Synching the injectors (the detail)

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blackduck

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Hi,
I have set the gauge up and the injectors are out of synch. One is higher that the other. The question is which one do I adjust, the higher or the lower. The idle is spot on 1100 as you might expect.

I hope to sort this out tonight so any help today would be appreciated.
 
Could be having the throttle position sensor on the LH throttle body is a factor.

Look on the LH side as a datum. Apart from anything else, adjusting both sides doubles the amount of ways to scew it up.

Russ.
 
The left side has the Motronic connected to it and is therefore controlled by the Motronic, the right side is merely a slave so sync the right one only leave the left untouched.
 
Right

Yup I agree just tweek the right pot.

BTW: Have you considered measuring the output on pin 1 of the throttle position sensor ?

It is worth doing. According to Rob L on ibmwr.com it should be 370mV-400mV. I found mine to be 340mV. I put to 385mV then twinmaxed again and did find a little improvement. I'm sure the improvement was the adjustment of the throttle position sensor since a twinmaxed just 1 week before so all that changed was the adjustment of the throttle position sensor.
 
Interesting.......

The figures Malcolm quotes almost exactly mirror the figures I worked with when I 0=0 'ed my '98 GS because of a slowly worsening surging problem. This makes me very happy. My initial throttle position sensor [TPS] reading was .341mv which was adjusted to .381mv. This adjustment along with a move to Champion single electrode plugs totally removed any surging.

Rob Lentinis' 0=0 procedure [performed at 24k miles] is the only time in 33k miles I have ever touched the LH throttle bodies.

A basic outline of the method I use now to tune the injectors is.......

1. Make sure valve adjustment is spot on.

2. Back brass screws of 1.5 turns EXACTLY. I use a nail in BluTac, stuck to the throttle body as a pointer to line up with the slot in the brass screw to ensure both brass screws are out precisely the same amount - 1.5 turns.

3. Balance at idle using the RH throttle plate stop screw.

4. @ 3000rpm balance using RH throttle cable.

5. Using a TwinMax lift the flap that covers the petrol cap key hole then cable tie the TM to it. Go on a run and observe any out of sync readings. These can then be corrected by the side of the road by either increasing or removing 'weight' from the RH cable lock nut.

I think the bike now runs better than it ever has.

Russ.
 
City Slicker / Julian read this

Yeah, cool.

Incidentially my GS is a 98 also.

Recently I took measurements on 2 R1150GS's one was 355mV (? certainly < 360mV) and one was 365mV. It seems the one with more miles was the lower one. I wonder if the effect of age/more miles is for the reading to drop ? This may make sense coz I doubt it would increase since if you look at the Rob L doc he mentions that +400mV and you will need to reset the engine management computer and since people don't need to do this all the time I guess through time the reading decreases.

Certainly on the 3 bikes I have measured this does seem to be the case. In fact come to think of it I know of a R1100RS that also had a reading less than 370mV.
An important point to note is that if you set close to 400mV and there is any error in your digital voltmeter then you could set the actual (as opposed to the measured) to be greater than 400mV.

That would mean a reset of the engine management, so make sure you set a bit lower than 400mV. I think there is a recomendation that 385mV is correct for sea level so go for that and ensure the actual is <400mV. If you are worried about this then just take your time as the docs state that as long as you do not start the bike then there is no issue. To be doubly sure I measured the voltage once I had repositioned the sensor and tighted both allen bolts.

City Slicker / Julian hope this helps....

And while we are on the subject of balancing etc. Have you ever replaced the throttle cables ? I think the Haynes manual mentions doing this at 18k. I am coming up for the 24k service and thought I might do despite the fact the feel of the throttle is as new.

My advice to anyone trying these procedures is to read very carefully the docs on
www.ibmwr.com and you'll find it all quite easy it just appears a bit daunting but is actually OK. Plus second time around it takes seconds to ensure you are within limits.
 
Well I got the carbtune out last night and they were out of synch.
RH way down on the the LH but depite turning a 1/4 at a time all the way to a full turn it didn't help. So I put it back the way it was
Any suggestions?
 
I take it you are turning the big brass screws for the idle ?

If you are balancing in the 3-4,000rpm range you need to adjust the RH cable. And it takes very little to make a large diff. For me the 1st time I changed I moved RH cable about half a turn and it took the bike from vibrating at 90mph to not doing so. And by that I mean 110mph and no shaking.
 
Malcolm.

Can't really comment on the age thing, but yes, you may have a point. Mechanical/moving parts wear so the fact that an adjustment is required as mileage increases doesn't surprise me. Also, the TPS is not at all protected a knock could well alter the settings.

I've actually had the bottoms of my waterproofs catch on the TPS as I went to put my foot down at a set of lights. Trust me on this, the time it takes to work out why your foots tied to the bike and what to do about it had better be short.......real short.

As for replacing the cables - I have considered this but like yours mine still feel like new. IMO, the existing cables are fully 'run in', that's to say they've stretched as much as they're going to. I feel this stable cable length can only be a good thing as far as adjusting and maintaining injector balance goes.
I seem to have read somewhere that to access the cable junction box requires the removal of the ABS unit. *If* this is correct then I really would leave replacement of the cables as long as possible.
As for Haynes recommending replacement at 18k.........do they recommend adjusting the throttle body sensor.

If I may add my own word of warning to anyone using the 0=0 technique, make sure your meter leads are not going to fall off while your rotating the TPS. Turning the TPS back and forth trying to get the meter to work ain't a good feeling.

Rather than inserting a pin [bit doggy IMO] to measure voltage have you any thoughts on some how 'exposing' the cable prior to the plug?
 
As for Haynes recommending replacement at 18k.........do they recommend adjusting the throttle body sensor.
No. And I know what you mean Haynes is not conclusive.

Turning the TPS back and forth trying to get the meter to work ain't a good feeling.
I agree.

Rather than inserting a pin [bit doggy IMO] to measure voltage have you any thoughts on some how 'exposing' the cable prior to the plug?
No other than getting a male and female equivilant of the plug to connect straight through and allow for a connection to pin #1.

I don't like the stabbing pin either.
 
I also have pondered the wisdom of changing the cables. BMW and Haynes state that the cables should be replaced at 30,000 Klm's. My 98 1100 is just about to hit 60,000 Klm's and the cables are as sweet as anything. I'll be leaving them as they are for now!

I think that BMW are coming from the angle of keeping the throttle cable set up in an as new condition. The requirement for that would be to change the cables every 30,000 to 50,000 Klm's. I recently tried the twist grip on a friend's newly acquired 1100 it only has 13,000 Klm's on the clock and the twist grip did feel easier to pull than mine, even though mine is real easy to twist there is a difference and I would suggest that I will change the cables somewhere around 80,000 or so Klm's.

Getting the throttle junction box out doesn't require the removal of the ABS. With a fair bit of fiddling it slides out one side, I've done it so that I could have a gander at the cable set up. By the way don't do this unless you have a TwinMax or similar instrument.

Mick.
 
Having had a gradually stiffening throttle at the twistgrip for the last 10,000 miles and some rough running issues related to throttle body balancing, I lubricated the cables with silicone grease and Bingo! back to normal.

Does Haynes mention lubing cables? BMW does not do this in servicing, which I find unusual because all moving parts should be lubricated. I know that the later cables are plastic lined but still this hsould be on the list of maintenance tasks.

I was looking for graphite dry lubricant but settled on Silicone with PTFE from Maplins, which I injected using a cable luber. It required disassembly from each throttle body and the twistgrip but not a removal of the Bowden assembly (the cable junction under the battery). This was followed by re-syncing TBs.
 


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