alexandergreat

So, I installed new air filters on my clk550. Nothing too bad for a beginner like me who only knows what he reads and watches in videos...putting back the air filter box over the engine was the harder part..but looked like it ended up fitting.. after a big sweat...
Then I go for a drive. The previous owner must have have never ever changed these filters before, they were absolutely filled with a ton of dust, insects and so on, way worse than on videos that showed their worst case of dirty filters...so I'm thinking it's probably going to be a very noticeable improvement..which it did at first...smooth...nice...
Then I noticed some hiccups at idle, as if the engine is going to stall, but then, fights to stay on and in the end, each time, doesn't let me stuck in the middle of a L.A. street and keeps on. Maybe because of all the love I have for this car...she knows... The car drives fine, accelerates fine, but the idle keeps on jumping at times, at each red light and stop.
I'm bummed, for once I do something myself, it seems that I f..... something. I remember about reading about how sensitive the MAF is, and just a tiny misalignment with the filter box can mess it up...assuming this is the MAF, I opened the hood and push everything down to make sure everything is in place and aligned, hoping that the MAF maybe needs a better fit with the corresponding hole on the air filter box. I couldn't do much at this time and place, like unmount everything and check under as I was in a clinic parking at this point and also expected inside. So I just push down the filter box, a bit there and there...barely seems to move much..but who knows...
An hour after, I'm back at the car. Start it and drive 2 miles. Everything fine, no rough idle...Another stop for an hour and a half... Back in the car, I drive all the way back home, with one more stop for food, so about 50 minutes total with a 10 min break...
The car drives fine, as it did before, but also no more hiccups since I did the push down. No hiccups in the idle.
Can somebody tell me what happened?
From what 've read:
1. There's a little time needed for the engine to learn the new idle..after all it was EXTREMELY dirty before getting cleaned and replaced..
2. The MAF must have set better after I pushed down, in this case it would be a quarter of a mm, a hundredth of an inch , since I didn't feel anything moving much when I push the top down...
3. Pushing down on the air filter box, I might have plugged the MAF, which maybe was slightly unplugged during the process of removing the air box.
4. After a driving cycle, someysome reset the proper idle..

I don't know, I hope it's going to be fine from now on, but I'd love to understand what might have happened, was it the desperate push down? Was it a reset?
Thank you so much in advance for your inputs.

Fatz

There really isn't much to come undone with the MAF. It is pretty secure with the clips at the top and the elbow between it and the intake also has clips. Unless you could move it easily, my guess would be that it was fine.

You probably did not get the cover properly seated. There are 2 clips on the bottom of the cover/filter box that can be bent, if the cover is not replaced properly. I suspect pushing down on the cover got it such that the MAF got the needed seal.

You might check to see that the clips under the cover are not bent. If they are, they can be straightened if they have not been bent too many times before. So that it is easier to remove the cover, I use a bit of silicon lubricate on the fittings those 2 clips fit over to secure and align the cover. When putting the cover on, you can make sure it is aligned and seated properly by putting your hand behind the cover from the top and feel that the seal on the cover underside is over and around the MAF housing.

If the filters were really dirty it might be a good idea to clean the MAF sensor. You can see it through the screen over the MAF housing. You will see a small glass like object (maybe reddish in color) with a wire from each end. You can spray that object with some MAF sensor cleaner (CRC - available at any parts store). You do not need to remove the MAF. Just direct the spray at that glass object and spray it through the screen. Besides, it is a bit of a pain to release the clips to remove it without breaking the retaining clips of the housing.

alexandergreat

Thank you for your time and great answers.
The MAF looked actually very clean. So guess the joint wasn't all the way fitted maybe. I'll definitely keep in mind your advice when I need to remove this part off on the future..
​​​​​​ Now that it works fine i would rather not touching anything unless necessary.
thank you again, really helps!