Air Intake = rough running

[m3f_M3AutoXR]

On the weekend I put a K&N cone filter on my 97 M3. I used the largest one I had lying around ("9" diameter) made alitle bracket , all in all it cost me $20 to do it (filter was a freebie) I de-screened the MAF on the car , hooked everything up (made a nice little adaptor) and wouldn't you know it the car stumbles a bit when it's cold. I did notice a bit of an increase of upper end power...nothing earth shattering.



I went outto the car this morning on my way to work and it stumbles a bit more... i don't get it. this wouldbe the first car I have EVER experienced do this after an air intake. Does the system need to learn the new setup?



Just for the recond...no I didn't damage the MAF when I de-screened it... I am happy with the performance , but the stubling is annoying.



Oh yeah...only when it's cold does it stumble..



any ideas?





J. McCreery

97 M3

[m3f_97BLKM3COU_0f375e15e2]

Put the screen back in. Your car needs it to "Smooth" out the airflow going over the MAF. This has been discussed on other boards and taking it out on this car will hurt your performance.



There is a company that makes something called the "Green Gizmo" that replaces the factory screen with a less restrictive one, but it is questionable whether or not this really helps.



Your stumbling is coming from the MAF getting "non-smooth" airflow over it.

[m3f_96M3Power_4547fc3d60]

how do you remove the screen? I don't want to damage anything, but I have some stuff caught in there that I want to get at and I really didn't have time to look at it.

[m3f_n8nod9it]

how do you remove the screen? I don't want to damage anything, but I have some stuff caught in there that I want to get at and I really didn't have time to look at it.





The MAF screens front and rear, are slightly restrictive, and yes do help help create a laminar flow that is consistant. However, removing them will not damage anything, and do help to increase a slight bit more of air through the HFM. Some ppl report a slight idle dip, or some roughness in engine running. I have my screens removed, and have no problems with idle etc...The increase in flow is pretty marginal, %5+-. Removing the screens are as easy as uncliping the "c" clips that run the circumfrence of the inner diameter of the outside of the screens.

[m3f_M3AutoXR]

It looks as though it would be VERY easy to adapt a much larger MAF housing all together. I am used to working on Lt1's , but the BMW MAF sensor itself is a seperate peice. I am going to see what i can find that will work well as a housing. I don't want a hack job. but being a N/a Motor there's not a lot I can do.



my screens didn't have a c-clip , there were 2 "tangs" on the screens themselves that fit intot he housing itself. I just carefully popped it out... wasn't too hard.



Ultimate goal is a solid mid 13 sec car



JM

[m3f_black sheep]

Hey

I installed a while back a Carbon Dynamic AIRBOX FROM bmc:

And except for the light increas in power, and nice sound, I also F**cked up my Air mass meter, which made the car idle really bad n loose power at times.

I had no idea this was to happen, but after doing searches on a few M3 forums i did find others that had experienced the exact same problem.

The air mass meter luckily didnt cost me no more than a €46 clean out at BMW, but it could be a higher price if it actusally does break.

I removed my air intake,put orig, back on :bow: and shes back to being fine now.

This is a typical problem for the 3.2euro engine, but may happen to a 3.0 as well, allthough not as often. from what i have read.



BS

[m3f_M3AutoXR]

Put the screens back intoday. didn't realize how much they affected the car. It runs smooth and pulls better than without....Go figure!



Thanks for the help!



JM