rich07

Hi, I have an 82 4.5 Auto, Euro 928 please can you help. I have just carried out a lot of work on the car and my girlfriend was looking forward to spending some quality time with me after I have just spent the last 6 weekends under the bonnet. I don’t want to have to sell this car as I love it but I’m beginning to loose my sense of humour. After the camshaft snapped I replaced the belt, shaft, and camshaft. I then decided to investigate the ticking noises coming from my gearbox, this became a swap out for another when I started looking at the prices for an overhaul. I found a low mileage gearbox but decided to replace the bearings in the torque tube while it was all in bits. The bearings were £30 from a bearing company and gearbox was £350 exchange.
So with the car all back up and running I’m a little cheesed of that after a week of use a fault that I never sorted out has returned, the last time I looked into this it just resolved itself? The problem is when starting from cold would it sounds slightly different as it is started in the driveway, then as you pull away it will seem normal’ish(+ a lot of black round the tailpipe) until you try to exceed 2000 rpm this will result in a loss of power almost like someone turning the ignition off. If you let your foot of the accelerator to under 2000 the car would resume to drive o.k.????? But it would chuck out a lot of black smoke, something causing the mixture to be to rich??? This will stop if I drive the car for about 20 minutes, so could be to do with the warm up system? any ideas……Also I should mention that the car does start on the turn of the key hot or cold, with no problem.

This fault is not a result of the work that has been carried out, this problem was apparent last year but then just went away…..(I wish everything with 928’s was that way)

PLEASE HELP…..

Niels Jørgensen

I can't offer much help, but maybe some comfort in knowing you're not alone: Judging from previous posts (and my own car) I think these more or less random loss-of-power-problems are quite common with all MY 928's. I still love the car; when it works properly it's a blast, when it doesn't it still takes me where I need to go (albeit, slightly annoyed).

I think I've reached the point where I'm just waiting for whatever gizmo is failing to finally do the decent thing and break properly so I can find and replace it.

So far, everything I've tried have worked - for a while. I'm begining to think the car is a living creature that just likes to be tinkered with.

Old & New

Gosh, Rich, I've never heard of a camshaft "snapping", but I guess we learn something new every day.

Sounds like you need to look at the warm-up regulator.

rich07

Tested the cold start injector last night to see if it was running for to long but it's ok. Just a short 2 or 3 second burst as designed. I have'nt look at the warm up regulator maybe that's my next job as suggested by the Godfather? Not sure how to test the warm up regulator? Or does anyone have any other ideas of what could be causing problems, rich.

Mike LaBranche

Sure sounds like WUR. Cold start on a CIS is managed by the WUR, cold start injector, aux air valve, temp sensor. Most of it is simply WUR control pressure feeding into the distributor. Sounds like your cold pressure is low (allowing more fuel to be passed thru the control plunger in the FD; rich) and once it warms up you're warm pressure is ok.

The only way to know for sure is to hook up fuel pressure gauges to the WUR, measure system pressure, cold and warm control pressures. Too high of a control pressure produces lean. Too low produces rich. There's quite a bit written up about it in the archives.

Good luck and let us know how it turns out.

Old & New

rich,

Do a search for "warm up regulator" and you will get a couple dozen hits with lots of good information in there.

The regulator has an internal heater (via the electrical connector) which leans the mix as it warms up. If you lack the current at the connector, or if the regulator has an internal malfunction, then the car will run rich longer than desired.

rich07

I borrowed another warm up regulator from another 928 owner. Different symptoms, but i was told that with this WUR the car will run quite weak. With this WUR the car barely idle's and i have to leave it running on the spot for a few minutes. Taking it for a drive it's a little slow to move up through the revs but then after 2 or 3 thousand rpm it's fine. This leads me to believe that the old WUR was broken. I have since richened the mixture up which in turn brought the idle back up to normal running and the car seems to be o.k if anything it's a bit rough for the first couple of minutes. I think if i get the mixture set up correctly and it should be fine!!! I'll keep you posted and thanks for all your help..