p0128 Engine temp below thermostat temperature/ strange O2 sensor values

[nonickatall]

Many replacement radiators are MISSING the restrictive fitting, which will cause the flow to be too great, preventing the engine from reaching the correct temperature. I am curious, but I don’t believe OP mentioned whether this had been replaced recently, or for how long he’s had this problem.

ETA: Re-reading the original post, it sounds like he’s always thought the engine wasn’t getting to normal operating temperature, so I’m guessing that rad was replaced before he acquired the rig.

I have the problem since the beginning and i don't now if the cooler was replaced by the former owner..

 

[Fless]

A restriction in the radiator would cause the vehicle to overheat when driven, maybe not so much at idle in a driveway. The temperature switch turns on and off the electric fans and does nothing but that. The Engine Temp Sensor tells the Instrument Cluster Temp Gauge the coolant temp as well as is also an input into the PCM for engine control. I never assume the part in the box matches the part number on the outside of the box. I just fail to see how anything other than incorrect thermostat or at the very least a stuck open thermostat would cause an engine to never get up to fully normal operating temp. Your radiator didnt become 400%+ efficient by becoming restricted or clogged up.

I agree that a restriction in the radiator could cause overheating. But, to be clear, the necessary restriction I mentioned is -- or should be -- in the small hose to the surge tank. As @Sam Harris mentioned, too much flow in that hose will cause the engine temp to be low.

This short thread might help:

07 Tahoe engine hot ac turned off

You are on to something there, with the radiators. Struggled with the hot, AC off bs for a while. I made a number of cooling system improvements at the same time, so it took a while to figure it out. But I think I have it solved on my machine. Source of the problem: Aftermarket radiator...

www.tahoeyukonforum.com

 

[nonickatall]

I agree that a restriction in the radiator could cause overheating. But, to be clear, the necessary restriction I mentioned is -- or should be -- in the small hose to the surge tank. As @Sam Harris mentioned, too much flow in that hose will cause the engine temp to be low.

This short thread might help:

07 Tahoe engine hot ac turned off

You are on to something there, with the radiators. Struggled with the hot, AC off bs for a while. I made a number of cooling system improvements at the same time, so it took a while to figure it out. But I think I have it solved on my machine. Source of the problem: Aftermarket radiator...

www.tahoeyukonforum.com

I will check that tomorrow, for today i am done..

Disassembled a bmw diesel to find out, where the massive oil consumption comes from. Oil rings failure at 152,000 miles...

 

[rockola1971]

I agree that a restriction in the radiator could cause overheating. But, to be clear, the necessary restriction I mentioned is -- or should be -- in the small hose to the surge tank. As @Sam Harris mentioned, too much flow in that hose will cause the engine temp to be low.

This short thread might help:

07 Tahoe engine hot ac turned off

You are on to something there, with the radiators. Struggled with the hot, AC off bs for a while. I made a number of cooling system improvements at the same time, so it took a while to figure it out. But I think I have it solved on my machine. Source of the problem: Aftermarket radiator...

www.tahoeyukonforum.com

Yup we are talking about 2 very different types of "restriction" here. You are referring to the restrictor intentionally put in the radiator inlet/outlet. Im referring to a restriction within the radiator core which is usually caused by the mixing of 2 different types of coolant and/or the permanent type getting exposed to too much air which causes it to chunk up and look like someone threw up in your radiator. Then of course using tap water full of calcium in a radiator will also do the same thing and plug the core up.

 

[nonickatall]

I agree that a restriction in the radiator could cause overheating. But, to be clear, the necessary restriction I mentioned is -- or should be -- in the small hose to the surge tank. As @Sam Harris mentioned, too much flow in that hose will cause the engine temp to be low.

This short thread might help:

07 Tahoe engine hot ac turned off

You are on to something there, with the radiators. Struggled with the hot, AC off bs for a while. I made a number of cooling system improvements at the same time, so it took a while to figure it out. But I think I have it solved on my machine. Source of the problem: Aftermarket radiator...

www.tahoeyukonforum.com

Checked that today, I clamped the hose from radiator to the surge tank, and drove for 6 miles. I saw the temperature rise and when the thermostat opened, at above a quarter of the gauge, it dropped. Then the temperature rise, drops, rise, drops and was fluctuating between a bit over a quarter and a bit below half. When the engine was warm and stable it continued fluctuating. Then I released the clamp, to see if there is a difference. No change.

Maybe rockola1971 is right and I have a problem with my new thermostat..

What i wonder:
How our trucks react normal with engine temperature? This is my second american car and I know it from German cars like Mercedes or BMW, that temperature rise and then stay nailed in the middle of the gauge, anyway if you drive slow in winter, or 250km/h on the highway in hot summer.

I have a Chrysler LeBaron convertible and i know from many other LeBarons in our community, that the temperature fluctuates as well.

How is that on our engines? Or is that normal at American cars?

 

[adventurenali92]

Checked that today, I clamped the hose from radiator to the surge tank, and drove for 6 miles. I saw the temperature rise and when the thermostat opened, at above a quarter of the gauge, it dropped. Then the temperature rise, drops, rise, drops and was fluctuating between a bit over a quarter and a bit below half. When the engine was warm and stable it continued fluctuating. Then I released the clamp, to see if there is a difference. No change.

Maybe rockola1971 is right and I have a problem with my new thermostat..

What i wonder:
How our trucks react normal with engine temperature? This is my second american car and I know it from German cars like Mercedes or BMW, that temperature rise and then stay nailed in the middle of the gauge, anyway if you drive slow in winter, or 250km/h on the highway in hot summer.

I have a Chrysler LeBaron convertible and i know from many other LeBarons in our community, that the temperature fluctuates as well.

How is that on our engines? Or is that normal at American cars?

Under normal operation the truck will run about 200 degrees. The gauge on the dash should park at just below 210, like a hair below the 210 mark. I’ve heard a lot of guys here say that actual running temp with a scan tool hooked up will show about 199. It shouldn’t move while running especially after more than 10 or so miles depending on ambient temp. It should stay at the 210 mark on the gauge once it’s warmed up so it’s definitely not normal to see it fluctuating. The only time mines runs colder is when I’m driving down off the mountain I live on to the base area below. We have three highways in and out of town and the primary highway I use only has one little stretch of tight windy corners where I’m using a mix of throttle and letting off to get through that stretch. The majority of the highway is long sweeping corners that are properly banked where I’m doing about 50ish MPH, and when going down the truck is just coasting down the grades in 3rd gear, so it’ll drop from the 210 mark to 180ish because I’m not using enough throttle and gravity is keeping the truck moving. Unfortunately hurricane Hillary rolled through socal in late august and brought tons of rain and heavy wind that took a huge section of the highway, so it’s been closed and under repair since. With no projected opening date. So the last few trips I’ve had to take the other highway, what we refer to as the “frontside” and it’s much more windy and twisty and average speed is 35-40 MPH through most stretches. Ironically there’s longer stretches that tend to be more flat as it travels through a couple little tiny towns, and the grades are below the town. But even on that highway through several portions where the truck is just coasting through corners the temp will drop to the 180 mark. But it’ll go back up within a couple minutes of throttle to stay moving and then will stay at the correct temp.

 

[Fless]

The gauge circuit is programmed to be a bit "stupid" in that once it gets to the middle range it's not going to fluctuate much over a 10 or 20 degree range. If it did fluctuate and was highly accurate people might panic when they see it moving around. Generally the display is like @adventurenali92 stated, and remains the same indication (in the middle) over a fairly wide range of the operating temp.

 

[nonickatall]

The gauge circuit is programmed to be a bit "stupid" in that once it gets to the middle range it's not going to fluctuate much over a 10 or 20 degree range. If it did fluctuate and was highly accurate people might panic when they see it moving around. Generally the display is like @adventurenali92 stated, and remains the same indication (in the middle) over a fairly wide range of the operating temp.

Not mine...

Probably a European version?

Don't care about their feelings, just be brutally honest.

 

[afpj]

I'm starting to wonder if your propane setup just runs at a different temp and exhaust gases are different. Although your PCM is tuned for propane, are the sensors specific to propane or just regular O2 sensors? This is what we call a WAG...Wild A$$ Guess

 

[nonickatall]

I'm starting to wonder if your propane setup just runs at a different temp and exhaust gases are different. Although your PCM is tuned for propane, are the sensors specific to propane or just regular O2 sensors? This is what we call a WAG...Wild A$$ Guess

A good wild a$$ guess, well done.

But the propane system is perfect adjusted to the engine and at least it is technically very simple. The normal PCM is used, no tune at all.

The fuel injectors signal is just routed over the propane controller, and this controller decides, based on if i drive on fuel or propane, if the signal is just passed to the fuel injectors, or converted and send to to the propane nozzles. It must be converted, because the amount of propane is different to fuel, so the opening time for the propane nozzles differ from the calculated fuel injectors time.

The PCM does not know anything of the propane system, so to speak.

The PCM use the O2 Sensors, the mass air flow sensor and all other engine parameters like running on fuel. If i drive on gas, i can switch just with a push on a button to propane and opposite. My car behaves exact the same. You feel no difference.

And also the temperature behave, does not change at all.