Gas Milage Tip: Check your connection

A quick tip that I found made a dramatic improvement to a "mystery" loss of fuel milage. With pretty much all new sensors, a recently rebuilt engine, and a recent tuneup, I was surprised one day when filling up to see my milage drop from the 16-17 MPG range to the 10-11 MPG range. Obviously, I was running in open loop.

What I noticed was that recently, my temperature gauge was registering low compared to normal. Some was attributable to the weather, but I couldn't hit 210° no matter how long I let it idle. On close inspection, I realized the electrical connection to the threaded fitting on the engine temperature sensor was a bit loose. I tightened it with a pair of needlnose and cleaned it good with contact cleaner.

The results were dramatic: I went from 13 MPG on fillup before fixing to 16.9 MPG when I filled up today after the fix.

good no know! I'll have to check mine out.

You just squeezed the female ends of the plug tighter and then slid it back onto the sensor?

Hm.

Is this the sensor at the back of the head? I thought that was only for the gauge and the computer temp sensor was on the T-stat housing(OBD1-2) and on the drivers side of the block(RENIX)??

I know the ONLY way my RENIX will run in closed loop w/closed coolant system during the winter(below 40 degrees F here in VA) is with the grill blocked and the splash guard installed under the engine, otherwise the over efficient closed system w/3 row radiator will only get to about 130-190 or so and yo-yo's up and down as the T-stat opens and shuts.

xjtrailrider said:

Is this the sensor at the back of the head? I thought that was only for the gauge and the computer temp sensor was on the T-stat housing(OBD1-2) and on the drivers side of the block(RENIX)??

I know the ONLY way my RENIX will run in closed loop w/closed coolant system during the winter(below 40 degrees F here in VA) is with the grill blocked and the splash guard installed under the engine, otherwise the over efficient closed system w/3 row radiator will only get to about 130-190 or so and yo-yo's up and down as the T-stat opens and shuts.

Click to expand...

You know what, I think you're right.

Well, it made me feel better now that my guage is working.

Not sure why I got such shitty milage for a while. Could just be the ass-biting cold weather we've had lately and my short, 7 mile commute.

I suffer the cold operating temp thing with a 3 core, and wonder if Go-Jeeps flow blocker wouldn't help. It's made out of plastic cutting board with a hole saw and sized orifice, slid into the rad hose at the thermo housing.

It should smooth out the peaks and give the block coolant enough time to pick up more heat. Like most 3 core owners, the radiator has no problem handling the job - it works too well. Mine disguises an non working e-fan until late July.

I never had a problem with my 3 core overcooling except once when I was on the highway last winter when it was very cold out.

I do run an OEM thermostat. I have a 3 core CSF.

I also contribute the running cooler on the highway because I do not have any of the original fans and have electric fans. I have not made any shrouds yet so there are gaps around the fans where air is free to flow right through the radiator, possibly overcooling it compared to if I had shrouds blocking the gaps.