MAF relocation on the M111 (230) engine for better performance

[vijilants]

In this month's MB Club Gazette, there is an article on relocating the MAF on the M111 engine of a 1996 SLK230.

Basically the MAF on these usually sit vertically down the side of the radiator, but apparently relocating it to the horizontal position close up to the throttle body is supposed to give better throttle response, smoother etc.

The article is a full HOW TO with pics etc.

The engine quoted is the M111 973.

My engine is the c230K M111 975 .

I was wondering if anyone here has tried this mod and the results as I may give it a go on my C230K engine ?

 

[jamesmc]

Basically the MAF on these usually sit vertically down the side of the radiator, but apparently relocating it to the horizontal position close up to the throttle body is supposed to give better throttle response, smoother etc.

I'd be interested to see how this might work. I can't see, from a mech point of view, what the difference might be.

 

[Number_Cruncher]

>>I can't see, from a mech point of view, what the difference might be.

If an engine ever ran in a truly steady state, with no fluctuations, there would be no difference at all.

However, air flow in manifolds is always changing, there may be a changing demand, the engine speed may change, and most importantly for this discussion, the air pulses in the manifold as each intake of air ino the cylinders is a discontinuous process.

From an engine control point of view what you are changing is the time lag between sensing the passage of some air, and that air actually finding itself in the cylinder. Technically, this is called reducing a transport lag, and usually promotes stability.

I would expect the mod to improve smoothness and response, particularly at low engine speeds, where the transport lag is at its longest.

So, the brief answer is that re-siting the air flow meter tends to improve the dynamics of the system.

 

[vijilants]

Yep....apparently the improvement is from about 2100 - 2800 according to the article.

So why didn't Mercedes puit it close to the throttle valve in the first place ?

 

[Bazzle]

They (MB) moved it on the post 2000 models. Many have moved the original one. Common mod.
Especially noticeable if you have a larger engine pulley .

Bazzle

 

[Adam230K]

In this month's MB Club Gazette, there is an article on relocating the MAF on the M111 engine of a 1996 SLK230.

Basically the MAF on these usually sit vertically down the side of the radiator, but apparently relocating it to the horizontal position close up to the throttle body is supposed to give better throttle response, smoother etc.

The article is a full HOW TO with pics etc.

The engine quoted is the M111 973.

My engine is the c230K M111 975 .

I was wondering if anyone here has tried this mod and the results as I may give it a go on my C230K engine ?

You've caught my interest Whats the exact name of that magazine??

 

[Dieselman]

From an engine control point of view what you are changing is the time lag between sensing the passage of some air, and that air actually finding itself in the cylinder. Technically, this is called reducing a transport lag, and usually promotes stability.

Good point.
Also if hte MAF contains a temperature sensor it will be affected byt he radiator temperature so may reduce fuellig accordingly as the apparent density of the air will appear lower due to heat soak.

 

[Shude]

They (MB) moved it on the post 2000 models. Many have moved the original one. Common mod.
Especially noticeable if you have a larger engine pulley .

The 2000 models also had some slightly different plastic pipework for the air intake, this might be one of the reasons why they had about 4bhp more according to the book.

 

[vijilants]

The 2000 models also had some slightly different plastic pipework for the air intake, this might be one of the reasons why they had about 4bhp more according to the book.

In the article, the guy gives the part number for the new intake pipe aswell.

I think its worth giving this a go !

 

[vijilants]

You've caught my interest Whats the exact name of that magazine??

The magazine is the the April version of the Gazette - you get it if you are a member of the Mercedes-Benz owners Club.

I could have scanned it and emailed it to anyone thats interested, but my scanner has packed up

 

[jaymanek]

its a very good article... at first i thought dont be silly but it seems that later MB did the change so its really just a mod rather than an invention!

 

[Adam230K]

Oh damn Guess that membership your talking about has nothing to do with this forum (cuz i think i'm a member here right??). Would've loved to read up on it

 

[vijilants]

Oh damn Guess that membership your talking about has nothing to do with this forum (cuz i think i'm a member here right??). Would've loved to read up on it

If I can get it scanned I will email it to you...pm me your email address.

The membership required is for the link below. Howevere, they do publish their Gazette on the web and it is usually a couple of months old so, this one should come up. Also I see plenty of these Gazettes kicking around in the dealership. It is the only officially recognised owners club.

 

[vijilants]

OK,

I did this modification yesterday - The MAF is now located horizontally and resides next to the washer bottle and as close as possible to the throttle valve.

Verdict: The response does appear to be smoother but it is difficult to judge the fact that it is supposed to give a faster throttle response, as I use a sprintbooster, hence am used to a very fast throttle response.

Id have to go back to driving without the sprintbooster for a while (and I don't really want to do that) but then again I will not be able to compare the results unless move the MAF back to its original position,(no sprintbooster) drive around, and then move the MAF to its new location and drive around and compare.

Unfortunately no time for all of that, so theoretically I would have to go with the fact that there is some increase in throttle response.

 

[Whitey]

Sorry to revive an old thread, but I will going to MB soon to get an up to date price on the parts needed.

If the parts are reasoably priced I'll do the mod and give a seat-of-the-pants verdict as I don't intend to do any rolling road/0-60 tests.

Just thought I'd post for those who are interested !

Whitey

 

[Justin1600]

This mod also reduces the chances of the MAF getting contaminated with oil. Early cars suffered with this

 

[Whitey]

After a bit of sucking through teeth and checking the parts database with superb help from Andrew @ MB World, parts were ordered at £53.66.

It's a bit steep, but curiosity together with the fact that MB moved the MAF on later models anyway, helped make the decision.

Chris

 

[Whitey]

Carried out the modification today.

You get value for money for your £53 as the pipe is larger than I thought !

Initial observation is that my idle has become rock solid - an issue I had looked into briefly before.

After the drive to work, here's what I have noticed :

- with normal driving gear changes, the transition between the gear box starting the change and engaging the next gear is longer; this means a smoother drive.

- there appears to be more engine braking

- the engine will drop into 1st smoother when in slow traffic

- on a dual carriage way run, a hose I didn't play with was blown off ! So I guess this either indicates there is more pressure with the ECU closing the bypass valve or it was just settling down with the new position of the MAF; tightened this up so hopefully won't happen again.

With the pipe off, the car will not idle, so I guess the MAF does have it's part to play with regard to idle regulation.

Power wise, it just feels smoother which equates to thinking it is slower.

We'll see how it adapts over a tank of fuel and crucially if miles per tank is changed.

Whitey

( pics to follow )

 

[BlackC55]

Do a 0-60 comparison.

 

[Whitey]

Do a 0-60 comparison.

I haven't got my 0-60 timer any more (can't even remember what it was called - stuck to the windscreen).

But everything seems positive so far.