K12GT Throttle Valve Potentiometer

[dan cata]

Hi all,

 

A friend of mine brought his 2003 K122GT, it has the servo brakes and all.

 

Among other routine maintenance, when connecting the GS911 diagnose unit, and trying to set up the TPS, this error appears:

 

 

Can someone please enlighten me what this valve is? Is it the TPS or something else? Can it be cleaned or repaired, or does it need replacement?

 

Alos, how am I suppose to adjust the TPS? It all seems so tight in there, not sure how I can loosen the screw in the back...

 

Thanks,

Dan.

[NCStephen]

From my limited knowledge this is the sensor that you adjust with throttle roll on before starting. So evidently the sensor position sensor is bad and thus you cannot do a TPS. As for steps to replace it I have no idea other than general location which may mean taking off a bunch of parts. While there church the distribution rail as it is due to be crumbling due to age. Good luck. Keep us informed.

NCS

[Dennis Andress]

Morning Dan.

 

First off the TPS can get dirty. It mates up to the shaft from the #4 throttle body. If the throttle body is dirty inside it's likely that some of the crud has seeped into the TPS. It can be cleaned with electrical contact cleaner. But, you'll have to remove the throttle bodies to do it. Not fun.

 

Okay, to adjust the thing. Remove the electrical connector. Loosen the two screws that hold the TPS in place. Patience is needed for the inboard screw. There are 4 connector pins on the bottom of the TPS. Connect an ohmeter to he rightmost two, the ones closer to the center of the bike. Turn the TPS on its mounting screws until that reading is as low as it can go. It's been my experience that the bike runs best when this reading is less than 1 ohm. If you can't get it that low I'd recommand cleaning the TPS. If you do get it to less than 1 ohm tighten the TPS screws and enjoy the ride.

 

If you find yourself removing the throttle bodies also remove the little intake stubs that sit between the throttles and the head. There are O'Rings there that typically last 2-3 years before they start sucking air. Replace them, they're cheap.

 

The cruise control cable is a ridiculous pain to disconnect from the throttle bodies. After doing it several times, and replacing one cable, I learned that the cable can be disconnected from the cruise control box and left attached to the throttle bodies. Protect it somehow so as to not damage it while cleaning the throttles.

 

The TPS has control over the idle solenoid on these bikes. If the idle is eratic, or too high or low, look to the TPS for the cause. My wife and I each had 2002 RS's. I bought one new TPS before I learned to how to clean them. With practice I was able to RxRxR (Remove, Repair, and Replace) the throttle bodies in less than 4 hours.

 

After all that work, might I recommend spending the money for new spark plug wires and plugs? The wires are absurdly expensive, but like the O'Rings I mentioned above, they seem to be worn out after 2 or 3 years.

 

Dennis

[dan cata]

Hi Dennis,

 

You obviously have experience in K TB's. More than I have

 

So... in this picture...

 

 

Link from here

 

Which one is the Throttle Valve potentiometer? What does the throttle actuator do? Does it only affect idle speed? As for adjusting the TPS, I have my GS911 diagnose unit that tells me where to set it to...

 

There's no cruise control on this bike. It only has 1 throttle cable, so I am assuming that the second slot in the handle cable arrangement is for the cruise control.

 

I will want to sync these TB's at some point, using the Harmonizer (great tool, btw) Where would I adjust the TB's from?

 

Thanks,

Dan.

[ESokoloff]

Hi Dennis,

 

You obviously have experience in K TB's. More than I have

 

Dennis has forgotten more about K's then most of ever knew

[Dennis Andress]

 

#2 is the TPS

#3, the throttle actuator, controls idle speed.

BMW says the throttle bodies are synched at the factory and shouldn't be adjusted. I've tried it a couple of times, never making things better. Early K12's, the ones without the throttle actuator, had air bypass screws on the throttles which could be adjusted.

 

Bikes with cruise control have three cables. The cruise control cable connects to a seperate bellcrank between #1 and 2 throttles. They had a reletivity short cable for the curise control that ran to a box above the left radiator. All the K12s I've seen have open and close throttle cables. Maybe this isn't true in all countries...

 

 

To make a K12 run like new.

• Replace the O2 sensor if the bike has more than 60,000 miles. Or, replace it if the bike has ran poorly for any length of time.
  
• Replace the sparkplug cables if they are more than two years old
  
• Replace the sparkplugs
  
• Remove and clean the throttle bodies
  
• Clean the TPS
  
• Replace the O'Rings between the throttle stubs and the head (#3 in the diagram below. From here)
  
• Upon reassembly, adjust the TPS so pins 3 and 4 measure approx. .75 ohms.
  

 

 

 

Dennis

[Dennis Andress]

Hi Dennis,

 

You obviously have experience in K TB's. More than I have

 

Dennis has forgotten more about K's then most of ever knew

 

Sadly, forgetting things goes beyond the K12...

 

Hey, I bought a decent bicycle! Been riding 4 or 5 miles every morning. Lots of fun!

[ESokoloff]

Hey, I bought a decent bicycle! Been riding 4 or 5 miles every morning. Lots of fun!

 

Great

You have about a year to get ready.

I did the Double Metric Century last Saturday & surprised myself by actually finishing

[Endobob]

To make a K12 run like new.

• Replace the O2 sensor if the bike has more than 60,000 miles. Or, replace it if the bike has ran poorly for any length of time.
  
• Replace the sparkplug cables if they are more than two years old
  
• Replace the sparkplugs
  
• Remove and clean the throttle bodies
  
• Clean the TPS
  
• Replace the O'Rings between the throttle stubs and the head (#3 in the diagram below. From here)
  
• Upon reassembly, adjust the TPS so pins 3 and 4 measure approx. .75 ohms.
  

Dennis

 

Hi Dennis,

 

Looking forward to seeing you and Laney in July!

 

My K12 now has 45K on it and has been running like new (after your help and tow to Sierra BMW for a new clutch slave cylinder at the UN 2 years ago). I will file your list away for future reference and hope that I will not need any assistance at this years UN Rally.

[dan cata]

Great, I think I have all the info I need now, to work on the bike.

 

One more thing - this friend of mine reported that during a trip on the Transalpina highway (a road that you must not miss if ever coming to Romania, along with the Transfagarasan), his engine cut out, because of overheating. The road is full of curves and I guess the water temp. has gotten to high. Does this bike have any kind of protection for overheating, like cutting the engine off or not letting you start it again until it cools down? Both fans seem to be working ok when testing them. He did change the coolant and my guess is that he did not exactly follow the manual procedure - I only have the manual for the k1200rs bike, but I guess it's the same engine and coolant circuit and process of replacing the coolant as on the GT, right?

 

Dan.

[Endobob]

Does this bike have any kind of protection for overheating, like cutting the engine off or not letting you start it again until it cools down? Both fans seem to be working ok when testing them. He did change the coolant and my guess is that he did not exactly follow the manual procedure - I only have the manual for the k1200rs bike, but I guess it's the same engine and coolant circuit and process of replacing the coolant as on the GT, right?

 

Dan.

 

Engine/coolant system exactly the same on RS and GT of the same year. I have never had the engine cut off on my K12 and am unaware of any mechanism to cut off the engine if it starts to overheat. I assume Dennis Andress would know. Hope he will post - if not send him a PM.

 

[Dennis Andress]

I've not heard of any kind of an engine cut off due to overheating. Maybe the fuel filter needs to be replaced. I've never seen a K12 overheat either -- as long as the fans are working. I replaced my thermostat once, but only because it was no longer completely closing. On a cold day the bike would never get up to normal operating tempature.

 

It's odd, but the thermostat is not completely open until the fans come on. So the fans being on don't mean the bike is too hot.

 

You can clean the cooling system with any mild radiator cleaner, as long as it's safe for aluminum. Use distilled water when refilling. I once came across a gallon of premixed coolant made by Honda for the Acord that I liked a lot.

 

One other thing. The oil pump and water pump share the same housing and shaft. There's a seal between them that is known to fail. You might want to look for oil/water mix in the raditors.

 

 

On a completly different note. The ignition switch can get dirty and cause all kinds of stupid electircal things. There's a small screw on the side which when backed out will allow the electrical mechanism to slide out the bottom.

 

 

Dennis

 

[tallman]

Me three on cutoff/overheating, never seen.

 

Dennis,

Wasn't the thermostat used in the K12 from the 1100 and basically the 1200 gauge and the thermostat feedback display gave the impression the engine was running "hot" but really isn't.

A difference in calibration I think.

[Dennis Andress]

Yeah, something like that. I think the fans came one when the temp guage reached the bottom of the red zone.

 

For the engine cutting out, I'd start by looking for a dirty ignition switch, and then check fuel pump pressure.

[Endobob]

Thanks for posting Dennis - very interesting!

[dan cata]

This may sound dumb to you, but how do I get that plastic thingy off the fuel tank, to change the fuel filter? I only have the k12RS and LT manual, and in there, there are 6 screws that need to come off...

 

Dan.

[Dennis Andress]

It comes out from the bottom of the tank, Dan.

 

This image is drawn as if the tank were upside down. The big plastic ring, #14, is unscrewed, and then the filter and pump can be pulled out as an assembly.

 

 

 

There are two plastic quick disconnects on the bottom of the tank (#1 and 2 below). Be careful with them, they break easily. In fact, they've been known to fail all on their own, spraying fuel on a hot summer's day.

 

[dan cata]

I knew where it was, just did not know hot to open that large jar cap

 

It came off in the end by using an oil filter wrench that has some leather belt like, made a torque with that one and voila!

 

I only have to change the carter oil hose and then put it all back together. Oh, and take it for a long trip, I cannot give it back to him unless it is properly tested

 

Dan.

[Dennis Andress]

K bikes always run better after hitting the rev-limiter a couple times....

[dan cata]

My RT runs like an electric motor after I come off the highway, doing 180 km/h for 50 kms

 

Dan.

[dan cata]

Well, I put the bike together and took it for a ride. I was riding it for about 30 kms or so, all seemed normal, the water temp stood on the half of the scale, where the white line is.

 

Then, my friend came for it. He took it and again, he is having problems. He says that it's overheating (the temp is hi these days over here too).

 

He also reported that the water temp needle started to rise fast, like the accelerometer needle does. This leads me to an electrical sort of problem.

 

So here's the question: how many water temp sensors does the k12gt have and where are they located? Are there 2? One for the dash and one for the motronic? Or just one sensor that supplies info to both?

 

Dan.

[SailorJean]

Well, I put the bike together and took it for a ride. I was riding it for about 30 kms or so, all seemed normal, the water temp stood on the half of the scale, where the white line is.

 

Then, my friend came for it. He took it and again, he is having problems. He says that it's overheating (the temp is hi these days over here too).

 

He also reported that the water temp needle started to rise fast, like the accelerometer needle does. This leads me to an electrical sort of problem.

 

So here's the question: how many water temp sensors does the k12gt have and where are they located? Are there 2? One for the dash and one for the motronic? Or just one sensor that supplies info to both?

 

Dan.

 

I am assuming we are dealing with a K1200GT between 2003-2005 (brick engine) - same engine as a K1200RS or a K1200LT.

 

This engine as 2 temperature sensors:

 

1) The front one ONLY drives the temperature gauge on the instrument panel and is located below the water-pump (font of the engine). With ignition OFF, using an OhmMeter between the single wire connector and the base of the sensor (or the engine) as a ground, you should read approx 630 Ohms at 20 celcius (70 F) and approx 35 Ohms when the engine is very hot (just as the radiator fans start). All values in between are also valid as the engine is warming up.

 

 

2) The other sensor feeds data to the ECU (BOSCH Motronic) to adjust the fuel-air mixture - this info is also used to start the radiator fans at 105 celcius. This one is bolted into the back of cyclinder #4 (rearmost) and has a long wire with a 2 pins connector attached under the seat. See this link for pictures and instructions how to test with an Ohhmeter (ignition should be OFF):

https://picasaweb.google.com/101489741192933663432/BMWK1200RSEngineTemperatureSensor#

 

[Dennis Andress]

That sucks.

 

The forward temp sensor that John mentioned, the one for the guage, can get saturated with oil which eats up the wire insulation. Worth looking at.

 

Take the bike for a ride and see if you can duplicate the problem. If so, are the fans on? They are not controlled by the guage so if they are not on when the guage reads high I'd suspect the problem to be only related to the guage.

 

I replaced the engine temp senseor, the second one John mentioned, on one of my K100's, and on both my wife's and my K12 RS. They made a world of difference in the way the bikes ran. My seat of the pants feeling is that checking it at different tempatures with an ohmmeter doesn't give the full story as to the health of the sensor. I think how the sensor reacts to tempature changes is what we feel when riding, and something we can't test.

 

Dennis

[NCStephen]

The assumption here is that something is truly wrong I think. Depending upon who is riding it, the overall conditions, the speed being ridden as well as the RPMs being used, can create very very different readings on the gauge. In warm to hot temperatures at steady speeds 35 mph to 75 or so and in gears keeping the rpms as low as possible with air flowing cleanly into the front of the bike, my gauge seems to hang around the middle of the range. If I stop at lights and then repeat stop and go it is in the upper range. If I run behind trucks and vans it climbs to the near the top of the temp icon. If I am running so the rpms are above 5000, the needle is clearly in the upper part of the range. If you ride faster with the rpms even higher, the needle remains high. I recently had the experience of riding fast in temperatures of 100F. The rpms were almost always between 7500 and 9000 with full throttle on and off. The needle remained just a faction below the red line, above the point where the fans turn on.

 

My point is, you rode the bike and all seemed fine. Your friend rode his bike and said something seems amiss. I think I would first look to what the variation of the two rides was.

 

NCS

[dan cata]

 

 

so, I have replaced the #5 part, the hose... It was leaking and just replaced it with a regular hose... Does the OEM one have some kind of valve in it to limit the carter oil? Because now, it does give some blue and black smoke under heavy acceleration...

 

Also noticed that the rear water temp sensor is bad. Will have that one replaced asap too.

 

Dan.

[Dennis Andress]

No, there is nothing special in that hose. Maybe the smoke will clear up after the temp sensor is replaced.

 

Dennis