Cold mornings.

[kneeslider]

Morning all,

Something I recently noticed but never took the effort to look or trouble shoot it.

I live in Malaysia, tropical country, where in the morning it may be 20deg C.  So not exactly cold mornings for most of you all.

Anyways, my DT200 starts up fine, it's when I ride off and before the oil temp indicator displays the normal operating temperature of double bars.

During that short interim time, the scooter would feel lethargic, inputs to the throttle would seem laggy. Today I tried a WOT just to see what would happen as I cruised along at 60km/h. It just choked and coughed.  The situation improves as she gets warmer and return to normal at normal operating temperatures.

I never noticed this before till probably about 6 months ago.

Mileage is now almost 68,000kms. It's a 2013 Downtown 200i.

And clues what's happening or is she just getting old?

Thanks in advance.

[ScooterWolf]

I've had similar problems, but not coughs and chokes at high speeds. I have a DT300i. I've come to the conclusion that she's not a cold weather girl. Check your oil brand/type. It may not be a cold weather oil. that seemed to be part of my problem.

- Wolf

[kneeslider]

Do you think the auto choke isn't functioning?

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[CROSSBOLT]

200 or 200i? Carb or EFI?

[kneeslider]

200i fuel injected.

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[CROSSBOLT]

Now wait a minute! I am certainly not the cold weather expert here with De dee and Stig riding in frigid weather regularly but cold starting problems seem to plague only the 500's. The DT & GT 300i, the Like and the Yager all were generally ALL WEATHER starter-runners. Sumpthin' must be wrong.

[Stig / Major Tom]

So, starts well, and runs fine after it is warmed up?
- it starts and runs fine at all speeds when the engine is hot?

Can you source a service manual for your scooter - specifically one with a "trouble shooting" section.
With an EFI engine there are a number of sensors which feed in info in order to operate properly - one could be causing this symptom. (I'm thinking temp sensor is faulty.)

It is not a young scooter - so a service manual to trouble shoot would be very helpful.
You have a Downtown 200i - is it the 163cc '200i' ? or a different engine?

Stig

[hypophthalmus]

One possibility is that it's correcting a bad air/fuel ratio once the O2 sensors are hot enough to run.

[hypophthalmus]

This could be an actually bad air/fuel ratio, for instance with a vacuum leak or injector leak. Or it could be a air/fuel ratio that was erroneously calculated, if one of the sensors was bad.

[kneeslider]

So, starts well, and runs fine after it is warmed up?
- it starts and runs fine at all speeds when the engine is hot?

Can you source a service manual for your scooter - specifically one with a "trouble shooting" section.
With an EFI engine there are a number of sensors which feed in info in order to operate properly - one could be causing this symptom. (I'm thinking temp sensor is faulty.)

It is not a young scooter - so a service manual to trouble shoot would be very helpful.
You have a Downtown 200i - is it the 163cc '200i' ? or a different engine?

Stig

Yes to both Stig.

I do have the serive manual, will look at the trouble shooting section. Totally slipped my mind. RTFM right?

Mine is the one with the 205cc engine.



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[kneeslider]

This could be an actually bad air/fuel ratio, for instance with a vacuum leak or injector leak. Or it could be a air/fuel ratio that was erroneously calculated, if one of the sensors was bad.

Biggest culprit would be the O2 sensor?



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[hypophthalmus]

Nope, the O2 sensor would be working correctly in this scenario.

Here's a brief explanation:
EFI engines have a computer that calculates how much fuel to inject based on its sensor data. When the engine is cold, all it can do is assume it's doing a good job making the correct air/fuel ratio.

The O2 sensors are there to check the computer's work. But they can't do that until they're hot. Once the O2 sensors are hot enough to work, the computer stops assuming it's doing a good job, and starts adjusting how much fuel it adds based on what the O2 sensor is telling it.

So the fact that the engine runs better hot suggests the computer is doing a better job when the O2 sensors kick in. This could be because of a defective sensor, messing up its calculations. Or extra air or fuel are entering the system where its not supposed to.

[CROSSBOLT]

Well, actually in the Kymco EFI systems, there is a heater in the O2 sensor. The sensor has 4 wires to it and not just two. The heater is for the start from cold phase of operation.

[hypophthalmus]

Whoops!

Okay, so assuming the heater is working it'll probably have something to do with a heat-sensitive component.

Besides Stig's suggestion for the temperature sensor (or some other sensor), maybe the compression is improving as it warms up.

Something that I think was missed is this isn't remotely a cold weather problem -- 20 C is 68 F.

[hypophthalmus]

If it is a bad sensor causing it to miscalculate things, you should be able to see this in the O2 sensor and fuel trim data. I have no idea how accessible these are though.