throttle body re-install

[joeb]

Morn all. This is an offshoot of my topic, strange engine noise, where it was determined that a throttle body rebuild may be in order. Just trying to figure out how big a can of worms I'd be opening when I decide to reinstall. Dirt Rider mentioned using voltage to reset the TPS on the body. My Haynes manual said the TPS is pre-set and can be a pain to set. Starting to sound complicated. To my Neanderthal naive mind, I envisioned just reinstalling the TB and adjusting the cable so that the butterfly opens at the same time as the other side. If this is not the case, how big of a job is it, and is there a link already existing where I an go to read about it. Thanks much.

[Michaelr11]

Going back to your original post it sounded like your left TB wasn't really an issue. If you only rebuild the right TB then you only have to perform a simple TB sync.

 

But, if you do rebuild both sides, then yes you have to remove the TPS and then set it when reinstall it. I don't have the link to it right now, but setting TPS is not all that difficult. Moving the TPS even a tiny bit changes the TPS voltage setting a lot, so trying return it to the original position by eyeball won't work. There are four wires in the TPS connector. I believe wire 4, Red/White is the wire you must read to set it. You get a really thin wire and strip off some insulation then position it on terminal 4 so you can attach a voltmeter to the other end of the wire. The terminal has to be reconnected to the throttle body. I believe you are looking to get .375 volts from that lead with the throttle resting on the idle stop.

 

If you can get hold of a GS-911 (for the R1100RT) you can just plug it in and it will tell you if the TPS is set correctly. It won't tell you the voltage but it will tell you if it is in the accepted voltage range. The 1100 GS-911 is a unique tool - only works on the R1100 and only does a few functions. Not at all like the other GS-911.

 

The whole thing is harder to explain than it is to do it.

 

Edit - the red/white is pin 1 not pin 4. The write-up is in the Oilhead_Maintenance Manual. Throttle Position Sensor - Bob Gorman.

[dirtrider]

Morn all. This is an offshoot of my topic, strange engine noise, where it was determined that a throttle body rebuild may be in order. Just trying to figure out how big a can of worms I'd be opening when I decide to reinstall. Dirt Rider mentioned using voltage to reset the TPS on the body. My Haynes manual said the TPS is pre-set and can be a pain to set. Starting to sound complicated. To my Neanderthal naive mind, I envisioned just reinstalling the TB and adjusting the cable so that the butterfly opens at the same time as the other side. If this is not the case, how big of a job is it, and is there a link already existing where I an go to read about it.

 

Afternoon Joeb

 

Any time that you install a new throttle shaft or even remove then re-install the throttle plate you disturb/change the air flow past the throttle plate with the TB throttle cam resting on the idle stop screw.

 

The base idle screw setting vs air flow is a big factor in proper TB balance & engine operation.

 

If you just start replacing parts (like bushings & throttle shafts) then you will need to do a proper base idle screw setting & that is based on air flow vs throttle plate angle.

 

Seeing as you have no way to measure the air flow vs throttle plate angle at home about the only way to do that is by using TPS voltage (or TPS resistance).

 

As I mentioned above (IF) you only do one side at a time then re-balance the system before doing the other side you can probably get by without messing with the TPS settings (especially if you only replace the R/H side throttle shaft & bushings.

 

Even if you need to re-do the TPS settings it really isn't that big of a deal if you have a good digital voltmeter.

[Michaelr11]

The Oilhead Maintenance Manual is located in the resource section of the Internet BMW Riders site.

 

http://www.ibmwr.org/r-tech/oilheads/index.shtml

 

It's labeled the Tuneup Manual there, 02/2002.

[dirtrider]

Afternoon Joeb

 

Do not use the 0=0 from that site as it will give you the incorrect base idle screw settings.

[joeb]

Beginning to think ear plugs may be the answer to reduce engine noise.

[dirtrider]

Beginning to think ear plugs may be the answer to reduce engine noise.

 

Afternoon Joeb

 

I have owned a number of BMW boxers that had a R/H TB rattle at idle. As long as the throttle shaft to bushing is relatively tight, & the TB balance is easy to do, & it maintains TB balance for a reasonable time then I just didn't worry about it.

 

My first BMW oilhead boxer (single cable system) rattled like crazy even with only a couple of thousand miles on it. Nothing loose on the TB shaft or bushings but the single cable systems need a tight cable to R/H side to maintain balance properly.

 

It bothered me as a rattling anything didn't seem right. So I spent a few hours making a longer TB shaft cap to allow a spring & ball bearing to put pressure on the end of the throttle shaft. That stopped the rattling but was a lot of work for no real gain in performance or function so I never did another one.

 

Just adding a dead TPS to the R/H side (if possible) would probably cure the rattling also as all it takes is a little spring pressure on the TB cam/shaft assembly to stop the rattle.