Jerky at slow speed

[Chris Terry]

My 12GS has just completed 1000 miles and had it's first service. So for the first time I took my wife out for a spin. All was fine until we got into heavy traffic. The bike did'nt want to crawl along smoothly in a low gear with low revs. It felt like a slack chain (remember them) and a on and off switch instead of a variable throttle.
This is my first BMW are they all like this??

 

[Le singe]

My 1100 does this sometimes,I get around it by using a bit of front brake.
I let the engine work against a bit of front brake when doing full-lock turnarounds as well,it smooths it out no end.
Wouldn't recommend it for 10 miles in a very slow- moving queue!

 

[sjwb]

See post Rough Idle

This IS a known problem to BMW - and one supposes their dealers. There is a software update due (the first one has a glitch) which will attend to the very touchy, open to closed and closed to open throttle operation. I had the first version of the download which along with an adjustment of the base idle made the bike much more acceptable. Sadly a condition then exists whereby the ECM detects (or believes that it detects) a fault and imposes a 'default' idle setting which is elevated and rough. This can be re-set by an ignition on off cycle.
I am in contact with my dealer over this and we are awaiting the new download.
Incidentaly the cause of poor idle will be evident when you check the balance (sync) at idle and discover up to 2" (50mm) mercury difference left to right.
Do not accept that a rough idle is a feature of the engine - it is not; push your dealer to fix it.
The rider to this of course is how finicky or sensitive you may be!

 

[Wraithwrider]

sjwb

This idle adjustment issue on the 1200 is a topic that has 'done the rounds' on this forum.

Throttle body adjustment at idle is done automatically by the bike's own sensors using linear (stepper) motor's.

What this means is that the dealer cannot adjust the idle, even by plugging in the workshop computer.

That's not to say that there may not be a fault in the automatic system though and there has been cases of stepper motors failing or sticking evidentally.

But the amount that the idle adjustment can be 'out' and still in spec according to BMW is quite large. (Hang on while I check the manual).

It's 15 mbar. That needs converting to mmHg.

That's 11.25 mmHg.

My bike had a lumpy idle but was in spec according to the computer.

Another factor, is that according to BMW the stepper motors interfere with balance adjustment above idle too, unless they are put in a 'park' position using the BMW workshop computer.

Peter

 

[sjwb]

Peter,
My response was a copy of my answer to a previous thread.
An observation or two:
The tolerance of 11mm hg is quite small and would probably go unnoticed. What is an issue is the inability of the GT1 to measure accurately said imbalance. Mine showed OK on the diagnostics but was in fact 35 to 45 mm hg unbalanced. This obviously was evident in a very poor idle quality.
The dealer can adjust the idle balance and let us be clear, it is the equalization of left to right air flow at idle which is the issue - not idle speed.
I would suggest that the stepper motors have NO effect off-idle; the prime function is to maintain idle speed and quality independent of electrical load and temperature.
To the original issue; there is a forthcoming software modification to smooth transition from open to closed and closed to open throttle and as intimated, I am waiting for my dealer to notify me of availability. Interestingly the ST is nowhere near as sensitive.

Chris,
Talk to your dealer and be persistent.

 

[Wraithwrider]

Chris

I have it from 3 sources that the dealer cannot adjust idle balance.

1. Dan, the 'top' tech at Jefferies
2. From reading the manual, which is quite clear.
3. From a Swedish poster who had this info. (I didn't believe him at first either).

Sources 2 and 3 confirm that although the stepper motor's function is to adjust idle balance they do, also effect the measurement of balance at higher revs unless GT1 is used to place them in a parked position.

This isn't as daft as it seems when you consider how little throttle opening is understandably required to maintain 4,000 or 5,000 rpm with no load.

I don't deny that you can go through the process of balancing the throttle bodies off idle and make make the bike run more smoothly (a success) but you won't know if the stepper motors have effected the process and made it less worthwhile.

Peter

 

[Wraithwrider]

Chris

Sorry to 'harp' on here but just to add that there are two stepper motors, one on each throttle body. While they do indeed regulate idle rpm overall the respective positions must also regulate balance.

I accept what you say about the GT1's inability to measure the pressure differential properly. My bike was in spec on the GT1 and using a Carbtune II it was 20 to 30 mmHg out.

It would seem to be that the system doesn't work very well, maybe having to great a hysterisis or stiction in it's control function.

My bike has smoothed out a lot at idle over the past few hundred miles so perhaps the motors have eventually done their stuff. I wonder how long for though?

Peter

 

[Dinger]

This thread has gone off the original point, rough running at low speeds (not idle).
I've done nearly 3000 miles and mine is getting to be a right bitch at 2-3000 rpm. It makes me ride like an amateur at junctions and roundabouts and is verging on the bloody dangerous. I find it necessary to ride the brake and clutch to compensate for it's "all-or--all" throttle control. Everywhere else it's fine.
My dealer assures me that the software update was done at the first service.
I'm going to need an interim service to set me up for a big Euro trip at the end of the month and I hope they'll sort it then.

 

[Rich]

I cant decide if Im on topic now but I find first gear running, i.e. the old walking pace low speed control very jerky unless I slip the clutch a little. This seems especially apparent on rough surfaces where I'd like to pootle along at v low speed.

The flipside seems to be that first is actually useful at slightly higher speeds, i.e. not too short (I think thats how to describe it).

I find Im geeting used to it but my ultra-slow riding isnt as smooth as Id like.

Otehrwise Im finding it fairly smooth through the range.

 

[Garfieldus]

I'm not trying to be funny/facetious/anti12 here but if you're not happy give it back. That's what I did and got another adventure. I'll never be a BMW beta tester again.

 

[Gonzo]

This thread has gone off the original point, rough running at low speeds (not idle).
I've done nearly 3000 miles and mine is getting to be a right bitch at 2-3000 rpm. It makes me ride like an amateur at junctions and roundabouts and is verging on the bloody dangerous. I find it necessary to ride the brake and clutch to compensate for it's "all-or--all" throttle control. Everywhere else it's fine.
My dealer assures me that the software update was done at the first service.
I'm going to need an interim service to set me up for a big Euro trip at the end of the month and I hope they'll sort it then.

Thought it was just me. Now doing most riding out of London so have "forgotten" about this "engineering feature".

Park Lane have been at elast willing to (apaprently) listen on this subject so I'll be calling next week to see if they want to own up the aforesaid imminent software update.

 

[Dinger]

Thought it was just me. Now doing most riding out of London so have "forgotten" about this "engineering feature".

Park Lane have been at elast willing to (apaprently) listen on this subject so I'll be calling next week to see if they want to own up the aforesaid imminent software update.

Top man, that will be in time for my service (on the 16th), do me a favour and keep me posted so I can fire one off at my dealer.

 

[GrinningGSer]

The bike did'nt want to crawl along smoothly in a low gear with low revs

Chris Terry
I fully agree with you. Most of my riding to date has been with a pillion and I find that this is more noticeable than when riding solo. In fact anything under 30mph and under 3000rpm just cannot be called smooth!

However- I am sort of getting used to it and the bike IS changing for the better as I clock the miles. Now 1500 and so much more flexible. I can actually do 30mph in 4th now, which was not possible when new and I could hardly believe it when others here can do this!

SJWB

I am sure that something is amiss with the software fuelling control cos I get a marked surge when decelerating at 2500rpm (Feb05 delivery, but Nov04 bulid), Dealer says he is awaiting software update but and cannot give a date, It would be helpful if you can let us know when you have achieved the update and what the effect is ?

Waithwrider

Yes we have been through this before under several different threads. Idle balances are out of sync, stepper motors control this and dealer cannot alter this, but maybe a software update can- I wait with anticipation

Paul

 

[TerryM]

Having only recently noticed a similar roughness at low speed in town I wondered if it was my imagination. Now I will follow it up with the dealer.

Previously it seemed only that the off throttle engine braking on the upchange needed sensitive control compared even to Ducatis. Great big pots and piston inertia I suppose along with tight fueling off throttle.

Terry

 

[d.d.d]

8K, still jerky

the symptoms you guys describe are spot on. The bad news they don't go away. I,ve had the 6K miles tuneup a while ago, didn't make a difference. The dealers here on the US West Coast haven't heard of any upgrades to the FI software. In addition to that, lately it's acting up when getting on the gas relatively aggressively after a few seconds of coasting at 3- 3.5k rpm. Example: I'm doing 70mph on the freeway when I have to cut the throttle because of heavy traffic, no passing opportunities. I'm off the gas, engine breaking in 5th, rpm drops to about 35 hundred. An opening comes up, iget on the gas again. I know some of you will say i should be downshifting, and I do most of the time. my point is that the boxer should be this torque monster capable of accelerating from 3k. Well, it doesn't. It starts stuttering and coughing back into the airbox while going nowhere. My intuition is telling me that it's the spark reterding feature that is supposed to prevent detonation, because it happens under circumstances that used to cause pinging on all my three previous GSes: hot motor, extra lean mixture under engine braking/ coasting, piss-poor quality of american gas. opinions anybody? I'll be taking it in for inspection next Sat, I'll keep you posted.
Thanks, d.d.d.

 

[d.d.d]

excuse my typos...

... I'll be more careful next time.

d.d.d

 

[drdata]

Took delivery of my R12GS last September. At my 6K service last month my dealer (in LA) also informed me that there were no SW updates, or recall for rusty fuel pump connector, pending my ride.

I mention this becuase right after I got the bike I saw posting about an updated fuel map, and assumed I would be a candidate.

Cheers

 

[Wraithwrider]

My bike was serviced and updated on 5/11/04 and as of a month or so ago I was told that there were no new updates to the software.

Peter

 

[birdseye]

Re: 8K, still jerky

the symptoms you guys describe are spot on. The bad news they don't go away. I,ve had the 6K miles tuneup a while ago, didn't make a difference. The dealers here on the US West Coast haven't heard of any upgrades to the FI software. In addition to that, lately it's acting up when getting on the gas relatively aggressively after a few seconds of coasting at 3- 3.5k rpm. Example: I'm doing 70mph on the freeway when I have to cut the throttle because of heavy traffic, no passing opportunities. I'm off the gas, engine breaking in 5th, rpm drops to about 35 hundred. An opening comes up, iget on the gas again. I know some of you will say i should be downshifting, and I do most of the time. my point is that the boxer should be this torque monster capable of accelerating from 3k. Well, it doesn't. It starts stuttering and coughing back into the airbox while going nowhere. My intuition is telling me that it's the spark reterding feature that is supposed to prevent detonation, because it happens under circumstances that used to cause pinging on all my three previous GSes: hot motor, extra lean mixture under engine braking/ coasting, piss-poor quality of american gas. opinions anybody? I'll be taking it in for inspection next Sat, I'll keep you posted.
Thanks, d.d.d.

For what its worth, my 1200 running on Euro petrol definitely doesnt do what you describe. There is a surge under engine braking about 2500 rpm but at no point does opening the throttle cause the hesitation and spitting back that you describe. Barring a specific problem on your bike, my guess is that this is some US inspired pollution requirement which BM have met by dialling in a really weak mixture