Stumbling CVT fix. Yes fix.

[LPSISRL]

Do you have one of those CVTs that likes to stumble when you come to a stop? I had it with mine when I first got it and it kind of went away by itself. A number of other guys in this forum had the same problem. We all thought it was the CVT. You may recall I had my CVT replaced under warranty a couple of months back. After the CVT was installed, the stumble was back. So I naturally thought it was CVT related. Maybe for some reason the CVT torque converter does not untorque (I know that's not a word but an apt description) quickly enough causing RPMs to take a dive and hence the stumble. We fast forward to this morning. Started it up and the SERVICE ENGINE SOON came up on the display. I've got an "Automatic" bluetooth OBDII device and DashCommand on my phone. I read the codes and there was a P050A. Cold Start Idle Air Control System Performance. Not much on this forum for that code, but a few other sites indicated a dirty throttle body. Watched a couple of UTube videos to make sure I wasn't going to destroy anything and set out to clean it. Yup, that's what it was. A can of throttle body cleaner and a rag and she's idling great and the stumble coming to a stop is gone as well.

All you need to do is remove the intake tube which is held on by a couple of stainless clamps. A standard screwdriver is the only tool needed. You have to disconnect some metal tube that pulls right out from it and a small wire bundle that goes over the top. Set it aside and clean out the throttle body. You can spray it with the valve closed to start with. Wipe it clean with a rag. I would not use a shop cloth. Too much opportunity for some of it to get inside. Then hold open the valve and really clean all around it. You may have some gunk really stuck but you need to get it all off. I sprayed the cloth and then rubbed and rubbed with the cloth. Do as much of 360 degrees as you can. On some of the videos, the wife's toothbrush was used to help loosen the gunk.

So if you have a stumbling, poor idling CVT, and a dirty throttle body is the issue, this will really make your day. It made mine!

[Ronzuki]

Good stuff. Thanks for the heads-up.

[KuroNekko]

Awesome. Was your intake and TB rather dirty? Any chance of any unfiltered air entering the intake for it to get that dirty? TB fouling can also be a problem among those who use oiled cotton air filters like the K&N if it's over-saturated with oil.

[LPSISRL]

Awesome. Was your intake and TB rather dirty? Any chance of any unfiltered air entering the intake for it to get that dirty? TB fouling can also be a problem among those who use oiled cotton air filters like the K&N if it's over-saturated with oil.

The intake tube was clean assuming that's what you mean. I didn't remove the TB to get any further looks and I cleaned as far as my fingers would reach. I'm using the stock filter as I'm not much of a believer in the CIA stuff. The throttle body was not very dirty, however, there was a ring of black stuff built up where the valve meets the body. I'm sure this was restricting airflow even if it was just a very thin layer. Once it was gone, the stumble was gone. I'm pretty sure that no unfiltered air was getting in. I read about "back-spray" causing some of the buildup. Not sure how that happens but it sounds like it would happen when you shut the engine off.

[Ronzuki]

Awesome. Was your intake and TB rather dirty? Any chance of any unfiltered air entering the intake for it to get that dirty? TB fouling can also be a problem among those who use oiled cotton air filters like the K&N if it's over-saturated with oil.

I was wondering if a non-standard (K&N type) was ever used on the car. I had one of those things in my Dodge pickup and it let all kinds of fine particulate (mostly coal dust from wheeling) pass through it which ended up on every single intake component south of the filter.

[LPSISRL]

I bought it with about 33K on it. It was a naval officer's wife's car. Pretty sure it never say anything but the stock filter. I know I haven't used one.

[Ronzuki]

well that's interesting...wonder how all of that got in there? Ah, never mind...I know. At last year's annual inspection, my Ex-Suzuki dealer told me my air filter and cabin filters were "cruddy", presumably in hopes of selling me a service. Said pass I have filters at home. I get home to look see just how "cruddy" it was , or wasn't, and one of the fasteners holding the air box closed tight wasn't secured at all. There ya go.

[KuroNekko]

well that's interesting...wonder how all of that got in there? Ah, never mind...I know. At last year's annual inspection, my Ex-Suzuki dealer told me my air filter and cabin filters were "cruddy", presumably in hopes of selling me a service. Said pass I have filters at home. I get home to look see just how "cruddy" it was , or wasn't, and one of the fasteners holding the air box closed tight wasn't secured at all. There ya go.

Seriously. I helped a co-worker who came back from an oil change with an "unusual loud engine noise". I checked the air filter box and it wasn't sealed properly, leaking in unfiltered air. I seated the filter properly, making sure the gasket properly formed a seal. I then clipped the box down properly. Everything fixed. It's troubling when the people who are paid to make things better make things worse.