P0128 code questions [Archive]

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JoshH

February 4th, 2011, 06:25 PM

My dad recently bought a 2006 Silverado with a 4.8 that has had some work done to it. It seems to have a lower temp thermostat in it (temp runs up to around 200 at idle, but drops to 160ish when you drive it), and it threw a P0128 (low coolant temp) code the other day. I quickly looked through the tune, but I couldn't find anything. Is there a way to change the parameters of this code (such as what temp it is looking for), or is shutting it off my only option?

Taz

February 4th, 2011, 08:12 PM

slows10

February 5th, 2011, 05:05 AM

What area of the country do you live in? But to answer your question you can shut the code off.

JoshH

February 5th, 2011, 09:16 AM

Hello Josh,

I would recommend replacing the thermostat with one that has a stock temperature range.

Take a look at this thread ….

http://forum.efilive.com/showthread.php?14382-160-Deg.-Stat-Fan-Settings

The thread discusses coolant temperature effect on engine longevity, power output, and emissions.

Regards,
TazAfter reading that thread, I may recommend that we put in a 180 degree t-stat.

What area of the country do you live in? But to answer your question you can shut the code off.
NE Texas

slows10

February 5th, 2011, 10:49 AM

You should be ok with a 180. I can see why you would want a 160 in texas in the summertime. But a 160 is to low in the winter there. 180 is good all year round. Wouldnt run a stock thermostat in the summer. This is all assuming that it has a 160 in it.

Taz

February 6th, 2011, 04:33 AM

Thermodynamics may sometimes end up being counterintuitive - especially when dealing with all 3 states of matter - solid (engine), liquid (coolant), and gas (atmosphere - that absorbs heat from the radiator).

The coolant needs to spend sufficient time in the radiator (heat exchanger) for the absorption of heat, from the liquid to the gas, to occur.

In a hot summer climate like Texas, a stock cooling system in good condition should have no problem reaching equilibrium with a 195F thermostat - that is, the ECT should be stable - probably just above 195F. On a 100F day, you would have a 95F temperature differential between the coolant and the atmosphere.

With a 160F thermostat in the above scenario, the temperature differential is reduced to 60F. A stock cooling system will not stabilize at 160F in this example - it would operate above 160F most (if not all) of the time.

A thermostat that remains fully open all of the time actually reduces cooling efficiency, as the coolant does not remain in the radiator long enough for an optimal exchange of heat to occur. A 195F thermostat, even in the summer months, will oscillate from open to closed (or nearly closed) and actually promotes cooling efficiency.

Some competition vehicles use a restrictor (rather than a thermostat) to allow the coolant to spend sufficient time in the radiator to achieve appropriate cooling. The orifice diameter of the restrictor is increased / decreased until the desired operating temperature is stabilized.

Regards,
Taz