Different engine, but very similar symptoms on mine one time on a long hiway
trip. I stopped, disconnected the O2 sensor, and it ran just fine from there
on. I reconnected it a week later and it's operated just fine since, but
that was the variable that made the difference when I lost power at speed,
and the more I pressed the accelerator, the slower it wanted to go, until
the O2 disconnect.

bob

----- Original Message -----
From: "Marc Perdue" <marcperdue@ADELPHIA.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, February 14, 2005 10:37 PM
Subject: Boston Bob Big Valve Update? Not really... (LONG)

> Hi y'all,
>
> I've been away for quite a while, mostly working on my new daily driver,
> an '85 BMW 528e, another phenomenal German driving experience, and
> attending to my daily life, three full-time jobs in itself.
>
> Anyhoo, some of you may recall my trials from last summer, when my
> engine blew up just after getting an oil change at the dealership here
> in Charlottesville, VA.  While my traumatic experience couldn't be
> directly attributable to any doings on the part of the dealer, you can
> rest assured that I will never go back there . . . except maybe to buy
> parts I can't get anywhere else.  I wound up buying a big valve engine
> from Boston Bob Donalds, who was a true gentleman to work with, a man of
> his word and a total straight-shooter.  I had the van, an '87 Westfalia
> w/ AT, towed down to Salem, VA, where the engine was installed by Mark
> Deering of Salem Imports.  Mark was also a pleasure to work with and has
> an encyclopedic knowledge of Vanagons and other transporters.  He had
> lots of good suggestions of things to do to properly maintain my new
> engine, as did Bob.
>
> Somewhere in this mix of great people, product and service, however,
> something didn't quite click right and I'm still trying to figure out
> exactly where the problem is.  When I went down to pick up the van, I
> was surprised at the sound of the new engine.  This may be something to
> do with the big valves, but it sounded kind of burbly (technical term)
> to me.  Not knowing what to expect from the big valve engine, I figured
> this must be normal, so I headed off down the road.  I hadn't gotten two
> blocks when I went to accelerate from a stop and had almost no power.  I
> had had this kind of problem with the old engine and thought it would be
> gone with the new one.  After all, much had been replaced, with a
> complete tune-up, new plugs, rotor, distributor cap, plug wires, other
> such things.  The fuel injectors were not replaced however; neither was
> the AFM.  I had, in the previous year or so, replaced the ECU, cleaned
> the idle stabilizer valve, and replaced the idle control module.
>
> I turned around and returned to Salem Imports, where one of Mark's
> technicians adjusted something on the AFM and that improved the idle.  I
> drove home with no further incident.  I drove the van no faster than 55
> mph for the first 1,000 miles per Bob's recommendations (and that was no
> mean feat, let me tell you), and changed the oil at the recommended
> intervals.  The new engine has never really had much power, not even as
> much as my old engine, but I attributed that to the fact that the engine
> was new and the valves probably hadn't seated properly yet.  One thing
> that was most surprising to me is the drop in torque when the van
> shifted from second to third.  I found myself downshifting more often
> than I had in the past.  One surprising benefit was that I was now
> getting about 17 mpg on the highway versus the 15 I had been used to.
> The low power problem did not re-occur . . . for a while.  When summer
> ended and the temperatures dropped down into the 60s and 70s, the
> problem came back.  So did the low mileage, down to about 14 mpg now.
> The typical scenario, at first, was like this: I would drive to work, 15
> miles, and the van would run fine.  At the end of the work day, I would
> start up the van and within a few minutes it would lose power, as if it
> were flooded.  If I kept my foot in the pedal, the engine would run
> progressively slower and then stall.  If I pumped the pedal, the power
> might come back . . . or not.  Sometimes I'd have to pull over, if there
> were space to do so, and turn the engine off and back on.  It would
> usually start back up and run fine after that.  When the weather got
> colder, the problem seemed to occur less, but I can't say for sure
> because the van has mostly been parked and I've been driving my BMW
> more.  Well, a few weeks ago I had to park the BMW because of a problem
> with the rear axle and I've been driving the van every day since.  The
> problem does seem to be worse when the temperature is between 40 and 70
> degrees.  Now it sometimes loses power when I've only gotten a few miles
> from home on my way to work.  Sometimes, when coming home, I've gotten
> ten miles before the problem shows up, usually when I'm going up a hill
> and need to downshift to accelerate up the hill.
>
> This has been very frustrating to me, not to mention dangerous, and I'm
> trying like mad to get my BMW back on the road so I can figure out
> what's going on with the van and get it fixed before festival season
> starts back up.  Is any of this directly attributable to the new big
> valve engine?  I don't think so.  My theory is that I've had a bad AFM
> all along and this is messing with the idle and causing the engine to
> run rich.  I also think that Mark, or one of his technicians, didn't
> trust Bob's instructions regarding adjusting the valves and that they
> didn't set the valves correctly.  I think that, as a result, the valves
> are probably not closing all the way and this is causing the engine to
> run even more richly and to not have as much power as I feel that it
> should.  The only good thing I can say at this point is that I haven't
> driven the van much since the new engine was put in and maybe, just
> maybe, no damage has been done.
>
> I'm hoping that maybe you all can give me some feedback on my theories
> and how I might go about troubleshooting these problems.  I haven't
> adjusted valve lash on an engine in a LONG time, but I no longer trust
> any of the local shops to do this, so I'm up for doing this myself.  I
> might need some guidance in this though.
>
> Thanks for bearing with me and this long post.  I hope you have all been
> well and had a great Valentine's Day.
> Marc Perdue
>