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Restricted air flow vs. O2 manipulation ??
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hoozadoctor Offline
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Post: #21
RE: Restricted air flow vs. O2 manipulation ??
Baracuda

I did not say the ECU didn't take reading from the other sensors, of cause the ECU listens to the other sensors, but I was not talking about the other sensors, I was talking about the oxygen sensor, and said under certain conditions the ECU did not go into closed loop mode.

The following is a exert from my vehicles original factory workshop manual.

"The HEGO sensor, located in the exhaust manifold, provides the ECU with a signal indicating whether the engine is running "rich" or "lean". The sensor has a built in heating element to bring the sensor to it's operating temperature quickly and to prevent it from dropping below it's operating temperature during periods of extended engine idle. The ECU uses the HEGO sensor signal in two ways

. It adjusts the amounts of fuel injected to matain the ari/fuel ratio at stoichiometry. This is know as the Closed Loop mode of operation.
. The ECU compares the amount of fuel that is being used in closed loop operation to the amount of fuel it predicts would be required if it had no HEGO information.

If there is a difference the ECU adjusts it's "Open Loop" (i.e.no feedback) predicted values to reflect the actual requirements of the engine as signaled by the HEGO sensor. These corrections are stored in the KAM, for use when the system next operates in the open loop mode. i.e. in cold drive conditions, wide open throttle operation or in lean cruise mode. This 'adaptive learning' enables the ECU, to tightly control the air/fuel ratio, in engines with slightly different characteristics, and to account for component wear and injector clogging during the the entire life of the engine"



Now I would have thought this proves what I was saying. It takes that long for the motor to warm up that if I am only going a couple of blocks it's still cold. cold drive conditions

Lean cruise, doesn't that mean anytime you take your foot of the accelerator.

Wide open throttle = any time you push your foot down on the pedal.

IF I am driving into town and I come to a set of lights as the lights change I push the pedal town .. open loop .. it is only down for a minute or so then I have to take the fot total off the pedal to cruise to a stop at the next set of lights so you see around town I don't think it gets a chance to go closed loop.

Doc
(This post was last modified: 07-26-2008 05:29 AM by hoozadoctor.)
07-26-2008 05:23 AM
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Atfab Offline
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Post: #22
RE: Restricted air flow vs. O2 manipulation ??
visek Wrote:
Atfab Wrote:Sounds to me like it's time to replace ALL you vacuum lines. They must be porus by now.

No...vac lines have been gone thru...have +20" hg at idle. Can't say for sure, but this might be the way it was setup OEM.

Well that sounds good, sorry but I'm not up on many imports, I just learn what I own.

Atfab
99 S-10 Pickup 2.2L auto, Std cab, Short bed, Alum cap
Stock, Ave. 25.5 MPH
07-26-2008 05:13 PM
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visek Offline
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Post: #23
RE: Restricted air flow vs. O2 manipulation ??
hoozadoctor Wrote:The ECU compares the amount of fuel that is being used in closed loop operation to the amount of fuel it predicts would be required if it had no HEGO information.

If there is a difference the ECU adjusts it's "Open Loop" (i.e.no feedback) predicted values to reflect the actual requirements of the engine as signaled by the HEGO sensor. These corrections are stored in the KAM, for use when the system next operates in the open loop mode.

If most ECUs work this way...i.e...a learning mode...then the lack of closed loop running with my 4x4 truck isn't that important...as long as the ECU sees an O2 cycling sample now and then??

I was under the impression that running in "open loop" was running with a rich default map...the system only leaning out when actually IN closed loop.

I've heard some claim that this ECU learning really doesn't take place though....with some vehicles...maybe earlier ones.
07-27-2008 03:37 AM
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hoozadoctor Offline
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Post: #24
RE: Restricted air flow vs. O2 manipulation ??
visek Wrote:
hoozadoctor Wrote:The ECU compares the amount of fuel that is being used in closed loop operation to the amount of fuel it predicts would be required if it had no HEGO information.

If there is a difference the ECU adjusts it's "Open Loop" (i.e.no feedback) predicted values to reflect the actual requirements of the engine as signaled by the HEGO sensor. These corrections are stored in the KAM, for use when the system next operates in the open loop mode.

If most ECUs work this way...i.e...a learning mode...then the lack of closed loop running with my 4x4 truck isn't that important...as long as the ECU sees an O2 cycling sample now and then??

I was under the impression that running in "open loop" was running with a rich default map...the system only leaning out when actually IN closed loop.

I've heard some claim that this ECU learning really doesn't take place though....with some vehicles...maybe earlier ones.

I am not sure what actually happens, as I said that was an exert from the original factory manual for my 1992 Ford Fairlane. I have heard all sorts of varying statements and to be honest most people don't seem to really know.
To complicate things even more my car is running on LPG and uses the Sprint gas system with an AEB 295 ECU. this unit only looks at the oxygen sensor, the tacho and the throttle sensor position.
Now AEB say there is actually 4 types of oxygen sensors.

1. Normal narrow band sensors having 1 2 3 or 4 wires.
2. Narrow band 3 wire resistor type oxgen sensor.
3. Wide band 5v direct (0 to 5v)
4. Wide band 5v inverted (5v to 0 )

Now the only obvious different between the narrow band 3 wire and the narrow band 3 wire resistor type is .

Whte = heater ground
Black = sensors signal
white = +12v heater

resistor type sensor

Black= signal 0 - 1v
Red = +12V heater
White = signal ground.

The problem is "how do I know which type of three wire sensor my car is meant to have" ?

if it is the resistor type then the EFIE is not going to work unless it it hooked up properly.

In the manual the good folk at AEB in Italy send me, it shows that if you have a normal sensor then the grey and violet wires have to be hooked up. On the other hand if it is the resistor type then only the violet one is connected and the grey one if isolated. Although they don't explain how you get a completed circuit without the grey wire, unless you don't actually cut the wire original wire but just join to it.
You can bet your life the gas fitter would not know what sensor i had or even care what I had.

doc
07-27-2008 04:54 AM
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11-19-2011 04:03 AM
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