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On 20 Sep 2002, at 0:13, Jens Vagelpohl wrote: > the only failure modes i have seen with l-jetronics so far is > backfiring into the intake tract, which can possibly bend the airflow > meter's flap. that's it. i never had any other fuel injection problem > in the 9 years/30,000 miles i had my 412 wagon so far. See my responses to Keith's comments on this same subject. I will also note that a single observation of 9 years and 30,000 miles means very little. It's just not a big enough sample. > a vacuum control unit that seems much more dependent on close > tolerances to work correctly seems more brittle to me. There are no close tolerance parts in the D-Jet PS. They were however adjusted at the factory after assembly to a state that we don't yet know how to duplicate. In most cases this is not a problem as long as the factory setting has not been altered. Note that there are a couple of factory settings in the L-Jet airbox and how to "reset" these is a matter of great interest in the L-Jet community. The L-Jet airbox DOES, however, have quite close tolerances in the air flap, and distorting this flap can kill the airbox. > not to mention the mechanics i have spoken to who told me of cars being sent > from vw shops to bosch shops and back because no one wanted to work on > d-jetronic cars... It's true that competent D-Jet service can be hard to find. It might be a little harsh to blame the FI system for this, but one might be able to make the argument that Bosch & VW failed to do a very good job in educating their people in this area. Personally, I think VW did a pretty good job with their dealers, but what I saw in the independent shops was just complete resistance to the FI revolution and a refusal to learn a new system. In the end, this reluctance wore finally wore down around the time D-Jet was being replaced by the K & L systems, so there was little motivation for mechanics to learn the older D-Jet system. Unfortunately this meant that our D-Jet systems became orphans. We're lucky to have this list to help with this, because I don't know anywhere else to refer people who need D-Jet help. > besides, just like keith mentioned, very similar air-flow controlled FI > systems were used until a few years ago when air-mass metering > supplanted air-flow metering. Aren't air flow and air mass metering the same thing? D-Jet was different in that it sensed air pressure. I think it's at least somewhat interesting that the first generation system used air pressure (or vacuum) to meter fuel, which is the same principle that carbs work on. In the end, all the systems are trying to do the same thing: measure the rate of flow of air mass. It's only a question of how to do this so that we can get the most accurate measurements under all conditions. Carbs generally do a pretty poor job of this and FI systems are better, but work continues on ways to do a better job across the complete spectrum of operating conditions. - ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/