Cutting the MAF mesh

[Saint_]

I want to cut the MAF mesh. Anybody did this on 2.3? Xedos did to his 2.5, but seems like 2.3 mesh is much thicker.

And should I expect any side effects? When does it use MAF sensor data? I dont think it needs MAF sensor data anymore when cruising at constant speed. It is already in closed-loop with O2 sensor. So fuel economy at constant speed shouldnt change, it may even get better.



More images from ebay:

[shikoku_iv@msn.com]

I have cut out the honeycomb part but left the mesh screen behind the honeycomb in. I picked up 2 horsepower cutting it out,haven't really noticed a difference when driving.

[Xedosman]

I've not discovered any negative side effects. It may have improved my milage abit too, AFAIK I'm the only Xedos owner to get beyond 30 mpg, measured between tankfillings. My mesh was different though, as you point out. Just a single layer of wowen stainless mesh. A piece of cake to remove with a scalpel.

[yel-low]

Wow ... venturing into the danger zone huh??

Someone correct me if I'm wrong but I did some reading years ago about the purpose of the screen and honeycomb structure. Its purpose was to provide a more "laminar-ish" type of flow rather than the air bouncing all over the place and the MAF sensor getting erratic readings.

I know the Millenia 2.5L pretty much just has a screen but in some other cars there is a sort of grid/fin/honeycomb pattern behind the screen. I could see how removing the grid could lead to all sorts of CEL codes but I have no clue how the Millenia would react.

Afterall its just a screen, perhaps there mostly to trap debris rather than have any substantial affect on airflow.

Edit: Found a nice little article that goes over the mod. Its far from an engineering fluid flows textbook (in terms of substantial proof) and talks about an entirely different beast of an engine but never-the-less is still a good read. FWIW
Mesh

[millyowner]

The mesh is designed to straighten the airflow before it reaches the sensor element. A sort of air turbulence filter to increase sensor accuracy. This mod was popular among the DSM crowd back in the day. Those were a little different though. Those had two possible airflow paths...a metered (sensor) path and a "bypass" path without a sensor. Each path has its own honeycomb and the idea was to remove the bypass chamber honeycomb so that more air would flow through the bypass chamber than before, throwing the sensor calibration off and making the system run a little leaner. The affect was the same as the MAF "resistor mod."

Some DSM owners removed the honeycomb on the main chamber too...with mixed results. Some had no issues. Other cars had problems idling. There seemed to be a correlation with choice of air filter and success with the mod with K&N cone filter users having more success...presumably because the airflow has less turbulence as it was entering the sensor chamber.

[milly00]

I thought of doing this also, but after seeing the dirt that was on that mesh when I recently cleaned my intake and the MAF I decided not to. It actually does keep the soot and dirt out that the filter didn't collect. That MAF cleaner spray made a **** of a difference in throttle response too.

[Saint_]

I also plan on a K&N cone filter just before the MAF. I can imagine the cone filter will give more homogeneous air flow than a bent paper filter setup. IMO the air will concentrate on the center but it is deterministic rather than random. And since ECU has some correction to MAF sensor output it should learn the new offset it has to apply. I can also imagine making the straight pipe from filter to MAF longer will help correct the air flow density. Maybe I should connect the MAF to the resonator and use some pipe between the MAF and filter. Is there a document describing how MAF is used in Milly?

Yel-low, I skim the reading, I am gonna read more carefully. Thanks.

Based on Matts measurements removing some restriction of MAF will have benefits in terms of max torque/hp.

The fuel saving should be coming from less required throttle for the same engine output. That should make the tranny shift faster to higher gears.

[Xedosman]

Yel-low, surely a good read but I don't buy the story. So the throttle body represents a larger flow obstacle than the MAF mesh? Fair enough, but that doesn't mean ripping out the mesh won't improve flow. Transferred to electricity: two resistors in series will equal a certain resulting resistance. Now if we alter one of them, the resulting resistance WILL be altered.

Anyway my approach to the MAF modification was like WTF is that mesh doing there? So I ripped it out. Issues: none. Gains? Good question. But I do challenge everyone on this forum to improve my 33,1 mpg during a 400 mile trip, FULLY loaded. Unbelieveable? My second best run is 32 mpg. Also fully loaded. Average speed probably 50 mph, typical cruising speed slightly beyond 60. Secret trick: determined acceleration but not beyond 5k (1st and 2nd) upwards 40 mph, then keep the TCC engaged! The imaginary egg under the throttle is no good.

[Saint_]

I didnt get this point either:

"ONLY if you already have the horsepower to free up by a modified throttle body and intake."

Whatever car is there removing an air restriction will improve max hp. More air=more fuel=more power. Now wheather MAF mesh is restrictive in all applications or not is another question. For 2.3 it definitely is.

[themechanic84@gmail.com]

i wouldnt do that...all it takes is something hiting the maf sensor with enough force to damage it can cost u a few bucks no matter how tiny the debree is