Date: Thu, 2 Sep 2004 08:26:55 -0700
Reply-To: Craig Oda <craigoda@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Craig Oda <craigoda@GMAIL.COM>
Subject: Re: O2 sensor problems
In-Reply-To: <vanagon%2004090210165611@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=US-ASCII
Dennis,
thanks for the information. This is good to know. I'll make sure it
is running rich at wide open throttle. I forgot to check this last
night.
I've got a voltmeter mounted on my dash that consists of different
colored LEDs. I checked it with a digital voltmeter and I think that
each LED corresponded to 0.2 volts. The unit I bought was $40 from JC
Whitney. I thought this was relatively cheap when compared to the
time I was spending trying to adjust the fuel/air mixture by nose and
feel. Also, in my case, there was a range of problems affecting the
settings. Some of the problems were caused by me when I introduced
"fixes" into the system. Other problems were the result of lack of
knowledge on my part. The voltmeter (marketed as a fuel/air mixture
gauge) helped me, with my limited knowledge, to isolate the problem.
The JCW cheap (IMO) gauge is here:
http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/storeId-10101/p-70/c-10101/catalogId-10101
This book on fuel injection systems helped me to understand how the
general system works:
http://www.bentleypublishers.com/product.htm?code=gfib&stickyEmail=&ticket=none
I thought it had a much better coverage of the Bosch-derived fuel
injection systems in our vans.
I was adjusted the fuel/air mixture to be as lean as possible and
still keep idle steady. With your info, I'll also make sure that the
kick down switch at full throttle is enriching the system.
It occurred to me that maybe I can keep fiddling with the system to
get better fuel economy and save some money on my longer trips, money
I could use to regularly buy replacement parts for my van ;-)
I drove the van to work this morning and it's running great. Man, it
sure feels a lot different when there's not these little issues with
the van that I'm thinking about on the drive over. Weather in the SF
Bay area is also awesome today.
Regards,
Craig
On Thu, 2 Sep 2004 10:12:53 -0400, Dennis <guskersthecat@yahoo.com> wrote:
> One more thing to check....when you set the AFM statically at idle, you are
> adjusting the air/fuel curve throughout the engines rpm range. I would
> monitor the O2 sensor output under load at WOT (wide open throttle) and
> make sure you see .8V or better. As you probably already know, the O2
> sensor is not accurate beyond 14.7:1 air fuel ratio, and varies
> significantly with operating temperature. However, the reading of .8 or
> above will tell you that you are not running excessively lean under load.
> Your engine will be very unhappy with sustained lean operation. If you
> really want to monitor accurately you will need an air/fuel ratio meter
> combined with a wide band O2 sensor. These will very accurately measure
> air fuel ratios from 10:1 to 20:1. I'm not sure exactly on the vanagon,
> but the ECU probably goes open loop above 3500rpm, you should see the
> voltage go from oscillating around .45V to a steady .8V or better.
>
> I'm using this LCD device to monitor...
>
> http://www.lascarelectronics.com/PRODUCTS.CFM?STOCKNO=EMA%
> 201710&CFID=904178&CFTOKEN=88389902
>
> You may actually need to set your AFM a little rich at idle and let the ECU
> lean the mixture for you in closed loop operation.
>
