Hesitation under acceleration

[GIdriver]

The car hesitates when I step on the throttle on higher gears (6,7) at low rpm's (1.5-2k). Past 3k rpm's no problem at all. 2011 DCT, e90, Dinan pulley, Akra Evo, ESS Akra tune, 25k miles, original owner, 93 octane, sometimes mixed with Sunoco 100 (~ 95). I use Techron fuel system cleaner with every oil change (~7k miles). AA filter less than 10k miles.

Before I get the "just drive above 3k rpm's " replies: I do drive above 3k most of the time. I first noticed this while driving up a hill on D3. The car did not downshift initially and hesitated, until it finally made the downshift. Since it felt weird, to test it I have been (on occasions) accelerating while holding a higher gear (7th) at low speeds/rpms and it constantly does it. I'm afraid this could be related to mods (ESS tune/Akra Evo) since I don't think it happened before (or it happened but I didn't notice and now it is more obvious due to increase noise from the exhaust, I don't know). No CEL's/warnings.

These are my possible explanations:
1. It's normal, I'm almost stalling the car
2. Bad spark plugs (25k miles)
3. Torque dip from Akra Evo
4. Tune issue
5. Bad gas (less likely, using same since prior to mods).

I will appreciate any input on this issue, specially from fellow owners with similar setup.

Thanks in advance

[m3an]

considering this car is pretty laggy down low and short on torque some of what you may be experiencing (albiet weird) could be normal. I was gonna suggest plugs as a starting point to check but w/ 25k I don't think those are culprit. Fuel Filter? Again, 25k on the car I wouldn't worry.


You mentioned the Akra Evo torque dip which I don't get why this is the most popular/expensive exhaust and it has a drop in power?? And torque of all things? When viewed on a dyno plot its def quite apparent.. I have never driven one w/ Akra so can't comment on that but after seeing it plotted on a graph I could def see that being felt while lugging the car around

[ilya335]

This may be a long shot, but my car was acting hesitant one time when I tried to punch it in higher gears at low rpm. It turned out one of my rear tires was 10psi lower than the other.

[GrussGott]

Originally Posted by GIdriver

The car hesitates when I step on the throttle on higher gears (6,7) at low rpm's (1.5-2k). Past 3k rpm's no problem at all.

2011 e93 dct, no mods
Over the course of about 3 months that's what mine did ... then it trended into a rough idle, then more hesitation at low rpms - it would kind of pause, then it died during start up once, then a few days later I got all of the lights.

Turned out to be a failing bank 1 throttle actuator valve - they have to pull the manifold to get at it.

http://www.m3post.com/forums/showthread.php?t=769035

[GIdriver]

Originally Posted by m3an

considering this car is pretty laggy down low and short on torque some of what you may be experiencing (albiet weird) could be normal. I was gonna suggest plugs as a starting point to check but w/ 25k I don't think those are culprit. Fuel Filter? Again, 25k on the car I wouldn't worry.


You mentioned the Akra Evo torque dip which I don't get why this is the most popular/expensive exhaust and it has a drop in power?? And torque of all things? When viewed on a dyno plot its def quite apparent.. I have never driven one w/ Akra so can't comment on that but after seeing it plotted on a graph I could def see that being felt while lugging the car around

I'm leaning towards yor assessment. I know the torque dip is unpleasant but the sound and the hp gain at higher rpms (where the S65 really shines) with the Evo is delightful. I appreciate your opinion and input. Thanks!

[GIdriver]

Originally Posted by ilya335

This may be a long shot, but my car was acting hesitant one time when I tried to punch it in higher gears at low rpm. It turned out one of my rear tires was 10psi lower than the other.

Thanks! I don't think this is the culprit, but believe it or not I just got a left front tire low pressure light. LOL! Will check it first thing tomorrow. Thanks for your input!

[GIdriver]

Originally Posted by GrussGott

2011 e93 dct, no mods
Over the course of about 3 months that's what mine did ... then it trended into a rough idle, then more hesitation at low rpms - it would kind of pause, then it died during start up once, then a few days later I got all of the lights.

Turned out to be a failing bank 1 throttle actuator valve - they have to pull the manifold to get at it.

http://www.m3post.com/forums/showthread.php?t=769035

This sounds plausible. However, since no warning lights have turned on, I will just wait until it gets worse (if it ever happens). The stealer will do nothing until some message lights up... Or the car dies in their hands... Thanks for your input!

[BPMSport]

Flash back to stock and see if that corrects the issue. It's impossible to make it perfect in that area but with some camshaft position changes you can definitely improve it with the akra.

[MKE_M3]

I assume the transmission is set to auto? If not, I would not recommend going full throttle in a high gear at low RPM in any car. It can cause bad harmonic distortion to the bottom end where the crank gets torqued in ways its not supposed to. If you are in auto, then it should quickly shift, and that sounds more like a transmission problem than engine problem? I have a 6MT, so I can't provide much other help.

Good luck and keep us informed!

[GIdriver]

Originally Posted by Mike Benvo

Flash back to stock and see if that corrects the issue. It's impossible to make it perfect in that area but with some camshaft position changes you can definitely improve it with the akra.

Thanks for the suggestion! I will do that but I'm afraid I will have to wait a couple of days to play with the car

[GIdriver]

Originally Posted by jdemetry

I assume the transmission is set to auto? If not, I would not recommend going full throttle in a high gear at low RPM in any car. It can cause bad harmonic distortion to the bottom end where the crank gets torqued in ways its not supposed to. If you are in auto, then it should quickly shift, and that sounds more like a transmission problem than engine problem? I have a 6MT, so I can't provide much other help.

Good luck and keep us informed!

Well, there's something I did not know. Thank you! I was doing exactly that to test it (in manual mode). I also thought that it could be the transmission not downshifting earlier on D3. The truth is I've been babying the car lately and perhaps has "adapted" to soft driving. On D5 it does not happen, the transmission shifts preventing the hesitation to happen.


Thanks all for the brainstorming. I will keep you posted.

[Morrisc]

Originally Posted by GIdriver

Well, there's something I did not know. Thank you! I was doing exactly that to test it (in manual mode). I also thought that it could be the transmission not downshifting earlier on D3. The truth is I've been babying the car lately and perhaps has "adapted" to soft driving. On D5 it does not happen, the transmission shifts preventing the hesitation to happen.


Thanks all for the brainstorming. I will keep you posted.

Did you ever find out what was wrong with your car as mine has the same symptons at the moment

[JDM_CL9]

Originally Posted by Morrisc

Did you ever find out what was wrong with your car as mine has the same symptons at the moment

This is quite the old post now but looks like the OP fixed it by getting a MB with more power to mitigate the power loss.

[Morrisc]

Anyone else shed some light on this?