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gjm4l 12-07-2012 07:13 PM

Duratec coolant sensor replaced, now acting weird
Replaced the coolant sensor in the top of the block. It's the "updated" sensor so I had to cut and spice a new pig tail to make it work. I first tried just modifying the sensor itself to fit the old pigtail (removed a small shelf of plastic) but it was giving me these same problems so installed the recommended pigtail but it's the same.....

When started cold and allowed to idle until warm the gauge goes up into the normal position as usual (dead center) but as I'm driving the further I go the lower the gauge reads. During continuous driving it settles at the top of the white block and seems to stay there. If I stop at a light after about 30 seconds it begins to go back up. If I sit there long enough it will return to normal centered reading. Then it will start going down again as I drive. It never goes over the middle. Also when the gauge is reading normal the car idles as normal but when the gauge is below normal while driving and I'm stopping for a light, etc. I get hanging revs(like it was still warming up) until I come to a complete stop, then it returns to normal idle.

What gives? Anybody had this problem? Could it be something to do with the "revised" sensor. Does the computer need to "learn" the new type of sensor? I get good heat and all hoses warm up as they should, when they should and even used an infrared to verify so I'm pretty certain it's not a tstat.

Oh and no check engine light on. The light is why I replaced it in the first place.

elsolo 12-07-2012 10:50 PM

The hoses heat up, the thermostat is not stuck closed then.
It could be stuck open, your engine will get up to normal operating temperature if the car is sitting still or low speeds.

Get driving down the highway and you get airflow through the radiator, the coolant gets below normal operating temperature and the computer does the hanging revs because IT IS warming up.

gjm4l 12-10-2012 09:19 AM

tstat in a dtec can be replaced without intake removal (ymmv)
Yeah I knew it was in the warm up cycle because I "thought" the computer thought it needed to warm up but was thinking it was a malfunction and there was a glitch somewhere between the sensor and the cpu......

Regardless I'll say it, I was WRONG. Meaning on this issue I pulled a "part swapper pro" move and threw the wrong part at it so I spent an extra $65 I didn't need too.....

Replaced the tstat assembly (non sensor one thankfully) and now it's got enough heat to cook me out and no more warmup cycle after it should be warm, all seems to be working as it should. Guess never having had a stuck open tstat made my fuzzy little head explode. An interesting observation to me was after the cpu "learned" the new sensor (50 miles of driving) it went from the first posts description of the gauge to operating like normal but throwing a code which duplicates the original problem leading me to the obvious as stated by elsolo (thanks btw). I'm going to wait until the computer has "learned" it's new parameters before I declare victory but here's hoping!

In case anyone is curious you CAN replace the tstat assembly on a 2.0 dtec without removing the intake. It seemed silly to me to remove all that crap just to get at two hoses and 3 bolts. I can see why you would/should but it wasn't worth it to me. Be aware that the housing itself is super easy to unbolt and pull out and replace. It took half a beer. The Devil is the bypass hose(? I think) and the lower radiator hose. There is NO room to get at the clamps holding them on. I fought with them for two beers worth to get them out even using a fancy hoseclamp tool on a cable (pepboys tool is TRASH) but gave up after it kept sticking closed. Then using a pair of pliers fought the lower radiator hose on without much trouble but spent a full hour of cussing, kicking, and contemplating setting fire to the thing trying to get the clamp back on the bypass hose after getting it into position. As already stated ther is NO room to work, I know now that my left wrist is just barely smaller than my right from sqeezing between the intake and the upper radiator support (which btw is sharp as HELL where the two panels are joined)

I stand by the fact that it can be done without intake removal but if you have ham hands (I wear medium gloves) or have extra long arms (I'm 5'6" 200lbs (short and wide) and I was shoving my entire left arm as far as it would go up my bicep (made it just past my elbow to wedge myself nicely on one try, did I mention that sheetmetal is SHARP!) between the PS rez and the inner fender to get at the hair of room under the intake and beside the fan/radiator to be able to get at the clamps with pliers, you may be stuck taking off the intake depending on your contorting ability and the number of 12oz curls you do.

All in it took a little under 3hrs including several breaks to remain calm and the entire last hour working on that one little clamp but truly it wasn't terrible! According to my neighbor it was incredibly entertaining to watch[popcorn]

sailor 12-10-2012 03:35 PM

Sounds like the 12 oz. curls & the breaks to stay calm saved the day!

good job!

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