Mercedes-Benz GLA Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
So....Nice to meet you all, first post unfortunately is a problem for me. So here it is and i would like your opinion so that i can get something off my mind

Bought my baby on 5 July as a second hand directly from previous owner with 37k km. The reason he sold it as he said was because it wasn't good for daily driver.

For the first month i didnt want to push the car, went to a mercedes benz, did a full service and changed more things than i was supposed to change for the mileage of the car.
Due to the fact that i was working all the time and my 45 is also my daily driver i didnt have the time to rev it up and have some fun...

Almost 3 months later i had the chance to play with it a bit an it was a blast....BUT

i saw some wierd behaviour of the car on 5th-6th gear at around 4300 + RPM and goes until 6000. The behaviour feels like for half a second there is loss of power. goes back to normal and then back again.....all this in half second interval. At that time i thought that something was maybe wrong with the fuel, maybe bad fuel or something.

Also at that time I had scheduled to change dp, intake and have the car remapped. Oh god....what a blast it was BUT

The problem remained and in fact it was more conceivable with the extra noise from the dp the sound was up down up down all with the half second interval. (As an engineer myself i would like to congratulate me for being the most idiotic engineer when my car shows a problem and i am going "oh who cares lets go remapping") Anyway

So i called my mapper, we took out the remap, we did a factory ECU reset, and we brought back everything to what it was before. My best friend happens to be Chief engineer at local benz dealer and he said to do an update on the ECU along with having a check on the road. We plugged the original MB diagnostic in the obd and we went for a ride to see if something comes as fault. i revved to 4300 +, the instant loss of power happened and the diagnostic showed no error at all...the car was totally flawless.

Then my mapper came and plugged his PC and actually showed that the fuel pressure was instantly dropping at 150 bars when going more than 4300 rpm
Since Original diagnostic showed nothing we could only go blind as to what parts to replace. Luckily for us there was a brand new original high pressure pump that we could use. We installed it, nothing, we replaced the fuel regulator/sensor, nothing. Now we are looking into Low pressure pump or aka "Pump in tank".

While i am waiting for the pump to arrive, i run a search in the forum to see if someone else has had something similar to my case and i havent seen anything. Any thoughts what else should i see?

Thank you in advance
 

·
Registered
Joined
·
7 Posts
mine was doing the same thing and i would get a check engine light so i took it to the dealership. They said it's the crankcase vent kit, so I'm getting that replaced under warranty
 

·
Premium Member
Joined
·
102 Posts
mine was doing the same thing and i would get a check engine light so i took it to the dealership. They said it's the crankcase vent kit, so I'm getting that replaced under warranty
Do you happen to remember the code(s) reported by PCM ?
 

·
Registered
Joined
·
483 Posts
So....Nice to meet you all, first post unfortunately is a problem for me. So here it is and i would like your opinion so that i can get something off my mind

Bought my baby on 5 July as a second hand directly from previous owner with 37k km. The reason he sold it as he said was because it wasn't good for daily driver.

For the first month i didnt want to push the car, went to a mercedes benz, did a full service and changed more things than i was supposed to change for the mileage of the car.
Due to the fact that i was working all the time and my 45 is also my daily driver i didnt have the time to rev it up and have some fun...

Almost 3 months later i had the chance to play with it a bit an it was a blast....BUT

i saw some wierd behaviour of the car on 5th-6th gear at around 4300 + RPM and goes until 6000. The behaviour feels like for half a second there is loss of power. goes back to normal and then back again.....all this in half second interval. At that time i thought that something was maybe wrong with the fuel, maybe bad fuel or something.

Also at that time I had scheduled to change dp, intake and have the car remapped. Oh god....what a blast it was BUT

The problem remained and in fact it was more conceivable with the extra noise from the dp the sound was up down up down all with the half second interval. (As an engineer myself i would like to congratulate me for being the most idiotic engineer when my car shows a problem and i am going "oh who cares lets go remapping") Anyway

So i called my mapper, we took out the remap, we did a factory ECU reset, and we brought back everything to what it was before. My best friend happens to be Chief engineer at local benz dealer and he said to do an update on the ECU along with having a check on the road. We plugged the original MB diagnostic in the obd and we went for a ride to see if something comes as fault. i revved to 4300 +, the instant loss of power happened and the diagnostic showed no error at all...the car was totally flawless.

Then my mapper came and plugged his PC and actually showed that the fuel pressure was instantly dropping at 150 bars when going more than 4300 rpm
Since Original diagnostic showed nothing we could only go blind as to what parts to replace. Luckily for us there was a brand new original high pressure pump that we could use. We installed it, nothing, we replaced the fuel regulator/sensor, nothing. Now we are looking into Low pressure pump or aka "Pump in tank".

While i am waiting for the pump to arrive, i run a search in the forum to see if someone else has had something similar to my case and i havent seen anything. Any thoughts what else should i see?

Thank you in advance
Wow, sorry to hear all this, but please keep us posted.
Good luck .
c
 

·
Registered
Joined
·
19 Posts
I have this strange feeling too.

May be less than you. But at full throttle from 3000rpm the power seems to fluctuate . I feel more like a smooth turbo charger pressure that fluctuate.

I've instal mishimoto air intake. New Downpipe. And tomorrow I will make a remap 😂
will keep you inform.

I have a check engine light ( due to new doown pipe) but car run fine. I've try top speed and I hit 250 km/h easily. So the power is there dispite this strange behaviour.
 

·
Premium Member
Joined
·
102 Posts
I have this strange feeling too.

May be less than you. But at full throttle from 3000rpm the power seems to fluctuate . I feel more like a smooth turbo charger pressure that fluctuate.

I've instal mishimoto air intake. New Downpipe. And tomorrow I will make a remap 😂
will keep you inform.

I have a check engine light ( due to new doown pipe) but car run fine. I've try top speed and I hit 250 km/h easily. So the power is there dispite this strange behaviour.
well if you have tools to write to the ECU, have you access to to cel tables? all the big name Mappers have that option to disable the codes for the missing cat with a DP install. its nice not having the light on all the time.
I assume you have a wot log,

the way you describe it, I get a feeling mebbe more its the ecu pulling some spark rather than having a little fuel supply issue
 

·
Registered
Joined
·
19 Posts
Hi all.

My fluctuation was due to the down pipe instal and air intake mishimoto. The original map had some problems to regulate boost pressure.

I just had remap today . And tuning of my ecu.

No fluctuation anymore . And power and torque result is huge and feeling When driving is amazing. 431 hp and 626n.m 😳😳
26169
 

·
Registered
Joined
·
483 Posts
Hi all.

My fluctuation was due to the down pipe instal and air intake mishimoto. The original map had some problems to regulate boost pressure.

I just had remap today . And tuning of my ecu.

No fluctuation anymore . And power and torque result is huge and feeling When driving is amazing. 431 hp and 626n.m 😳😳 View attachment 26169
the next step is to buy draggy for $150 and go 1/4 mile or 1/8 run to see what is actually happening. really fun toy.
 

·
Registered
Joined
·
19 Posts
the next step is to buy draggy for $150 and go 1/4 mile or 1/8 run to see what is actually happening. really fun toy.
It's not easy to find drag strip in france ;), but it should be very interesting you're right.

Anyway I'm not a big fan of drag race as for me a flat out start is mechanicaly very agressive, specially with the torque of my car today.
 

·
Registered
Joined
·
483 Posts
It's not easy to find drag strip in france ;), but it should be very interesting you're right.

Anyway I'm not a big fan of drag race as for me a flat out start is mechanicaly very agressive, specially with the torque of my car today.
no need for drag strip. you can do it while getting on highways or any empty areas.
here is the lick for the part.
 
1 - 11 of 11 Posts
Top