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Discussion Starter · #1 ·
Hi, all. I got a (pretty loaded) GLA 250 4Matic last year. I have liked most things about the car, except two things. The throttle response, and the shift points.

Let's start with the shift points, because Mercedes has fixed this. When I got the car, the "E" mode upshifted extremely aggressively. It was not uncommon to be going down the road at 30 MPH in 5th-6th gear at 1000 RPM -- the car was grunting and on the verge of stalling. "S" mode was ridiculous in the other direction -- not at all uncommon to be coasting with little or no throttle input at 50 MPH in 3rd gear with the engine whining between 3500 and 4000 RPM. And it didn't shift into 7th until well after 70 MPH. All in all the two modes were 2-3 gears apart. I deeply craved a middle ground.

I took the car in to service a few months back (Mercedes Benz of San Diego) and they told me everything was "normal". Last week the check engine light lit up, so I took the car to a different dealer (Hoehn Mercedes in Carlsbad). They found a few things -- a few loose pins in the ECU connection, and, most importantly, installed new ECU and TCU programs from Mercedes. What a difference! The car now shifts in "E" less aggressively (when it has about 1500 RPM after the shift) and in "S" a little more aggressively (so the two modes are 1-2 gears apart instead of 2-3). Much more reasonable. Could be tuned a little more, but much better.

Take-home: get thee to the dealer for the ECU/TCU upgrade.

The main issue I am having right now is throttle response. I can do things like take the pedal all the way to the floor and let it go, and there is very little response from the car. Now, I came from an Infiniti G35 which had phenomenal and instantaneous throttle response. I consider any delay to be a safety issue. The real eye opener was when I rented a Ford Focus (the base model, not the ST) in December. 2.0L engine, no turbo. The throttle response was as good as the Infiniti! Instantaneous. Before you could get the pedal to the floor the car was leaping forward. (Oh, and the shift points were exactly where they should have been, to boot. If only the ST came in an automatic, I have knee arthritis and can't do a manual...)

(Oh before anyone asks, I have done the "turn the car on two clicks, hold the pedal down 10 seconds" reset trick. It changed the car from "dangerous" to "drivable".)

I test drove my GLA with one of the Mercedes "senior engineers", and when I demonstrated the "floor it" trick, his response was, "that is anomalous input, of course the computer is going to ignore that". In other words, Mercedes "bakes in" a throttle response delay to see if you "really mean it". I think they are after a "luxurious" rolling start. When the engineer asked if I expected the car to leap forward immediately, I said, "of course, that's what I asked for!" He shook his head and looked at me like I was some sort of alien.

I guess after all that I have two questions:
(1) Is anyone else frustrated by this?
(2) Is there any "tune" that gets around this? In particular, the Carrlson (sp?) and related units modify the input to the ECU but don't change the ECU program itself. And even at full throttle there is a baked-in delay in the ECU programming. So I would need a bona fide ECU reflash. I have not seen this available anywhere.

And... I am very, very interested to see how Infiniti tunes this same engine for the GX30. I think I might have to switch over if it's as good as my G35 was.

Thanks all,
Dan
 

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I dropped my GLA off for "A" service this morning at my dealership, Raisor Imports in Lafayette, IN. It's also a GLA 250 4matic built in August 2014 build and I took delivery on 6 October.

I asked if there were any software upgrades available. The service advisor checked in the system and said there were no available updates listed.

Was your GLA built earlier, or is there a vast difference in what individual dealerships see or have access to? My dealer appears to be in same category as MB of San Diego
 

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I am also not aware of any software updates from MB. Maybe the dealer simply reflashed/reset the TCU/ECU software? If your pins were loose, then the software would've been learning from a bad input signal.

Throttle response - get a PedalBox or similar unit. Huge difference.

TCU tune - I am very happy with the TMC Autoflash and highly recommend it. shift points are much, much improved. I am not aware of any other tuners with a similar product for the GLA.

ECU tune or piggyback - won't do anything for your shift points. HG Motorsports I believe are the only tuner in the US who can write directly to the ECU. Otherwise, you're looking at a piggyback. I tried the TMC piggyback and liked the the performance, but didn't like how it connected into the car via multiple wires - seems like something could go wrong easily. So I sent it back and am looking at my other options. Leaning towards HG or Carlsson.

Honestly, if I hadn't experienced the performance boost of the piggyback, I would've been really satisfied with just the PedalBox and Autoflash.
 

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Honestly, that "engineer" sounds like any other MB pawns who will say anything to assure you it isn't a problem. It's like that vibration problem driving over 80mph, I think the service adviser told the owner that it was illegal to drive over 80 anyways so he shouldn't be doing it. If that were me, I would have beat that adviser with a steel chair like we were back in the WWE Attitude Era!
 
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Discussion Starter · #5 ·
I got the car in around August. Mine was the first GLA on the lot. My recent statement of work said the following:

9212 ME and transmission control unit software performed quicktest, no faults. Found updated software for engine and transmission control units. Updated, SCN coded, adapted trans clutches, test drove, runs and drives normally at this time.

I don't have any more information.

I agree that the engineer was full of it. Throttle response is throttle response.

TCU tune: I wish they gave a description of the tune with respect to stock. How are the shift points moved? Are the paddles more responsive? Is there any objective comparison of the factory and modified tunes? Is the reflash really undetectable? Worried about warranty...

Regards,
Dan
 

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Honestly, that "engineer" sounds like any other MB pawns who will say anything to assure you it isn't a problem. It's like that vibration problem driving over 80mph, I think the service adviser told the owner that it was illegal to drive over 80 anyways so he shouldn't be doing it. If that were me, I would have beat that adviser with a steel chair like we were back in the WWE Attitude Era!


A few years ago I would have thought about that as well now I just shake my fucking head........:rolleyes:
 

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I shared this before...

I will never EVER go near an ECU tune again. I busted the tranny in my Mitsubishi ralliart because I flashed the software with a tune. It ran awesome for 40k miles, and BAM! Shift fork, 4th gear.

Had to buy a new tranny, sold the car, ended up with a GLA250.

Just dont mess with it. I'm happy w the fuel economy and ruggedness of the 250 4matic, but if you want more power, get the AMG. Its that simple.
 

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TCU tune: I wish they gave a description of the tune with respect to stock. How are the shift points moved? Are the paddles more responsive? Is there any objective comparison of the factory and modified tunes? Is the reflash really undetectable? Worried about warranty...
I agree, some more technical detail would have been nice from TMC. I went ahead and ordered it based off favorable reviews on the CLA forum.

I didn't really notice a change in shift speed when using the paddles in manual mode - maybe a hair faster at most. The biggest difference is in normal E mode city driving, the shift points at 1/2/3 are much higher than stock. I can't quote exact RPM's as they'll vary on throttle input. (I never use Sport, just E or Manual). However, I was extremely pleased with the difference as soon as I installed it and continue to be.

I'll have to ask my mechanic next time to see if it left any trace. I know that the OBD wasn't throwing any codes post-install.
 

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Solve slow throttle issue for me, please

The explanation of sluggish starts exceeds my mechanical ability. I am only an academic. Can I drive in a manner to avoid the safety concerns of slow starts? Does sport mode address the problem?

We have not taken ownership of our GLA 250 yet. We had the "wrong" GLA given to us for a week, and then only discovered the hesitation issues. We did not notice the hesitation in our test drive before purchase. We are getting a well-optioned GLA 250 and hope we are making the right decision. So how do you solve the slow response driving problem? I value having this opportunity to address the forum on this issue.
 

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The explanation of sluggish starts exceeds my mechanical ability. I am only an academic. Can I drive in a manner to avoid the safety concerns of slow starts? Does sport mode address the problem?

We have not taken ownership of our GLA 250 yet. We had the "wrong" GLA given to us for a week, and then only discovered the hesitation issues. We did not notice the hesitation in our test drive before purchase. We are getting a well-optioned GLA 250 and hope we are making the right decision. So how do you solve the slow response driving problem? I value having this opportunity to address the forum on this issue.
I own a GLA250 4Matic, owned it for roughly 3 months, and I'm EXTREMELY glad I settled on this car. In the past I've owned some great cars w/fast engines (WRX, Volvo T5 AWD, Mitsubishi Ralliart). You're making the right decision. If you need to depress the gas pedal an extra 1/2" for extra pickup, that's all you do. It will still giddy up and go in ECO mode. It just wants confirmation.

The size, clearance, 4Matic, fuel efficiency, creature comforts, power, and affordability are all there. I tried like ****, was really looking to get a Jeep Renegade, and man am I glad I found this at the last minute.
 

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I had the same thing happen to me today. From a dead start, I got nothing from the throttle when I first tried to start. Pretty dangerous.
 

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Confidence renewed, gear selection error

We have a GLA250 4-magic on order and went to another MB dealer today to test drive again. The car performed excellent. Apparently, when my wife had the car for 4 days when I was out of state, the transmission was inadvertently shifted into manual and she was driving it like 2nd gear in a standard transmission. The salesperson today explained the use of the gear options and it performed as we first remembered. It's a well-performing car and we could not duplicate any of the issues the Edmond's article referenced. Our excitement for the car is renewed and we look forward to its delivery.

I think the transmission sophistication of the car takes a little more education than paying and driving off the lot. From another MB we own, I know that MB began an excellent series of how to videos on YouTube. I think MB needs a video for the GLA explaining how to drive it after you leave the dealer. MB customer service in our other MB exceeded our expectation and we look forward similar service when needed for our GLA.
 

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Discussion Starter · #13 ·
With the latest software the car is performing much more sanely. However, the baked-in throttle delay is very annoying. I am assuming that Infiniti's take on this car (the upcoming QX30 - shares the same platform and engine) will have a much more lively throttle response. Will be interesting to see.

Dan
 

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Dan, I too find the throttle response odd at times....I ordered a Sprint Booster which arrives tomorrow....I installed one in my previous car (an E Coupe350) and it dramatically changed the character of the throttle and made the car so much more enjoyable to drive (it had the typical Benz lazy gas peddle)...I'll post my results this weekend.
 

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How was the install? Results?
My 45 is in the shop in hopes of a tranny software or hardware upgrade. Might have to go your route with the Sprint Booster.
Looking forward to your response.
 

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Discussion Starter · #16 ·
Dan, I too find the throttle response odd at times....I ordered a Sprint Booster which arrives tomorrow....I installed one in my previous car (an E Coupe350) and it dramatically changed the character of the throttle and made the car so much more enjoyable to drive (it had the typical Benz lazy gas peddle)...I'll post my results this weekend.
From what I understand, the SprintBooster alters the voltage from the Throttle Position Sensor, effectively tricking the car into thinking you are pressing the pedal faster and further than you actually are. It does nothing beyond this. I can press the pedal fast and far -- and there is still a delay. The car should respond in milliseconds, not seconds, and I don't think a SprintBooster is really going to do squat.

The issue is the built-in throttle delay in the computer. This needs a reflash to fix, IMO. And I don't mean a plug-in tuner, I mean a bona fide reflash.

How it should work:
- The computer is fully capable of responding on a millisecond time scale. A 1 GHz processor can do 1M instructions per millisecond...
- Let's say it takes me, oh, 250 ms to push the pedal down really fast. This is about as long as a blink and is probably as fast as humanly possible.
- A dual-clutch transmission shifts in about 200ms.
- Engine revs can be altered much faster than that.

Result: If I am pressing the pedal down really fast, the car should realize this by looking at the speed and position of the pedal. By the time the pedal has reached the floor, the computer should have significantly rev'ed the engine and COMPLETED a downshift. There is no technological reason that this is not possible. And I have not gotten an explanation as to why this isn't how it is. Aside from "this is not how Mercedes tunes their cars".

Again I am VERY curious how Infiniti -- renown for their throttle response -- is going to tune this exact platform, in their QX30. If they get it right, I will switch.

Dan
 

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I actually installed a Sprint Booster in my GLA....it radically changes the nature of the throttle...I drive mostly in "E", with the stop/go feature turned off, with the Sprint Booster set on "Green"....huge improvement...no delay anymore...throttle feels "natural" now....nice consistent progressive "feel"....I highly recommend this device
 

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Voteup on the Sprintbooster - this fixes everything! It may not turn your 250 into a 45, but boy does it remove the hesitation! Best $300 I ever spent.

I would recommend to anyone interested in spirited driving who does not want to endanger their warranty with a reflash or tune.
 

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I have the pedal commander. I don't recommend it, or any device that just intercepts the pedal signals to the rest of the car. It doesn't provide the desired effect here, which is to improve responsiveness in a way that makes the driver feel in control of the car.

The GLA is just not a driver's car, plain and simple. I just don;t dart out into traffic anymore, and that provides a serviceable solution. One that is acceptable for a car that is a joy to drive for someone like me 99% of the rest of the time.
 
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