mff@wuphys.UUCP (Swamp Thing) (11/15/85)
I tried mailing this and the mailer burped, so I'm posting it instead. In article <558@petfe.UUCP> you write: > >My car recently developed the following symptom: > >Under large load, the engine "cuts out". When I'm accelerating, >or going up a steep hill, or any time that the accelerator is almost >fully depressed, after a few seconds the car will lurch as though the >ignition system was cut off for 1/4 second. If I back off of the >accelerator, the problem stops; if I keep the pedal depressed, the engine >will come back, then cut out again, then come back on, etc. > I have a '68 VW with Bosch fuel injection which had similar problems. It turned out to be a flakey preasure switch. On my system, the preasure switch measures the intake manifold vacuum (not really, but close enough) and, under heavy load conditions, when the vaccum would drop to normal air preasure, the switch is supposed to turn on, which tells the computer to kick in a little extra gas. As I said, the switch got a little flakey, and would turn on-off-on, etc., in rapid succesion, which produced surging. Another possibility is the throtle cut-off switch( assuming yours has one), which signals the cumputer when the throttle is not being depressed. The computer then shuts down the flow of gas to an amount which allows the car to idle. If this were screwed up, it could also produce surging, but I don't know how this could be related to hi-load conditions. Another possibility (when it comes to fuel injection, there are always more posiblilities) is that the preasure sensor, which, like the preasure switch, measures the vacuum, but sends a variable signal to the computer (instead of just off/on), could also be flakey. In general, there aren't any easy answers, and the parts are too expensive to just shotgun it. I work on my own, so I really can't suggest how to deal with dealers and such, but if they screwed up your car, mabye you should find another one. At any rate, good luck, and I would be interested in hearing how it works out. Mark F. Flynn Department of Physics Washington University St. Louis, MO 63130 ihnp4!wuphys!mff "There is no dark side of the moon, really. Matter of fact, it's all dark." P. Floyd