I just what to relate my experiences with a recent RENNtech ECU tune for my 2012 CLS550 4Matic. I've been researching and considering a tune for a year now, but medical concerns have been a much higher priority. My goals may be different than others... I don't race at all, but simply wanted a reliable and efficient street tune. I wasn't worried if I didn't have the most horsepower... I crave usable street torque. In the end, there were many qualified tuners to choose from, but I selected RENNtech based their years of experience, excellence in engineering, and close relationship with Mercedes Benz.

Since I have some decent mechanical skills, I opted to remove the ECU myself. This operation is extremely simple to accomplish... provided you can find the battery first (they hide it well). Once the ECU was removed, I sent it to Florida on a Monday afternoon and it was back on my doorstep in Massachusetts by 9:00am on Wednesday. Reinstallation was a snap and the Benz easily roared back to life. Altogether, there was not much down time on the vehicle.

The initial shakedown cruise was next. In local city driving, there were no adverse issues... it was comfortable and docile in traffic. But when I hit the expressway on-ramp... oh yeah, I began to smile. And squeezing the throttle to merge and change lanes was impressive... it definitely was a new beast. For some strange reason, I remained somewhat skeptical, yet highly intrigued... I wondered just how much the dyno would reveal?

Fortunately, I had the foresight to do a base dyno nearly a year ago. Recently, I returned to 'Enhanced Street Performance' (ESP) for another Dyno Day. Although the main focus of the day was devoted to Corvettes, the group of guys welcomed me and ESP was first class with their professional service. The dyno used here is a Mustang 1100-SE AWD chassis dynamometer. Though I have no proof, I'm told that measurements on the Mustang Dyno are traditionally about 10% less than a Dynojet. Furthermore, the guys also indicated that this particular dyno was even lower than other Mustang dynos they have tested on. All in all, since this was the same dyno for my base numbers, the overall gains should be accurate.

Setting up my CLS550 4Matic, the traction control was turned off and the pulls would be done in 4th gear... same as last time. The first dyno run was somewhat uneventful... the tranny was difficult to hold gear and kicked down. With some slight initial feathering, the second pull sounded great and everyone was eager to see the results. I was ecstatic when the huge projection screen spit out the uncorrected readings... 426 horsepower and a whopping 515 lb/ft of torque!

I could be mistaken, but I don't believe there have been any dyno postings from a CLS550 4Matic in the past. Since this is an AWD vehicle, I estimate drivetrain loss at between 15-20% (though MB is very efficient). Therefore, I feel crankshaft figures are a good 500HP and over 600 lb/ft of torque... utterly amazing on a conservative Mustang dyno.

Overall, I'm extremely pleased with RENNtech and highly recommend dealing with technical advice from Lenny or sales aspects with Tomas. I'm not sure if medical science will note this, but my RENNtech tune also helps to cure my disability... every time I slam down the throttle.

Regards,
427

-----------
RENNtech ECU Tune:



Before & After Results:


Dyno Day Video (mostly Corvettes):

 

thanks for the posting and sharing your dyno run.

Every dyno is different and weather, fans, calibration and gearing play a big role.

Overall your car making very good daily driver power with the ability to have AWD to help put it down.

I went to 285/35 rears with 9.5" rim to cope with my E coupe inability to put power down on skinny 255/8.5" rim.

I won't be able to pull on AWD from a stop for sure.. but I should be able to hang.

OE tuning is next. ..

 

Love the look of your coupe... give us some feedback when you get your OE tune.
BTW- Will you be doing any before/any dyno testing?

 

Was there any external signs that the ecu had been apart?
I have read but cannot recall where, that a hole is drilled in the ecu box and that this may indicate to an MB technician that the ecu has been opened.
Thanks in advance

 

When my ECU was returned from RENNtech, I looked carefully for any visual signs of opening/tampering... I could NOT see any such evidence. The only difference I could detect was that the ECU appeared much cleaner... almost new looking.

 

I have posted a few placed.. got the OE tune Friday..

did not have a chance to give the car solid freeway runs... but in empty areas "non residential" i was able to make a full pulls .. never going past 4k or so.

around town.. car seems like stock.. but with more available torque.. At this point going from 440WTQ to 520+WTQ will be hard to tell the difference.. the car is already making more torque than it will ever need.

But its after 2.5K.. and when the car hits 3k and up.. you can feel the power increase.. going past 4k feels just as strong as my stage 1 E55 on top the power band.. but E550 has plenty more to go.

My wife drives my coupe to work few days of the weeks.. so this is perfect for me.. car feels like stock around town.. but if you place in "S" mode.. it will pull very hard when needed...

This engine is very smooth even when tuned ...

 

Enjoy the tune!

 

Please help me to understand. I have been reading various posts on ECU tuning and it seems most of the major players (Renntech, Kleemann, Brabus, OE, Eurocharged, others) seem to offer essentially the same gains (+/- 10% or so) but WILDLY differing prices. I'm particularly interested in the tune for my engine (M278 biturbo) and I live well within driving distance to OE, Kleemann, and the MB dealer who installs Renntech. Why one over the other? If they are not essentially the same would someone help me to understand why? I know nothing of horsepower, transmission losses, etc.

Money is not the issue; spending it wisely is.

Thanks.

 

It all comes down to your comfort level. Renntech charges more because they are well known and it is the only tuner that some MB dealers will install.
I personally refuse to pay their high price and have been very happy with Jerry from Eurocharged.
However, I would pay extra for the peace of mind of warranty if your local dealer installs Renntech. I am fully aware that if something bad happens, they still can deny warranty but at least they will work with you.

 

Excellent question... I'm glad you're doing some due diligence before the tune. Unfortunately, there may be no clear cut answer. Granted, the software 'may' be similar... but I'm sure they are not all exact copies. Some tunes have on-site engineers, while others could even purchase their base tune and then customize it. Some tuners drill a hole in the top of the ECU (telltale evidence), while others don't. It goes on and on...

Personally, I contacted several of the tuners and evaluated my options. All were very professional and seemed to generally want my business. I analyzed the data (not everyone had dyno results), reviewed the online posts and contacted some members (via PM) for their candid thoughts and experiences. I didn't want a hole in the top of my ECU, so that eliminated some tuners. Published dyno results were good, but drag videos showed some of the best evidence. Even though I don't race, knowing that some tuners could backup their claims with real world testing was important.

I opted for RENNtech for a few reasons... most importantly:
a) Many years of experience with Mercedes and AMG
b) Their affiliation with many MB dealers (important for warranty issues)
c) Proven dyno and track testing results

In closing, consider the purchase of an expensive watch or handbag... why pay the original price when you can obtain a knockoff at a huge discount? Is RENNtech expensive... indeed. Are they worth the difference... to me, they earned it.

Your mileage may vary,
427

 

With regard to 'b' - I had a long talk with the RENNtech representative at the MB dealership where i purchased my car. It turned out he was also the service manager - perhaps a conflict of interests? Anyway he stated there was no way for the servicing technician to know whether the ECU had been altered. His answer to my 'warranty issue' question was answered with "I've never seen a car with a warranty repair that could be attributed to a tuned ECU. It just doesn't happen." I skeptically interpreted his response as an artfully constructed non answer.

I appreciate the above responses.

Scott

 

Again, I'm glad you are delving into these issues ahead of time. Do I disagree with your findings? Yes and no... let me explain. First, any decent tech should be able to 'guess' you had a tune when they see that a hole was drilled into the top of the ECU (by some companies). I do agree that a tune may be a non-issue when it comes to repairs and reliability, but a tune friendly MB dealer may not be so likely to flash your ECU for no apparent reason (just making sure you are up to date). If you are local to your tuner, that might be a simple fix... others may need to mail their ECU back to reinstall the tune.

I can't tell you which tuner option you should select... thatz totally your decision. Would I buy a knockoff watch... no problem, it doesn't mean anything to me. As for a first time ECU tune, I took what I felt was the safest and most reliable route.

 

What were your number before the Tune? Any other mods to the car besides the tune?

 

Based on their own dyno numbers, I don't know where RT gets their claimed 530/606 numbers from... Unless they're calculating a lot more than 15% driveline loss. I'd be curious to see some real world user dyno results... Not just dyno runs from RT themselves.

Does anyone know how these results compare to OE Tuning for the M278 motor? Again... User dyno results, not manufacturer claims.

 

The second dyyo sheet has the before (in RED) and the after figures (in BLUE).
The other mods (resonator delete and K&N filter) should be insignificant to power gains... they were done strictly for sound.

 

These are indeed real world dyno numbers... RENNtech did NOT run this test at all (purely independent results on a very conservative Mustang Dyno).

If one estimates 18% drivetrain loss on an AWD vehicle (which I believe is fair), my crank numbers are approximately 520HP and 625TQ.

Again, these are my independent results... I have no affiliation with RENNtech and they had absolutely nothing to do with the dyno runs.

BTW- If someone would like to post their own dyno results (from any tuner), I respectfully ask that you start a new thread.

 

Do you see any difference with the Tune besides power increase?

 

The main difference is the constant smile on my face.
In all seriousness, it feels 'normal' in daily driving circumstances... nothing adverse (if thatz what you are asking). When the situation calls, there is a very noticeable difference in power.

 

[QUOTE=427;5639161]I just what to relate my experiences with a recent RENNtech ECU tune for my 2012 CLS550 4Matic. I've been researching and considering a tune for a year now, but medical concerns have been a much higher priority. My goals may be different than others... I don't race at all, but simply wanted a reliable and efficient street tune. I wasn't worried if I didn't have the most horsepower... I crave usable street torque. In the end, there were many qualified tuners to choose from, but I selected RENNtech based their years of experience, excellence in engineering, and close relationship with Mercedes Benz.

Since I have some decent mechanical skills, I opted to remove the ECU myself. This operation is extremely simple to accomplish... provided you can find the battery first (they hide it well). Once the ECU was removed, I sent it to Florida on a Monday afternoon and it was back on my doorstep in Massachusetts by 9:00am on Wednesday. Reinstallation was a snap and the Benz easily roared back to life. Altogether, there was not much down time on the vehicle.

The initial shakedown cruise was next. In local city driving, there were no adverse issues... it was comfortable and docile in traffic. But when I hit the expressway on-ramp... oh yeah, I began to smile. And squeezing the throttle to merge and change lanes was impressive... it definitely was a new beast. For some strange reason, I remained somewhat skeptical, yet highly intrigued... I wondered just how much the dyno would reveal?

Fortunately, I had the foresight to do a base dyno nearly a year ago. Recently, I returned to 'Enhanced Street Performance' (ESP) for another Dyno Day. Although the main focus of the day was devoted to Corvettes, the group of guys welcomed me and ESP was first class with their professional service. The dyno used here is a Mustang 1100-SE AWD chassis dynamometer. Though I have no proof, I'm told that measurements on the Mustang Dyno are traditionally about 10% less than a Dynojet. Furthermore, the guys also indicated that this particular dyno was even lower than other Mustang dynos they have tested on. All in all, since this was the same dyno for my base numbers, the overall gains should be accurate.

Setting up my CLS550 4Matic, the traction control was turned off and the pulls would be done in 4th gear... same as last time. The first dyno run was somewhat uneventful... the tranny was difficult to hold gear and kicked down. With some slight initial feathering, the second pull sounded great and everyone was eager to see the results. I was ecstatic when the huge projection screen spit out the uncorrected readings... 426 horsepower and a whopping 515 lb/ft of torque!

I could be mistaken, but I don't believe there have been any dyno postings from a CLS550 4Matic in the past. Since this is an AWD vehicle, I estimate drivetrain loss at between 15-20% (though MB is very efficient). Therefore, I feel crankshaft figures are a good 500HP and over 600 lb/ft of torque... utterly amazing on a conservative Mustang dyno.

Overall, I'm extremely pleased with RENNtech and highly recommend dealing with technical advice from Lenny or sales aspects with Tomas. I'm not sure if medical science will note this, but my RENNtech tune also helps to cure my disability... every time I slam down the throttle.

Regards,
427

-----------
RENNtech ECU Tune:



Before & After Results:
Hi guys just had my 2012 cls550 4metic tune at renntec, amazing results, but any on notice when you step on gas pedal as you're driving the car cuts down for a second and then kicks back on, is that normal? ............................................. .................................................. .....................:nix :

 

Hi guys just had my 2012 cls550 4metic tune at renntec, amazing results, but any on notice when you step on gas pedal as you're driving the car cuts down for a second and then kicks back on, is that normal?

 

You may be experiencing some throttle lag... consider Sprint Booster (or something similar).