[Surly73]

Just observed something odd with my fairly recently purchased 02/2007 328i last night.

I had the battery out a few days ago just to check the fluid level in the cells and confirm the condition of the "green eye" since I could not get perfectly above the battery to inspect it with it installed.

I had no apparent problems when reinstalling it, and I can't say I really noticed much of a difference in how the car starts, drives or runs (so I'm not sure that any adaptations were actually cleared by the 15 minutes without a battery installed).

Last night when merging onto the highway, I was in 3rd or 4th (6MT) around 4k accelerating at around 50% throttle and I squeezed it down to WOT. As I got close to WOT acceleration actually LESSENED and then increased again when I lifted up to 75% or so. It wasn't dramatic (a passenger wouldn't have commented) but it wasn't my imagination. It also seems that overall power output is lower than it was a week or two ago but I only noticed when calling for WOT - normal city driving was unaffected. It seems like the car was capable of being significantly faster on a country road run I did 2-3 weeks ago. The only significant change has been the battery disconnection. I did transmission and diff fluid but I don't remember if it was before or after the country run I'm thinking of, and there's no possible way that either fluid would make WOT slower than 75% throttle anyways.

No CEL, but I don't have my K+DCAN cable and DIS (or BT or AE) yet so I can't check for shadow codes.

Adaptations? Misfire (didn't feel anything)? Cosmic rays? Anyone ever heard of such a thing before? Please don't just tell me that I need a 335 to solve the acceleration problem These are just some of the reasons I hate drive-by-wire - you have no idea what the DME is actually doing with the "throttle" and how it corresponds to where the pedal is.

[Tom K.]

Maybe a long shot, but did you re-register the battery? The IBS can apparently do some pretty strange things when not properly programmed.

Tom

[Surly73]

Originally Posted by Tom K.

Maybe a long shot, but did you re-register the battery? The IBS can apparently do some pretty strange things when not properly programmed.

Tom

Nope. I reinstalled the same battery, not a new one, so registration shouldn't be required. In fact it would be a bad idea, I would think, since the car would think it was a fresh new battery instead of a 5+ year old one.

[Tom K.]

Originally Posted by Surly73

Nope. I reinstalled the same battery, not a new one, so registration shouldn't be required. In fact it would be a bad idea, I would think, since the car would think it was a fresh new battery instead of a 5+ year old one.

My understanding is that the registration procedure includes an analysis of the "new" battery, so I can't see how it would be harmful.

At any rate, good luck & let us know when you solve your problem.

Tom

[Surly73]

Originally Posted by Tom K.

My understanding is that the registration procedure includes an analysis of the "new" battery, so I can't see how it would be harmful.

Hmmm, that's not what I thought but I'm also new to the platform. I'll see if I can dig up any more info on this just to be sure...

At any rate, good luck & let us know when you solve your problem.

Tom

With any luck it's some kind of adaptation and it will just go away. I only had the briefly squirt of WOT today and it seemed the same as 50% (which is in itself potentially a problem, but at least it wasn't slower).

[iv-128i]

do you have any updates on your problem ? I have the exact same thing on my 128i 2011 after a battery disconnect....

[Surly73]

Originally Posted by ivan-128i

do you have any updates on your problem ? I have the exact same thing on my 128i 2011 after a battery disconnect....

No, other than it seems like 100% is about the same amount of acceleration at 50%, and the 100% feels like less than it used to do (but 50% feels about the same).

I've been wondering about he possibility of one of the previous owners installing one of those lame accelerator pedal remapping devices somewhere along the line. That could explain 50% being the same as 100% and also how I notice that slowly lifting the pedal when accelerating briskly results in a jerk forward (even at 50mph). I inquired about this jerking on any throttle lift in question #3 of my first post here.

I'd like to figure out *ALL* of the places to check for these devices. Remapping the throttle like this and not actually making the car any faster just seems lame to me, and may confuse the DSC functions where "rapidly" lifting from the throttle will pre-tension the brakes and cause other things to happen. This might be causing my throttle lift "jerk" problem.

[Dirk Diggler]

Honestly my '08 328i feels that way too, but I think it's normal. No difference in 3/4 throttle vs full throttle, and when I slowly let off the pedal, it seems to continue to pull the same as it did at full throttle right up to about 1/4 throttle. I think the throttle mapping changes depending on what gear you're in.

In my 6MT, first gear throttle is very mushy and insensitive. I think that's to help the driver have a smooth start. In the higher gears, the throttle is much more sensitive and it's those gears where I don't feel much difference from 1/2 throttle vs full.

Perhaps your car had adapted to your driving style and lost those settings when you disconnected? Just a stab in the dark...

[iv-128i]

Originally Posted by Surly73

No, other than it seems like 100% is about the same amount of acceleration at 50%, and the 100% feels like less than it used to do (but 50% feels about the same).

I've been wondering about he possibility of one of the previous owners installing one of those lame accelerator pedal remapping devices somewhere along the line. That could explain 50% being the same as 100% and also how I notice that slowly lifting the pedal when accelerating briskly results in a jerk forward (even at 50mph). I inquired about this jerking on any throttle lift in question #3 of my first post here.

I'd like to figure out *ALL* of the places to check for these devices. Remapping the throttle like this and not actually making the car any faster just seems lame to me, and may confuse the DSC functions where "rapidly" lifting from the throttle will pre-tension the brakes and cause other things to happen. This might be causing my throttle lift "jerk" problem.

Well actually I have the BMS PBX(throttle remapping) installed and it was doing great job, but since I had the battery disconnected for 1day I started to notice that weird throttle response which was great before I disconected the battery... I don't understand how this problem is linked to the fact that I disconected the battery, but that's when I started to feel a different throttle response...

[Surly73]

Originally Posted by Dirk Diggler

Honestly my '08 328i feels that way too, but I think it's normal. No difference in 3/4 throttle vs full throttle, and when I slowly let off the pedal, it seems to continue to pull the same as it did at full throttle right up to about 1/4 throttle. I think the throttle mapping changes depending on what gear you're in.

I could handle having little difference between 75% and 100%, but having LESS power at 100% than at 75% isn't cool. I've never read concrete proof anywhere, but I also believe that the DME does different things with the engine in lower gear. I remember in my comparatively ancient 1998 E39 with old-fashioned bowden cable throttle (no mapping here) and 5MT the car was noticeably slower in 1st with ASC on than without, even if there was absolutely no wheelspin (on PS2s). I played around one night with the E90 and noticed something similar.

A thing that's really annoying me (before and after the battery removal) is that when I slowly let off the pedal, it will suddenly jerk the car forward. I usually see drive-by-wire doing what you describe - you lift the pedal and the power does not taper off. That annoys me too, but less than a sudden lurch forward as if I had lifted right off the pedal from WOT.

In my 6MT, first gear throttle is very mushy and insensitive. I think that's to help the driver have a smooth start. In the higher gears, the throttle is much more sensitive and it's those gears where I don't feel much difference from 1/2 throttle vs full.

Perhaps your car had adapted to your driving style and lost those settings when you disconnected? Just a stab in the dark...

Well, not sure. I've only had the car since May 1 and I didn't really notice it changing behaviour for me. I did get used to a certain amount of additional pull when squeezing from 50-100% but to be honest I hadn't been using that very much. I was mostly trying to get used to drive-by-wire, CDV (it's coming out as soon as I can arrange a bleeding helper) and drive smoothly. If anything I'd almost expect that it was the PO's adaptations which might have been cleared but....

I guess I'll inspect the connectors and wiring around the pedal module to see if there are any unwelcome add ons. I do really wish that the huge lurch on slow pedal release (even in 4th at 50mph+, this isn't a 1st gear thing) would stop. I'd love to find some stupid add on in there, remove it and have relative throttle bliss.

[Surly73]

Originally Posted by ivan-128i

Well actually I have the BMS PBX(throttle remapping) installed and it was doing great job, but since I had the battery disconnected for 1day I started to notice that weird throttle response which was great before I disconected the battery... I don't understand how this problem is linked to the fact that I disconected the battery, but that's when I started to feel a different throttle response...

Any underlying adaptations in the car itself would have been lost with a 1 day disconnection, I bet. For my disconnection interval I'm not sure that it's a sure thing.

I'm cool with removing adaptations and starting to "train" the car myself instead of having learning from the PO in there, but a reduction in WOT power versus 75% is just kind of weird and didn't sound like adaptation.

The only common maintenance I haven't yet completed since taking ownership of the car is plugs and PS fluid. Parts for both are waiting to be picked up at a friend's place in the US and his trip got delayed so I'll be waiting a couple more weeks for the parts to show up. I have no other planned maintenance/service other than getting a coding cable, changing some coding and possibly reading for shadow codes and resetting all adaptations.

[iv-128i]

I'll be going to BMW tomorrow. Will let you know if they fix it !

[iv-128i]

So I am at BMW right now and the only thing that they can do is a reset....
I'll let you know after if it is any better

[Surly73]

Originally Posted by ivan-128i

So I am at BMW right now and the only thing that they can do is a reset....
I'll let you know after if it is any better

I assume that they mean a "clear adaptations" or something like that?

I was planning to dig into the driver's footwell and the accelerator module yesterday to look for add-ons but something came up with the kids and stopped me just a couple of minutes into the job.

[iv-128i]

So they found out that my radiator fan is dead .... I dont think that it is related to my problem but we'll see...

[davidkotok]

ARE THESE AUTOMATIC TRANSMISSIONS?? if so the ecu probably needs to relearn your driving. theres no way you are experiencing a 50% power loss in a n/a engine after a battery swap...

[Surly73]

Originally Posted by davidkotok

ARE THESE AUTOMATIC TRANSMISSIONS?? if so the ecu probably needs to relearn your driving. theres no way you are experiencing a 50% power loss in a n/a engine after a battery swap...

6MT here.

I didn't say 50% power loss. I said that 50% throttle was stronger acceleration than 100%

[Dirk Diggler]

Surly, so did the dealers fix it up yet?

[tanginaglaz]

I noticed the same symptoms with the 328 loaners that I get. Could've have been a dealer car in its past life and they installed something funky to limit people from beating on their loaners.

[Surly73]

Originally Posted by Dirk Diggler

Surly, so did the dealers fix it up yet?

It's Ivan who had his car at the dealer, not me.

I'm out of factory warranty and DIY. I avoid the dealer like the plague I haven't had time to dig into the pedal wiring to see if there's any aftermarket stuff installed in the pedal circuit.

[iv-128i]

So here is the latest update :
I brought back the car to the dealer and they found out that my fan was not working ... they've ordered the fan to realize that the problem is not the fan but the DME .
So now they've ordered a new DME and I have to wait 2 weeks for it to arrive

[Surly73]

Originally Posted by ivan-128i

So here is the latest update :
I brought back the car to the dealer and they found out that my fan was not working ... they've ordered the fan to realize that the problem is not the fan but the DME .
So now they've ordered a new DME and I have to wait 2 weeks for it to arrive

Yeah....I'm obviously hoping my weirdo issue isn't the DME.