I've been having an ongoing issue with rough/hard startups cold and hot, as well as a rich condition. I also, for the first time today, had the engine buck during secondary boost. While this happened the CEL flashed on and off and then came on and stayed on. I checked the code to get 09 (water thermosensor). After work the car started up normally and ran perfect (no CEL).

My question is this, what are the symptoms of a bad water thermosensor? Could it cause rough starts, stalling/flooding, and a rich condition as well as bucking at high rpms?

When I was replacing the FPR and pulling the injectors I OHMed the water thermosensor and it checked out ok at 68 and 170 degrees. Assuming that the water thermosensor (the one that signals CEL 09) is the green one towards the top on the back of the thermostat housing?

Thanks,
-Charlie

 

I dont think your problems is going to be there. the ECU will tell u if that is bad. u might want to look somewhere else. unless.... after the car warms up, u unplug that sensor (fans come on) and for the ten minutes MAX that you drive the car, it runs better, then MAYBE you should keep your focus on that part of the car

 

Thanks for the response. The thing that I thought was odd was that the CEL came on right as the car was bucking in the high RPMs, and the only code it threw was 9. Then later that night, no code and no bucking. Could this just be a coinsidence?

-Charlie

 

same thing happened to me....first my car would buck and the cel would light on while driving..then after playing it off my car finally wouldnt start b/c the sensor was completety bad...yes it is hte green connector just left to the alternator..just go to autozone and pick up a water temp sensor replce it then your car will be perfect. If that doesnt fix it then the next thing would be a faulty ecu.

 

Sorry for the two year bump.

Last week i posted a thread about an intermittent CEL, number 9 (thermosensor) then, today, my car stalled out about 4 times before i could get it back home. It's having a hard time getting started, idles, then the fans almost immediatly come on and the car dies. When it starts back up again, i get a nice cloud of smoke and if i keep on the gas to about 1500 rpms, it'll stay running.

Is the thermosensor related to my recent problems? My car has an intake, downpipe, AST, turbotimer and i recently added a dual RB exhaust.

 

Start with fixing one issue at a time. If you know you are intermittently getting code 9, then replace the sensor. After that, see if your other symptoms still persist. If they do, you can rule out that code in causing the problem.

 

O so the sensor could be faulty to a point where it can still work but not really?

Cause i am having some cold startup bucking in low rpm's. To a point where i have to pull over cause it wont even let me accelerate a bit to get moving.

The one time the car was already warmed up (185F) and i came out of the store and the car bucked a bit in first gear but then after a minute or 2 of idling, it cleared.

Could that be a symptom of a bad thermosensor? I dont have any CEL.

 

I would look more towards the Double Throttle control than the Water Thermosensor for symptoms like that.

 

I have the TB coolant bypass if that makes it any difference.

But doesnt the water thermosensor tell the ecu if the car is cold or not thus feeding more fuel into the engine (when its cold). Maybe upon startup, whether the car is actually hot or cold, the ecu is getting a signal that the engine is cold therefore having more fuel dumped in causing it to run rich and buck? Does that make sense?