Date:         Tue, 22 Sep 1998 14:18:00 -0400
Reply-To:     Terrence Tickle <tickle@ENG.MC.XEROX.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Terrence Tickle <tickle@ENG.MC.XEROX.COM>
Subject:      83 h20 fuel injection problem
Comments: To: Vanagon@vanagon.com

Hi,

I have an 1983 Vanagon.  The first year for the water cooled engine.  1.9 liter, with Bosch Digijet fuel injection, and automatic transmission.  140,000 miles.

This longstanding problem which has persisted between motors manifests itself as follows:
1) richness - black exhaust when accelerating and carboned up sparkplugs (all sparkplugs look the same)
2) runs very rough at several speeds:
                at 25 miles/hour (sometimes)
                at 40-50 miles/hour (almost always)
   (although sometimes this symptom is not present)

Here is the recent history:
1) new motor (from VW, not rebuilt)
2) new plugs/wires/distr. cap/rotor
3) ground connections have been checked, cleaned, repaired
4) new air box (measures airflow and air temp)
5) new air filter and fuel filter
6) cleaned and sealed gas tank
7) new engine temperature sensor

**** Static checks: ****
1) continuity checked all wiring from airbox to Fuel Injection Control
2) continuity checked all remaining connections to Fuel Injection Control
3) bench checked the aux air regulator
4) checked out throttle position switches back to Fuel Injection Control

**** Dynamic checks: (I borrowed a scope from work this w/e) ****

[The "stumbling" that occurs at 25 and 40-50 will occur sometimes when racing engine at mid-range rpms.  I made most of these measurements while the stumbling was occurring.]

1) Ignition coil signal (from pin 1 of the Ignition Control) looked good during stumbling condition.
2) Timing signal from Ignition Control (pin 7) to Fuel Injection Control (pin 1) looked good during stumbling condition.
3) Fuel pressure measured OK.
4) Fuel injector timing - looked about as expected EXCEPT when stumbling occurs.  During stumbling the injector pulses stop (no fuel) for 150 - 200 millisec or more.
5) Oxygen sensor - most of the time the sensor output measures around 800 millvolts (rich).  However, ONCE when racing the engine, I found the O2 sensor output switching between 800 millivolts and 200 millivolts with a period of 400 milliseconds (200 millseconds at 800 millivolts and 200 milliseconds at 200 millivolts).  After racing the engine the O2 sensor output will drop down to 100-200 millivolts (lean) for the time that the injectors shutdown (following the idle switch actuation).
6) Checked out the engine temperature sensor with the engine hot.

Perhaps that is enough for now ... I would value any suggestions that may lead to a solution!  My wife likes the Vanagon better than our much newer, Extended Ford Aerostar Wagon.

Thanks a lot,
Terry Tickle
tickle@eng.mc.xerox.com