Help!!!! No boost or power!
11-15-2018, 09:47 AM
#26
I was there for the vacuum line test @ zero pressure. We replaced the lines and boost control valve...still no boost over 4,000 rpms. I asked if they pressured system...did not pressure past 25 psi, but will be done if these actuators don't solve the problem. Thx for that. We reset everything again yesterday with xentry and had no battery voltage codes.
Update later this morning...
Update later this morning...
My issue was confirmed. After the dealer fix, my flap stuck again. I ask them to replace the muffler. They said I have catless DP, so the warranty cannot cover this. I already ordered AWE exhaust. I think you better check can your flap completely open or close. If the issue come from the exhaust flap, power is restored after an ignition reset. I did a test, when my car is warm, shut down the car and get off the car, lock it. Then unlock it, start the engine, floor it. Power is back. Only one time, after first acceleration, power lose again. You can try it.
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raudiace4 (09-02-2020)
11-15-2018, 06:41 PM
#28
My issue was confirmed. After the dealer fix, my flap stuck again. I ask them to replace the muffler. They said I have catless DP, so the warranty cannot cover this. I already ordered AWE exhaust. I think you better check can your flap completely open or close. If the issue come from the exhaust flap, power is restored after an ignition reset. I did a test, when my car is warm, shut down the car and get off the car, lock it. Then unlock it, start the engine, floor it. Power is back. Only one time, after first acceleration, power lose again. You can try it.
Forgot how ridiculously quick this thing is. lol
11-15-2018, 06:49 PM
#29
OK. My car is fast again! Driver side muffler exhaust valve was jammed shut, and guide was missing. Actuator was fried, due to the stuck valve. Replaced both exhaust valve actuators, unstuck the stuck valve, cleared codes, and bam...booooost! Greased the valve for good measure, but will still upgrade to AWE exhaust, as I'm sure it'll fail again. But good news for sure.
Forgot how ridiculously quick this thing is. lol
Forgot how ridiculously quick this thing is. lol
11-15-2018, 06:50 PM
#30
That's the interesting thing...no fault code until my guy pulled the good actuator from the car. Then, with only the bad actuator and valve hooked up, the car threw a code. So, no codes to help diagnose until you start removing stuff...very quirky.
11-15-2018, 06:56 PM
#32
edit: they actually did bring my car to the dealer, but the dealer had no idea how to solve the problem...
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Jan AMG (12-01-2019)
11-15-2018, 07:15 PM
#33
Sounds like your shop is more competent that's for sure.
11-19-2018, 07:14 PM
#34
Wellll, problem came back a few nights ago. Went to the drag strip to run the car....we had a very low DA night with temps in the 50s. Car ran great all day long, including the 30 minute drive to the track. Launched the car, and it went into limp mode. As of today, the car runs hard, then goes limp, and repeats. I can hear the exhaust flap trying to close when I shut the car off. It's spent. Will replace the exhaust.
11-20-2018, 11:12 AM
#35
Wellll, problem came back a few nights ago. Went to the drag strip to run the car....we had a very low DA night with temps in the 50s. Car ran great all day long, including the 30 minute drive to the track. Launched the car, and it went into limp mode. As of today, the car runs hard, then goes limp, and repeats. I can hear the exhaust flap trying to close when I shut the car off. It's spent. Will replace the exhaust.
11-20-2018, 11:18 AM
#38
edit: this is purely a mechanical failure of the exhaust flaps...if you have the performance exhaust, you have three flaps, all poorly designed. if you do not have the performance exhaust, you will have two flaps. The mechanical failure is seen by the software, and the software locks out boost past 4k rpms. Not super necessary, but the AMG engineers decided it was important. Talked to an Audi guy last night about his S4....seems he had a similar issue on that car.
Last edited by Ralcbah; 11-20-2018 at 11:23 AM.
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raudiace4 (09-02-2020)
11-20-2018, 02:40 PM
#40
Thanks you, that makes sense. One question though - what's causing the exhaust flap to become stuck?
It's actually just an interlock in the software. The actuator does not see additional load, nor does it care about it. In my mind, it's just bad programming, and should not lock out the system (or in this case trim boost past 4,000 rpm). This problem will continue to arise on stock and modified cars. Hopefully this makes sense...if not, ask again.
edit: this is purely a mechanical failure of the exhaust flaps...if you have the performance exhaust, you have three flaps, all poorly designed. if you do not have the performance exhaust, you will have two flaps. The mechanical failure is seen by the software, and the software locks out boost past 4k rpms. Not super necessary, but the AMG engineers decided it was important. Talked to an Audi guy last night about his S4....seems he had a similar issue on that car.
edit: this is purely a mechanical failure of the exhaust flaps...if you have the performance exhaust, you have three flaps, all poorly designed. if you do not have the performance exhaust, you will have two flaps. The mechanical failure is seen by the software, and the software locks out boost past 4k rpms. Not super necessary, but the AMG engineers decided it was important. Talked to an Audi guy last night about his S4....seems he had a similar issue on that car.
11-20-2018, 03:50 PM
#41
No prob. Well it's a cheap mechanical part; not a knock on MB. It just is. There is a guide in the valve, which does as it name specifies, for the flap. The guide becomes damaged as the exhaust valve/flap opens and closes. It can also become so deteriorated, it goes missing. The design of the muffler is not modular, and as far as we can tell, does not allow for this simple component to be replaced.
01-20-2019, 10:37 AM
#43
MBWorld Fanatic!
dealing with your dealership would be free under warranty but indy shop has to charge for parts + time right?
01-20-2019, 11:00 AM
#44
01-20-2019, 11:02 AM
#45
MBWorld Fanatic!
01-21-2019, 07:22 AM
#47
Senior Member
Nice thread guys! Lots of useful info.
Unbelievable how the dealers don't know how to properly handle their own brands
Unbelievable how the dealers don't know how to properly handle their own brands
10-21-2019, 07:43 AM
#50
Super Member
