Air box hoses

Ok folks, question time, looking into my stepper motor and no warm up idle at cold start issue.When starting from cold there is no rise to 1200-1300 rpm as it used to. The bike idles fine once warm. Recently the bike sometimes stumbles and stalls on first start up. Looking through the info on this forum the stepper motor that controls this could be at fault. Now the stepper is fed via a hose to the airbox. The airbox has two hoses that i can see conneted at the front, one on the left and one on the right. On inspection the one on the right is not connected to the airbox. Will connect it up later as its a bit awkward to get to. Could this be a cause of the problem?

Assume you mean right as you sit on bike ?...anyway & on that basis the right hand pipe brings oil entrained blow-by gases from the front separator canister under the steering head; the left hand one (as you sit on bike) draws fresh air from the airbox into the stepper motor (and also pulls some of the oil mist with it - but less). If the left hand one is not connected it doesn't make much difference as you are just sucking unfiltered air into the stepper (and into the air box). I've never pulled the RHS blow-by return off whilst engine is running, and although I wouldn't expect it to affect things, I could well be wrong.

Mine normally idles at 1400 rpm but higher when cold (first with richer mixture for first minutes; then until I pull clutch and close throttle at first stop). I've never seen cold start low idle issues with stepper, despite I have lots of random high idle issues at any temperature.

Assume you already set TPS & balanced throttle bodies high speed AND only one air screw is actually open for idle speed balance ?

Thanks for reply Paul...Yep all that is done, checked the air screws and yes one open one closed. Have reconnected the hose, will have to wait till engine is cold to check. Connected guzzidiag and reset params and tps, Checked for faults and it did find a stored fault of po135 no signal...???? Lamba sensor maybe??

Lambda heater would explain it on heat up as it won't get mixture right....I quickly moved to lambda off & Mark's fantastic maps to solve jerky throttle behaviour and although I tried std map w/o lambda it was always crap. Guess best check is just switch off lambda in map (or unplug) and see if it just the same....then check lambda ....then get Mark's map & switch it off forever....doesn't sound like the stepper. But best to refit hose first as oil over rear tyre might be next problem !

Ok thanks Paul, ok will look at the Lambda tomorrow. How do i turn it off . Is there somewhere in guzzidiag for that?

Looking back through previous posts from Beetle (below) it seems worth looking at when problem starts as lambda is out of loop until first three conditions are met. Before that it is 'just' stepper.

Easiest way to take lambda out is disconnect (although will create warning) and see if it makes any difference on basis that no difference = lambda is faulty. (Else you need [You must be registered and logged in to see this link.] to show how to copy map using Tunerpro, switch off lambda, reload). If it is continuously throwing lambda heater fault warnings and if you aren't happy with low rev throttling,it's worth getting one of Mark's maps as they all run lambda-off anyway.

Previous stuff.....

You're misinterpreting the document. The 5AM uses lambda at idle when:

Air temp >19
Engine temp >30
Warm-up period is finished (100 seconds)

When air temp is at 19 or less, lambda is ignored, but technically it's still in CL because the stepper motor controls idle.

Once the TPS signal is outside the idle range (1150 - 1250), air temp is ignored with regard to lambda and only used for injection pulse-width correction. Lambda is active and the system runs CL once the engine temp rises to 55 degrees and above. It is active in the 1200 - 4000 RPM range, approximately.

So my guess is from this info Paul, is that the Lambda heater wouldnt cause this no idle warm up problem. If a lambda fault would cause this i guess people running Bettles map with the lambda sensor turned off would have the no idle warm up, and from what i understand this is not the case.

So maybe a stepper motor problem, gummed up with oil?? i will investigate further.......with a can of carb cleaner

Marks maps are built for no Lambda so they have a 'fixed' warm up instead of a controlled warm up with lambda (although even with lambda, the lambda doesn't work until the three limits are reached - so they are basically running fixed map with no closed loop up to that point. If your problem is straight away and during the period the lambda isn't active then it's probably not the lambda; if its in the twilight of all three limits met but not yet warmed up lambda then it could be the lambda heater that has failed; when it's hot the lambda likely doesn't need heating.

I'll see what happens if I close my (custom valve) stepper air feed when cold & see if that causes idle issues

Thank you Paul,
yes its from cold only. once the bike has been warmed up it will start and run fine. The bike idles steady as a rock at about 1100 when warm. and the bike runs and performs very well. Think it maybe a tank off job, to investigate the stepper at some point.
J

O2 sensor heater is always active when engine is on. With lambda off in the map, the sensor signal is ignored. Furthermore, if the heater is on the fritz, you will get a SERVICE warning when running a stock map.

GuzziDiag has a stepper test under 'Actors'. You can also hear the stepper whirring when you turn the key to off. No need to start the engine, turn the key to on, then after the fuel pump had primed, switch it off. You should be able to hear the stepper 'reset'.


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Hi Beetle,
Not getting any service warnings at all, just had a stored fault of PO135 no signal in guzzidiag.
Regards the Stepper test in guzzidiag. I have tried that but it doesn't do anything. i just start the engine and press the button and nothing happens? maybe im doing it wrong? or maybe this points to a stepper fault? Would there not be a service warning or fault if the stepper is shot?

No need for the engine to be running for the test. Try the key on-off test above. If you can't hear it whirring, or it makes a funny noise, chances are it's shot.

There no feedback to the ECU from the stepper (AFAIK), so you won't get any errors. The ECU just drives the stepper. If it doesn't move (or move far enough), there's no way for the ECU to know.

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So, in essence, one could disconnect/isolate the stepper drive cable (after reset) to get rid of it?

Depends. Is the stepper open or closed after reset? Fuctifino.

If the ECU doesn't care, then it would be quite easy to force the stepper into the right position (closed) and disconnect the bastard. Not as simple as shoving an 8 mm bolt in the end of the hose, but...

Just run the 'experiment'. Bear in mind I have lambda off & Beetle map, currently runs perfectly from cold through hot; (slight high idle until a bit warmed up & first stop with clutch in and put in neutral).

So if I fire it up it fires and idles perfectly. Shut the air supply to stepper and it starts to go erratic and finally completely stalls and won't idle (garage fills with petrol fumes). .

On that basis my thinking currently runs:
- Your lambda shouldn't be influencing mixture when cold so not likely that is issue
- No idea why you get lambda warm up
- Did you actually connect back the air hose from breather box ?, unlikely but should be connected
- Else it's wrong mixture when cold = stepper or tuning
- if it is stepper I would have thought hot would also be affected (haven't checked that)
- one check would be pull and block stepper feed; then open air bleed and see if you can get stable cold idle - then it must be stepper blockage/issue.

Thanks for this info Paul, much appreciated
Yes i reconnected the hose on the right hand side. I can hear the stepper in action when i turn the ignition off. So maybe a blockage or oil gummed up.
Its just the initial start up from cold bike idles perfectly once warmed.
I will investigate the steppers air hoses and take it from there.
Thanks for your help folks !

Mine was like that and the cure was to set the valves at Inlet 0.10 mm=4 thou
Exhaust 0.15 mm=6 thou. I had them at 0.15 and 0.2 and had the same problem as yours.

Thanks...hmm i guess that is worth looking at. I intend to get a Beetle map, at some point but wanted to sort out all other issues first..think they are the clearance specs beetle states for his maps.

Although lots of stuff about engine being mega sensitive to valve clearance; I can only say my previous flat tappets could widen out big enough to stuff almost the entire feeler gauge set and the idle was sweet as a nut. Would also add that any dicking around with the clearances also means reset the TPS & re-tune the balance so it's hard to split effects....
Common sense says pull the air pipe to stepper (2 seconds job), and put finger over end to see if it changes the cold idle problem. If it has no effect then the stepper is blocked; if it does then move to the next easy thing to change...finally you will get to balance, valve clearances......new bike :-)

Also tried shutting air feed to stepper with bike hot and partially shutting it still makes idle go unstable as mixture goes rich and I think stepper is even trying to react - so I don't think there is any problem with your stepper.

Just going back through thread where you say you have already balanced throttles and air screws, are you sure it is perfectly balanced/tuned ? Asking as my normal idle is higher than you are saying (as measured on dash :-) & I can adjust air balance screws to drop the idle but it isn't stable and the balance goes off between cylinders. Could it just be slight off-tune that shows up when cold but not hot ?

Cheers Paul,
yeah i just did the same and by pulling the stepper air feed and blocking the pipe the idle dropped and the stepper seemed to try and compensate. Didnt have time to try it when the engine was cold this morning, will try tomorrow morning. Ill check the tune setup but its all running very well when once warmed. Plan on pulling the tank and checking hoses tomorrow.

paulbrice wrote:

Also tried shutting air feed to stepper with bike hot and partially shutting it still makes idle go unstable as mixture goes rich and I think stepper is even trying to react - so I don't think there is any problem with your stepper.

Just going back through thread where you say you have already balanced throttles and air screws, are you sure it is perfectly balanced/tuned ?  Asking as my normal idle is higher than you are saying (as measured on dash :-) & I can adjust air balance screws to drop the idle but it isn't stable and the balance goes off between cylinders. Could it just be slight off-tune that shows up when cold but not hot ?  

The idle speed is hard coded into the ECU and is non adjustable. If your bike is idling poorly it is either incorrectly tuned or it has some sort of mechanical issue.

Pete

Once warm the bike idles steady at about 1100 rpm which it always did, i presume this is correct? Its just cold start up, thanks for all the help guys, i will get to the bottom of it .....hopefully