Steptoe's cat code 'plug' - it works!

I've been trying to sort out a minor but annoying problem with my 1150 for two years now, and finally appear to have cracked it thanks to Steptoe.

It's a bit of a long story, but bear with me:

This is my second GS, both were from new, the first one which I had for three years was completely standard.

The latest one had a Y-piece fitted from new, and while I was in a spend-happy mode I asked my dealer to fit a K&N air filter, but kept the stock exhaust as I like my neighbours and prefer my speeding to be stealthy.

It never felt right at low revs. The best way I can describe it (and this is what I told my dealer) is that the throttle response was "fluffy". For example when blipping it between down changes the engine always felt like it was lagging a split second behind the twistgrip movement. If you blipped fast enough the engine would actually 'bog down' as if the mixture was too rich.

Sometimes, usually after a spot of high-revs action, the engine would simply cut as I shut the throttle and pulled the clutch in when coming to a stop.

And it felt weird on the overrun, like the fuel supply was being cut off as the bike rolled down through 2500-3000 rpm, forcing me to declutch much earlier than I should have to.

I knew this wasn't just subjective, because my first bike didn't exhibit any of these faults. I also knew it must be down to a combination of the Y-piece and freer-flowing air filter, but I didn't want to change it back to stock because (i) I'd thrown the cat away and (ii) I really liked the extra mid-range oomph that this set-up produced.

The service manager (who's an ace bloke and reads this forum) was sympathetic and helpful but couldn't really see what it was that I didn't like, other than the engine cutting out. I had the throttles synched several times under warranty, but the BMW diagnostic stuff couldn't spot anything wrong.

So for 16,000 miles I've been riding around the problems, accepting them as the price I had to pay for the performance. I read stuff on here about cat-code plugs and noticed that my bike didn't have one. I think the dealer removed it when he fitted the Y-piece.

I tried putting the standard one back in but it made no difference so I assumed that the cat code plug was not related to my problems.

Then last month the bike's warranty ran out and I thought about maybe fitting a power chip to see if that would help matters, however at £270 a go I thought I'd read up on them first.

A web search turned up a fair bit of stuff on chip makers BB-Power, including the fact that in conjunction with their chip they used different combinations of wire jumpers to connect the cat-code terminals to each other (I then realised that in effect that's all the cat-code plug is - a fancy connector between terminals in its socket).

The eight different set-ups go from stock bike (cat, can, K&N air filter) right up to having high-lift cams fitted. The second stage was for my set-up, Y-piece, K&N with standard can.

Then I did a search on this forum and discovered that Steptoe had used the same jumper connections, but with the standard BMW engine chip.

"What the heck, I may as well try it," I thought. And so I did just this morning.

BLOODY HELL WHAT A DIFFERENCE!

The bike has been transformed for the cost of three inches of wire and two spade terminals.

The low-rev behaviour is completely different, it's now like my first GS - but I've still got the extra mid-range punch from losing the cat.

I suspect those who have written on the forum about the Motronic system going into a kind of generalised safety mode when the code plug is absent may be right.

It certainly seems that the dealers don't know everything about the subject.

Sorry the posting is so long, but I thought it was important to give you plenty of detail.

And Steptoe, if we ever meet the drinks are on me!

HeatedGrips said:

The bike has been transformed for the cost of three inches of wire and two spade terminals.

Click to expand...

You could have saved a fortune by buying only an inch of wire.

Did it to mine a few weeks back and it has transformed the bike, seems to have more power.

Yep its a brilliant and simple mod. I have the same set up as you having ditched the remus end can for the standard due to the noise. I get the odd backfire though but i guess thats inevitable now.

Nige, on another post you say you have to power down the motronic fuse. Sorry to be a pain but what exactly do you have to do? Heated grips and Steptoes post make no mention of it... (if I remember...)

Cheers

Heated grips, could you post a picture of what you did please. thanks

alpmeister said:

Heated grips, could you post a picture of what you did please. thanks

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Err, sorry I don't know how to post pics on here. But if you do a search for "Steptoe catcode" you should find his post which does have a picture of where the leads go.

Essentially you get a short piece of wire, put two small spade terminals on it, then plug it into the catcode socket.

I put one end in terminal 5 and the other in terminal 6.

Hope that helps

Here is the Link......



And here is the LINK

No one takes me seriously, when i post up some technical stuff i get carping remarks -

i.e. when my 95K mile loan bike just wouldn't start and it was flattening the battery, i tested and tried everything, in desperation i changed the Lambda sensor, it shouldn't have made any one iota of difference to the starting -

But it worked instantly -

i put the old one back and it wouldn't start again, put the good one back and instant starting -

so i posted it, and was told thats impossible, it makes no difference -

but i've got the proof sitting in my drive, believe what you want, but my loan bike now starts instantly.

back to the "cat code jumper wire", i think there's an element of something so cheap and simple isn't as effective as something costing £££££,

BUT, it hasn't worked on every bike i've tried it on, don't ask me why, i haven't a clue ?

The only explaination for your Lambda affecting starting was that it had suffered a mechanical failure resulting in 'odd' voltage readings being sent to the Motronic.
In normal use the Lambda has no part in the start-up procedure,hence understandable doubt with your findings.
Reading all the questions raised with injection issues,it is becoming worrying that so few owners understand how their bike functions,(comment not addressed to you,Steptoe),and how few 'technicians' can give a 100% account of each component's function.
I admit when I first bought my GS,the injection was new to me,a trip to the dealers showed that I was wasting my time asking anything more complicated than 'so the spark plug ignites the mixture'.
Fortunately,a friend of a friend designs injection systems so everything was explained very clearly,but the lack of knowledge shown makes you concerned about the 'well,I did this and it worked,try it' ideas.

Bet He caught that on a " haddock flavoured pop up boilie "

can't work out if it's a "mirror or Leather" carp

Le singe said:

In normal use the Lambda has no part in the start-up procedure,hence understandable doubt with your findings.

Click to expand...

me as well, thats why it was the last thing i tried, and also why i posted it on the site - in case someone else had the same problem ( or might get the same problem), and after trying everything else they would still be looking for the problem.

Thats why i told Tsiklonaut
HERE , try the standard things first -

some things are strange, they shouldn't be, but who knows

subtle effects

Tried this last night and thought it made a subtle difference. It does seem smoother and more down grunt but not amazingly so.

I'm hoping for an improved fuel economy too...

Maybe I was expecting too much after reading about the "big Bang" R1 engine!!

Thanks Steptoe, great tip....

Le singe said:

,it is becoming worrying that so few owners understand how their bike functions.

Click to expand...

Don't be silly, I'm a journalist, not a mechanic or fuel systems engineer.

What is lacking is clear, concise, documented information on some of the electronic systems.

I now know why the cat code fix works, but it took a lot of reading around the subject, not just on this forum either.

HeatedGrips said:

I now know why the cat code fix works, but it took a lot of reading around the subject, not just on this forum either.

Click to expand...

well, go then, tell us.......

cookie said:

well, go then, tell us.......

Click to expand...

I thought I had

The Motronic has several settings for different states of tune, no cat, open exhaust etc.

These are programmed by different connections between the cat code socket pins.

The one I used is for my set-up: K&N filter, Y-piece, standard can.

Steptoe said:

No one takes me seriously, when i post up some technical stuff i get carping remarks -

Click to expand...

HeatedGrips said:

I thought I had

The Motronic has several settings for different states of tune, no cat, open exhaust etc.

These are programmed by different connections between the cat code socket pins.

The one I used is for my set-up: K&N filter, Y-piece, standard can.

Click to expand...

yeah, i know all that, but what map are you selecting with steptoe's link? it's certainly a different map, but what's it for exactly?
it probably is for an open pipe just as we suspect. funny no one from bmw seems to use it when they fit remus systems

i find it amazing after all the seaching i've done, that i've not found anyone who can/will answer that with some kind of evidence.

I've tried to explain the different maps in 'Beakchat and Bollox' under 'Cat code plug'.
What do you not understand?

Le singe said:

I've tried to explain the different maps in 'Beakchat and Bollox' under 'Cat code plug'.
What do you not understand?

Click to expand...

your post:

The different coding plugs merely access a number of fuelling maps in the Motronic memory. As all engines are assembled from parts having been made to a tolerance,there will be engines that are built closer to the optimum and hence perform better than others,therefore some engines will be on the limit of any manufacturer selected fuelling map,(biased towards richness or leanness). For some bikes,the 'Steptoe link' will move the fuelling further towards that which the engine requires,for others it won't,plus the variables of modifications made complicate matters further. The only way to optimise settings properly is to try every link on the dyno,quantifying air/fuel ratios throughout. You may be fortunate and find a standard map which works acceptably throughout the range,after your pipe/silencer etc mods,or if not,you may have to use a Techlusion or similar for fine tuning. The reason there is not one answer for all the 1150's or 1100's is because of the variables of production tolerances and modifications. The modified link may work better for MOST bikes,but certainly not for ALL bikes.

is there another post where you explain what the standard maps are specifically intended for? eg. what hardware configurations the steptoe link is intended for?

we know there's a standard link for cat fitted & one for low octane fuel available. my point is, what is the steptoe link OFFICIALLY intended for?
bmw must have put it there for a purpose. what?