I am doing this for another person remotely. It turns out that he never
installed an O2 sensor to start with. I think the engine may be too old for
transmission inputs, but this is an avenue we will have to investigate. Thank
you all, but there may be a round 2 after the O2 sensor gets installed, and
transmission input possibility gets explored. Those race car-hot rod setups
can be pricey, so I am trying to avoid that, along with redundance, since this
is a surface vehicle without the high dollar costs of an aircraft. (although
it can and they do get into areas well away from civilization where a breakdown
will be very embarrasing and inconvenient.)

Subject: Chevy 4.3 L V-6 and Misbehaving Engine Control Unit
From: "Keith Olivier"
Date: Sun, Aug 17, 2003 1:57 PM
Message-id:

Barry, are you running on leaded gas ? If so, why ? Modern engines are
profoundly sensitive to stuck valves with leaded fuel.

I don't think you will get the ECU to work without at least 1 oxygen sensor.
Where you mount it is not important as long as you are absolutely sure that
the exhaust system is absolutely gas tight until at least 200mm downstream
of the sensor. If you have leaks, it will add O2 and force the mixture
richer (same reason why manifolds and catalysts have to be gas tight).
There are strong pulsations in the first part of the exhaust system, so
there are standing waves which cane reach pressures below atmosphere in
certain positions which change with the RPM. This is what causes air to be
sucked in to the exhaust.

If you need to simulate particular voltage levels, the best way is to use a
resistor or one of the 3 legged regulators to the positive supply. It will
generally live forever and not be forgotten about like a battery. Best bet
would be to build a "black box" which produces outputs for all the inputs
which you require. You have pots to set up all the individual voltages (and
keep a nice log of what you did for each and why...) and when youre done you
seal it up and forget it.

I suspect that the ECU definitely needs some sort of input from the
transmission if is was an automatic (very likely in the US), since there are
shift modes (upshifts, downshifts etc) programmed with co-ordinated throttle
actuation. It needs to think that you are in top gear and the switch at
full throttle deflection (which triggers downshift) needs to be open/closed
deending on how it is supposed to be set up. An ECU from a manual
transmission model would be much simpler to impliment.

Regards
Keith


"Barry Palmer" schrieb im Newsbeitrag
...
The setup has an O2 sensor, and I suspect it is polluted.

I do not have the error codes but can look them up after reading them. I
suspect the 02 sensor. Has anyone noted the sensitivity of the 02 sensor
when
mounting it in the exhaust pipe away from the engine as opposed to near or
on
the exhaust manifold?

Also, I suspect the signal voltage is very low, perhaps 1-2 volts. Has
anyone
tried to fake the ECU out with a alkaline, ni-cad or nickel metal hydride
battery cell applied to the 02 sensor wires?

The engine is on a sev, or hovercraft, pushing two belt driven 2 blade
Power
Fin propellers and a pair of 30 inch 12 bladed fans, all at once, and the
load
characteristic is rpm^3 = power, much different from an auto.

Subject: Chevy 4.3 L V-6 and Misbehaving Engine Control Unit
From: "Keith Olivier"
Date: Sun, Aug 17, 2003 3:46 AM
Message-id:

Hi Barry

I'm not an expert on ECU's, but have had to find ways to get them to
behave
when running engines on a dyno without many of the bits that are fitted in
the vehicle.

If you definitely have no O2 sensors, you would need to rig the inputs
(the
second sensor) to indicate a Lambda 1 condition, since otherwise the ECU
may
continuously cycle the mixture to try to find the right operating point.
I'm
not sure it would be possible to achieve success without at least 1 sensor
(closest to the manifold) since this sensor drives the basic mixture
setting
and the second the fine tuning The next problem is that once it finds a
"failure", it may switch into a "basic strategy" mode, which may reduce
the
performance significantly. If this is the case you may need to have a
dealer reset the ECU, then fix all the signal level issues before powering
it up again.

The best way to avoid these issues is to look at the signal levels of all
the inputs in the car under normal driving conditions (engine hot,
transmission in drive etc), then simulate these signal conditions at all
the
inputs that are not used in your application. You should also check if
you
are getting plausible signals from the accessories which you are using
(massflowmeter, crankshaft & camshaft sensors at the very least)

Be aware that full throttle will always result in a rich mixture. If you
back off just slightly from full throttle the mixture will be leaner
without a significant power reduction.

Best of luck
Keith
"Barry Palmer" schrieb im Newsbeitrag
...
Anyone out there work with EFI engines. I have a 4.3L Chevy V-6 that
was
removed from a car with its ECU and when operated with a propeller load
does
not want to get above 1500rpm, (should go to 4200rpm) while it hunts up
and
down for the correct mixture ratio. The transmission is removed, if
there
are
any sensors on it they are caput. I hate to just blame it on the O2
sensor.

Anyone have any suggestions as to newsgroups in the hot rod area that
work
with the ECU's?

Barry Palmer, for Sevtec (http://members.aol.com/sevtec/sev/skmr.html)




Barry Palmer, for A
HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec

BRBR

Barry Palmer, for A
HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A