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Truck Hesitation


Greg K

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues? :confused:

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues?  :confused:

 

 

 

 

when you checked the temp at the t-stat what was it

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues?  :confused:

 

 

 

 

when you checked the temp at the t-stat what was it

 

 

 

 

 

It was 198.5. Whatcha thinking?

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues?  :confused:

 

 

 

 

when you checked the temp at the t-stat what was it

 

 

 

 

 

It was 198.5. Whatcha thinking?

 

 

 

 

 

 

so the temp guage show 165-170 but at the t-stat it is 195. have you taken the temp at the sensor

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues?  :confused:

 

 

 

 

when you checked the temp at the t-stat what was it

 

 

 

 

 

It was 198.5. Whatcha thinking?

 

 

 

 

 

 

so the temp guage show 165-170 but at the t-stat it is 195. have you taken the temp at the sensor

 

 

 

 

 

Yep. Its the same. Our probe can be placed right on the head. I believe the temp is supposed to be 190-200 so it should be with in spec.

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I have a 2000GMC 1/2ton 4X4 with the 5.3liter. I've had a hesitation upon acceleration for (4) months that no one seems to be able to figure out. It's harmonic and not intermittent. I've replaced the following components and had the following work done to cure it, but nothings worked.

-Replaced Mass Air Flow Sensor

-Had the Fuel Injection Completely Cleaned at the Dealer

-Changed the fuel filter

 

I think the weather and or temp out side is also related because during the winter months it ran great! I noticed that the temperature gage was reading incorrectly and when ever that was incorrectly reading it ran terrible and hesitated. I replaced the following items to try to cure that issue that I beleive is related

-Replaced the thermostat

-Replaced the water pump

-Replaced the Temp Sending Unit on the driver side head

 

The gage is still reading wrong 165-170 Degrees and the truck is still running poorly. I checked the temp at thermostat with a pyrometer and I know the truck is running the correct temperature. A buddy told me there is another sensor that has to do with the fuel and temperature and also runs the gage. Anyone know where it is and will it fix my issues?  :confused:

 

 

 

 

when you checked the temp at the t-stat what was it

 

 

 

 

 

It was 198.5. Whatcha thinking?

 

 

 

 

 

 

so the temp guage show 165-170 but at the t-stat it is 195. have you taken the temp at the sensor

 

 

 

 

 

Yep. Its the same. Our probe can be placed right on the head. I believe the temp is supposed to be 190-200 so it should be with in spec.

 

 

 

 

 

the spec is 190-210,

do you have a volt meter,

I need to know what the voltage is at the temp sensor.

What you will need to do is.

Hook the pos & neg to the two wire for the sensor pos to yellow wire and neg to gray. (note you have to do this with the sensor hooked up normaly there is a rubber seal where the wires go into the connector slide that out and you should be able to hook to the wires, if not you can splice into the wire not a method I would do, but some times nessasary)

start the truck take a temp reading write down the temp and the voltage do this about every 25 deg (ex.. 80 deg voltage is 4.12v / 125 degs voltage is 3.5 v)

your veh may very than the example, but you will see voltage decrease as the engine warms up.

 

The reason for this it in need to know what type of read the temp sensor is giving the pcm, I know you replace the temp sensor but that sensor could be bad, you could have resistance in the wires, the pcm calibation is off, or the insturment cluster is bad. which all of these can cuase the vehicle to run poor, and yes even the insturment cluster can cuase your problem

 

I will send you my phone # in your email on this site if you have any questions or need more help. once you got that info it would be better to call me if done this weekend, or post it and I will see it on monday. do to I will be off this site at 6pm cst

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