Date: Sat, 19 May 2001 14:59:55 EDT
Reply-To: Brewhogger@aol.com
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike Vanderzanden <Brewhogger@aol.com>
Subject: Still running rich
Content-Type: multipart/alternative;
Still have a major rich running problem. My original description of the
problem is attached. Since that posting, I have tested the Temp II sensor
over its entire operating range and it falls nicely in the curve shown in
Bentley. Also went through all the other resistance checks shown in Bently
(mostly at the ECU connector plug, which is where I also took my Temp II
sensor resistance measurements). Everything is right on the money. I have
triple (at least) checked my connections and grounds. I checked for any
blockage on the fresh air intake. No restrictions. Revving the egine in
neutral yields thick black smoke. I observed that blipping the thottle
quickly but to wide open throttle causes the AFM to snap fully open, of
course, momentarily. Anybody ever take notice of this?
I have been told of other cases where all tests of the fuel injection system
are positive and the problem being cured by replacement of the F/I wiring
harness. Has anyone ever heard of or experienced this? VERY expensive thing
to replace without being positive that its the culprit.
Will have the exhaust gas analyzed this week in hope that it will point to
the problem. Hopes for long-planned Memorial Day weekend vacation are slowly
dieing.....
ORIGINAL MESSAGE
My '84 GL is running very rich. Mileage is 10 mpg at best. Blows thick
black smoke when loaded (i.e. under acceleration). Down on power in general.
Idle speed is eratic but does not stall (yet?). Been driving her daily
under these conditions for months.
Things I've done:
Checked/adjusted ignition timing. Was retarded. Now correct (at least
close). Made no difference.
Measured fuel pressure: 36 psi at idle with vacuum connected. 42 psi (at
any engine speed) with vacuum line disconnected. If increase engine speed
(with vac. connected), fuel pressure decreases (yes, DECREASES) to about 32
psi.
Swapped out the air flow meter for another (used but serviceable) one. No
significant change in behavior.
Examined the spark plugs. All four were equally black and sooty.
I also cleaned (with electrical contact cleaner and, in case of ground
connections, emery cloth) and exercised all of the connections I could find
on the engine management wiring harness.
I plan to measure the Temp. II sensor resistance tomorrow.
An observation: I noticed that the position of the AFM wiper is about 20 or
25% "open" with the engine idling. This seemed surprisingly high to me, but
I have no reference. Could be normal. Anyone have any input? I also
adjusted the CO adjustment screw (under the plug on the AFM housing) and this
had no real effect on the position of the AFM wiper. Had a small effect on
the quality of the idle.
I did a mechanical rebuild on this engine two years ago (did not do anything
to the fuel injection/engine management system). It ran fine and gave me 19+
mpg overall fuel mileage until this problem cropped up a couple months ago.
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