2003GT Tickover Speed/ECU/TPS - K-Bikes.com - Excellence in Motion
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post #1 of 7 (permalink) Old Oct 21st, 2007, 9:53 am Thread Starter
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Location: Nairn , Highland, Scotland, U.K.
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2003GT Tickover Speed/ECU/TPS

As a very recent purchaser of a 2003 GT having come from an 1100RS, I was delighted to find this site to obtain loads of invaluable information about my new purchase. I have been particularly pleased to read the various bits of info regarding ECU/Cold start issues,as it was a big concern when I first got my bike, but having found that it is a peculiarity of this model and, with the help of other contributors, I was able to greatly improve the situation by re-setting the Throttle Position Sensor to the ECU. However I wonder if anyone has ever tried re-positioning the TPS after having done the re-set to try and fool the ECU into thinking that the throttle is open more than it actually is and thereby delivering more fuel, i.e. giving a richer mixture. Most contributors seem to think that the ECU mapping is set to give very lean running and a look at the colour of the sparkplugs confirms this.
As someone who has grown up on carburettors, like the nice old Amals on my Norton Commando,I confess to being somewhat out of my depth with fuel injection but all of the characteristics of my bikes tickover/small throttle opening faults would have had me reaching for a screwdriver to turn the air screw in half a turn. The faults are :- 1) The tickover is too fast at 1100rpm ( sometimes up to 1300rpm)
2) Throttle pick-up when cold is very flat.
3) There is some misfiring on small throttle openings when trickling along in the lower gears.
Does anyone know how to slow the tickover down ? I have checked all the cables for free play, and you can hear the butterflies closing with a metalic click, but onto what?? There's no stop screw for them. There's one for the cruise control cut-out micro-switch which had me fooled for a while !
Speaking of Cruise Control- When I turn mine on, the bike surges slightly. Disengage it and switch it in again, no surge. Is this normal ?
Finally, a safety issue !! Have a look at your back brake resovoir feed pipe. Mine was clipped to the pipe from the master cylinder with a plastic clip which held it out such that it was being rubbed by the swinging arm. This action had rubbed through the pipes rubber sleeving and, if left in this position, would have eventually rubbed through the hose itself !!
Any thoughts would be much appreciated particularly on re-positioning the TPS to improve all my slow running gripes. Oh ! and if anyone knows how to cure the " Box of Rocks" tickover rattle, I would love to cure that too.
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post #2 of 7 (permalink) Old Oct 21st, 2007, 10:14 pm
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K1200GT Idle speed

Check the vacum hoses at the throtle bodes. This motor has it's idle speed controlled by a stepper motor, so you can't adjust it, but idle speed can rise with a vacum leak. Also check the battery terminals; loose terminals cause more trouble with running on K motors than any other.

Poor throttle response cold may be due to a faulty motronic-there is an updated motronic unit for these bikes. Have your dealer check it's service history.

The box of rocks idle is due to it's powerful alternator. "They all do that"!
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post #3 of 7 (permalink) Old Oct 22nd, 2007, 4:12 am
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Just my personal view that messing with the TPS is a big danger area. I believe the ECU does checks at startup which define the map for the entire throttle range. The reference point is the electronic zero (which is actually an offset) at the TPS rest position.

The idle speed is controlled by the ECU responding to the crankshaft sensors, so I'm pretty sure that a good engine will always idle at 1100rpm. If yours is doing 1300 then something is wrong. Vacuum leaks may force a higher idle, but that would mean the ECU is outside its adjusting loop. My older KRS does have adjustment screws on the throttle bodies which I played with last week using vacuum guages. The idle didn't change too much, but some roughness disappeared when the vacs were in balance. Presumably you've checked that the throttle butterflies do return with a nice 'click' and there is some free play in the throttle cable at full locks? This rest position must be achieved with slack so the ECU can initialise correctly at start up.

I cannot find much in common with carbs and the Efi systems used on these bikes. They are in fine balance mainly controlled by software versions and electronic feedback. A whole new ball game and easy to screw up. The mechanical TPS setting is extremely sensitive and critical to adjust, and much easier to check and adjust on their Moditec.

I don't use dealers for most of my maintenance, but I do think 1/2 hour on a Moditec diagnostics computer driven by a competent tech. is money worth spending.

If your K bike doesn't rattle then it must be a Japanese bike!

The box of rocks is due to either the intermediate output shaft gears (our bikes don't have the crank directly driving a large heavy flywheel, or it's connected with the clutch in some cases. Don't worry, wear ear plugs!

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post #4 of 7 (permalink) Old Oct 22nd, 2007, 8:35 am
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Cruise Control

I believe your initial engagement for the cruise control is identical to mine. Try accelerating ever so slightly as you engage the set function...I think you'll find it will engage without any surge. It's a very fast acting engagement......so just a small adjustment by the rider and you and the Beemer will be very happy.
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post #5 of 7 (permalink) Old Oct 22nd, 2007, 12:01 pm
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Same model and year as me; so the chances are, the same ECU et al ! Lots has been said in this forum about faulty ECU etc. I am pretty sure I have the "faulty" one because the bike definitely needs 2 mins warm up before she will reliably pick up from a closed throttle.

What I am unsure of is what your problem is; I read your post and thought oh gosh, another super technical rider; Voxmagna will be here in a flash, (and I was right!); but what problems are you having with your GT. Mine is superb, after the initial warm up.

John I. Stephen - Tunbridge Wells, Kent, UK
K1300 GT (quite superb ! )
Triumph Tiger 1050 (2008)
K1200 GT (2003)
R1150R (2002)
Suzuki GS 750 (late 1970s)
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post #6 of 7 (permalink) Old Oct 24th, 2007, 4:31 am Thread Starter
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Location: Nairn , Highland, Scotland, U.K.
Posts: 28
Happier Now

Hi Guys,
Thanks to the four of you that responded to my query.
After having posted my "thread" I realised that I had not exhausted the " related threads" links which more or less confirmed that the running characteristics that I am experiencing are pretty much the norm for this model and coupled with your additional comments and technical info have put my mind at rest.
It's always the same when you buy a secondhand vehicle that is out warranty from a private individual, if it sounds or runs unusual you are convinced you have bought a knackered dog. This one rumbles a bit (normal !), ticks over at 1100rpm when the handbook says 900-950 (normal !), runs lumpy at low rpm (normal !) and surges a bit when you engage cruise control ( normal !). I suppose I expected more from BMW on this latest development of K series engines having owned a K75, K100 and K1100 all of which showed none of these characteristics. Thats progress for you eh !! Incidently, the 75 and 100 models both had far better gearboxes and the 1100, although not as precise as the others, was not so sloppy in the transmission as this 1200. Ride any of the latest models and you will find the same. Nevertheless this is a great bike, goes like stink, is extremely comfortable and practical and is an absolute joy out on the open road. Just "bar-backs" and a taller screen are on my shopping list.
Nobody mentioned my observations on the rear brake hose issue which seemed pretty important. Was mine unusual ?
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post #7 of 7 (permalink) Old Oct 24th, 2007, 9:34 am
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Hello Neville. You are not alone; I went through the same concerns as you. However, I have just had to realign my view on "normal" so that when I am sitting at the traffic lights sounding like I have a knackered engine (full of old nails), I just smile knowing that the moment the lights go green, all the on-lookers disappear in the rear view mirror as the tacho heads due north

Enjoy while you can. Th new K series is totally different and just buzzes; not nice IMHO.


John I. Stephen - Tunbridge Wells, Kent, UK
K1300 GT (quite superb ! )
Triumph Tiger 1050 (2008)
K1200 GT (2003)
R1150R (2002)
Suzuki GS 750 (late 1970s)
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