[Three_thirty_I]

These adaptation things are a pain! My car has just been to the agents for her last check before going off motorplan and they updated the car's software and reset all adaptations. Since then the throttle character has been a bit of a handful! And now I need to remove my car's front bumper to have it resprayed, and since it has front PCD was going to disconnect the battery to play safe in case any errors come up from this. But now I am a bit hesitant. Although, probably can't make it worse than it is right now - so maybe just has to re-learn what I had taught it all over again...

[Surly73]

Well now I'm not sure which thread to post this in, but I noticed something interesting just this morning concerning my sudden lurch forward when slowly releasing the throttle.

1/ If the throttle isn't pressed past a certain point (something like 50%) for more than a second there is no lurch on release. If I'm giving it a little squeeze for a corner exit or something it can be completely smooth without the lurch when lifting.

2/ I did a squirt of WOT in one of the lower gear and was slowly lifting the pedal back towards 50% and partway through the pedal release it suddenly lurched to a lower amount of acceleration. This is the first time I've ever really been able to isolate the event and observe before and after. Usually I'm in the process of shifting when it does it. Pedal near WOT -> hard acceleration -> slowly releasing pedal -> slightly less acceleration -> sudden lurch to gentle acceleration at around 60% on the pedal, gentle acceleration effect continues and continues to reduce as I continue to smoothly release pedal.

I'm not sure where I should be going with this. Still don't have a K+DCAN cable to start looking for codes or clear all adaptations that a battery pull may not have done. Pedal module issue? Valvetronic issue? As far as I know the pedal module is a digital bus device and I can't just measure it with an ohmmeter to see that the values change smoothly on application and release.

Again, I'll reiterate that I'm being smooth with the controls and this happens at speed, not just first gear where driveline lurch is most evident. It'll still clearly do it in 4th. This is definitely something with the throttle operation like it's snapping Valvetronic "closed" suddenly when it was still accelerating briskly.

I still haven't been able to tear into the pedal module looking for aftermarket throttle remappers from previous owner(s). Unfortunately there's a lot of personal stuff keeping me tied up.

[Three_thirty_I]

Mine also doesn't like somewhat quicker throttle position changes, never has. For instance, if you suddenly push the throttle down hard from a partial throttle position it usually has a nasty hesitation followed by the surge of acceleration - not a nice feeling! Even at speed I do sometimes feel a noticeable change when going between on and off throttle positions no matter how gently you go, sometimes the more direct you are the smoother, strangely enough. But I have also noticed that if you go off throttle very briefly and back on again it does behave somewhat smoother.

One thing that I have made peace with is that this car does not really like fast gear changes - clutch delay valve and laggy throttle makes this quite hit and miss. Can change gears very quickly and precisely on my diesel pickup by comparison. Even things like the dual mass flywheel adds to this equation...

Just to make sure, when you say it lurches forward, you mean straight after taking your foot off the throttle it's like it briefly over-runs from the drivetrain before beginning to reduce speed? Could very well find that this is simply due to the way the dual mass flywheel behaves.

[Surly73]

Originally Posted by Three_thirty_I

Mine also doesn't like somewhat quicker throttle position changes, never has. For instance, if you suddenly push the throttle down hard from a partial throttle position it usually has a nasty hesitation followed by the surge of acceleration - not a nice feeling! Even at speed I do sometimes feel a noticeable change when going between on and off throttle positions no matter how gently you go, sometimes the more direct you are the smoother, strangely enough. But I have also noticed that if you go off throttle very briefly and back on again it does behave somewhat smoother.

I'm trying, but perhaps failing, to communicate that none of my changes are particularly sudden. High performance driving schools, some time spend with fairly quick cars with no driver aids and two decades driving stick has led to me always being progressive with all of the controls. I never yank, jerk, stomp or jab at anything. I'm like Jenson Button. Even though I like to drive "spirited", my brakes and tires last relatively forever (considering the softness of the tire compounds chosen).

For instance, I may be releasing the throttle from WOT at a rate which would take a good 3 count before it reaches fully released. Somewhere around halfway, the car will "suddenly" stop accelerating as if I just side-stepped off of a bowden-cable throttle car. I don't even think I can make a drive-by-wire lurch like this if I tried.

One thing that I have made peace with is that this car does not really like fast gear changes - clutch delay valve and laggy throttle makes this quite hit and miss. Can change gears very quickly and precisely on my diesel pickup by comparison. Even things like the dual mass flywheel adds to this equation...

While this is my first drive-by-wire car, I've had cars with DMFs for a long time. I'm not a power-shifter and don't mash the stick around. I have slight pauses in my shifts through the neutral gate and pause to let the synchros do their work. I haven't removed the CDV in my E90 yet, but it was removed on my E39. My 1998 E39 still had its original clutch and DMF when it was totaled.

Just to make sure, when you say it lurches forward, you mean straight after taking your foot off the throttle it's like it briefly over-runs from the drivetrain before beginning to reduce speed? Could very well find that this is simply due to the way the dual mass flywheel behaves.

It lurches the occupants forward due to suddenly cutting power output. It's like hitting a brick wall rev limiter (except I'm nowhere near the rev limit). As a matter of fact, the first couple of times I felt it, I thought maybe I did hit the rev limiter right before shifting even though I didn't think I was anywhere near 7k (and I wasn't). I've experienced "over run" drive by wire and that's the opposite - where you've lifted off the pedal but the car keeps accelerating. I actually haven't had that with the E90 (touch wood) but have felt it in E46s and E39s with drive-by-wire. Furthermore, I'm not even off the pedal when the sudden cessation of acceleration happens - it's still halfway to the floor. When the pedal was on its way down, there was quite a bit of oomph at 4k RPM at 50% throttle, but on the way up it'll suddenly snap to "light" acceleration. On the other hand, if the whole squeeze and release only spans 1 second, then it doesn't do it a lot of the time.

Now, this usually happens in conjunction with getting ready for a shift and I haven't been able to dissect what's happening, until that experience I wrote about just recently where after the lurch it kept accelerating slowly with the pedal halfway to the floor. If I'm out on twisty rural roads in a situation where speed varies a lot, I'm running through the gears and sweeping 3k-5k RPM a lot it can happen every shift and take a lot of the fun out of it. If I'm driving to the mall, I'll probably never experience it.

I don't know what it's doing, but it makes any "fun" driving clunky, embarrassing, hard on the equipment (driveline shock) and a touch scary just because you don't know what the car's going to do. I'd almost rather be driving AT (GASP!)

IMO, get rid of all of this adaptation BS and give me a setting I can code that adapts to act like a bowden cable and stop thinking for me, thank you very much.

[Three_thirty_I]

It's kind of a old Boeing versus Airbus fly-by-wire thing! I'd rather have full and direct control than a "moderated" second guessed control that evaluates all of your inputs! Computers are fast, but lack the subtle feel that we as humans have!

At the end of the day, I can get into any car and pretty much get used to the feel fairly quickly, but then takes a while for me to get used to my car again afterwards!

But from what you are experiencing with it lurching forward, doesn't sound right, or at least not quite what I am experiencing in general.

[Surly73]

Originally Posted by Three_thirty_I

But from what you are experiencing with it lurching forward, doesn't sound right, or at least not quite what I am experiencing in general.

Yes, I just need to figure out what it is. Once I have a chance to inspect the pedal module I'll know that no cheesy aftermarket stuff is inline. Once I get a K+DCAN cable I can use DIS to clear all adaptations and, perhaps, monitor the realtime output of the pedal module to make sure it's an ice smooth signal.

Unfortunately I'm kind of dealing with a family medical emergency and these things aren't priorities right now...

[Three_thirty_I]

Originally Posted by Surly73

Yes, I just need to figure out what it is. Once I have a chance to inspect the pedal module I'll know that no cheesy aftermarket stuff is inline. Once I get a K+DCAN cable I can use DIS to clear all adaptations and, perhaps, monitor the realtime output of the pedal module to make sure it's an ice smooth signal.

Unfortunately I'm kind of dealing with a family medical emergency and these things aren't priorities right now...

Let us know what you find! Very interested to know!!

[iv-128i]

So after waiting 2 weeks for the DME...
Dealer called me and said that they've replaced it, reprogrammed it and it was still not the cause of the problem...
They've finally discovered that there was some shortage between the front fan wires and the some valve in the exhaust system (that's the explanation they gave me).
At least the car is back to how it felt before with no hesitations and good throttle response
For the valve in the exhaust system maybe they were talking about the valve in the muffler that opens up depending on RPM... but I'm not sure if this is electronically controlled or not

[Three_thirty_I]

Any updates on this guys?!

[Surly73]

Well, from my perspective the car still does it but less than before. Unlike any other car I've had, this E90 isn't as fun running up the revs with decent throttle angles because it does "weird stuff" when I lift and/or go to shift. I've had it almost 3 months, I can't still be getting used to it.

At any rate, my K+DCAN cable just showed up just over a week ago. I've done some coding and also upgraded the battery. I'll start digging into throttle sensor readouts and clearing adaptations soon.

[Three_thirty_I]

Originally Posted by Surly73

Well, from my perspective the car still does it but less than before. Unlike any other car I've had, this E90 isn't as fun running up the revs with decent throttle angles because it does "weird stuff" when I lift and/or go to shift. I've had it almost 3 months, I can't still be getting used to it.

At any rate, my K+DCAN cable just showed up just over a week ago. I've done some coding and also upgraded the battery. I'll start digging into throttle sensor readouts and clearing adaptations soon.

Just out of interest, and sorry if you may have mentioned doing this already, but have you ever tried the throttle adaptation reset? I tried it once almost 2 years ago and put the results down to the placebo effect where you want to feel a difference. But now with my car's throttle behaviour lately I decided to give this another go this afternoon.

Key Fob in, ignition on, foot flat on the throttle (don't go near the clutch pedal) for 30 sec, then push the Start button. Leave everything as is for 2 minutes, then switch the ignition off. This should reset all throttle adaptation values.

With my car I can feel a slight improvement of the throttle feel, but the engine also seems to be smoother in general and less affected when taking your foot off the throttle. Went for an extensive drive on familiar and not familiar routes so that this is not down to muscle memory etc. Worth a try if you haven't done this yet - there are a few other threads about this on this forum.

[Surly73]

Originally Posted by Three_thirty_I

Just out of interest, and sorry if you may have mentioned doing this already, but have you ever tried the throttle adaptation reset? I tried it once almost 2 years ago and put the results down to the placebo effect where you want to feel a difference. But now with my car's throttle behaviour lately I decided to give this another go this afternoon.

Key Fob in, ignition on, foot flat on the throttle (don't go near the clutch pedal) for 30 sec, then push the Start button. Leave everything as is for 2 minutes, then switch the ignition off. This should reset all throttle adaptation values.

With my car I can feel a slight improvement of the throttle feel, but the engine also seems to be smoother in general and less affected when taking your foot off the throttle. Went for an extensive drive on familiar and not familiar routes so that this is not down to muscle memory etc. Worth a try if you haven't done this yet - there are a few other threads about this on this forum.

No I haven't done this. This will start the coolant bleeding process too (at the 10-12 second mark), right?

I was going to try to get my German in order and see if INPA or DIS could be used to clear various adaptations and know that they're all definitely done (as opposed to wonder if a "user" procedure worked or not). Some of my INPA is in English and other parts are die hard German regardless of settings. Maybe there's some kind of process I could use to get more English in there - don't know - still learning.

As I'm writing this, I'm wondering if I didn't read somewhere that this was a transmission adaptation reset and not throttle. This was your 6MT you tried this on, right?

[Three_thirty_I]

Originally Posted by Surly73

No I haven't done this. This will start the coolant bleeding process too (at the 10-12 second mark), right?

I was going to try to get my German in order and see if INPA or DIS could be used to clear various adaptations and know that they're all definitely done (as opposed to wonder if a "user" procedure worked or not). Some of my INPA is in English and other parts are die hard German regardless of settings. Maybe there's some kind of process I could use to get more English in there - don't know - still learning.

As I'm writing this, I'm wondering if I didn't read somewhere that this was a transmission adaptation reset and not throttle. This was your 6MT you tried this on, right?

I've heard about the coolant bleeding process, but didn't notice anything else happening when I did this, so not sure. If only there could be a way to disable adaptations, period!

Well, there is plenty of conflicting info on this, so read through as many of the threads and replies that deal with this to find the general consensus, especially for manual gearbox cars...

[Three_thirty_I]

A friend of mine with a 130i M has been struggling to get to the bottom of a strange throttle hesitation problem and had a tuner run diagnostics (pics up more than what most dealership machines can) and it turns out that the accelerator pedal module is fluctuating in terms of voltage at various throttle positions and causing this strange hesitation. Not sure if this relates to your car's problem...

[csukoh78]

Hello all...

First post! Anyway, I've got a '12 E93 and took it into the dealer so they could fix my wheel where they scraped it...anyway when I get the car back, the battery had been disconnected because I had to reset the time.

After driving it this morning, it's positively sluggish and doesn't leap off the line like she used to. I've searched and only found this thread...is a battery reset something that can affect the throttle like that?