Engine runs cool ... ?

cruzecontrol88 · Post by **cruzecontrol88** » Wed Sep 21, 2011 8:55 pm

Hey guys, ive noticed my engine temp never reaches the middle of the gauge. its always at least an inch away from middle and i suspect its killing my fuel mileage. Im going to change the plugs and wires this week hoping hat will help a little but ive only put 300 miles on the car since i filled up and had to fill up 2 times already!

Also im noticing that at times when i start the car up the fuel level seems lower than it was the last start up. Ive checked underneath the car and its dry as a bone indicating no leaks anywhere. What is a possible cause for it?

jamieely · Post by **jamieely** » Wed Sep 21, 2011 9:03 pm

You're temp gauge could be off or you CTS could be malfunctioning. I would manually check engine with a thermo gun or other means before I started throwing parts at it. If you prefer throwing parts at instead of trying to diagnose the problem I would start with a CTS. Did it just recently start doing it? Has it been like that since you bought the car? If it has always been like that the first thing I would do is check to make sure there is a thermostat in it.

My fuel gauge does the same thing and has always done it since I bought the car 7 years ago. Don't really know the cause and never really worried about it.

cruzecontrol88 · Post by **cruzecontrol88** » Wed Sep 21, 2011 9:15 pm

ive only had the car for about a week lol. been doin it ever since i got it. i was gonna replace the plugs with ngks and oem wires anyways.

whats cts??

jamieely · Post by **jamieely** » Wed Sep 21, 2011 11:44 pm

CTS = Coolant temp sensor. If its been like that since you got it I would definitely check to see if someone removed the thermostat. Plugs and wires are always good to change when you take over ownership regardless of what the previous owner says unless they have receipts. Probably the easiest way to check your actual coolant temp would be go to autozone and have them hook it up to their obd2 scanner, if they use one of the better ones that shows data not just codes. My local autozone uses one just like I have and it will tell the actual temperature of the coolant.

cruzecontrol88 · Post by **cruzecontrol88** » Thu Sep 22, 2011 12:41 am

and if it is infact running too cool i should have them look at the cts?

2drSRT4 · Post by **2drSRT4** » Thu Sep 22, 2011 12:44 am

Have them look anyhow. I know my car was running cool like that too. It wouldn't ever heat up. And at times it would OVERheat. It would go full hot. Then I would coast down the hill or something and it would cool off. I'm re-doing the entire cooling system with the new engine.

cruzecontrol88 · Post by **cruzecontrol88** » Thu Sep 22, 2011 12:46 am

this is prob whats killing my fuel mileage right?

jamieely · Post by **jamieely** » Thu Sep 22, 2011 3:17 am

A cool running car can cause horrible mileage. I believe the pcms response to a cool running car is too richen the fuel mixture. I know it does this on start up and people used to throw lower temp themostats in their cars to make them run cooler to richen the fuel mixture because people think richer means faster. I tried that trick in my old cougar after reading it on a forum and all I got was shitty mileage. The coolant temp sensor itself wont make the car run cool though.

If you come to conclusion you are running cool then your sensor is probably working like it should. First thing I would do in this case is check for thermostat and make sure it is the proper heat range, 196 i think is correct.

If you find out you are running at normal operating temp you could either have a bad sensor or someone could have tampered with the needle. A new sensor is only $20 if you want to replace it without checking anything. First thing I would do is check voltage on the signal going to gauge, it will vary depending on the actual coolant temperature. I could hook my scanner up and get you some readings for what voltage you should have at normal operating temp. If the voltage is good someone may have tampered with the needle and it needs to be reset back. I hope this all made sensor I was posted in kind of a hurry.

cruzecontrol88 · Post by **cruzecontrol88** » Thu Sep 22, 2011 2:08 pm

makes perfect sense thanks!

2drSRT4 · Post by **2drSRT4** » Thu Sep 22, 2011 11:21 pm

Hmmm, my gas mileage wasn't that bad. I don't think my coolant temperature sensor was bad either. And I re-did the gauges myself, so I know they were reading properly. I think the thermostat I had was 180 which was the autozone replacement one.