Stock Active Engine Breaking

[pnw.96]

Hi all.

I have had my 2011 128i for a few months now, however, I can't shake the feeling that in first and second gear, there is somewhat noticeable active engine breaking. The car is an automatic and therefore anything under about 30mph feels somewhat touchy?

I can't find any other discussions as to if this is stock or not. The car has an Active Autowerkes tune and downpipes and I am wondering if the tune is the reason why the engine behaves like it does. The original owner was the one who installed these things and although I also ride motorcycles which all have engine breaking, the 128i just does not feel the best with it at the moment.

Any suggestions or insight? Is this something that I should look into correcting with a re-tune?

Thank you!

[olds350]

I'm a bit confused on your description. You said down pipe, which is generally associated with a turbo car, so I could see this on a 135, you have a 128, so are you referring to headers?

That said, I'm trying to follow your issue. Engine braking and being "touchy" are sorta 2 different aspects of driving. Engine braking to me says lifting off of the throttle and the car starts to slow down faster than normal, like a "Jake Brake" on semis. Touchy on the other hand means the car is quick to respond to throttle response.

Can you add more details please?

[Thunderguts]

I would guess there's something in your tune that effects the throttle mapping. I will say that the N52 loses revs faster than any engine I've experienced, but the reasons affect manual cars, not yours.

[chris_flies]

My 128i is really hard to drive smoothly in first and second gear as well, but it's always been that way. The engine has a lot of mechanical advantage in first and second, so it's guaranteed to be more sensitive/touchy.

[MightyMouseTech]

Our cars have a version of micro hybrid. The car tries to only recharge the battery on decel. You are probably just feeling the alternator engaging.

[olds350]

Originally Posted by MightyMouseTech

Our cars have a version of micro hybrid. The car tries to only recharge the battery on decel. You are probably just feeling the alternator engaging.

Can you explain that please? First I've heard of this...

[spidertri]

I've noticed this on my 128i as well. Sort of a very light pulsing/surging feeling if I let the car decelerate without using the brake pedal.

I've read about the battery recharge thing but figured it would be more transparent to the driver.

[Thunderguts]

Originally Posted by olds350

Can you explain that please? First I've heard of this...

I read that in BMW's product literature sent to dealers. The alternator goes into high load mode when you let off the gas to charge the battery. When you get back on the gas, it goes into standard mode to lower the drag on the engine. I wish I could code it out because it really drops the RPM between shifts. This wouldn't affect the OP since he likely isn't letting off the gas in an auto.

[MightyMouseTech]

Originally Posted by olds350

Can you explain that please? First I've heard of this...

The car will try and only recharge the battery while decelerating, unless battery charge drops below 60%. This is why registering proper capacity is so important. Wrong capacity entered into the DME can result in under (car may not start), or over (Boom!) charging of the battery.

[jlc45]

Engine breaking sounds undesireable!

[WDE82]

This has nothing to do with battery charging. Stop it.

128i is just stiffer than your E46 and the TC locks up and stays locked up longer. The auto in 1st and 2nd is more like a manual in the E82 than it is in the E46. Heavy engine braking is normal in these gears. I can't hit over 25-30 on quite steep downhills gliding in 2nd in my manual. I'd expect the same of an auto.

[gjm120]

On slowing down my AT downshifts at about 1500 rpm. So if the alternator is varying the load, I wouldn't notice b/c of the downshifts.