I notice that the throttle body on my '07 XK base has a water/coolant connection so that heated coolant heats the throttle body.

My previous rides were GM autos with LS motors that had similar coolant inlet/outlets on the throttle bodies. My go-to source (TPiS, Inc.) routinely disabled this function. Their sources at GM told them that this provision was to eliminate an icing problem that rarely occurred. They felt there was no reason to further rise intake air temps. I disabled this heat source on my '05 Cadillac CTS-V and drove it 90K miles without any problem.

I am thinking of disabling this function on my XK. My plan is to use a connector pipe between hose ends so as to preserve coolant flow.
I consider this in the category of a minor "tweak". Anyone tried this?

 

The reason for the heat is to prevent icing as you suggest. Even if that's not an issue for you, rerouting the coolant will not really gain anything in the performance department. The amount of heat transferred to the incoming air is miniscule.

Not worth the the bother IMHO, vs. that odd time that the anti-icing feature might actually be required.

 

If you live in a warm climate that never freezes I would say go for it. Theoretically the cooler the intake charge the better, so why heat it if you don't need to?

I may do this on my car as well since it rarely gets below freezing where I live, and even if it did, it does not freeze in my garage ever.

Good idea overall.

 

It is a de-icer per se, but when air is in movement it cools be moving moisture which at high enough speed will ice above freezing temperatures. This de-icer just keeps the throttle opening from the contracted moisture and really does not heat the fuel to disrupt the economics of ignition.

 

I intend to follow through and disconnect the coolant pipes from my throttle body. I will report any observed problems.
All in all, I cannot see the benefits of such a contraption. Seems to me that any throttle body freezing (and attendant throttle plate sticking) will occur when the motor is cold. Coolant will also be cold, may be above freezing temp. but still cold; and I wonder just what/how much a coolant flow when cold will help? Once the motor is warm then the chances of icing should be minimal - then the coolant flow serves no purpose.
No doubt this is a minimal modification, which is unlikely by itself to be noticed by the average owner. Nevertheless, any reduction of intake air temperature is beneficial.

 

I've noticed a few heated pcv valves as well. Some electric and some coolant heated. Sometimes the manufacturer will not tell you the real reason they do stuff because it's not very flattering. I beleive that a major benefit of heating a throttle body is to prevent carbon build-up on the throttle plate and bore. That may be the real reason they want to keep em hot.

The blow by gases are routed to the atmospheric pressure side of the throttle body on moderate to heavy loads. These gases are pulled to the vacuum side of the throttle body to be re-burned for smog reduction purposes. As the blow by vapor goes past any "colder" parts like the throttle body, pcv, and intake valves, The gases condense and deposit oil/carbon particles. Over time this will cause build-up that can result in a sticky throttle body and low idle, sticky or plugged pcv valve and hoses, and intake valve build-up as well as other parts getting contaminated or plugged.

I don't think any manufacturers want to come out and tell you that they have a "blow-by" problem. Control of icing sounds better. I have noticed a few manufacturers using plastic throttle plates lately and I don't recall them being heated.

 

Thanks for all your comments.
I think the purpose of a forum like this is to share research, results and opinions. I can state that based on my own personal vehicle with 90K miles on the clock with throttle body "heat" disconnected that I never knowingly had a throttle body icing problem. That is not saying I never had throttle body ice, I really do not know. If I did have ice it never became a noticeable problem.
In the auto industry these subjects are deeply researched. Often research data is kept confidential or proprietary. Other times research is published. Here is one paper on icing: http://delphi.com/pdf/techpapers/2008-01-0439.pdf. It was written by engineers at Delphi. Delphi is one of the largest producers of OEM auto motor parts (throttle bodies). Perhaps I missed something, but I saw no references therein to throttle body heating with engine coolant.

 

i kinda feel left out on this topic!

my XJS V12 came without any TB heating,from the factory!

 

ADMIN-- Please delete this troll

 

He is toast.

I've also edited out the same commercial links from your quote.

Graham

 

I understand the coolant helps control tighter emissions from the engine on cold starts, along with things like EGR valves. I've never heard or seen frozen throttles from either efi or carbs, as petrol doesn't freeze normally.

 

It's not the petrol that freezes. It's the condensate from the incoming air.

You might not see the syndrome depending on how could it gets in UK winters.

On my Rover, they never accounted for -35C in the fuel maps. So to avoid overenrichment, the starting drill was to pull up on the fuel cutoff plunger while cranking, and then release to get just enough fuel to fire. Not a whole lot of fun, but at least it always worked to get home on a cold night.

 

I've had a frozen carb twice in my life. Once on a Norton 750 motorcycle that was being operated in winter like conditions when it should have been put away for slumber instead of riding, and the other on an American car where I had foolishly stripped off all the devices that would have prevented carb icing. In each case, the engines were only partially warmed up and the weather conditions were just right to cause the air to drop below the dew point in the intake and the suspended moisture to freeze.

Again in both cases I had to shut off the ignition to bring the vehicle to a stop. Not fun.

 

Did a little more research on the subject. Seems that carburetor icing first became a big issue on aircraft. Typically, aircraft descend on a closed throttle and sometimes through clouds, with high humidity. Air accelerates across the almost-closed throttle plate, and in so doing drops temperature. The moisture in the air can then separate and freeze, sometimes freezing the throttle plate.
We had heated intake manifolds in some carbureted autos for many years. This was particularly prevalent with V-motors where exhaust gases could be routed through the intake manifold somewhat easily. Lore was that this was emission friendly. Nevertheless, it was common hot rod practice to block off the exhaust passages in the intake manifold.
My speculation is that throttle body icing will never occur on a warm motor for obvious reasons. I think the condition where throttle body icing will occur is a cold startup followed by prolonged idling. This can occur in temperatures above freezing so long as humidity is high. While the motor is cold, so is the coolant, but the coolant is probably still above freezing and can assist in thawing an icy throttle body.
Years ago, it was common practice to cold idle a car to warmup, thinking this was best for motor life. Now, it seems, common practice is to bring the motor to operating temperature as fast as possible through normal gentle driving, a condition where throttle body icing is very unlikely.

 

False- see my two examples above. Quick warmup is the most likely scenario for icing.

 

if thats the intent then its a big "fail"
it is for icing and reduced emmissions and increased economy. It does heat the incoming air slightly which we all(that paid attention in science) know expands(thins) air which needs less fuel(better economy=reduced emmissions) yeah its small but removing a 100 # from a car isnt done by looking for1 thing to drop a 100# from. Its from finding a 1000 things to remove ounces from...like plastic nuts and retainers as an example, all the little things add up.
Ive deleted the coolant on mine for years with a hose connector and 2 clamps and never an issue... As a result
i lost 5 pounds, my hair came in thicker and my johnson got longer win win if you ask me

 

Any opinion as to why this throttle body from a 2005 BMW X5 is not heated in any way? There is no preheated air before the throttle body or air cleaner housing. It has a fresh air duct (from above and in front of the radiator support) to the air cleaner housing. Why do you suppose the icing is not a problem here?

It does have a pressure controlled crankcase ventilation valve. Many manufacturers are using this design. No blow-by gasses are directed before the throttle plate. Notice the clean throttle body plate and bore on this high mileage (150,000+ mile) BMW engine. I know it's just a coincidence that there is no blow by residue problem here and the throttle body is not heated.

Any thoughts?

 

^^right, key being the crankcase is NOT vented to the inlet track BEFORE the TB. This is common on most cars because you need to vent before to allow flow during higher rpm and low to no vacuum. Then its ported behind the throttle body for venting when vacuum is high and rpm is low. Im sure there are other ways this can be done. But the current setup has been used for decades. The info Iv egiven on the WHY, is from ASE Advanced diagnosis training as to functionality of differant systems

 

Thanks, Brutal. I understand how the pcv system works on both the traditional pcv sysem and this newer pressure controlled crankcase valve system.

The topic of this thread is "Why heat the throttle body?". The answer on this thread is that it's to prevent "icing".

My question is "Why is this throttle body not heated?". What did they do to overcome the icing problem and not require the heating? I'm sorry if you already explained it and I have not yet grasped the answer.

 

No Joe, you grasp it which is why I said "^^^^RIGHT" and then just went alittle further for all reading. auto engineers do many things the same way theyve always been getting the same results theyve always gotten. Until.....someone goes out of the box and then we get things like variable valve timing that morphs to variable lift and duration, to injecting fuel IN the chamber instead of in the intake track. and we end up with smaller engines putting out way more hp, way better mpg, and lower emmissions than ever before. Cant wait to see where we are gonna be in another 10-20yrs