Date: Mon, 10 Nov 1997 17:24:32 +0000
Reply-To: Harry Yates <hyates@BCIT.BC.CA>
Sender: Vanagon mailing list <Vanagon@Gerry.SDSC.EDU>
From: Harry Yates <hyates@BCIT.BC.CA>
Subject: '90 engine bucking & smog test (long)
Hello All. Our '90 Syncro Westy behaved rather strangely on Saturday
on the way to the AirScare emissions testing facility, and I thought
I would share my experience. First the problem and then the
emissions results following:
About 2 km from home (engine just warming up) the engine went into
violent bucking between 2000 and 3000 rpm. There was no way I could
drive in this rpm range, in any gear. The van really got pounded by
this event with all the bucking. My wife first thought I was doing
it as a joke, but I wasn't laughing. We drove for about 30 minutes
to the testing facility, even on the highway, and same thing.
Everything was fine below 2000 and above 3000 rpm. In between, and
it was not happy at all with the bucking quite severe at one stage.
When we arrived the testing facility, I pulled over just before the
entrance and checked out the engine compartment. All connections
looked tight, etc. Nothing obvious to me. Plugs and wires were
tight, etc. I tried to get the van to run up between 2000 and 3000
rpm again, and no way. I would slowly increase rpm to 2000, and
still giving more throttle, and more throttle, and more throttle, and
then suddenly the rpm's would go from 2000 rpm to over 3700
rpm. Same thing coming down the scale. I would slowly decrease the
throttle from 3700 and when I hit 3000 rpm it would drop to 2000 rpm.
Full throttle was fine, idle was fine. We had to turn back as there
was no way we could get the vehicle tested in this state. It was
clear, sunny, dry, about 5C outside.
So, after 30 minutes going back home, it suddenly went back to
normal. Like, huh?? So, off we go back to the testing station
again. The van ran flawlessly. Any ideas here??
The van has 145000 km (90000 miles) on it, with 10000 km (6000 miles)
on Bosch Platinum plugs that I put in this spring. I still have the
original plug wires, and oxygen sensor. Distributor cap and rotor
also fresh in the spring with Bosch parts.
The van passed emissions, but the results are not normal for this
van.
Date Odometer (HC) (CO)
1993 099000 km (61508 mi) 5.00 ppm 0.00%
1994 111000 km (68964 mi) 8.00 0.00
1995 126000 km (78284 mi) 3.00 0.00
1996 134000 km (83254 mi) 18.00 0.00
1997 145000 km (90088 mi) 102.00 0.04
Hope all this lines up after all the juggling I had to do here :(
Maximum allowable results are 240 ppm for HC and 2.00% for CO. Note
that this is a Syncro, so there are no NOX tests. The above results
are for high idle tests only taken at 2500 rpm.
Does anybody have any ideas as what has caused the sudden jump in HC?
Could ignition wires actually cause this to happen? BTW, I've been
running on Bosch Platinums for 3 years now, and my smog results have
been excellent with these plugs.
I had the engine basics done in May of this year at 135000 km, so I'm
sure they couldn't have drifted off so much in just 10000 km.
Any feedback would be greatly appreciated.
Thanks,
Harry.
---------------------------------------------------------
Harry Yates, Langley, BC, Canada
'90 Syncro Westfalia www: http://syncro.cr.bcit.bc.ca/hyates
'87 Golf Diesel email: hyates@bcit.bc.ca
'91 Miata (Millie)
