To answer your question about the AutoZone scanner giving you the temp, that depends on what scanner they have. We have 3 AutoZone stores around here, and depending on which one you go to, some have the scanner that will give you temperature and all kinds of other fun info, but another store only has the basic code reader. So it just depends. Kind of dumb to me haha

Pettyfrog brings up another good point with the Vacuum leak. If there is a vacuum leak, the engine will idle higher and thus causing more fuel to be burned. If there is a vacuum leak you might notice your HVAC acting weird, cutting out or changing positions whent he vehicle is under increased load, etc.

 

If it can achieve 195 does it mean that its in close loop operation? When its temp reading is at 195 and if the ECT sensor isn't functioning properly it won't necessarily go into loop operation correct?

How do I identify if its going into closed loop operation?

 

Anyone?

 

A scanner will be able to tell you if it is in closed loop

 

Michigan weather now has the temperature in the upper 30s. I haven't been driving my bravada at all. I took it to a trip to Tbell about 20-30 min trip total with on and off hard driving. The gauge never went past the line between 160 and 210. It also took a while to warm up. This is my first year with this vehicle in the cold so my knowledge is limited.

As pettyfog stated it may be a Engine Coolant Sensor or Thermostat.

Is this where your gauge sits after about 20-30 min of driving?





Is this where your guy's gauge sits?

 

mine actually sits a bit lower than that.

 

Mine sits right below the 210 mark, I think you're thermostat is stuck open.

 

Wrong. My truck runs fine, even during the winter, with a 180* tstat. Gas mileage is still 20+ mpg, no fast idle, nothing. and it reaches closed loop just fine, as verified at work with our Tech2.

Have you experienced this or are u just talking out of your ***, repeating what you've read?

 

Problems usually are experienced with P0128 codes & open loop operation with the 170* t-stats. 180* t-stats allow the engine to warm up to >167*F fast enough to not trigger the code, but I have seen (not read about ) 180* stats used in vehicles that are run for short periods of time cause a drop in mileage that was gained back with a 195* stat. Same with people that have drilled their stat with too large of a drill bit.

Without programming changes though, you aren't taking full benefit of a cooler (marginally) running engine, but that's a discussion for another thread.

If the engine temperature does not exceed 167*F, the PCM will not enter closed loop operation & it will not run optimally. That's the only thing that is wrong with nineTnine's response. When this happens, the mileage can most certainly take a hit. As stated, either the t-stat isn't regulating the temperature in the proper range or the ECT sensor isn't reporting the proper temperature. The trouble shooting steps in the P0128 code listing in the OBD2 dtc section lists how to test the ECT sensor.

 

Parts came from Rockauto yesterday so I installed them. Temp gauge now goes up to slightly under 210 mark now in under 10 mins. I have yet to find out if the MPGs have improved. I will check back to see it solved this issue as well. If not maybe the cat is on its way out... no codes yet regarding the cat tho.

Thanks for everyone's help!