Date:         Tue, 21 Feb 2006 15:19:09 -0800
Reply-To:     mark drillock <drillock@EARTHLINK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mark drillock <drillock@EARTHLINK.NET>
Subject:      Re: Compression braking & Power Loss
Comments: To: Geza Polony <gezapolony@SBCGLOBAL.NET>
In-Reply-To:  <vanagon%2006022116505206@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

The ECU intentionally cuts power to the fuel injectors when you are
going fast down hill with your foot off the gas. It only knows that your
foot is off the gas from reading the idle switch on the throttle body.
When you push your foot on the gas pedal again the idle switch is
supposed to click off and tell the ECU that you want power again. If the
switch sticks in the idle position, the ECU never turns the injectors
back on because it thinks you are still coasting.

This is how the 2.1 FI works and I can only assume the 1.9 is similar.
You can test this theory by disconnecting the idle switch connector and
driving over that hill again. The symptom should go away. Then get a new
switch so everything  works the way it is supposed to.

Mark

Geza Polony wrote:

>My '84 Westy 1.9 runs great--most of the time. Full power, like 70+ mph even
>going up long inclines. Had it to 82 on I5 yesterday, drove excellent.
>
>However, and ESPECIALLY AFTER GOING DOWN LONG HILLS, she loses power to the
>point where, even going downhill, she won't accelerate. For some reason,
>COMPRESSION BRAKING seems to throw something out of whack.
>
>Is this a clue? Or a red herring? If it's a real clue, where would you look?
>
>Ken Lewis' O2 sensor monitor shows the engine running extremely lean (low
>voltage from O2 sensor) when she's out of power. When she's running with
>full power, the monitor is either fluctuating back and forth near center or
>almost to the right side (running rich.)
>
>I've installed the capacitor in the AFM, checked/replaced all grounds,
>replaced O2 sensor and Temp II, checked and replaced all vacuum hoses,
>checked charcoal canister. New fuel injectors, distributor cap, plugs, and
>plug wires less than 5k miles ago.
>
>Thanks for any help here.
>
>
>
>