bucking above 1.1 bar, max boost 1.3

Chris Covington malth at umich.edu
Mon Feb 25 09:15:40 EST 2002

Kneale, et al,

My fuel pump was replaced about 10K miles ago.

'91 200q20v

On Mon, 25 Feb 2002, Kneale Brownson wrote:

> My bet's on the fuel pump.
> At 10:42 PM 02/24/2002 -0500, Chris Covington wrote:
> >I took a nice trip this weekend to Burlington, VT to visit a friend and
> >give the 200 a nice 200 mile each-way trip.  No problems on the way there,
> >in fact I even got 23.8MPG.  On the way back, merging/passing a Volvo
> >after the I87 onramp in 3rd gear, at around 5K RPMs at WOT the 200
> >seriously bucked and I let off the throttle.  The engine ran fine as long
> >as it didn't get over 1.0 bar, without any missing / roughness, then it
> >would buck really hard as if it were backing off or intentionally
> >preventing high boost.  I let off boost for awhile then I then pulled over
> >to get gas and check the intercooler hoses, and everything seemed fine.
> >After the fill-up on 87 the 200 seemed normal again - I still got 1.7-1.8
> >but I didn't push it too hard because I was more concerned with getting
> >back.
> >
> >When I got home I tested it again and basically now get serious bucking
> >in any gear starting when boost gets over 1.0 bar, with 1.3 being the
> >highest I can get.  I thought it might've been the WOT switch because it
> >seemed to only do it at full throttle, but under further examination it
> >will buck at 3/4 throttle too, or in any other situation in which it goes
> >above 1.0 bar.  So it seems to be a boost issue (or the witholding of) of
> >some kind.  All my hoses are either new / in good shape.
> >Is this the WGFV?  Something else?

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