2002 XG350L with 42,000 miles has stumble when first strarting
driving. Car starts fine, revs up, idle drops down then I put it in
gear to drive. Car starts to bog as if it is going to die then takes
off. This is every day lately. Once warmed up runs fine.

I have tried a bottle of CHevron's Techron but did not help.

Any ideas HyundaiTech?

 

Dunno. If you've got a check engine lamp, you should start there.

But I'm presuming you don't. Try reinitializing the throttle: Turn the
key on (don't start the car) and back off immediately and wait ten
seconds. Your throttle will do a sweep.

Also do an idle learn. Start the car with the a/c on and let it reach
operating temperature. Let it run for 10 more minutes. Then turn the a/c
off and let it run for another ten minutes.

 

hyundaitech wrote:
> Dunno. If you've got a check engine lamp, you should start there.
>
> But I'm presuming you don't. Try reinitializing the throttle: Turn the
> key on (don't start the car) and back off immediately and wait ten
> seconds. Your throttle will do a sweep.

Is there any indication that the throttle sweep has been completed? Is
there a beep or any dashboard light indication?

Matt

 

Idle learn? Never heard of that. I did try the sweep but it didn't
help. With the idle learn I just leave it idling the whole time?

 

Unfortunately, no. The only way you'd know for certain is to have someone
listen or watch under the hood while you try to make it happen.

 

Yep, just leave it idling. It'll watch and learn where it needs to leave
the throttle plate for proper idle rpm.

 

Is it safe to clean the throttle plate with cleaner? Engine running or
not?

I know a lot of cars can be harmed if this is not done properly (ruin
O2 sensors, remove coatings, set trouble codes, etc).

Also, thanks for all the assistance on here. Your feedback and advice
is invaluable!

 

It's okay to clean the throttle plate with carb cleaner (while not
running).