G1100 idling - low revs throttle response problem

Well ...
GRiSO 1100 in absolutely standard situation - 15,000 km.
Installed is the factory map in the latest update (2009?).
Lately when riding with very low revs when the engine is warm, the operation of the throttle  is almost entirely on-off. Also, after closing of throttle from low revs (2000) these fall momentarily down from 1000 to 700 and then back to idle (~ 1250).
After cleaning and checking throttle bodies balance (NOT very dirty and did not require setting) and tps reset the problem remains unchanged.
Before about 4,000 km I had the same symptoms and after cleaning and synchronizing the throttle bodies (quite dirty) and tps reset the problem was eliminated.
I note that at that first check by pass screws were both open. While NOT tampered with the restricted stop screw.
For throttle bodies balance I use carbtune. For tps reset ScanM5X.
During the last test I saw trouble code "P0135: O2 Sensor Heater Circuit Malfunction - No signal; Warning lamp on ". Which and reset. The same code appears again after driving. When I checked the resistance Heater circuit resistance I read about 20 Ω at 16ο C, and I also have 12 V at the heater power supply.
When start at idle tps reading do not remain at 4.6-4.7 but drops to 4.5. Is this problem?
At idle the stepper indicator is 147 and the lambda 0.0 (which rises to 0.1 when increasing revs).
I keep the oil level a little below the middle in the index, but for the last 3,000 miles was a little above and found little oil in the filter box.
Also, I have no slack on throttle cables.
Can someone help me to deal with the problem;
Thanks in advance

Voltage across the heater is only about ~9V. I believe there is a shunt internal to the ECU to monitor heater current. If the sensor is malfunctioning, then your fuel trims may all screwed up. I'd replace the sensor and reset the autolearning parameters. You could also just turn off lambda in the map.

TPS value can swing +/- 0.2 or more of a degree when the engine is running. I wouldn't be concerned.

Beetle thank you for your answer.
Before I buy new sensor, I would like to try closing the lambda.
I guess it should be done through GuzziDiag. Because I'm not familiar with its use, could I have instructions on how to do it?

You'll need to download the map from the ECU (if you don't have a copy of it) and open it in TunerPro to turn off lambda. Have a look at the TunerPro Howto I wrote: [You must be registered and logged in to see this link.].


Before you try turning lambda off, use GuzziDiag to reset the autolearning parameters. If your sensor is causing bad trimming, you should immediately notice an improvement.

OK. I 'll try the reset.
Can I reset the auto learning parameters just by taking off the 30A fuses?

Yep.

Yep.

Yep.

Hi again.
After my last post, random dashboard errors began to appear (codes 07 and 08).
By checking continuity between O2 connector contacts and the blue ecu connector , all were OK.
Also on retesting the O2 heater resistance does not get stable readings.
After checking compatability for a cheaper "λ" sensor than the genuine part, ended in buying a BOSCH with code 0258006206 which also has exactly the same length of cable.
After the installation no ecu error reappeared, and also narrowed the problem at very low revs.
Nevertheless, operation near idle is better, the throttle on-off phenomenon remains and there is little drop below 1000 rpm by closing the throttle.
Could I check something else?
Would it be better to install a new beetle map?
Thank you in advance.

Revs dropping below idle then returning to normal may be indicative of a rich condition. Idle is controlled by the stepper. The only variable is engine temperature. The air flow is presumed to be within the margins determined on the bench in the factory. Assuming spark and injectors are functioning within normal parameters, then either the throttle body butterfly angle isn't right, or the stepper is sticky or partially blocked or dirty. Temp sensor might be dicky, but you would have other symptoms.

Changing the map at this stage would not be advisable. The map won't fix an underlying issue.

When the engine is cold, revs do not fall below idle.
This indicates that the stepper work properly?
If so, maybe have problem whith the temperature sensor?
However I have  correct (I guess) temperature readings when monitoring with ScanM5X.
Should I have to try to clean stepper firstly?

No, as the stepper only operates above 60 degrees.

Thanks Mark
I 'll try stepper cleaning.

Nobody has buggered about with the throttle stop screws and/or linkage rod have they?

Pete

Definitely nobody.

Here I am again
Between family and work obligations, just yesterday I managed to clean the stepper (as possible) by spraying with plenty of carb cleaner in the three passages also when the motor was in motion by turning the switch on-off. I found that when the stepper was "closed" I had just little air supply. Is this acceptable?
Again I checked the throttle body balance, and I had to adjust only the left bypass screw.
The problem is still here.
Also, I checked the resistance of the temperature sensor: at about 20 ° C and in boiling water and received values KΩ 3.39 and 289 Ω respectively and which I consider as acceptable (values workshop manual: 3.7 KΩ and 220 Ω).
Any thoughts?

And something unrelated to the problem: During the test I had petrol leakage which was due to very small crack at the plastic “T” junction. By the way I replaced gas pipes too.

Temp sensor is good. As far as the stepper is concerned, I don't know how much leakage when it's closed is acceptable. One way to confirm would be to block the intake of the stepper. If it's leaking too much, idle should be good with it blocked? No?

Only when warm though...

When cold it will probably stall, or even be more erratic

Thanks Tony. Yes, engine will need to be above 60 degrees. I don't actually know whether the pintle is completely closed when hot. I've always assumed 'yes'.

I don't think it is, but I have been known to be wrong (you have no idea how many years in therapy it took to admit that). I think that there is always some "trimming" at all temps, though over 60, it is less critical.

There's the thing. The docs say the stepper operate in closed loop mode. That's usually above 60 degrees.

Here's the scenario:
- engine up to a good temp >60 degrees;
- stepper disconnected;
- Dash errors show up (probably ecu) - can't remember what;

So, even if it is not used above 60, there is still some checking done at a low level to see if it's still there, which implies that it is still in use or at a minimum, of some use. Logic may be flawed, but I think you might get my drift, Mark.

I don't really know, just extending what little logic I have.

Hi all
Cannot visualize this little thing called the 'stepper'
Please excuse my ignorance but what's it do? Where would I find it? How would one 'clean it'? Anyone got a picky?
Since I've had my 1100 it hasn't missed a trick and since Mark kindly remapped it, it goes like the proverbial 'smooth' train so obviously this 'stepper' must be going as it should also.
Cheers

Stepper is attached to the throttle body carrier, Trev. It simply adjusts the amount of air into the throttle bodies, to match the fuel from the injectors to ensure a smooth tickover.

To clean, there is a tube from the airbox, simply spray some carb cleaner or valve (trumpet) oil in there and let it clean itself out.

If you look at your throttle bodies on the *Inside* of them you'll see two rubber hoses, (one from each TB.) that go into a black device that is bolted to the centre of the throttle body and linkage assembly. From the top of this device another hose goes to the air box and the device has an electrical plug on top.

That is the stepper motor. Its basically an electronic valve that passes air when *Told* to by the ECU. The more air the weaker the mixture and the higher the idle.

The idle speed is hard coded I to the ECU and is not adjustable in the conventional sense. The ECU monitors the engine speed. If it rises too high it shuts the stepper. If it drops too low it will open it.

Clear as mud?