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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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