Date: Sat, 28 Apr 2001 12:20:51 -0800
Reply-To: Mark Keller <kelphoto@islandnet.com>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Keller <kelphoto@islandnet.com>
Subject: Re: Fuel Injection Adjustment
Content-Type: text/plain; charset=us-ascii
Steve,
Well in terms of the ground being a culprit you have to begin with
assurance that the grounds have been inspected, and are good. I cover
this in a post, but basically, I used Tarn-x to chemically clean every
connection, ground or otherwise, I could, and coated the connector with
Ox-Gard. Additionally there is a Service bulletin in effect to add a
ground strap, NAPA $4.00 16" long, to the AFM and the engine block.
Other service bulletins deal with weak connectors, so insuring that the
all of the actual harness connectors are snug is another service to do.
As to the "slow warm up" I've notice that my OEM Temp II sensor put the
system into closed loop, faster that the aftermarket one I'm using, by a
minute or so. Perhaps the internal material's specific heat transfers
are different. I've felt that this could contribute fuel economy more on
Vanagons, because the engine seems to cool off when shut off for a short
time, requiring the Temp II to run open loop again. Again, small points
to make, but I believe to have a cumulative significant impact.
I'm sorry I wasn't clear about low vacuum and high fuel pressure, were
dealing with small degrees here. I meant that if your engine timing or
internal wear was contributing to an overall lower than programed vacuum
supply to the fuel pressure regulator, say 10" at idle as opposed to 12"
at idle, then pull of vacuum motor on the fuel pressure regulator would
not be able to overcome the spring pressure on the valve seat and thus a
higher fuel pressure at idle would occur. How much?, does it matter?, I
don't really know, but low vacuum can occur with out having leak. If
all else fails, check that you have a good vacuum at idle.
By the way, my vacuum gauge is installed permanently and have noticed an
improvement from 10" to 12" and no "rattle" that I attribute to the use
of a Submicronic Oil filter system, installed at 50K miles now over 100k
. 30-50 microns being the "published" range of free flow oil filters
that come OEM. The Gulf Coast system tees off the oil pressure sender
supply, and filters to less than 1 micron. This has been on about two
and half years, 55k miles, 15k of hard towing service and the engine
seems so silky smooth.
Again it sounds like your going after every possible improvement, so
that's why I've included the finer points of tuning the system.
Sincerely,
Mark Keller
91 Carat "Lazarus"
Cowichan Bay, BC
Steve Blackham wrote:
>
> Thanks Mark
>
> I appreciate your info. Vacumn leaks would cause a lean situation.
> I'm too rich. Not enough air getting to the combustion chamber or to
> much fuel. I think I'll start with the AFM and clean the idle bypass
> passage first. Then check the exhaust system for small leaks. They
> cause the O2 system to think its to lean and richen the mixture. A
> small enough leak would show up at idle and the pressure of a full
> exhaust would eliminate the leaking in air at a throttle.
>
> The Temp 2 sensor is fairly new but merits a check as I think its
> still to long for the engine to warm up and go to the O2 cycle.
>
> I know the cat is a straight tube but it shouldn't effect the
> capability of getting to factory idle settings which are usually
> taken ahead of the cat.
>
> Last, because of the labor required, I'll check the individual
> injectors for flow and leaks.
>
> Could this be a ground problem by chance. Normally I would think
> that would cause a lean situation (no input to actualte fuel) but I
> don't know?
>
> Thanks
> Steve
>
> >Hi Steve,
> >
> >I also wanted to mention a couple of other little variables that could
> >influence your readings.
> >
> >The rubber seal at the dipstick and consider adding a hose clamp where
> >the plastic oil filler neck slips over the metal oil filler tube- it's
> >junction is right in them middle of the alternator belt's path. It
> >seems that these two items have a tendency to allow "false air" to enter
> >the system, that why they are sealed. The oil filler is just a friction
> >fit over a raised lip in the steel pipe. Since they are source of
> >additional un-metered air their effect is a lean idle.
> >
> >Also on the emissions side of things, crankcase oil can have gas in it
> >which also would be
> >a false reading point. I think this last point get's overlooked, but it
> >seems I read a considerable number factors that need to be address, but
> >basically baby the oil until your done testing. Avoid lots of cold
> >starts without letting the engine oil recover from the rich mixture, the
> >testing instructions in your CO meter may address this too. An oil
> >change along the way could give your more accurate readings too.
> >Sincerely,
> >
> >Mark Keller
> >91 Carat
> >Cowichan Bay, BC
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