Gents,
Based on my experiences with a 1994 Chevy Lumina Euro (with the "Hot" 3.4L),
it sounds like you have a vacuum leak. Unlike a carberator, most FI systems
will "just" add fuel to compensate for the extra air and then "try" to bring
the idle speed back to normal. I say "try" because of my Lumina. I was in an
accident which, along with >$6,000 of sheet metal damage, the EGR valve had
some carbon knocked loose (Chevy says) which resulted in an occasional
backfire, which blew the intake manifold gasket. The car showed no power
loss and no fuel consumption change. But driving it was scarry! Cold, it
took both feet on the brakes to stop it, and warm it would "idle" at 55 mph
in drive. And as you said, engine braking was non-existant. Replacing the
intake manifold gasket did solve the problem. The damaged gasket had about a
3/8" piece blown out of it, so it was not a large vacuum leak.
Food for thought. :-)
Larry
1976 TR7 fhc - died of poor build quality, awaiting resurection
1980 TR7 dhc - bought dead, being resurected
Galesburg, Michigan USA
Geographical Position: N 42deg 31min W 85deg 43min
----- Original Message -----
From: "James Howard" <jhoward@sextans.lowell.edu>
To: "Pieter Erasmus" <pietere@adsmr.co.za>
Cc: "Buick-Rover Mailing List" <buick-rover-v8@autox.team.net>;
<debrown@srpnet.com>; "Franc Buxton" <fab@dcs.warwick.ac.uk>
Sent: Wednesday, February 19, 2003 12:02 PM
Subject: Re: FW: 14 CUX EFI
Pieter Erasmus wrote:
The RR has almost no back
> compression when decellerating and when stopping, the revs would sit very
> high, at 1100, and only after a few seconds would start to drop. This is
> very annoying when changing gears at low RPM's because as I depress the
> clutch to change, the revs would go up and the brakes are working
overtime.
> To my mind it seems as if the stepper motor is not responding for some
> reason and/or the ECU does not cut off the fuel supply on overrun. I can
> just add the the stepper motor worked fine before fitting the road speed
> sensor. Any help/advice on this will be much appreciated.
Pieter, this sounds similar to the problem I have been having with my 89
Range Rover with the 3.9 engine. Everything on mine is stock. It is a
little less annoying for me because I have an automatic, but I have to
hold my foot on the brake pedal a little harder when stopped at traffic
lights. I have tried two different idle air control valves and reset
the base idle and the ECU many times.
The only other weird thing is while the idle is way too high when the
engine is warm, when it is cold, it almost stalls. If it does stall,
the only way it will restart is if I reset the ECU.
James Howard
Flagstaff, Arizona, USA
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