Would TW sensor affect idle?

[jszuba]

I've been getting this idle surging issue that cannot be resolved.
Anyway, a couple of days ago the engine started stumbling and throwing a 06 code - Coolant Temp Sensor. This happened several times and also prevented me from starting up at one point (cranked, but didn't turn over).
So now I'm waiting for the sensor to come in and to replace it.

I was just thinking though... could it also be the culprit of the idle sticking randomly to 1100rpm?

This is my train of thought:
- Sensor fails (intermittently) and sends a false signal eg. coolant temp low.
- This info is somehow relayed to the FITV or IACV (they both have coolant lines running through them!), and they both react accordingly.
- Valves open/close affecting the air quantities added to fuel.
- Engine idles randomly during driving.

I'm a noob so please don't flame at me if I got it completely wrong

[quickangel93]

hmm. not really hear of this happening. but, it could be a coolant temp sensor, because its probably telling the engine is cold and that the engine has to stay at a certain idle to warm up.

[Otto]

The FITV has no electronics, its strictly a heat activated valve (hence the coolant line) independent of everything else, just like the thermostat. I believe its solely responsible for the fast idle when the engine is cold.
Have you gone through the stickie on idle problems already?

[jszuba]

Yeah, I did go through the sticky, though I plan a little tune-up so I'll go through all the processes again.

But this was just a loose thought that had occurred to me this morning on my way back from the dealership...

Indeed, the FITV is non-electric, but the IACV is... so

hmm. not really hear of this happening. but, it could be a coolant temp sensor, because its probably telling the engine is cold and that the engine has to stay at a certain idle to warm up.

Exactly my thought.

[HondaFan81]

These articles may help understanding:

http://autorepair.about.com/library/faqs/bl458h.htm

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

Quick answer: Yes can affect idle and startup, the TW coolant sensor. One reason I installed a new OEM unit in my white project accord, along with IAT sensor. Cheap insurance, I want reliability and to ensure proper function of my new performance motor.

[jszuba]

Thanks for the two links! The second one is especially helpful!
Still curious about the relationships between the components though.
I'll see tomorrow what the replacement will bring.
Knowing life and inanimate objects' cruelty, it will change nothing and I'll have to scrap my 'theory' :P

[HondaFan81]

inanimate objects' cruelty

If you make the attempt to understand the system and diagnose the madness, then they are not so cruel. There is always a reason, it is a matter of finding it out, or not. After all, the fact they are inanimate is what makes them simple and predictable.

[jszuba]

True... just like with magic and beliefs... anything incomprehensible to man was considered an act of God or the devil... until there came along Newton par example and explained the physics.

I guess I'm still in search of Newton asking these questions

[jszuba]

Well, I waited a whole week before I actually said anything...
but now I believe I can safely say that the sensor must somehow affect the idle.
Nothing has been done other than the TW sensor replacement, and the idle stopped sticking randomly.
It hasn't done it since. Not once.
I drive daily.
It would have done so... at least once during a drive.

So if your idle sticks to ~1100rpm on and off, chances are if you replace the TW sensor, you'll be alright.

Aaahhh, so nice to have a smooth drive

[HondaFan81]

Awesome, happy for ya. We nailed it.

[jszuba]

Yeah, I'm so damn happy!
It took 2 years, both valves and a lot of cursing