Dave:
I have been running a dual EGT for a couple of years. The problem is
I'm getting very high EGT readings despite various tuning atempts,
needle changes, etc. I'm wondering if the readings might not be some
sort of artifact and am curious aboput w3hat an A/F monitor would tell
me about my mixture at different loads and RPM. I have holed pistons in
the past on my vintage race car-- which is why I put in the EGT gauges--
and so these temps have worried me, although the plugs look good and the
cars runs well.
-John
-----Original Message-----
From: Dave Carpenter [mailto:d.carpenter7@verizon.net]
Sent: Thursday, April 26, 2007 9:28 PM
To: Deikis, John G
Cc: spridgets@autox.team.net
Subject: Re: Air/fuel ratio monitors
I had both an A/F meter and an exhaust gas temp gauge on my turbo car
that I drag raced. I think the EGT gauge was probably the better of the
two. It had a small probe that you drill a hole into the pipe and
wrapped the hose clamp around the pipe. No leaks. Got it from an
airplane supply for about $85. It was quick to react to changes in
throttle setting and load. Richer=cooler, leaner=hotter.
Dave
Deikis, John G wrote:
> A question for you engineering types:
>
> I'm thinking about monitoring my A/F ratio to try to keep my car from
> holing pistons at inopportune moments. I've read up on the
limitations
> of using the cheap 3-wire O2 sensors and the relatively inexpensive
> LED-segment or needle swinging processor gauges (total cost maybe $50)
> vs. using a UEGO sensor and 0-to-1.0 volt digital read out display
> (total cost $250-500). Keeping in mind: no ECU to control, no turbo,
no
> fuel injection...just Mr. Skinner's wildly exotic array of metering
> needle profiles to choose from. The issue that I've read about
> repeatedly is that the older narrow-band sensor samples a more or less
> binary output and averages the voltage to light up the appropriate
> number of LEDs on the gauge. This is non-linear and so only tells you
> are you "on the rich side", "on the lean side", or stoichiometric.
It's
> also criticized for being too slow in its response. The UEGO-volt
meter
> set-up is more precise and can give you an actual A/F ratio to look at
> more or less instantaneously.
>
> So...since I don't have to control any electronic engine management
> systems, do I need to know more than "too lean", "too rich," "just
> right" to diagnose high exhaust gas temp issues or to select the best
> needle profile for a modified motor?
>
> I am trusting you guys with my money, so advise me wisely!
>
> -JohnD
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