blegthbloo

Wasn't able to find knock stats, but IATs were between 70-90F (ambient was 45F)... didn't seem abnormal. Do you know if there's a standard PID for knock? I have the ability to put in custom PIDs, but I'd have to know what to look for.

BetterTomorrow

I second monitoring short term fuel trim and long term fuel trim. They can be indication of how your car is adopting to the tune.

On another note, I think MB of Bethesda is Renntech dealer? I contacted them about intermediate tune and am still on the fence. Perhaps if they can honor MB warranty, I may go through it. Not sure how your arrangement is with the tuning, but perhaps it may be worthwhile to leave it to the professional tuner, leave the car there and let them sort it out. Personally I've been down the road of "figuring things out" in the past and I would much rather just enjoy the end product now.

blegthbloo

Agreed... I'm at the point where I just want it fixed. I kinda skirted around the subject when I was there getting the plugs done, and tried not to allude to having a tune lol... just in case. I do get readings for fuel trim, so I'll see what I get with long and short term after work today.

cocobeex

What if you flash ECU back to stock ?


See if the problem still there.

blegthbloo

I could... but I'm not close enough to RT and this is my DD... so downtime would be expensive. I'm going to monitor the fuel trims and clean the MAF sensor(s) and see what I come up with. I have the UPD intake, so I wonder if those filters, being new, might've had some oil on them that gunked up the MAFs.

blegthbloo

STFTs look normal (+/- 5% each), but LTFTs show a pretty consistent -2 or -4% (for Banks 1 and 2, respectively)... I would think this number should be closer to 0 after awhile, although it did get to 0 after awhile under cruising load. Didn't get a chance to clean the MAF yet.

I wonder if I could have bad gas as well... I've been using Shell 93 (which I understand to be one of the best in my area), but the past two fill ups have been BP 93 and while the problem is still there, it's not as bad and harder to replicate (i.e. sometimes I'll get to 2000RPM and nothing happens except acceleration and the child in me saying "weeeee").

Mike450

Short term knock (stknk) and long term knock (lgknk) is what tells you if the ecu is pulling timing, which is what it sounds like is happening.


A single look at fuel trim won't tell you much. That's something you need to look at over a few engine speeds, over time to diagnosis an issue.

J.M.G.

The M278 does not have a MAF? It uses MAP sensors, as far as I am aware of.

By the way: In DYNO-Mode, Torque Management should be disabled. So for maximum quarter mile performance, one could try this out. But please keep in mind, that dyno mode does not only kill torque management, but also stability control and ABS...

mjec515

interesting! will probably try it when the snow is gone

J.M.G.

My car drops from 4.8s to 4.6s (0-62mph on normal roads) when using dyno mode... But please keep in mind, that ABS is gone AND Mercedes did apply torque management with certain things in mind!

mjec515

so if u have a tune it can possibly damage the tranny?

blegthbloo

Here's a couple of graphs that I recorded:


I guess that fluctuation in STFTs is normal, but seems weird that it needs that much adjustment with no change in RPM. I guess turbulence on the road can account for that.



This just illustrates my problem. I get on the throttle, something at 2500RPM freaks out the ECU and it cuts the fuel, then right afterwards I get the cut in RPMs. Then, fuel comes back on and RPMs keep increasing.

I agree it's definitely pulling timing, but without a OBDII PID for knock, I can't monitor it. And I can't find a PID for it. I'll keep looking though.

You might be right. I have to play around with it and see what I get readings from

cocobeex

What is the app are you using ??


Are you using iphone ? or android ?

J.M.G.

I would not call it instant damage. I would call it increased wear.

blegthbloo

It's called OBDLink, for Android. No iOS compatibility.

https://www.amazon.com/ScanTool-4272.../dp/B00H9S71LW

This is the code scanner I got, and it's "supposed" to be 4x faster than the run-of-the-mill Chinese scanner, but that could just be a gimmick. I had a speedo reading this morning that was lagging because the cycle times for the app were too slow and so I think it tries to anticipate the rate of increase, but I was going faster than whatever it was calculating, so it kinda just scooted around the dial instead of sliding smoothly.

Anyways, it's still pretty neat. I got a reading of 511hp/580tq @4600 RPM this morning... not bad. It's not 705tq like they advertised though. But I need to get it on a dyno and see what it's really putting down and see how far off this app really is lol

BetterTomorrow

Not to rub it in, but lessons learned (from my own), do not mod your daily driver. Per my previous post, you might want to get in touch in MB of Bethesda (appears to be an authorized RT dealer). See if they can help you out and see if you could get a loaner in the process. It will not be cheap but really...aggravation from dealing with troublesome daily driver is no joke either.

I assume your do not have wide band 02 sensor hooked up to your car. You normally would not need it even with a tune (if it really is a solid tune). But for your case, can you be sure that you are not shortening the life of your engine, turbo, exhaust systems (cat), etc.

If I were in your situation, I would have reverted to stock, would have gotten a refund, and called it a day. Regardless of where the fault is (your car's existing condition vs RT's tune), it does not seem worth it at all.

Look at it this way, with the time and resource lost during this time, you could have made more money, and traded up to E63S.

blegthbloo

Valid point. Of course, going through with this during the holidays was the first mistake, since it's hard to get a hold of anyone to even revert back to stock if I wanted to. I'll take it to MB Bethesda and have one of the techs do a ride-along. Maybe it'll be something they can pinpoint right away that I may not be relaying properly to RT.

Munich77

I think Euro even sells Renntech:

From Renntech:

Dealer
Euro Motorcars Bethesda
Representative
Rick Oxendine
Adress Line 1
7020 Arlington Road
City
Bethesda
State
Maryland
Zip Code
20814
Telephone
(+)1 (410) 409-7200
E-Mail
oxendine@euromotorcars
Website
www.euromotorcars.com

rhoderunner

If a tune removes the torque dropping in first gear I think yes, instant damage.

The tunes that keep the transmission protection are still beasts, but they are not going to give the expected quarter mile and 0-60 times.

It is my opinion removing this protection is not a good idea.

SpeedRacerX

Subscribed. I have a 2012 CLS550 4Matic with the M278 biturbo and there is great info in this thread. I need to hang out on the "E" side. Lol.

OP, I've had after market tuned cars, packaged tune and custom dyno tune, and my gut tells me something is not right with your tune.

I've been debating this new RT tune for my car also. Heavily leaning this way because of RT's years of research and experience BUT.... again, my gut tells me to take my car to my custom tuner who seems to know his stuff with the German cars, tuning, racing. At least, if I have an issue, he's 20 minutes away for tweaks.

Sorry to thread jack and very curious to hear how you make out getting this sorted.

blegthbloo

I don't think the RT tune removes the torque protection. It pulls hard in 1st, but not as hard as in 2nd -- like it always has.

I'll give RT the rest of the week to respond to the 3-4 emails I've sent over the holidays and see what they say to do next. Then I'm going to MB Bethesda to take them on a ride-along and see what they think. In the meantime, I'm also going to clean the MAP sensors and see if they have gunk on them from my UPD intakes.

RENNtechHQ

Correct, Euro Motorcars is one of our premier authorized Dealers.

cocobeex

Got a question for you.
If you do manual shift, what will happen ?

blegthbloo

Same thing. At first, it didn't happen in manual mode, but I've gotten it to do it a couple times now, both times in 5th (needed low RPMs and high gearing to get the power put on slow enough for it to do it).

RennTech is sending me a stock ECU to see if putting it back to stock fixes it and, if so, they will retune mine. If putting it back to stock doesn't work, then it's going to the dealer. I'll let you guys know what happens.

blegthbloo

Have been running with the loaner ECU for a couple days and the problems are gone. ECU is going back to RT for a retune. They sent me an overnight UPS shipping label, and I assume they will send me another label for returning their loaner ECU once I get mine back. Seamless... I think they should send the loaner when you're getting yours tuned initially, but I think I'm in the minority of MB owners (who only have one car), so they probably won't.