Throttle Body Lubrication

[gpalmer77]

Not the cable itself, but the plate in the bore. I removed and cleaned an MDK throttle body from a BMW M52TU motor, upon reinstallation the plate sticks closed in the bore..... should I lubricate the edges of the plate and the portion of the bore where it sticks? And what with? This is a cable actuated throttle with a secondary electrical actuator for traction control etc.

I probably need a new throttle, but at $500+ I want to exhaust all options first. The plate was stu-uck closed when I first reinstalled it, I had to pop it open with my finger when we were troubleshooting it. Now it just drags a little when it opens, but you can feel it in the pedal.

Thanks.

 

[mrg7243]

The plate may not be fully centered now. This can cause idle issues. You need to center the blade in the bore when you reinstall it. You will know as it will not drag against the bore at all

 

[gpalmer77]

The plate may not be fully centered now. This can cause idle issues. You need to center the blade in the bore when you reinstall it. You will know as it will not drag against the bore at all

Throttle is fully closed at idle, there is a separate idle control valve.

Perhaps I need to adjust the cable so the plate doesn't wedge closed, but is "just there" at zero pedal?

 

[gpalmer77]

****. Apparently, I can't do this, there has to be some slack in the cable before it moves from dead closed...... another source said to clean the throttle body and the edge of the butterfly again with a fine emery paper, then with throttle body cleaner.

 

[brawls43]

Can you loosen the screws holding the throttle plate to the shaft? I agree with mrg that it sounds more like its not centered anymore. Can you tell where the plate hits?

 

[theknurl]

tthrottle plate screws are ALWAYS staked....no undoing them

DO NOT SAND THE BLADE.....figure out which way the blade is off, with the throttle closed tap on the opposite end of the shaft.....
brutacaine is not the method

you can use paint to make the blades seal perfectly.....a trick from RC at RCEngineering the guy that taught Honda how to fuel inject cars

http://www.motorcyclemuseum.org/halloffame/hofimages/Collins1.jpg

 

[toms73novass]

On my Bmw, even though it is not a M52, there is a screw that sets the minimum closed distance. Mine is not fully closed, just a touch open, and the idle motor still controls the idle. The little bit of air that does go past the plate is not enough to keep the car running, the idle motor does that.

 

[theoldwizard1]

Not the cable itself, but the plate in the bore. I removed and cleaned an MDK throttle body from a BMW M52TU motor, upon reinstallation the plate sticks closed in the bore.

Throttle is fully closed at idle, there is a separate idle control valve.

A throttle plate should NEVER be "fully closed" because IT WILL STICK, period end of discussion. Different expansion rates and icing are just a couple of reasons why it will stick.

While you do want most/all of your idle air to go through your idle control valve, you need to be very careful about the minimum throttle plate angle. After setting a minimum throttle plate angle, Ford used to coat the inside of the throttle bore and the back of the plate with a semi-soft substance that would fill the small gap between the plate and bore.

Of course this issue and solutions goes away when you switch to Electronic Throttle Control.

 

[theoldwizard1]

On my Bmw, even though it is not a M52, there is a screw that sets the minimum closed distance. Mine is not fully closed, just a touch open, and the idle motor still controls the idle. The little bit of air that does go past the plate is not enough to keep the car running, the idle motor does that.

Exactly as it should be !

 

[gpalmer77]

Thanks guys. Turns out it was mechanically stuck from when I cleaned it, maybe I pushed the plate closed a little too hard. My kid was helping me too, so who knows. Anyway, once everything cooled down from running everything through the ICV, the throttle seems to operate normally again, with no adjustments required.

Wasn't all good news...... I just rebuilt the P/S system, and after 20 miles of driving, I pull back into my driveway with no P/S and all the fluid running out of the bottom. Need to pull the skidplate and check my new hoses..... doesn't seem to be anything visible from the top, and I can see the fittings at the rack. Must be at the pump, or a failed hose.

Grrr. Always something. I'll get this bad boy back on the road yet.

 

[theknurl]

A throttle plate should NEVER be "fully closed" because IT WILL STICK, period end of discussion. Different expansion rates and icing are just a couple of reasons why it will stick.

Of course this issue and solutions goes away when you switch to Electronic Throttle Control.

TOTALLY INCORRECT

throttle shafts are offset to the "uphill" side, making the "downhill" side of the blade larger in area. this larger area is acted on by atmospheric pressure
the offset is usually 0.020-0.040"
my Aprilia RSVR 1000cc twin has twin 57mm throttle bodies and they are light tight.....it has 100mm (4") pistons sucking on the throttle blades and there is no hesitation in opening
just for fun I put a tablespoon of solvent on the blades.....2 minutes later most of it was still there
the Aprilia uses a IAC motor for idle air

on the other hand my MV Agusta 1000S, 4 cylinder, the throttle blades are open ~0.85mm (0.033") at a TPS value of 2.3deg and the throttles stick because the TB were built backwards, the shaft is on the "downhill side".....
MV's solution????
retard the timing to -4deg to kill vacuum......because its retarded it runs HOT.....so they added a 2nd radiator

the next year '06 with the 1000R model they retarded it even more to -10deg......you can't ride one in traffic.....it'll be puking coolant in 3 blocks

fly by wire won't fix poorly designed/built TBs.....
its just another layer of electronic BS.....remember Toyota execs testifying before Congress?

 

[adam728]

TOTALLY INCORRECT

Actually, oldwizard is right. You never use the blade/bore interface as the stop. Something else should always limit travel to the closed side or you will have sticking, regardless of throttle shaft offset. You can still have it VERY closed up in terms of sealing. Pretty easy to have airflow around the blade to be <10% of the engine's idle air requirement.

Sent via morse code

 

[theknurl]

Actually, oldwizard is right. You never use the blade/bore interface as the stop. Something else should always limit travel to the closed side or you will have sticking, regardless of throttle shaft offset. You can still have it VERY closed up in terms of sealing. Pretty easy to have airflow around the blade to be <10% of the engine's idle air requirement.

i never said any thing about no stop screw!
the Aprilia's throttles have a stop screw, it is set, locked and sealed at the factory
its throttles are completely closed (and almost solvent tight) and don't stick

if you don't understand why the shaft is off set to the "uphill" side, look it up, its called physics

 

[adam728]

i never said any thing about no stop screw!
the Aprilia's throttles have a stop screw, it is set, locked and sealed at the factory
its throttles are completely closed (and almost solvent tight) and don't stick

if you don't understand why the shaft is off set to the "uphill" side, look it up, its called physics

I think we are arguing diffetent things here. If theres a stop screw, then I take that as not completely closed. Completely closed I view as blade stopping againt the throttle body bore, which will stick.

No need telling me about throttle shaft offset or how a butterfly valve works. I've worked on thousands of them, an engineering that has taken me around the world many times over. Theres a strong chance you have an engine with one of our products on it.

Sent via morse code

 

[theknurl]

I think we are arguing diffetent things here. If theres a stop screw, then I take that as not completely closed. Completely closed I view as blade stopping againt the throttle body bore, which will stick.

OK, Adam, it seals tight enough to barely leak solvent so its CLOSED, and it has a stop screw, you can view it any way you want

it doesn't stick because the big side of the blade is "downhill" and atmospheric pressure exerts more force on that side of the blade.......thats why there are TB return springs

the bypass ports are only 3mm so they are used for balancing with a Texa Axone or Navigator.......one is always closed

on my BMW R1150GS the blades are open a little less than 0.0005..... of course they don't fit for ****, the bypass screws have a 6mm needle shank, thats what you set idle with,
you set TPS at 381 Ohms, BMW says 300-400, then I use a analog electronic differential pressure gauge to balance the TBs, it'll even show you if you have sticky throttle cables

stock, 6th gear is only good over 50mph+, balanced it will idle down the street in 6th and pull cleanly away

stick a lambda meter on a BMW R1150GS and watch the fueling in real time......you'll die laughing.....

my buddy Bob hacked the Bosch Motronic ECU, you should see the fuel "curves" they are zig zag lines

like they have a clue

he MAKES ECUs and TBs

you think Honda Corp. figured out how to fuel inject cars????? oh, please.....

Russ Collins taught them, his shop was across the street from American Honda.....he's my God daughter's grandfather;
http://www.motorcyclemuseum.org/halloffame/hofimages/Collins1.jpg

they couldn't even understand his analog data until RC Junior digitized it

you think they could grind decent cams?????

not until Luther Iskenderian taught them .......as related to me by Dr. George Hadjis the former head of JPL.....he used to come by to see what crazy stuff i was up to

 

[theoldwizard1]

TOTALLY INCORRECT

throttle shafts are offset to the "uphill" side, making the "downhill" side of the blade larger in area. this larger area is acted on by atmospheric pressure
the offset is usually 0.020-0.040"
my Aprilia RSVR 1000cc twin ...

Well that may be true on your expensive motorcycle, but I recently had a discussion (in order to refresh my memory for another board) with a half a dozen engineers from on of the Detroit 3 company's who "lived" through the whole development cycle.

I stand by my previous statement, with some expensive motorcycles being the exception.

 

[adam728]

OK, Adam, it seals tight enough to barely leak solvent so its CLOSED, and it has a stop screw, you can view it any way you want

it doesn't stick because the big side of the blade is "downhill" and atmospheric pressure exerts more force on that side of the blade.......thats why there are TB return springs

the bypass ports are only 3mm so they are used for balancing with a Texa Axone or Navigator.......one is always closed

on my BMW R1150GS the blades are open a little less than 0.0005..... of course they don't fit for ****, the bypass screws have a 6mm needle shank, thats what you set idle with,
you set TPS at 381 Ohms, BMW says 300-400, then I use a analog electronic differential pressure gauge to balance the TBs, it'll even show you if you have sticky throttle cables

stock, 6th gear is only good over 50mph+, balanced it will idle down the street in 6th and pull cleanly away

stick a lambda meter on a BMW R1150GS and watch the fueling in real time......you'll die laughing.....

my buddy Bob hacked the Bosch Motronic ECU, you should see the fuel "curves" they are zig zag lines

like they have a clue

he MAKES ECUs and TBs

you think Honda Corp. figured out how to fuel inject cars????? oh, please.....

Russ Collins taught them, his shop was across the street from American Honda.....he's my God daughter's grandfather;
http://www.motorcyclemuseum.org/halloffame/hofimages/Collins1.jpg

they couldn't even understand his analog data until RC Junior digitized it

you think they could grind decent cams?????

not until Luther Iskenderian taught them .......as related to me by Dr. George Hadjis the former head of JPL.....he used to come by to see what crazy stuff i was up to

I am thinking we are agreering with each other, but you are still trying to "win" this agument?

All I am saying is that what you call closed valve isn't what we call closed valve. If the blade is hitting into the TB wall without a stop screw, then it's closed valve in my world, and will stick. We often set the zero point so close to that, and that's what you are calling "closed valve". Airflow is increased litterally nil, and standard TPS sensors won't even see the change in shaft rotation. You can block the airflow with a drop of oil. But that is not closed valve in my world.

And not all throttle bodies use an offset throttle shaft the way you explain. Many are centered. Many are offset in the opposite direction for equipment that runs a governor, such as generators, water pumps, tractors, lawnmowers, etc etc etc. It's heavily application specific.

But again, I'm just a moronic engineer, what do I know. We don't make tons of throttle bodies for OEM's or anything. I wasn't playing with a billet aluminum prototype yesterday. Yes, sometimes engineers do dumb things. Ususally its for reasons like everything being shot down unless it costs 1/10th of a penny. Or fuel maps that look crazy to "beat" an emissions drivecycle (not really the case anymore).

 

[theoldwizard1]

And not all throttle bodies use an offset throttle shaft the way you explain.

YEP ! Never seen one !!