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Registered 2001 SLK320
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24 Posts
Discussion Starter #1
Hello, so I’m currently driving an 2001 SLK320 with 110000k miles, bought it 6 months ago and I love it. I’ve toyed with the idea of getting a 2008 ish SLK350 but for a variety of reasons (mainly I just really like the R170 design and love the cool retro ness. I love the 18 yr old merc still kicks ass and I’ve already put a bit of cash into my 320 ( Trans service done recently, fuel pump and filter replaced, engine service every 5k miles, Those Angel eye lights and loads of other bits and bobs to tidy it up.) I’m going to hold off on the 350 for a few years.



Just like every other petrolhead We always want to improve our cars, I want to make my 320 a bit less of a cruiser and a bit more sportier feeling.



For the engine side of improvements my plan is to: convert the factory 2.5” intake with a 3” intake (MAF and TB from the m113), swap the factory airbox for a C320 airbox, Have a full catback exhaust made, remove 2 of the 4 catalytic converters. Get larger fuel injectors from an m113 and have a custom engine map made. Also going to replace things such as HT leads etc.



What I hope to achieve with these mods is:



Improved throttle response and the car will pull though the rpm range a bit faster and feel less “smoothened” and “soft” Don’t get me wrong, the stock 320 is a fast car but the lazy feeling engine and poor response detracts from the driving experience. (Maybe i should get a sprint booster too?)


Slight HP/TQ increase, yes it’s an NA so I don’t expect a massive increase, maybe +30hp ish from all the mods but I’m not too interested in max HP number I’m more interested in making the engine a bit more lively, quicker revving and more torquey in the midrange.


I’m going to start with the engines intake, a 3” conversion from the stock 2.5” and a C320 airbox.

So far I’ve read:

1. The airbox from the C320 is a bit larger and has better flow than the stock airbox and should fit and clip in just fine, will probably use MANN paper filters because I’m dubious about the amount of fine dirt aftermarket filter let pass.

2. The MAF housing from one of the M113 engines is a direct bolt on and with the MAF sensor from the M112 it still reads the correct airflow apparently.



3. The larger Throttle Body from the m113 are also compatible with the M112 and plug right in.



So basically I’ve read that you can install said intake track components for better intake air flow without any issue because everything is compatible.

My question is, is the M112 MAF sensor calibrated for the M113 housing, apparently you just plug it in and it works. I understand the basic physics how the sensor functions but I’m still dubious weather the sensor would read the correct airflow when placed in a larger diameter tube? Any one else tried this mod or knows anything about the MAF sensor compatibility with larger housings? Also I have read after installing a new TB you should leave the car in ignition position 2 for a few minutes because it will calibrate the TB?
 

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Premium Member 1999 SLK 5.4 M113
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1,432 Posts
Sorry, just noticed this!

You can do a quick parts search to see if the MAF is the same between the two engines. I can almost guarantee they are as I've pulled some V6 parts off for some of my V8 experiments. be careful, cars with ME2.8 stuff is a little different (different throttle bodies and electrical plugs) so be careful from what car your throttle comes from.

one thing about your throttle. yes it will be a little bit snappier, but that's only because your ECU thinks it's moving a smaller throttle plate. You might feel some hesitations when holding it steady (when cruising) because it will almost always over-correct as it's trying to maintain a certain RPM, but it requires different amounts of throttle than what are programmed so you can feel it adapting constantly. It may not be very noticeable with your swap, but when I went from my 230 engine to my V8, it was VERY noticeable.

Crossfire guys do the 80mm swap, some succeed some have some complaints. and yes, leave it in the ACC position and let it program itself or it wont idle right.
 

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Registered 2001 SLK320
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24 Posts
Discussion Starter #4
I’ll have to get round to swapping the maf soon then, did the throttle body and C320 airbox swap and used some 80mm silicone hose to go from the airbox to the grille. The car is noticeably snappier and more responsive, much less soft and more sporty, the top end seems like it pulls slightly harder and feels less restrained. Idles properly, no cel light.
 

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Yes Im doing this on my m112 E-320 wagon with hopes of improved MPG and also interested in upgrading the tuning on the ECU. I posted on TVT's old original (9 yrs old) thread but I see this is the same topic. The M113 parts are so cheap and available from ebay. Not interested in bigger injectors but perhaps an increase in fuel pressure might improve performance and MPG. Im barely getting 25 on the freeway and feel the car should be capable of better..

Much appreciation for the great forum and community, SLK guys..Thanks for letting me join with my E320.

Im also interested in learning to adjust the ecu parameters to tweak performance as we used to work on our mixture and timing to get it all just right...often getting very good performance AND mpg!
 
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