TroppoShark

G'day fellow rennlisters,

Some of you may recall my post at the end of last October: 'Euro 931 added to the garage...' with the accompanying pic of the handsome unit...

Since then, I've moved from tropical Queensland to temperate Tasmania, and finally took delivery of the car about a month ago.

The car is as good as it looks - actually better... I tracked down the PO, and learnt that in the past two years he'd had the gearbox completely overhauled, a new clutch installed, new brake pads, new injectors and the turbo re-raced and new seals fitted (and I believe it is running with synthetic oil). None of this info was known to me when I bought the car (sight unseen) because the dealer had lost the pile of receipts. Sometimes you can be lucky...!

The poor PO is a gentleman of 66 who had to have a hip replacement, and can no longer get in and out of the car.

Unsurprisingly, it has a hot start problem, but I'm going to try to solve that by installing a push-button switch to activate the thermo timing switch at the cold-start valve. (see http://www.924.org/techsection/hot_s...roblem_fix.htm)

There's also a gremlin in the wipers which activates them intermittently, and which seems to coincide with turning the steering wheel sometimes. (anyone been there?)

The biggest problem, though, and one which I'd like to hear your thoughts on, is that the turbo seems to spool up and boost for only a second or two before the engine balks abruptly... Changing up to the next gear will result in a repeat of the action when the turbo spools up again. I've only experienced this in the low gears, (and the car was properly warmed up, of course) because I haven't been out on the right stretch of road with the right traffic conditions to try spooling up in the upper gears...

It's as though the engine just shuts down for a split second, with a braking effect, which makes me think it's like the ignition being briefly cut, but the revs are nowhere near high enough to be activating the 'over-rev cut-out'

Does anyone have a suggestion as to what is happening?

Other than this, the car runs well and accelerates well, as long as the revs are kept up in the mid-range.

It might also help to know that when I first got the car it was running very roughly, which I now attribute to it having been under-used (only 500km in the past eight months). At first I was too busy to tackle this myself, and had a garage service it for me. They replaced a spark plug, and informed me that they couldn't set the timing correctly because they believe the flywheel has been re-installed incorrectly, so that the timing marks don't show through the bell-housing inspection hole... Could've happened, I suppose... Unfortunately, the only way to find out is to expose the flywheel, moving the bell-housing back. What a pain.

Being a 1980 model, I presume it doesn't have the digital timing off the flywheel... which was introduced in '81. But if a PO updated the flywheel and timing system, how would I know?

Any guidance by any member who recognises the 'boost and balk' syndrome will be gladly received.

Cheers,

Phill: 1980 Euro 924 Turbo

924RACR

Self-activating wipers tends to be caused by poor grounding of the steering column. Add a new strap and you should be less embarrassed. I added it under the column, by the CIS Lambda control unit.

IIRC you might be well served to check the rotor, as at least some versions of the 931 had a rev-limit function built into the ignition rotor. Beyond that, You could also verify that the overboost switch is not faulty. This is the ground for the fuel pump relay, and is on the charge tube from the turbo to the throttle body. It's normally closed (short to ground), and is supposed to open when max boost is exceeded. You could try grounding the wire and see if the problem goes away. Of course, if you truly are overboosting, this will mean possible damage.

Therefore I only recommend this if you REALLY know your boost is correct, and wastegate working properly. It is conceivable that your wastegate could be stuck instead, causing excessive boost (easier to achieve in lower gears) and popping the switch open. Best place to start might actually be to plug in a boost gauge and see how high it's going when the engine cuts.

But that may not be it at all. It's worth also checking the state of the wiring for the ignition; I've seen some ugly problems with misfires or intermittent loss of spark caused by flaky and corroded wiring and connectors on the ignition boxes.

TroppoShark

G'day Vaughan,

Thanks for that response, mate.

I will add another ground to the steering column. As you say, the main effect of the willful wiper is to embarrass you at the most inopportune times. I swear I can actually hear the gremlins giggling...

Hopefully this weekend I'll get a chance to check the overboost switch, by following the proceedure in Haynes...

The symptoms do seem to indicate overboost, and match pretty closely to '6.4 Turbo Overboosts' in www.clarks-garage.com/951faq.htm#problems

I wish I could find a similarly helpful page for the 931...!

I should have mentioned that a boost guage is fitted, and seems to indicate that the system is tight: the car idles on about 15lbs vaccuum; draws 20lbs vaccuum when fully retarding. On the few occassions that I've spooled up, the guage heads up towards 10lbs, I believe, before cut-out occurs, but I can't be sure because I'm mainly watching the road...It may go past 1 bar while I'm concentrating on the fast driving at that stage... I'm not real keen to repeat overboost situations, either...

Well, at least I know the turbo's working, which I would expect from what the PO has told me. He has no reason not to be honest with me, since he sold the car through auction months ago, and a caryard bought it before me.

He also told me that he tested the turbo 'a few times', which doesn't seem very much, so it may well be that the wastegate is seized... How can I test it in the car without taking it out?

Anyway, the very first thing I have to do is to ensure the timing and tuning are right, as a good foundation to further diagnostic investigating. And to do that, I need to resolve the enigma of the missing timing marks on the flywheel, outlined in my first post, above.

What do you make of the flywheel/timing issue, Vaughan?, or anyone else...?

Thanks for your help. Further contributions gladly received.

Phill.