I got to looking at why the power wire works. And came up with a question. What temperature does the intake air need to be for the PCM to go into it's normal closed loop configuration?
WOT and a cold engine condition automatically goes to open loop and fattens up the injectors until all the input sensors are up to normal temp. I think everyone believes the power wire install works, but at what cost? Is the engine management being kept in the open loop configuration?
Just thinking out loud.

 

I'm not sure at what temp you get closed loop, but I do know that with the power wire (or a simple 180* thermostat for that matter) you stay in open loop all the time, giving you a richer a/f ratio...

 

Running open loop all of the time certainly can't be good for gas mileage.

 

Hammer I didnt know that about the tstat doing that. Are you sure?

 

According to the performance shop that advised me to goto a 180* when my CAI, LT Headers and SC set to performance had me pretty leaned out, the 180* would keep me from entering closed loop, richening the mixture all the time. Air-fuel ratio since the addition of my 180* would bear that out.

If you think about it, it is no different than a power wire. The PW "fools" the PCM to think it is running 15* cooler. A 180* thermostat IS 15* cooler...

 

Intake air temp has nothing to do with open or closed loop. That is based off of engine temp.

If it was related, our friends in the north would be screwed no matter how long they let their trucks warm up.

 

snow-geden.

 

Frog,
I just took this from the manual. It also shows the sensor to be the one located on the air inlet.

5.7L V-8

The intake manifold air temperature (IAT) sensor
is installed into the front of the intake manifold air
box plenum (Fig. 27).

(

ENGINE WARM-UP MODE

This is an Open Loop mode. During engine warmup,
the PCM receives inputs from:

²

²

²

²

²

²

²

²

² Air conditioning request signal (if equipped)

CRUISE MODE

When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the PCM
receives inputs from:

²

Air conditioning select signal (if equipped)

²

Air conditioning request signal (if equipped)

²

Battery voltage

²

Engine coolant temperature sensor

²

Crankshaft position sensor

²

Intake manifold air temperature sensor

²

Manifold absolute pressure (MAP) sensor

²

Throttle position sensor (TPS)

²

Camshaft position sensor signal

²

Park/neutral switch (gear indicator signal—auto.
trans. only)

²

Oxygen (O2S) sensors
Based on these inputs, the following occurs:

²

Voltage is applied to the fuel injectors with the

ASD relay via the PCM. The PCM will then adjust

the injector pulse width by turning the ground circuit
to each individual injector on and off.

²

The PCM monitors the O2S sensor input and
adjusts air-fuel ratio. It also adjusts engine idle
speed through the idle air control (IAC) motor.

²

The PCM adjusts ignition timing by turning the
ground path to the coil(s) on and off.

²

The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.

ACCELERATION MODE

This is an Open Loop mode. The PCM recognizes
an abrupt increase in throttle position or MAP pressure
as a demand for increased engine output and
vehicle acceleration. The PCM increases injector

pulse width in response to increased throttle opening.

 

Agreed! We would be screwed! :P

 

Ok, I'll make a very clear statement here. "intake manifold air temperature" is one of the input signals that determines if the engine is running in open/closed loop configuration.
I believe a 180 thermostat and /or "power wire" causes the PCM to run open loop creating a wider injector pulse. Two different sensors, but both provide input to the PCM. There is nothing really wrong with this configuration other than open loop doesn't optimize fuel effiency.