Chevy 4.3 L V-6 and Misbehaving Engine Control Unit

Barry,

You are going to get some advise that will possibly get the computer
controller working correctly, for the most part, on your engine. Let's
see if I can point out some things that would make you go a different
route.

Regardless of the dependability of these computers on automobiles, and I
am going to use a cliché, you can't pull over to the side of the road
when the system quits. Hundreds and hundreds of Subarus have been
installed and flown with the automotive electronic controls. The failure
rate of these installations has been a part of the problem with the
reduced availability of insurance for auto-conversions.

THe first problem is figuring out the sensors and settings just as you
are finding right now. The next problem is redundancy. As dependable as
you may think this computer control is, they are susceptible to
vibration and in a few cases RF transmissions. There needs to be full
redundancy with a complete second computer that can be switched into
operation if a failure occurs on the primary system.

One of the advantages of an automotive engine conversion has been
simplicity; something that can be repaired in the boonies. Mechanical
fuel injection can meet that requirement but is usually a high
maintenance setup. Carbs have been the choice because they have a
century's worth of refinement and by electronic fuel injection standards
are dirt simple. There are few places in the world where you cannot get
parts for a Holley.

If your EFI is a throttle body type you will find that bolting on a
mechanically operated unit like the Ellison "throttle body" retains the
performance and simplifies operation. If your EFI is a direct injection
setup you can find an aftermarket controller available from race car
catalogs that is easier to back up with a second unit for redundancy.

If you retain the OEM automotive computer, the minimum safe set up would
be to obtain a second unit from a salvage yard and install it to allow
easy switching when the primary unit fails. Salvage yard prices for the
engine control computers is is usually in the range of $200 versus $2000
from the dealer.

Backup should include a stand by coil and other parts of the ignition
system depending on how inclusive are the components on the control
computer.

Barry Palmer wrote:

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)

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
Homebuilt Aircraft Newsletter"
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