Merc-Skycap

Hi guys,

Quick question for those of you that may know a thing or two about ECU tunes.

Other than punching out a few extra HP from your C63 AMG, what other benefits are there?

I ask because I don't understand why many people have decided to tune their C63's ECUs just for some extra HP that will end up burning more gas, creating more headaches at service, and possibly giving many LAPD & Highway Patrol officers a freebee?

Why change what AMG has already put so much research and effort into programming your car a certain way? I can understand if your car needs more power if you are going to compete with other racers where the extra HP really counts, but what advantage does an ECU tune provide a regular daily driven, or weekly driven car that is so important to AMGers?

I don't mean to be condescending here but am I missing something?

Maverick1975

Increased speed and acceleration add some additional excitement to my otherwise sad and miserable life...

I never used to be into cars at all, nt one little bit. Couldnt even be bothered reading car mags. Now its all i think about, i cant explain it.

Djovovic63

I dont really think you get the whole ecu tune idea for c63owners. Its that we get a detuned version of m156 amg engine. So while the rest of the amg fleet (SL,S,CLS...) with exactly the same engine is making 517hp we make 457hp because they detuned it on the ECU. So whats the benefit of ecu tuning c63? Its to wake up the engine.

propain

If you have to ask then its definitely not for you.

Roswell

I totally understand Merc-Skycap point of view, very good post & perspective!! This could be a good debate.

In my opinion, it all depends if you track your car or not. As a daily driver on regular roads, 50hp gain is not necessary as our cars have enough torque stock.

On the other hand, on the track or drag strip where every hundreds of second counts, then you will most likely benefits from the tune. Just my .02 cents.

khmergod

^

GMW

Just to clarify: 1) I consume slightly less fuel with my tune than before I had it. I got the tune after 20,000km so it was fully broken in before the tune. 2) No service headache as the service manager doesn't mind and is mindfull not to flash my ECU. He also agrees that it is the power level the engine was built for so... 3) You will have problems with the Police with or without the tune as either way the car is very fast! If anything the tune might scare you to not push it as hard lest you engage warp 9 by accident. 4) AMG designed this engine to have upto 530hp standard. If you don't want this much power a good alternative is a strong, torqueful CDI diesel engine. I am seriously contemplating buying my wife a CDI engine in the next ML when it comes out. Not only do we still get a bootful of torque but we can balance the fuel bills in the household. :-)

To be honest I initially didn't want to tune my C63 as I thought it had enough power. However, as time passed I realized my problem was not so much as in having more power (by tuning) but in worrying about the risk of causing some harm to my engine, especially as I hope to keep this car for the long run.

I used to have an Audi A4 1.8T quattro that I got in 1997 with its standard 150hp. I soon found many tuners with offers to increase the power to 200hp. 50hp increase was very noticeable and a lot of fun in that car. However, 5 years later some problems surfaced like oil mixing into the coolant system then the ECU failed. Of course I couldn't link these problems directly to the tuning but it did get me thinking about it a lot and sort of put me off tuning any of my following cars.

Therefore, after the C63 was launched I thought to just keep it stock as the power was plenty enough (it took me 2 months to stop shaking from each drive). Then a few months later, pretty much everyone confirmed it had the same 63 engine as the 'bigger' cars but was detuned from the factory. This news got me a bit intrigued at the possibility of tuning it and not being worried about damaging the engine in the 'long' run.

Then I visited the AMG factory in Affalterbach in Sept 2009 and spoke to a senior manager there about the C63. As much as he refused any possibility of AMG increasing my HP with a AMG tune he did confirm that the engines were exactly the same (components, blocks etc) as those being built and put into the E63, S63, CL63 and SL63 just with different ECUs. The engine assembler actually doesn't know if his engine is going in a C63, E63, ML63, S63 etc. Now this was the final real re-assurance, straight from the horses mouth, in a manner of speaking, that I needed. So once a friend of mine connected me with a german tuner, I was very excited about getting more power without worrying about damaging the engine at all!

I must say that the approx 67hp-73hp gain takes the C63 from road demon to Autobahn demon! The acceleration is just insane, at all speeds. The most G force creating part is when at about 40km/h in second gear you floor it so it shifts to 1st gear and takes off like a lightening bolt, traction allowing of course. It is a very noticeably difference and honestly only really useful on open, clear, no-speed-limit roads (a.k.a. Mexico). There is nothing like having enough power, it is just a natural instinct to always want more. That said I can see it getting a bit silly as we approach 600hp with only RWD. I hope there are some 4WD AMGs in the future so that we can use..sorry...enjoy cars with 600hp+. Bottom line: It was a ton of fun before as stock but with a tune, it's even more fun now. Plus I am getting better mileage which is probably due to the fact that this engine is now operating at the power level it was originally designed to.

kc2ntlh

Good post! I am considering a tune for my CLK63 Cab. Thanks for taking the time to provide helpful feedback.

AMGC60-3

Very nice write up GMW.

Merc-Skycap

First of all, thanks for the reply guys, especially GMW Also thanks to you all that are taking this a bit seriously to actually contribute some helpful pieces of info.

Now I understand that it's detuned and from what I have heard from tuners (not sure if this is valid) is that when the AMGs go to their respective destinations (i.e. Country, States) they are further modified, assuming this is for emission standards, octane level, etc. However, by detuning the ECU it then doesn't sync with the transmission of the 63 AMGs because the transmission control unit is in the transmission itself and can not be tuned. Therefore, we experience the delays in the transmission and that's why tuners say it's only natural to tune the ECU on these cars because not only are you missing time but then you are missing out on power and it's true for all the M156 equipped AMGs.

Now, me being new to all this, I can not verify if what I am told is true, hence the reason for this post, but if what they are sating is true (maybe someone could verify) then that to me would make much more sense to tune the ECU over just trying to get a few extra HPs out of the engine.

Also correct me if I'm wrong but, removing cats would give that extra HP jump on these cars as well? And with more power I'd assume you'd need better brakes as well?

dodger63

Can you tell us were you got your info from?? Seems someone is blowing some smoke up your ***.. And these breaks could stop a commercial airliner so added 100 Hp and the breaks will be fine

Merc-Skycap

Doger63 I don't want to name names but I can say that it came straight from some well known tuners. Hence, why I'm asking questions here to find out what is really true and false.

betrezra

If you like having your Throttle Body go from 100% WOT to +/-75% WOT after a certain RPM (even with the pedal to the MATT) then keep the stock tune.

dodger63

I have had my car tuned since 3,000 miles I have almost 30,000 miles on it, I wouldn't go back stock, car is powerful better on fuel and just plain old awesome the Mhp tune shifts faster responds better all around an improvement over stock. Certain tunes even at the track sounds like they don't shift quick but with the Mhp tune u can totally see hear and feel a quicker shift,. Im not a so called fan boy of any tuned I like my tune and I think it's great

cyberorth

I think it is safe to say that most tune-only customers are after the slight edge of hp and not necessarily any transmission improvements. Transmission in this car is slow and there isn't a magical solution. Also it constantly adjusts itself to the degree of "sporty driving" and therefore hard to nail it down to its own fastest potential. Personally, I scared myself a couple of times driving the car early on. Then it was normal and the tune created an added excitement that had become routine. I also didn't tell my ctsv neighbor that I got a tune just in case!!!

GMW

Thank you all for appreciating my post. Always feels good to be appreciated.

Merc-Skycap. It is true that the AMG models are further modified (through ECU) for bad fuel countries so as to work with lower Octane levels (by balancing out with slightly worse emissions levels) but retaining the target power output. They also have the catalytic convertor disabled depending on individual country regulations. Usually those countries with low Octane levels don't have very strict emission standards. From what I know, the fuel change settings are just enabled on the destination specific export unit, so that the local MB service center would be able to change the parameters to suit the local fuel quality. I believe there is a setting for 93 Octane (EURO rating not US), then 91 then 89 in the MB diagnosis system that can be accessed on the 'enabled cars'. These should not affect a tune according to a tuner I spoke to. Though you would have to be sure the dealer doesn't reflash the ECU while tinkering away. I'm not sure if these settings are 'enabled' on cars that go to strict emissions countries like the U.S., U.k. or Germany. So I don't know if they can manipulate the Octane levels. Maybe someone else can chime in here.

Now regarding your info on the transmission not syncing. That is not completely true. While the transmission may have been developed initially to handle a normal output of 525-530hp (till they did the 0-60 tests ), I'm sure it is just as adaptable despite the horsepower reduction. That said, I do notice quicker shifts with the tune (or a.k.a. removal of the power limiter) However, it all feels like it is within the parameters of the transmission. Just like M mode shifted faster when stock the difference between M mode and S mode is a teensy bit smaller.

As for the cats removal...... now you would be playing with other factors like back pressure, etc and moving away from 'my' safe zone of everything being within factory parameters. So I wouldn't do that. As far as I know, the ECU 'tune' and headers lead to the biggest power increase to a new output of approx 560hp. I'm not so keen on the headers due to 1) my primary fear as mentioned in my earlier posting and 2) they are a bit too loud.....I already have guys at the local bar knowing what time I get home everyday, a neighbor who knows what time I leave for work, some business friend down the road who uses me as his alarm clock as I join the road at the junction next to his house..etc

Merc-Skycap

Thanks GMW so if tuned to 525 or more don't you need to adjust the vehicle's brakes because even if you opt for P31 the brakes are now bigger so in order to compensate for the extra power you'd need extra braking, correct?

By the way, how have some of you U.S. guys dealt with the warranty issues of a tune or dealt with re-flashes to stock? I understand some tuners offer a free re-flash with their tune but I always assumed that if you were to modify any internal components, dealers would use that as an excuse to not service the car or void the warranty?

OrientBlue3

The brakes are fine. They are massive and cross drilled. IMHO, you are definitely worried about nothing there.

In terms of dealer issues, I'm sure a few guys have had some problems but since it's just a flash and no hardware most dealers won't even know. It's not like they would just pop your hood just to snoop around. Even if they did, they wouldn't notice anything unless they opened the ECU compartment, fully disconnected the ECU and pulled it apart to see if the glue has been heated to separate it. The odds of them getting that far are slim. Maybe if you have some ECU related issue or you're dumb enough to tell them you have a tune and they aren't cool with it. I too was very nervous when I first got my tune done but it's not something like LTH that the instant you pull in scream "modded car" to the service advisors or techs.

SonnyakaPig

Even with a tune, the TB's are not set to open 100%. But, from what I understand, they do open more than stock, which is in the 62% area.

The only way that it would make sense to me that an aftermarket tune on these cars would improve mpg would be if the stock tune was way too rich. And it's not.

Unless the tune does not change the spark advance in the low to midrange, I would expect more fuel consumption.

503C43 ////AMG

+1

503C43 ////AMG

Never fails, the old "back pressure" myth... Your engine is a giant air pump, the more air you can pump in and the faster you can pump it out = more power : back pressure = restriction = less power

simple as that

Here is a little article I found that explains it quite well:


Some say that "an engine needs backpressure to work correctly." Is this true?
No. It would be more correct to say, "a perfectly stock engine that cannot adjust its fuel delivery needs backpressure to work correctly." This idea is a myth. As with all myths, however, there is a hint of fact with this one. Particularly, some people equate backpressure with torque, and others fear that too little backpressure will lead to valve burning.


The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture, which will be described in more detail below.
The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.
The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.


Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.


Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. While a bad design, it was nonetheless used in a lot of vehicles. Once these vehicles received performance mods that reduced backpressure, they no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.


Modern BMWs don't have to worry about the effects described above, because the DME (car's computer) that controls the engine will detect that the engine is burning leaner than before, and will adjust fuel injection to compensate. So, in effect, reducing backpressure really does two good things: The engine can use work otherwise spent pushing exhaust gas out the tailpipe to propel the car forward, and the engine breathes better. Of course, the DME's ability to adjust fuel injection is limited by the physical parameters of the injection system (such as injector maximum flow rate and fuel system pressure), but with exhaust backpressure reduction, these limits won't be reached.

SonnyakaPig

Allowing more air to exhaust from the engine is great, but it should be optimized with appropriate tuning. Otherwise, you can potentially make less power with better headers if the ECU doesn't like what it's reading and decides to pull timing and dump fuel.

SonnyakaPig

@GMW,

Do you find that your post-tune mpg increased on fwy driving? Or all around city/hwy combined?

503C43 ////AMG

Correct, that was all explained in the article I posted. It talked about burnt exhaust valves due to running too lean, in other words not tuned correctly.

This is where the back pressure myth began, some guy with a Honda threw some huge exhaust on his car thinking bigger is better and wound up losing power. Honda guy puts 2 and 2 together and thinks lost power is due to lost back pressure and the back pressure myth was born.

Truly you want as minimum back pressure possible for the most part.

Merc-Skycap

What does that even mean? I thank you for your great contribution to this post but I don't quite understand that reply.

Anyway, I'm really not sure now what to think about all this now. Octane here is really pitiful compared to other places. We, in California don't have access to more than 91 for the most part. Therefore, I'd think that the stock ECU would be tuned to adjust for the 91 Octane. Now, if that's true then by tuning the ECU to put out more power, you'd need to run on higher octane levels to really achieve that power, right?

I apologize for my naiveness here, I'm just really trying to inform myself better since I'd like to really believe that tuning the ECU would not have any harmful effects during the long run of the car's life. It really bothers me to see that P31 offers more HP and it's completely fine, but my C63 may have issues with an ECU tune because it's not direct from the factory.