AMGeez

If I get a second ECU to have on hand in addition to a tuned one, how easy is it to swap them out for dealer visits?

stangxs

Snaps in and out, less then 2 minutes I'd say.


It's located on the top left (facing the car), under that black plastic piece, it comes off with 2 clips in the back, and one in the front.

bad pic for reference (it's located under that plastic piece all the way on the top left corner [again, when facing the car])

CELLryuu

when you get under the plastic thing in the top left corner. the silver box (ecu)(about 6 in by 6 in by 2.5 in) has two wire connectors. you have to pull the tabs away from each other and the male/female wire ports will unhook from the ecu. now just pop the ecu out of the rubber grommets.

JeffDL

This probably raises more red flags at a dealer then the tune ever would.

CELLryuu

id be interested to know how many dealership employees (that have authority) look at these forums. in my year experience with mercedes.....those clueless con artist dont know d-i-c-k unless you tell them.

ill ask questions in the tech sections of the amg private lounge forums and someone from amg will give me advice. the last time i had problems with my car i did this and took the info to the service department and they did it and it worked. they ask me how i found that out and i told them. they were clueless that there were forums about tech questions on the internet. im not kidding you.

so.....i inquired a little more to the head service tech. he said that they just hook the car up to a computer and it tells them what to do. i got the impression that if the computer couldnt figure it out, they try to find every excuse in the would for why they cant fix it.

i know i rant all the time on these forums about mercedes service departments but this is just yet another story that happened to me last week. I swear that the guys at my local dealership cant do anything but turn a wrench and the diagnostics computer tells them how to turn it.

end of me ranting

late_bloomer

Why is this? Does it leave broken tabs or some evidence that you changed ECU?

CELLryuu

i think he was talking about the dealership reading this post of him admitting to having a stock ecu and a tuned ecu.

DuaneC63

While I love the concept of having a stock ECU and a Tuned ECU, I think it fails on a few counts:
First you can only buy an ECU from MBZ (unless you can find a totalled car someplace).
Second it's not plug and play, only MBZ can mate the ECU to the car.
So they will know somebody has replaced the ECU and then the questions will start if you have a major warranty issue.

JeffDL

exactly.

propain

No more or less than having a tuned ECU. Probably less. There are so many variables. Yes, if you are running a tuned ECU and bring your car to the track and blow it up and then swap the stock ECU back in and bring it to the dealer and say "Duuhhh it broke" They will know the ECU in the car wasnt in the car when the car broke and you will be denied your warranty claim IF the ECU was the cause of the problem.

On the other hand if you want to have some track fun with your car and you dont want to bring your car in for an oil change and have some tech void your warranty because you have a tune on your car then tne 2nd ECU is a good idea.

Third is nice to have the stock map on the car for daily driving and not push the engine over what MB has designed. Running a tune only at the track will add miles to your vehicle due to not pushing it as hard 100% of the time.

Lastly, if you want to void your warranty or have warranty issues modify your exhaust. Every case I have seen on this forum from a denied warranty claim was due to exhaust work not an ECU modification.

ZephyrAMG

Great, knowledgeable assessment indeed...

AMGeez

So the ecu mods rarely are linked to any repair issues? Has anybody on here ever had a warranty claim denied due to a tuned ecu?

JeffDL

if you are even remotely worried warranty issues don't ever get a tune. I have a tune and am not worried. If things go really really bad the fix will be on my dime. it is what it is.

izzyAMG

Maybe swapping ECU is not the answer. I'd rather have a device like a mini computer such as the COBB ACCESS SPORT and be able to flash it yourself switching back and fort from stock to not just one tune but several pre programmed ones and since this device goes through your OBD port you can access other datas as well.

cptdaz

Better yet, something like a Power Commander that tap into the ECU output. It allows you to change A/F mapping on the fly like professional race vehicles. Not to mention real time read out of sensors data. Restoring to stock is matter of unplugging the PC unit.

izzyAMG

The COBB access sport does all that. They just don't have maps for our cars.

cptdaz

Doesn't sound like it from what I gather on their website. What COBB does is loading A/F maps directly onto the ECU, that takes time (not even sure it can be done when the vehicle is running). PC leaves ECU stock but modified the signal from ECU to throttle body. There's no way COBB system is capable of changing mapping as PC is capable of. I have a setup similar to COBB on my Triumph; I have to 'reflash' the ECU every time I want to test a new A/F setting, it's not 'on-the-fly' per say.

Also it's not just maps, you need a soft key to 'unencrypt' the ECU, which is unique to each vehicle. Bulk of the expense for re-flashing ECU goes toward that.

ezatnova

In my very limited and new experience with these cars, I think I remember hearing of a device from Renntech called the RAT, which allowed you do "flash-at-home". I wonder what happened to that, and why?

Merc63

Discontinued

ezatnova

Why? Flash at home is so much nicer than shipping the ECU. The COBB style interface is awesome and simple. Wonder if they can't crack the code?

izzyAMG

You're right... not on the fly. It takes me about 1-2 minutes to load maps. And about 3 minutes to totally take off the whole program and vise versa but it is a lot better than what our current tuners offer. Plus the ability to update to new maps from your tuner by way of downloading the file to your PC and moving it to your access port via USB is just nice!

cptdaz

You are absolutely right; it is better than sending the ECU to the tuner, but the power commander approach is better still. There are couple of advantages to modifying the signal rather the ECU software. For one, there's no need to "unlock" or "unencrypt" the ECU, which as I mentioned is the most expensive part. Think of it this way: assaulting the fort or ambushing an outgoing messenger, which one is harder/more costly? Second, unlike flashing the ECU, there are no trace of the modification anywhere in the system since it's altering the signal not the component.

ltcinf

This is happening to me right now. Waiting to pick up my car and $3100 in repairs Becuase my ECU was tuned. The dealership says Becuase the ECU box was opened that it voids the warranty.

The tune I had was with tuning USA. The car ran like a champ for 10k miles then began random misfires. Then it started 2 and 5 cylinder misfires. My car started chugging and blowing smoke out of the back.

Mercedes will void te warranty and the tuning shop won't pay for damages. Not happy at all. I am going to get the old ECU and have it reflashed to see if it will work. If so then I will probably sell it.

This is for a C350 btw.