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Date: Mon, 13 Dec 2004 20:31:00 +0100
From: Frode <>
Subject: Re: 99 Turbo update - vroom vroom

Dave Hinz wrote: > On Mon, 13 Dec 2004 15:57:41 +0100, Frode <> wrote: >> Dave Hinz wrote: >> >>> So, the inevitable questions. Where is the overboost sensor on >>> this thing? It seems to be cutting out the ignition just as I >>> get into the "red" on the turbo gauge, rather than up a ways as >>> I would expect. > >> I installed a 900T engine in my 78 99 some years ago, but didn't get >> any such luxury as overboost protection -- still I did experience the >> symptom as you describe, I think it was the warm-up regulator that was >> stuck, leaving too little fuel at high loads. > > It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter. Need > to try again tonight and see what RPM it's happening at; I was watching > the boost gage rather than the tach. The 99 fuel cutoff is really just the fuel-pump being switced off. I don't know how that feels since I don't have that feature, but I would think not quite as abrupt as total ignition misfire. The rev limiter is supposed to cut in at 6000 rpm and as far as I can tell from design, it will stay out until the rpms have dropped substatially. 6000 rpm is way beyond where I shift up and I have never experienced that. It is a simple spring-loaded centrifugal device in the distributor, quite easy to disable just for the sake of ruling out that possibility. It could be that the spring is getting old. Your original post indicates that it is boost related, not RPM. >> If you haven't already, try to increase the fuel/air ratio by turning the >> adjustment screw 1/4 turn clockwise at a time and see what happens. > > Which adjustment screw, please? This is a CIS fuel injected system, does > that change what you're saying? It is the green one here displayed at this page: An allen screw, buried deep inside the unit betwen the airflow meter and the fuel regulator. It is accessible from the top. You'd really need a tool like this: I have always used a long electronics-type screwdriver. Just remember to keep a record on how much you turn it. 1/4 of a turn is maximum between test drives. Also keep an eye on the spark plug deposits in the long run. I'm sure the web is full of info on CIS / K-jetronic, it was/is used in every kind of vehicles from the Golf to the 911 turbo and Lamborghini Countach, Ferrari Mondial And that V- thing too... >> Also >> check the so-called "control-pressure". If it is too high, as I said, the >> engine will run lean at high loads. more than 4 bar is too much. The >> Haynes manual for the 99 is quite informative on this part. When cold, it >> is approx. 1 bar, increasing steadily to around 4 when fully warm. > > Sounds like I need a Haynes for the 99T then. My 900 manuals are good for > almost everything, but they're too new for some stuff, and my 99 manual is > too old for the turbo stuff. Ah well. No big deal, I can take some photos of selected pages, and cite some key figures if needed. >> PS: Until you get the fuel mix mostly correct, you may find it convenient >> to use a set of "hotter" NGK-s than specified, I think I still use >> BCP6's, but then in Norway, continuous operation at highway speeds in hot >> summer days is soo rare! > > I put BCP6s in there, which I think is as hot as I should go, yes? In the long run, yes! Good luck with a fun engine! -- Frode

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