Tuned M278 e550, sudden power cut under heavy acceleration
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W212 E550
Tuned M278 e550, sudden power cut under heavy acceleration ( Resolved!)
2012 M278 e550.
I've had this car for several years, put an oe tune on it a couple of years back and it's been great.
It had an issue with waste gate chatter on cold start, which I got around to getting repaired recently. They had to drop the whole engine and remove the turbos to repair.
At the same time it was time for some new boots so I got some pilot sport 5s for it, seeing as traction was often an issue.
In the couple of days I've had it back from the shop I've noted that under heavy acceleration (1st and 2nd), it cuts power dramatically during the pull and not like traction control (which limits power, but doesn't cut it completely), so it jerks forward, then suddenly accerates and jerks again depending on the gear. I've also noted that the trans appears to be slipping (engine revving out during a hard pull, but not accelerating the carat the same rate).
Had a couple of thought on the issue; old tyres were 265 35 18s on the rears, theyve put 40 profiles on with the new tyres (all 4 corners), this wouldn't be tripping any speed sensors would it?
Could the Tcu be limiting the torque and cutting power now that I have good tyres and traction? Seems unlikely as its a common tune (OE tuning) and I imagine there would be a lot of complaints if this was the case.
Any other ideas?
Cheers
I've had this car for several years, put an oe tune on it a couple of years back and it's been great.
It had an issue with waste gate chatter on cold start, which I got around to getting repaired recently. They had to drop the whole engine and remove the turbos to repair.
At the same time it was time for some new boots so I got some pilot sport 5s for it, seeing as traction was often an issue.
In the couple of days I've had it back from the shop I've noted that under heavy acceleration (1st and 2nd), it cuts power dramatically during the pull and not like traction control (which limits power, but doesn't cut it completely), so it jerks forward, then suddenly accerates and jerks again depending on the gear. I've also noted that the trans appears to be slipping (engine revving out during a hard pull, but not accelerating the carat the same rate).
Had a couple of thought on the issue; old tyres were 265 35 18s on the rears, theyve put 40 profiles on with the new tyres (all 4 corners), this wouldn't be tripping any speed sensors would it?
Could the Tcu be limiting the torque and cutting power now that I have good tyres and traction? Seems unlikely as its a common tune (OE tuning) and I imagine there would be a lot of complaints if this was the case.
Any other ideas?
Cheers
Last edited by Matt.be; Jul 22, 2023 at 01:20 AM.
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2012 E550 sedan 2019 E63 Wagon
If your traction control light is not flashing, then it's not a traction issue. Mine only does it on really cold weather or on cornering. Check your wastegates actuator for leaks. I have a video somewhere showing how wastegates shake on idle on a leaking one. Also check your logs on a pull (avoid 1-2 gears pulls unless you want to swap motor mounts frequently). Check to see if boost is hitting targets. Also check if air/fuel ratio is within spec when doing a pull.
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2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
As mentioned you gotta log this -- boost, wastegate activity, IAT, etc all under WOT
Example:
https://mbworld.org/forums/w212-amg/...ge-issues.html
Example:
https://mbworld.org/forums/w212-amg/...ge-issues.html
Thread Starter
Newbie
Joined: May 2023
Posts: 9
Likes: 4
W212 E550
If your traction control light is not flashing, then it's not a traction issue. Mine only does it on really cold weather or on cornering. Check your wastegates actuator for leaks. I have a video somewhere showing how wastegates shake on idle on a leaking one. Also check your logs on a pull (avoid 1-2 gears pulls unless you want to swap motor mounts frequently). Check to see if boost is hitting targets. Also check if air/fuel ratio is within spec when doing a pull.
I'll do a few pulls later in the day and post some logs of the key stats here.
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Thread Starter
Newbie
Joined: May 2023
Posts: 9
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W212 E550
As mentioned you gotta log this -- boost, wastegate activity, IAT, etc all under WOT
Example:
https://mbworld.org/forums/w212-amg/...ge-issues.html
Example:
https://mbworld.org/forums/w212-amg/...ge-issues.html
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Thread Starter
Newbie
Joined: May 2023
Posts: 9
Likes: 4
W212 E550
If your traction control light is not flashing, then it's not a traction issue. Mine only does it on really cold weather or on cornering. Check your wastegates actuator for leaks. I have a video somewhere showing how wastegates shake on idle on a leaking one. Also check your logs on a pull (avoid 1-2 gears pulls unless you want to swap motor mounts frequently). Check to see if boost is hitting targets. Also check if air/fuel ratio is within spec when doing a pull.
Drive home confirmed issue not fixed, so back to the shop it goes.
Now that I've got it back I've been able to get some logs. This is a second to third pull, foot to the floor the whole time, multiple throttle cuts during the run.
Note, boost not making it over 10 (tune takes it to 14/15) & the two violent throttle cuts.
Thread Starter
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W212 E550
Thread Starter
Newbie
Joined: May 2023
Posts: 9
Likes: 4
W212 E550
Incase anyone else has this issue and comes across this thread, the issue is now resolved.
It ended up being a problem with the transmission adaptive shift. This presented as a large power cut when the engine went to shift (almost like hitting the brakes and then flooring it again, before finally finding the gear and shifting).
The fix was to rest the adaptive shift and have the trans relearn the shifts. This was done by a tech, and then just required driving the car around, initial shifts are rough as it learned but get progressively smoother.
Hope this helps someone in the future.
It ended up being a problem with the transmission adaptive shift. This presented as a large power cut when the engine went to shift (almost like hitting the brakes and then flooring it again, before finally finding the gear and shifting).
The fix was to rest the adaptive shift and have the trans relearn the shifts. This was done by a tech, and then just required driving the car around, initial shifts are rough as it learned but get progressively smoother.
Hope this helps someone in the future.
