Date: Mon, 15 Mar 1999 14:11:32 -0500
Reply-To: "Anthony L. Mourkas" <frankenstein@TELPLUS.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Anthony L. Mourkas" <frankenstein@TELPLUS.NET>
Subject: 2.1L Extremely Rough Running
Content-Type: text/plain; charset="US-ASCII"
My 87 Syncro has been running a little rough lately, overall lack of
power, poor gas mileage, and occasionally stumbling at low RPM's clearing
up at 2,700 RPM's or so.
On Saturday afternoon in the middle of a trip to obtain parts from the
local VW Dealer(!) for my wife's Jetta, the Syncro started running really
rough on I95. The fuel level was getting down to the red mark, so I
pulled off into the nearest service station and threw in 10 bucks worth
of gas. No stumbling/bucking/hesitation for a few minutes until I got
back on the highway when I again encountered severe drivability problems.
Made it to the Dealer and got my parts, checked out some new Audis, and
left for home. Van ran great, seemed better than usual(?), then the
stumbling/bucking/hesitation/misfiring returned. No power, hard to get
over 35mph, all sorts of hestitations and misfires. Pulled over,
switched off, waited a few moments, started up, ran fine for a couple of
minutes, then the problems returned. This was the pattern all the way
home, eventually I resorted to switching off the ignition and starting
right back up again. Worked every time - for about two minutes of clean
running - then the demons returned. I got home, parked the Syncro, and
fixed my wife's Jetta.
Yesterday, I turned my attention back to the Syncro for some diagnostic
testing. Here are my test results:
Key on Cold Hot
Test (Volts) Eng off Idle Idle WOT
Air Temp Sensor 1.88 1.92 1.83 1.59
Coolant Temp Sensor 1.93 1.83 .18 .16
Oxygen Sensor 7.5 4.6 .90
AFM .19 1.82 1.42 3.5(approx)
Test Notes:
- Ambient air temperature = 45 degrees Fahrenheit
- AFM voltage readings were smoothly rising throughout RPM range.
- Oxygen sensor readings unavailable at wide open throttle. By the time
I tried to perform this test the motor was bucking/missing/backfiring so
bad it wouldn't turn that fast!
- Black smoke and deposits emitted when revving.
- Idle consistent at 850RPM or so until onset of symptoms, then drops to
a lopey 650RPM.
- I noticed some backfiring into the AFM boot.
- Inspection of spark plugs a month ago revealed black deposits, not
greasy, which I attributed to rich mixture.
- Oxygen sensor readings noted above were slowly and constantly falling
in engine off and cold idle conditions, and fluctuating slightly around
.90v at warm idle.
- Oxygen sensor readings were constant 8.86v at ECU ( via Digitool) with
oxygen sensor disconnected.
- Disconnecting the oxygen sensor made no improvement in the drivability
of the van.
- My coolant temperature gauge works sometimes, not at others, can not
name a corresponding factor or condition. (a preexisting condition)
Any help would be greatly appreciated in diagnosing this problem as the
van is essentially undrivable. I am particularly curious about the
oxygen sensor voltage readings that seem way out of line with what I have
seen mentioned in various posts. Certainly nowhere near the .5 volt
standard.
Comments, suggestions, and incantations are welcome.....
Thanks,
Tony
Anthony L. Mourkas
Hampden, Maine, USA
1984 Vanagon Westfalia
1987 Vanagon GL Syncro
1991 Jetta Eco Diesel
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