Chevy 4.3 L V-6 and Misbehaving Engine Control Unit

Do you have a test unit to check for error codes, some units use a LED test
lamp you can make yourself or get a tech to make for a six-pack. I'm from
down under so we have holdens instead but most manuals give you the details.

That gives you something to start with. Check all the connectors for
corrosion as they can give problems. A lot of car ones are changed with no
real fault.

Do you have any spares to try against, or is one available from a wreckers?
Is the spark timing controlled by the same unit or is it correct? One of my
cars, a 1989 XF Ford Falcon had a failure on a level crossing one wet rainy
night when water flooded the vent and wet the spark control box on the
passenger foot wall. Removing the circuit board and flooding with a can of
cheap brand water dispersing spray and draining before putting it back
together and driving it home. Testing the unit was done with a paperclip
shorting the connector for distributor setting allowing the spark to bypass
the flooded box.

A good switch to mount on your dash may be a test mode for the distributor
to give you raw spark with no advance, and another to turn on the fuel pump
feeding the extra nozzle in the inlet manifold giving you enough fuel for
80% power to get you home when your ecu dies.

You could set this up on your test bench to help isolate your problem.

Hope this helps,
Peter

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)

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)

BRBR

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

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"
| Publishing interesting material|
| on all aspects of alternative |
| engines and homebuilt aircraft.|
*------------------------------**----*
\(-o-)/ AIRCRAFT PROJECTS CO.
\___/ Manufacturing parts & pieces
/ \ for homebuilt aircraft,
0 0 TIG welding

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