hopefully that's the end of that problem. I can now move the fuse box and wiggle wires and the car just keeps ticking over nicely so I'm pretty confident this time.