Flywheel or throttle mapping question

[Thunderguts]

I've only had my 128 for a week, but I'm looking for ways to improve the driving experience. One thing I find curious is how unresponsive the throttle seems when rev-matching. I've never driven a car with a dual mass flywheel so I'm not sure what to expect. Normally I just blip and downshift, but the N52 seems reluctant to do that. I'm not sure if it's a throttle mapping issue or a flywheel issue. If it were an unusually heavy flywheel, it wouldn't be losing revs so quickly so I think it has more to do with throttle mapping. Did anyone else get the same impression when they started driving their 1? If so, has anyone noticed a difference after a tune?

I've seen some "throttle enhancement" modules, but what I don't want is for 10% throttle to suddenly be 30% throttle. That makes it harder to modulate. I just want it to react sooner.

[The Wind Breezes]

Press the gas harder. You need to get used to the car. It takes time. Are you aggressively flooring the pedal for a split second? Work your way up to that if necessary and play with the timing. You'll get the hang of it soon enough.

[Thunderguts]

I'll do some experimenting like stabbing WOT and seeing how long it takes to react. So far my impression is that it reacts like an engine with a heavy flywheel. The main reason I wanted to stay with a N/A engine is that I like the instant throttle response. I'm sure there's a way to improve the feel, it's just a question of finding it.

[smeard]

Originally Posted by Thunderguts

I'll do some experimenting like stabbing WOT and seeing how long it takes to react. So far my impression is that it reacts like an engine with a heavy flywheel. The main reason I wanted to stay with a N/A engine is that I like the instant throttle response. I'm sure there's a way to improve the feel, it's just a question of finding it.

For downshifts I have to floor it for a split second and she normally responds. Obvi took some time to get used to. A/C tends to affect these cars in terms of revs so make sure you turn it off or downshift faster with more gas otherwise it is a jerky ride.

EDIT: Also, the CDV in our cars can be aggressive, so may be worth removing! Plenty of threads on that

[Thunderguts]

Originally Posted by smeard

EDIT: Also, the CDV in our cars can be aggressive, so may be worth removing! Plenty of threads on that

Oh yeah. The CDV was the first thing to go. It lasted a whole 5 days in my car before it was gone. I get the feeling BMW tried to tone down the responses of the car to suit a plurality of drivers. Yes, many people will appreciate smoothness over performance, but those of us who want sharp responses feel underwhelmed. Run-flat tires, muted throttle response, CDV, etc., they all conspire to create a safe plebeian experience. I can imagine a bunch of BMW engineers screaming "Nein! Nein! Nein!" as the marketing team won the day. Sadly, I also think it could stand to lose about 400lbs. I was shocked how much weight went into the silly cabin air filter alone. That support must weigh about 7 lbs and those wires could have been routed along the firewall. Don't get me wrong, I absolutely love my new 128, but I can make it better, and definitely purer.

[smeard]

Originally Posted by Thunderguts

Oh yeah. The CDV was the first thing to go. It lasted a whole 5 days in my car before it was gone. I get the feeling BMW tried to tone down the responses of the car to suit a plurality of drivers. Yes, many people will appreciate smoothness over performance, but those of us who want sharp responses feel underwhelmed. Run-flat tires, muted throttle response, CDV, etc., they all conspire to create a safe plebeian experience. I can imagine a bunch of BMW engineers screaming "Nein! Nein! Nein!" as the marketing team won the day. Sadly, I also think it could stand to lose about 400lbs. I was shocked how much weight went into the silly cabin air filter alone. That support must weigh about 7 lbs and those wires could have been routed along the firewall. Don't get me wrong, I absolutely love my new 128, but I can make it better, and definitely purer.

Yes fully agree. Although I am glad the U.S. still gets manual cars from BMW, they really need to relax on the whole "make it easier" stuff. My brother's new-to-him F30 328i has a stick (RARE) and he hates the shift action compared to mine. I drove it and indeed his feels like I was sticking an oar through a bunch of rubbery gates in the trans. EASY to learn, DIFFICULT to drive fast/smooth. I miss the old BMW

[rowsdower]

I am with you on everything you observed. I find my car difficult to rev match and find the RPMs drop way too quickly. I think it has to do with the Valvetronic system, which is very interesting mechanically. BPC did a great video with a disassembled head, I will try to find it later. Basically, under normal conditions, the N51/2 is throttled via an eccentric shaft that disengages the intake valves from the cam. With no throttle input, the intake valves basically stay closed. Whereas with a car throttled via a throttle body will have a little bit of air in the intake tract that the engine eats up over a split second after the throttle closes, our cars have no such thing. It causes a very abrupt drop in RPM compared to other cars.

Someone more knowledgeable than me will surely chime in shortly to explain why I am wrong but check out the vid if you can find it!

[Thunderguts]

Originally Posted by rowsdower

I am with you on everything you observed. I find my car difficult to rev match and find the RPMs drop way too quickly. I think it has to do with the Valvetronic system, which is very interesting mechanically. BPC did a great video with a disassembled head, I will try to find it later. Basically, under normal conditions, the N51/2 is throttled via an eccentric shaft that disengages the intake valves from the cam. With no throttle input, the intake valves basically stay closed. Whereas with a car throttled via a throttle body will have a little bit of air in the intake tract that the engine eats up over a split second after the throttle closes, our cars have no such thing. It causes a very abrupt drop in RPM compared to other cars.

Someone more knowledgeable than me will surely chime in shortly to explain why I am wrong but check out the vid if you can find it!

This is very interesting. With a standalone ECU, I think it would be easy enough to solve by keeping the valves open a split second longer. I wonder if there would be a simpler way to solve it with a piggyback tune. Basically when the vehicle speed sensor detects more than 5 mph, the throttle never drops below 3% or something.

[rowsdower]

Here's that video. The intake part starts around 3:45.

https://www.youtube.com/watch?v=3gRhDKE8vKU

[Thunderguts]

After doing some experimenting tonight, I realize that it's definitely a throttle delay. There's no reason a drive-by-wire throttle can't be instantaneous, but this one definitely isn't. It's a shame because it makes downshifting harder on the synchros and it's just not as pleasant.

Has anyone noticed an improvement going with a lighter single mass flywheel? I don't think that's the source of the problem, but it might mask it.

[Suhb]

Look into getting the 3 stage intake manifold and pair it with a BPC or AA tune. I know the tune sharpens the throttle response.

[Thunderguts]

Originally Posted by Suhb

Look into getting the 3 stage intake manifold and pair it with a BPC or AA tune. I know the tune sharpens the throttle response.

Yep! That's in the planning stages. So much for my Xmas bonus...

[smeard]

BPC and AA have some great tunes out there. I hopefully will get around to giving them a shot!

[minirips2]

The other thing I noticed about the engine, and I think it's because of Valvetronic, is the lack of engine braking. Get off the throttle, and it just coasts. No real vacuum to speak of with these engines, hence the vacuum pump.
I, too, feel a big difference in how the revs drop with A/C on. It's so much easier to rev match with A/C off. When you have a summer as hot and sticky as we've had here lately, comfort wins out. Every time!

[chris_flies]

Originally Posted by minirips2

The other thing I noticed about the engine, and I think it's because of Valvetronic, is the lack of engine braking. Get off the throttle, and it just coasts. No real vacuum to speak of with these engines, hence the vacuum pump.
I, too, feel a big difference in how the revs drop with A/C on. It's so much easier to rev match with A/C off. When you have a summer as hot and sticky as we've had here lately, comfort wins out. Every time!

I recently found that it's another thing that can be coded (I think in the DSC module), I may experiment with it. Apparently, it keeps fuel going, unlike most engines that kill fuel completely on liftoff...

EDIT: Here's a link: https://www.1addicts.com/forums/show...1216642&page=5

[Thunderguts]

I’m trying a variation of the no-lift shift. Basically I am forcing myself to keep my foot on the gas when shifting, just releasing the pressure slightly. This allows me much quicker modulation of the throttle to match revs, but it does require a lot of concentration to master. If my foot comes off the gas, forget it— the revs drop like a stone and won’t climb back up by the time I shift even if I blip the throttle. I definitely want to see if I can tune a bit less delay in the throttle when I charge out the intake manifold.

[rjahl]

The Valvtronic system is actually pretty quick. Speed is measure in milliseconds and I'd be surprised if you were actually noticing any delay in the ECC cam movement from Full throttle to partial and back.

I would not be surprised to learn the the DME Load management system is cutting ignition timing through the end of your shift. Making it feel like your throttle ECC cam is not full open.

The DME has a pretty advanced system to predict when Pre-ignition events might occur based on engine load, RPM, temp and gear. I'd log it and confirm if you ESS is slow or if its jut the ignition timing getting knocked down.

Both ignition timing an ESS values can be logged to 110 millisecond frame rates on your DME.

With my old N52 I logged big ignition cuts on throttle ramp ups, takes a few hundred milliseconds to get the timing where it should be for current the load and RPM.

It's also a big pain for the N54, N55 guys as well. Huge timing cuts after a gear shift.

[chris_flies]

Originally Posted by rjahl

The Valvtronic system is actually pretty quick. Speed is measure in milliseconds and I'd be surprised if you were actually noticing any delay in the ECC cam movement from Full throttle to partial and back.

I would not be surprised to learn the the DME Load management system is cutting ignition timing through the end of your shift. Making it feel like your throttle ECC cam is not full open.

The DME has a pretty advanced system to predict when Pre-ignition events might occur based on engine load, RPM, temp and gear. I'd log it and confirm if you ESS is slow or if its jut the ignition timing getting knocked down.

Both ignition timing an ESS values can be logged to 110 millisecond frame rates on your DME.

With my old N52 I logged big ignition cuts on throttle ramp ups, takes a few hundred milliseconds to get the timing where it should be for current the load and RPM.

It's also a big pain for the N54, N55 guys as well. Huge timing cuts after a gear shift.

It is impressively quick, and, more importantly faster than a turbo. I find myself doing the same thing as Thunderguts mentioned; I hold the throttle a little between shifts to keep the rpms in the right spot for the next shift, since I don't do racing-like shifts every time I'm driving...

[Thunderguts]

I found this in the training manual:

Intelligent Alternator Control (IGR) No fuel is drawn from the tank in overrunning mode. The injectors in the fuel injection system are shut off. The engine is driven by the kinetic energy from the wheels. The alternator generates the maximum possible electrical output and supplies the electrical equipment. The DME is in communication with the alternator and the intelligent battery sensor, which detects the charge level of the battery, and charges the battery with the maximum possible voltage.

I don't know how long it takes for the ECU to determine it's in "overrun mode," but the instant it does, all fuel is cut off. That explains why it's so slow to react when you try to get back on the throttle. This also explains why it's really quiet in overrun mode with no pops and cracks from the exhaust. I really wonder if there is a way to code this out to improve throttle response.

[MA128]

I had the Sprint Booster v3 installed last year while other work was being done. It reduces the throttle input delay but not completely. There are also further settings that over-interpret the throttle position to create a feeling of enhanced acceleration, but these merely make the pedal more sensitive. It's almost impossible to get a good technical answer about the differences between the many settings (I tried). Tunes apparently do a better job but I didn't want to mess with the ECU.

[steevo_102]

Bumping an old thread instead of creating a new one.

I'm looking into getting a 128i soon and was concerned about this issue as well. I previously owned an S54 swapped 330i and was able to make some adjustments as well as map the throttle using software from ECUWorx and was wondering if there's similar software that exists for the E82. I combed the forums and tried google searching but to no success. The only software I know that can make some adjustments to the E82 are:

Carly
Bimmergeeks
MG Flasher (I believe for F chassis only)
MHD Flasher (features only for N54, including throttle mapping )

Unfortunately, each of these don't allow for throttle adjustment (except MHD which is only for the N54). I know there's brands that offer hardware to connect to the pedal and such but I'd rather re-map it instead of adding clunky dongles and modules.

Anyone know of any software that allows the feature of throttle mapping?

[Thunderguts]

Interesting reading this thread after 4 years. I still have the same complaints about N52 throttle response, but I've learned to live with it. I have a 3IM sitting in my garage, but I haven't gotten around to installing it. I wonder if anyone noticed any difference going from a stock N52 to a 3IM. Is there any difference in throttle response between an N51 and N52?