924Board.org

pc_evans10 · Posted: Sun Jan 22, 2006 10:17 pm Post subject: Random loss of power

I've got very odd problems with my 924 that the local porsche garage can't diagnose.

When driving normally the car often experiences a sporadic but total loss of power.

When driving normally, if I apply a bit more gas the rev can counter dropsoff completely (as the car loses all power) and will then go crazy moving back to normal before dropping off again, rapidly and over and over again. The car meanwhile is jolting and backfiring (the rev counter works fine). This especially happens on the motorway - what sometimes solves it is switching the car off (still moving), then putting it into gear and coming off the clutch to effectively bump start it at 70mph. Power usually (but not always) then returns, but a few miles down the road I'll suddenly lose power again.

Has anyone got the slightest idea what the poblem is? As I say, the local porsche guys have no idea. Someone did once mention the ignition set though, is this related?

Not sure if it's related but it has starting issues too. Car runs fine, stop and switch off, try and restart and get nothing at all. Key in and switch on makes the lights and everything else work (battery is fine and alternator is brand new). Turning the key to ignition then makes everything go totally dead (no turnover, light switch off) until it's released on the spring, when everything comes back on again! Weird.

Are these two probs related and does anyone have any leads as to what the problem might be?

chris24 · Posted: Sun Jan 22, 2006 10:42 pm Post subject:

Hi

http://www.924board.org/viewtopic.php?p=107701&highlight=#107701

http://www.924board.org/viewtopic.php?p=114380&highlight=#114380

My 82 had terrible problems with this. The fact that it was intermittent actually meant that I didn't have too much of a hope of finding it at first. I replaced the ignition switch, coil, fuel pump relay and distributor with known good spares and that didn't affect it.

Then it went totally wrong, as in the second post. I eventually rewired all the important wires using my Haynes manual and it worked. Some problems are great fun to solve, this wasn't. Sorry. Hope the two attached threads help a bit.

I would get the ignition switch out. You could try to test it, but since it sounds intermittent, the test will probably be fine (sorry I can't remember the test now, search for it or lok at the haynes wiring diagram and use a multimeter across its points.

Chris
_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

Khal · Posted: Sun Jan 22, 2006 10:56 pm Post subject:

What Year/Model? If it's an '81+ Turbo, it's dead-set easy... click here.
_________________
'80 924 Turbo

Belgian924t · Joined: 07 Jan 2006 Posts: 104 Location: Belgium

Try the small box behind the left headlight. This is th eignition control unit on older cars, also powerregulator for the ignitioncoil.

I had it once with an '79 931. The car had the same behaviour like yours. After trying all other things, replacing this unit solved the problem.

Greetz
_________________
'79 931 with Carrera GT look
'86 944 turbo (sold)
'88 944 turbo S (sold)
'85 911 Carrera 3,2 (to be restored)
'80 911 SC "SOLD"
http://www.cardomain.com/ride/2224272

pc_evans10 · Posted: Mon Jan 23, 2006 6:23 am Post subject:

Cheers, I'll try those. Those links were good - reassuring to hear other people describing a problem I knew I wasn't imagining, despite what the mechanics said (car has an irritating habit of behaving good as gold whenever I take her to the experts). Normally when the problem sets in the engine seems to set itself a rev limit, ie it'll die as soon as it goes above around 3600rpm. This morning driving back from Durham with a hangover she wouldn't go above about 1800rpm, long morning!

She's an '85 Lux. Mainly in good condition but I'm sick of never knowing whether it'll start or not.

Going to start with replacing the ignition control unit. I've heard you can fit a more reliable Bosch unit for these - is it true and if so anyone know where I can get one?

Pete

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

try the German Ebay

there you will find most any porsche part
_________________
Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

chris24 · Posted: Mon Jan 23, 2006 6:11 pm Post subject:

In my opinion there isn't a lot wrong with the ICU for keeping the car stock. I know they often out survive the car. There are plenty of them on ebay, but difficult to know for sure they will be good. Buying a new one is prohibitively expensive here (and probably elsewhere) unless you are sure it is the problem point. Take it out and plug it into another 924 if you can find one!
Tell us how you get on.
Chris
_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

pc_evans10 · Posted: Mon Feb 13, 2006 5:07 am Post subject:

Update on how that seems to have gone:

Went onto eBay and picked up a second-hand ICU for about £25, have fitted that and seem to have solved the loss of power at least - North Yorks - London - North Yorks this weekend with no drive problems whatsoever, full power all the way.

Starting problems persist though. Managed to stall it just as I was driving in the gate and experienced exactly the same prob where on turning the key against the spring (with lights, radio, everything working up to that point) the entire car goes dead, only to come back to life as soon as the spring is released. She'll still bump start upon rolling down a hill though.

Also not to keen on starting first thing in the morning - just turns over very slowly and painfully. Again, can be rolled down a hill to start. Luckily I live at the top of a hill!

Considering replacing the starter motor, worth a go?