'Cat code plug' removal?

[Gromit]

I've often heard, on the older R259 Boxers, that removing the cream coloured plug from the electronics box gives the bike more go? Just wondered if any of you guys - who may have owned an 1100GS/RS/RT etc know anything about this? Thanks.

[Darth_1100S]

Grommit, I had an R1100R before my 'S'. I bought it used with 13k on the clock. All the time I had it, it was very thirsty on fuel and had a tendency to major backfires! Shortly after I got it, I took it into my local BMW dealer (Southport Superbikes) to have it sorted. The bike was put onto the computer analyser, and the mechanic proceded to go to work on adjusting the idle and cleaning the injectors etc.

In the end I was presented with a bill for over £60 for his 40 minutes work. Riding the bike home I noticed no difference whatsoever. In fact after the visit to the dealers it started to smoke quite badly on start up. I rang the dealer to tell them and was basically fobbed off with, "Oh it's a BMW sir, they all do that"

I carried on with it 'til it had done 22k , mostly on tours around the UK. Then a mate of mine bought an R1150R which was blessed with a really bad surge problem. To cut a long story short he went into the cat code plug technicalities, and along the way he asked me what colour my cat code plug was. We had a look only to find that there was none fitted!! I then found out that it should have had a pink one, which I bought and fitted myself. The difference in the bike was astounding! The fuel economy increased, it ran smoother and certainly produced more power. However, a slight surge manifested itself, nothing too bad but it was there.

Talking later to an ex BMW bike mechanic he told me that when the R1100R was new, some of them had a surge problem. The dealers idea of a fix was to remove the cat code plug and bin it! This sent the punters away happy due the surge having gone, but it caused all sorts of other problems.....Like excessive fuel consumpion, backfires etc.

Anyway shortly after sorting it I bought the 'S' but the guy who bought the 1100R from me lives locally and he loves it.
It just seems that a lot of us have been conned by BMW regarding the surge problems with the R1100 family and more so with the R1150.

The mate with R1150 gave up with it in the end and got rid - he couldn't stand the surge or BMW dealer excuses for a problem they wouldn't admit existed. He's got a Honda CB1300 now and loves it.

[Gromit]

Thanks for that - on my old 11R I was told that removing the beige/cream plug re-sets the Motronic a la 1100RS. I'll have a doublecheck on mine tomorrow - sounds daft but I can't remember if I've looked to see if there is one fitted on this bike!

Having said that, it does backfire like a b*stard - fun when you're having a play but a royal PITA when you're not.

[adamski49]

A guy I know with an 1150 RT changed his plug for the Canadian one to solve his surging problem - this was needed to allow him to ride super smooth at low speed due to him being a RoSPA and IAM examiner. The bikes performance and fuel consumption remained much the same and the surging disappeared.

I believe it's something to do with the differing emissions laws between countries hence the various code plugs available.

Adam

[stempy]

This is correct. The cat code socket has three connection which go straight to the motronic. The different colour coding plugs have different pins linked depending on the country of sale and model of bike and it tells the motronic which map to use. I made up a link wire and tried all the possible configurations on my S and without doubt it ran best with no link connected i.e. no code plug, which is how it was supplied anyway.

[Gromit]

Thanks for the tips guys - I'll go and have a poke around my plugs.

[Gromit]

I've just finally got off my *rse and had a look at the plug. The cream one's present and correct, as expected. I'll run it without and see how it goes.

I take it running without the plug puts the Motronic to some kind of 'default' setting?

[Gromit]

Latest on the plug - removed it for the w/e Yorks trip. The bike ran loads smoother - not even a hint of surging - but it was using 10% more fuel. The tail pipe also looked a bit sooty indicating a rich mixture...ah well, definite swings and roundabouts scenario.

[Darth_1100S]

Careful riding past horses Grommit! If it's anything like my 1100R was without the plug it'll backfire like a bast*rd

Dave

[Gromit]

Dave - this'll make you smile; my bike backfires less with the plug removed...

I love these bikes - they've got minds of their own.

[Darth_1100S]

Doncha just love Beemers Gromit? Absolutely no pattern to follow - every one's a totally different animal!

Dave

[Gromit]

Just found a bit of gen (relevant to all Oilheads I guess) off the UKGSer forum re the coding plugs. Seems that when a cat is fitted, the plug makes the bike run lean when the engine's cold, therefore causing hotter exhaust gases. This in turn allows the cat to heat up quicker and be more effective - it seems like the coding plug has more an effect on emissions than anything else. The surging is caused by the plug leaning off the mixture on a constant throttle opening. On a 'moving throttle' it doesn't come into play as much, if at all.

[Boxadog 2000]

I took a trip to North Oxford BMW on Saturday, whilst there I talked to the service manager and asked him if he had inherited the records from Hughenden.
His reply was only for bikes that had warranty issues, me thinks oh mine is ok then.
he checked the computer system and lo and behold mine had missed a BMW update/recall to fit a new cat code plug and relay, I asked what this was all about and was told that it was a BMW mod to increase the life of the cat.
As I dont have a cat I am in two minds as to weather to get the mod done, there again if something was to go bang in the future it may effect any recourse I may or may not have with BMW bearing in mind that mine is an August 2000 reg.

Bob