ambient air pressure

[botus]

I just found out the K1300 gets a a fuel pressure read out in diagnostics, but the R1200GS doesn't

as one has a sensor and the GS just has a regulator - then discover both bikes get an ambient air pressure reading - but which part of the bike provides this info ? I can't see a sensor on any of the parts lists


Air temperature : 21.0 °C
Engine temperature : 20.2 °C
Temperature (cylinder head 1) : 20.2 °C
Temperature (cylinder head 2) : 20.2 °C
Ignition angle : -96.0 °KW
Throttle valve position : 0.00 %
Ambient air pressure : 1011 mBar

 

[RadioFlyer]

The ambient air pressure sensor is integrated into the engine management ECU as there is no need for it to be elsewhere.

 

[botus]

thank you - I was wondering if they did that

 

[SnowMec]

Already in 1989/1990 when the BMW K1 (and K100RS) came out with Bosch Motronic the ambient air pressure sensor was in the ECU.
The sensor was needed because the air flow meter from the early K100 was replaced by an alpha-n system with the throttle position sensor and rpm as the main parameter for calculating the fuel mixture.
I owned a BMW K1 for a couple of years in the early 90s, a bike I really miss

 

[botus]

controls tech neighbour has been trying to teach me how the set up works...

my current interpretation of his ideas....

the only part that he wasn't aware of - is the idea of multiple maps and the bike morphing between them on the fly... his old school thinking was most stuff had one 3D MAP, the sensors on ambient pressure, throttle position, temps, rpm etc. guess at air flow pointing things to see the correct area of the MAP - then the lambda fines tunes the mess it actually got... with altitude / cold weather / various conditions, the sensors effectively raise or lower the map to go richer or leaner, but the general shape was fixed.

in which case a tool that added an adjustment layer (power commander) could be used in conjunction with Lambda sensors - when I said well they have to be off, when using the power commander, he couldn't believe anyone would try to run a bike like that - in his view the std set up would have far more ability to be correct thanks to info and tweaks from the lambda sensors - from what can only ever be an about right base MAP - sadly as most know that's not the case, either from utter incompetence by the manu or rough and ready hacks to land emission regs

I've begun to think from what I see with an AFR gauge fitted - each gear runs a different MAP (in my mind as some BMW load compensator), as trying to ride at the same throttle, revs and load from one gear to another gives wild AFR changes all the way through every rev, throttle and RPM condition you can have - with low gears clearly far richer (particularly 2nd). Hence why a power commander can't really work.... as each gear change you'd need to load another layer of fixes into the box of tricks bringing the adjustment layer....

 

[botus]

this bike has always run drastically different on very hot days (almost normal with far less glitches) - so I got my control tech neighbour to make me a pot adjustable offset to the AIT - half a turn and it thinks its 14C warmer... so far its brought MPG up 7 MPG and today it felt as if running smoother - but only just fitted and as its map has moved - now need to re tweak fueling via my two wideband sensors as its now "warmer weather running at 28C today"

one turn on the pot

 

[Mistacat]

I tried messing with the AIT on hexheads years ago , mainly to see how fast the ecu can adapt to changes, answer = very quickly.
How are you measuring your air fuel ratio ? and what AFR are you running ?

 

[botus]

I have one nasty ebay digital gauge and two Bosch wide band sensors - I have to flip flop back and forth - its a right pain, tweak the fuelling on one cyl and it must be the balance pipe, it really impacts the other cyl - so you dance back and forth

the wide eye'd things are -

1) cold start enrichment lasts for double what it needs regardless of temps - even in the Summer when it was scorching hot @ around 25C ambient at start up - it makes the bike drink - with AFR of 12 for first 4 miles every single ride
2) since New CAT sensors and trying to make the bike 100% stock with cold and summer adaptions for over 2k miles it still runs like a dog
3) Bike std - I thought the bike would self-destruct on a 1000 mile trip there and back to Germany in late May. It was so horrifically rough at 5500 (running 98 super) keeping up with the group I thought the crank was going to fall out
4) So when I got back, CAT sensors off and PC3 back on in June - and I made it run best everywhere I could feel it - smooth and no strange stuttering, running like a stuck pig like the stock bike does at 1700 and 2100rpm, overall I was convinced it was much better than BM manage - the stuttering pick up off idle was gone running +28 and +20 on the other cyl at 1700, and about +15 at 2250 using the PC3
5) I just couldn't work out how to improve so got the AFR gauge - and almost fell of a cliff - it was so rich everywhere (and I had aimed trying to set it as lean as I could and get it to run OK) - the stuttering that vanished was with it running around AFR 10 !!! - Now using the AFR gauge I'm running -9 and whilst not as smooth its not hunting as BM make it in those just of idle areas to bring the AFR in around 14.5 - 14.8 but it wanders so fast
6) so far every change is leaning out what BM have !!!! and its mostly running so much better than BM manage all the time and performance has really picked up - I'm still only working on low speed light throttle stuff its taking forever

Other than - on 100% throttle from 4k rpm to the red line I've taken a blanket -5 on both pots - and at 60% around 6k I've taken out about the same - and both was a transformation, top end it so much better - it hard to see the gauge and look where you are going - but basically BM have it AFR 11 if accelerating at any point of the grip and on full chat 10 - which is just a waste

Its like BM just made everything up really badly.....

I guess maybe I'm more sensitive than the average numpety - but when I get on my like new 10k mile 2011 GSA its fuelling is fucking terrible - and far worse than the 2007 I'm on about above

and now I just got a new bike - the 6 sept build 2025 R1300GS also runs like a dog hunting as you trickle along - but I guess it very early for its adaptions - after all at 67 miles its only got 10 errors in diagnostics - and the dash lit up with two suspension failures (after deliberately not ordering the junk fail every ride - ride height joke)

 

[botus]

@Mistacat - any idea how you get engine load at 45.58% when its not even running ?

Umm, the GSA says 0.00%

K16 and R13 don't have this field

 

[Mistacat]

I assume the engine load at 45.58% when not running is a default setting to run the pump for a couple of seconds and force a long injector pulse width when first cranked.
Not something I have ever had need to look at but next time I have the diagnostics plugged in I will take a look...
I found the PC3 was good on early very basic Japanese injection systems, I tried a PC5 along with the autotune on an early Hexhead it was so unstable when trying to control the AFR.
I was at the motorcycle trade show at the Nec many years ago and spoke to the Techs at Power Commander about getting a stable map, They said just set it rich the customer wont know any difference. This destroyed any faith in the products.
Having previously used an Innovate LC1 for lambda offset when the AFXied`s became available it was a no brainer.
Trying to watch an AFR meter whilst under hard acceleration apart from being dangerous is impossible to to remember at what AFR vs RPM vs Throttle position etc.
Use an Innovate LM2 dual channel with wide band sensors which also plugs into the OBD2 port to monitor up to 32 channels of ecu data at the same time.
These can be played back on a graph or using LM Programmer play the results back on a dashboard of virtual gauges whilst sat in the house in front of the PC.

 

[botus]

info on the 45% bit would be reassuring

on the new PC6 they have more columns for adjusting - with a 15% and I think others... with the AFR gauge I can see on a small throttle setting the BM map trying to go one way as the PC 3 is about to reach another rpm or throttle column and force it the other...

you're not wrong trying to work out whats going on mid ride....

I wonder if these decent ecu remap shops have got the old GS right... or maybe I should go mad and by woolich racing stuff (and really get in a muddle up) - they "refuse" to do older BMW's - but after I nagged them to get with it and do BMW - they must sell - as they seem very into BMW products these days - I see the home page still forgets to mention BMW !

https://www.woolichracing.co.uk/products/bmw/bmw-ecu-flashing.aspx#productTable

for the twin cam I can't think the R nineT map can be a million miles off as a starting point

 

[Mistacat]

I would chuck the Power Commanders over the hedge and fit a pair of AF- Xied`s set at setting 7 and forget about fuelling.
I like to play with the AFR`s on the 4 barrel carb on my V8 and the Bing carbs on my Airhead but these results from Xied`s on my Hexhead can`t be improved on.

 

[botus]

so my little Pot of fun shows exactly why a Power Commander can never be a sensible solution on any BM bike....

As post #6 above I have an adjustable gadget to tweak the Ambient Air Temp the bike believes is incoming - And it makes dramatic differences to fuelling and highlights BMWs way of writing maps is "interesting".

I have run for two weeks with the gadget inflating incoming air temp 12C above ambient, at temps 17C to 20 C the bike was running well and very consistently and minor tweaks to the PC3 got me a fairly stable 14.6 AFR most of the time
But in the last few days temps have dropped to 13 to 14C and the bike has become much more unhappy, feeling like it needs a bit more fuel everywhere. I have ignored this and ridden on.

Till yesterday about to make another 40 mile round trip - So I tweaked the pot to bring ambient temps to only 6C above actual and the bike suddenly rides happier at these lower temps. I'm quite surprised a hot engine needs such different fuelling at only 4C change in temps - the change in AFR is significant

in 6th gear 70 mph at 12C over ambient the bike was running AFR 14.6
but 6th gear 70 mph at 6C over ambient its running at AFR 13.8 - but many other riding conditions its not significantly different

so I don't think any power commander can work around that change - as it only has one adjustment layer - but what BMW does with the map is not consistent so every temp change needs a new different power commander map

which begs the point with an AF-XieD, are the bikes adaptations sophisticated enough to manage and remember every nuance of fixes required - I find it hard to believe it can be that effective ?

at Mistacat, I really need the legend on the picture above or I can make sense of things

 

[Mistacat]

As you now have a gadget to read AFR, alter the temperature pot and see how quickly the mixture goes rich and how quickly it is adapted out. did this experiment years ago.
The AF-Xied is a lambda offset device it receives a signal from the lambda sensor 14.7 to 1 and processes it to read say 13.8 to 1 or whatever you set it to. This is done digitally not a simple impedance job.
Over 20 years ago I purchased an Innovate LC1 to drive a gauge to read AFR from a wide band lambda sensor, one of the ability's of the lc1 was that it could be programmed as a lambda offset device.
@Roger04Rt fitted an innovate LC1 to his oilhead RT ( only one lambda sensor on the oilhead) I followed his experiments with interest, but the LC 1 is too bulky to fit 2 of them on a hexhead.
Roger collaborated with Nightrider and the AF-Xied was developed working on the same principle as the Innovate LC 1 .
As soon as the AF- Xied`s came to market I purchased a pair knowing the history. They worked perfectly when tested with a Dual channel Innovate LM2 and now have done over 100K miles on this bike and 50k miles on my previous bike .
The power commanders were disposed of.
The photo in the earlier post was just a snip of over 8 minutes of data being played back from a road ride. I feel that data from a road ride is more representative of genuine fuelling than artificial loading on a dynometer.

This is a clip from my library that I did to explain the graph, obviously different bike and fuelling but should explain.

 

[Mistacat]

 

[MWH]

This closed/open loop stuff still confused me!! I read a thread at the time with Roger and Mistacat with vast amounts of info. Think the amount of detail flummoxed me!

As a result of that thread I bought the AF Xieds, fitted them and put them on no 7. Quite a few years ago now and have never had to touch them since.

The bike doesn't feel quicker but it was a lot smoother and you could pull away or roll on cleanly with no chugga chugga feeling. I mainly got them to richen the mixture to help keep the cylinder temp down so the exhaust valve didn't burn out as quite a few had.

 

[botus]

well I'm confused about the AF-Xieds - I get how the bike works as std. I get why a Power commander doesn't work correctly and never can. And I get AF-Xieds are clever and do things that works in conjunction with the way BMW go about stuff, which is very desirable.

But then I get confused how they will react to doing what I want

Now I have tweaked the ambient air temps the bike sees, upwards - it starts up away from the cold weather running my bike has struggled with since the 2008 Map update was put on this bike in 2018.
And with the AFR gauge I can see its far too rich far too often - particularly low down <4k rpm <20% throttle - and the bike is more stable and less erratic having leaned it out - But the AFX-ieds are design to make it richer - and I want the opposite ???

Indeed the cold start is now quite good (I'm convinced it could still be way better) - then I rode my new Sept 2025 R1300GS and I was shocked how hideously the new bike on a cold start - it was truly terrible till it had done a mile or so (about 12-14C ambient)

As for power output the R1200GS is far faster with -5 widgets off using the power commander at anywhere from 40% throttle and 5K rpm onwards - Again this makes it run like it did prior to the 2008 Map update by BMW

 

[RadioFlyer]

Just about every device works to make the engine run a richer mixture. Shifting the perceived ambient temperature upwards results in the engine running leaner. What's up with that?

For example the "Booster Plug" is an AIT spoofer that shifts the perceived ambient temperature down by 20C.

 

[botus]

the bike has always run incredibly well in very high ambient temps as if its running a half decent map - both on its original map or the later one, it works across the entire range idle to flat out

but in the UK we seldom have those riding conditions - until you fit my gadget - then every day is bearable after re optimising the still interesting gaps in fuelling

on the later BMW map from there down its like a sliding scale of incompetence as temps drop, it then hits a wall of utter incompetence below 12 C where its so rich its enough to fuel three bikes

that 12C temp change over swaps the bike into an unrideable mess and was the joy that BMW brought in with the CIP 11.2 engine ECU update - where the release notes state dramatically altered antiknock set up !

cold running on its original map had been as perfect at it was between 13 to 25 C and didn't need to be touched - the later BMW Map was put on this bike in cold temps in Feb 2018 and the sudden cold weather fuelling change was so stark it was blatantly obvious it was plain wrong - it went back multiple times and had a puma case asking for the original map back - but they know best (they don't) ! - as this cold weather madness is so significantly off whack - you either live with it or would need to redo the power commander - which I would do if I could get a multifunction hub cheap - where I could manually switch between summer and winter layers of fun

unless you mean wind up the ambient temp to find that least bad high temp map and then fit the AFX-ieds ? which I guess would make sense - but that far down the line I think the box of tricks from woolich racing would bring the ability to see what those idiots did - which would be of interest to me