Recent Topics
burn feel?(car)
by yvon_la
04/28/17 06:42 PM
Car extended warranties
by chiefsfan1
04/28/17 06:28 PM
New to me 2012 Sierra SLT
by CKN
04/28/17 06:20 PM
NAPA Gold 1516 10K OCI
by Jason_Michaels
04/28/17 05:18 PM
Harvest King 15w40 Conventional
by beanoil
04/28/17 04:43 PM
Replacing tires on Honda Element
by sleepery
04/28/17 04:26 PM
Springfield Armory XD-E New DA/SA sub compact gun
by 901Memphis
04/28/17 04:23 PM
Rotella T6 5w30 Multi-vehicle?
by Lex94
04/28/17 04:03 PM
New QSUD spec sheet
by Lex94
04/28/17 04:01 PM
Redline Walk-Through
by beanoil
04/28/17 03:54 PM
Just want to brag a little About My OPE
by andyd
04/28/17 03:45 PM
Run Fram Ultra XG3600 for 3 years, 10k?
by WillsYoda
04/28/17 03:16 PM
FL400S/68hrs/2yr/Bri
ggs ELS 23hp C&P

by Scorpion67
04/28/17 02:59 PM
Warning: Wal-Mart Oil Filter ST9688 Defect, Nissan
by 86jag
04/28/17 02:27 PM
State motor vehicle deaths per 100k. `
by Nick R
04/28/17 02:26 PM
Angle Die Grinder Recommendations
by dlundblad
04/28/17 01:53 PM
torque converter lock up
by hardheaded
04/28/17 12:34 PM
Valvoline Synthetic 10w30 MaxLife - Impressive
by FlyPenFly
04/28/17 12:24 PM
Honda Accord question
by aquariuscsm
04/28/17 11:28 AM
Battery water level low -- is it permanently dead?
by BobandWeave
04/28/17 11:12 AM
Newest Members
ZiRT, Rat12, cmm3, steelwindmachine, merchantmarine
61367 Registered Users
Who's Online
90 registered (andyd, 64bawagon, AnthemBassMan, ag_ghost, 2015_PSD, 7 invisible), 2243 Guests and 9 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
61367 Members
66 Forums
264402 Topics
4366678 Posts

Max Online: 3590 @ 01/24/17 08:07 PM
Donate to BITOG
Page 1 of 2 1 2 >
Topic Options
#4331641 - 02/17/17 04:09 AM Why are IAC Valves Heated?
artbuc Offline


Registered: 12/02/05
Posts: 951
Loc: West Chester, PA
Why are modern computer controlled IAC valves heated with coolant? From what I have read, it appears coolant is there to prevent freezing. However, many believe coolant warms the IAC and controls operation. I think that used to be true with older designs where IAC valves had bimetallic springs and slowly closed as coolant temperature increased. With a computer controlled IAC valve, coolant lines to/from IAC valve do not affect operation, right? Thanks.

Top
#4331654 - 02/17/17 05:16 AM Re: Why are IAC Valves Heated? [Re: artbuc]
Linctex Offline


Registered: 12/31/16
Posts: 652
Loc: Waco, TX
Some engineer felt it was a good idea.

I absolutely GUARANTEE you that "feature" isn't added unless there was a good reason for it.
If you can save $0.75 per vehicles over a million vehicles, that's $750,000 saved.

So, during the course of extreme temperature testing, someone felt it helped drivability in some way - - or it wouldn't be set up that way.

Top
#4331657 - 02/17/17 05:27 AM Re: Why are IAC Valves Heated? [Re: artbuc]
sdowney717 Offline


Registered: 10/01/05
Posts: 298
Loc: Newport News, VA
Air pressure drop as motor runs drops the air temp and could lead to iced up throttle valve.


Edited by sdowney717 (02/17/17 05:28 AM)

Top
#4331695 - 02/17/17 06:53 AM Re: Why are IAC Valves Heated? [Re: sdowney717]
supton Offline


Registered: 11/09/08
Posts: 10569
Loc: NH
Originally Posted By: sdowney717
Air pressure drop as motor runs drops the air temp and could lead to iced up throttle valve.


That would be my guess, although stabilizing air intake temp is probably a good thing (attempting to limit the variables that the ECU map has to work around).
_________________________
2011 Toyota Camry, base, 2.5L/6MT, 136k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 138k, ours
1999 Toyota Camry LE, 2.2L/4AT, 151k, his

Top
#4331717 - 02/17/17 07:28 AM Re: Why are IAC Valves Heated? [Re: artbuc]
DBMaster Online   content


Registered: 09/18/12
Posts: 4655
Loc: Greg Abbott Land
The IACV (that's what Honda called it) in my 1989 Accord had coolant piped through it. So, this is nothing new.

Top
#4331772 - 02/17/17 08:42 AM Re: Why are IAC Valves Heated? [Re: artbuc]
ARCOgraphite Offline


Registered: 05/17/09
Posts: 10726
Loc: N.H, U.S.A.
Prevent freezing. Nothing new, Carb bases were heated with exhaust or coolant. PCV can plumb near there too which has a lot of water vapour during warmup.

If you were around in the 60s and 70s with manual choke and throttle you would probably had a carb freeze up a few times in the winter. My AFB on my 65 buick would do this - esp when I was late to class. Yes I did the heated base block off and intake stove delete for more power. Silly Kid, me.
_________________________
2014 Nissan Rogue S CVT, OC#7 29472mi-QSUD 10W30 + M1 110A Filter; 2017 Subaru Crosstrek CVT 2K+ miles

Top
#4331800 - 02/17/17 09:17 AM Re: Why are IAC Valves Heated? [Re: artbuc]
The_German Offline


Registered: 01/13/17
Posts: 128
Loc: Montreal (West Island), Ile Pe...
IIRC it is to establish a reading where inrush air can warm or cool on a 5V sensor to a baseline that would work in all climates.

If Cold there is less Resistance than when Warm, and this balance has to be within a sensible range to work where the PCM is only interpreting a Voltage 0-5VDC, and that window may not work in extreme heat or extreme cold so this problem is solved with the coolant warming (or cooling) in a range that the sensor can read a mid range.

Very hard to explain I guess that is my attempt this is a while ago.
_________________________
Independent Honda Sales, Parts and Service
My baby: 2010 Honda Fit DX-A Black
Sopus Synthetics and Wix 57356
Genuine Honda Parts

Top
#4331805 - 02/17/17 09:20 AM Re: Why are IAC Valves Heated? [Re: The_German]
Rand Offline


Registered: 08/20/03
Posts: 11511
Loc: NE,Ohio
Originally Posted By: The_German
IIRC it is to establish a reading where inrush air can warm or cool on a 5V sensor to a baseline that would work in all climates.

If Cold there is less Resistance than when Warm, and this balance has to be within a sensible range to work where the PCM is only interpreting a Voltage 0-5VDC, and that window may not work in extreme heat or extreme cold so this problem is solved with the coolant warming (or cooling) in a range that the sensor can read a mid range.

Very hard to explain I guess that is my attempt this is a while ago.



Are you talking about a MAF sensor? they are talking about the IAC. Idle air control valve.
_________________________
2017 Jeep Cherokee Trailhawk V6

Top
#4331813 - 02/17/17 09:28 AM Re: Why are IAC Valves Heated? [Re: artbuc]
SHOZ Offline


Registered: 06/28/03
Posts: 4417
Loc: Illinois
Almost all throttle bodies are heated by the coolant. First mod I do is to bypass the coolant hoses.
_________________________
2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual

Top
#4331837 - 02/17/17 09:46 AM Re: Why are IAC Valves Heated? [Re: artbuc]
The_German Offline


Registered: 01/13/17
Posts: 128
Loc: Montreal (West Island), Ile Pe...
Rand you are correct I didn't read it right.
_________________________
Independent Honda Sales, Parts and Service
My baby: 2010 Honda Fit DX-A Black
Sopus Synthetics and Wix 57356
Genuine Honda Parts

Top
#4331840 - 02/17/17 09:52 AM Re: Why are IAC Valves Heated? [Re: artbuc]
KrisZ Online   happy


Registered: 12/23/06
Posts: 6410
Loc: Toronto, Canada
Machine optimal operating temperatures are much, much higher than the temperatures humans feel comfortable with. Hence a lot of people feel the need to lower those temperatures by removing thermostats, bypassing coolant hoses, installing extra coolers. Most of the time, this emotionally driven behavior causes more harm than good.


Edited by KrisZ (02/17/17 09:52 AM)
_________________________
2015 Dodge Grand Caravan-15k miles.
2006 Mazda 3-145k miles

Top
#4331851 - 02/17/17 10:01 AM Re: Why are IAC Valves Heated? [Re: artbuc]
SHOZ Offline


Registered: 06/28/03
Posts: 4417
Loc: Illinois
If you want maximum gas mileage then keep it all hot. If you want to not so much heat up your intake manifold then remove the TB hoses. If you have a turbo you are using an Inter cooler to cool down the air going into the throttle body. No sense having the throttle body at 200F or so.

The most popular reason for keeping the TB hot is so the throttle plate doesn't freeze at high humidity, barely open TB(fastest flow past the plate and resulting pressure drop) and temps just above freezing.
_________________________
2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual

Top
#4331857 - 02/17/17 10:04 AM Re: Why are IAC Valves Heated? [Re: Linctex]
Tegger Offline


Registered: 03/20/06
Posts: 2236
Loc: Canada
Originally Posted By: Linctex
during the course of extreme temperature testing, someone felt it helped drivability in some way

It's meant to counter the icing that results from the venturi effect, something that can manifest at ambient temperatures well above freezing.
_________________________
2013 Toyota RAV4 - 72,000 miles - Toyota 0W-20, Toyota filter

Top
#4331860 - 02/17/17 10:12 AM Re: Why are IAC Valves Heated? [Re: artbuc]
VNTS Offline


Registered: 03/01/07
Posts: 1563
Loc: NE
No coolant or heating on mopar Throttle Body, most of them have TPS Sensor and the AIS Motor, no heating just power to operate the pintle in and out to meter the air what throttle blade is shut.

Top
#4331888 - 02/17/17 10:49 AM Re: Why are IAC Valves Heated? [Re: Tegger]
artbuc Offline


Registered: 12/02/05
Posts: 951
Loc: West Chester, PA
Originally Posted By: Tegger
Originally Posted By: Linctex
during the course of extreme temperature testing, someone felt it helped drivability in some way

It's meant to counter the icing that results from the venturi effect, something that can manifest at ambient temperatures well above freezing.


This is what I believe.

Top
Page 1 of 2 1 2 >