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-   -   Delayed Throttle Response, (w/ solution) (http://www.bimmerfest.com/forums/showthread.php?t=615898)

TJPark01 04-20-2012 04:52 PM

Delayed Throttle Response, (w/ solution)
 
Delayed Throttle Response, no it's not your imagination.
(Bonus solution @ end of post)
Quote:

Since I picked up our long-term X3 from the South Carolina factory last April, I've noticed an annoying delay in its acceleration. Everyone on staff who's driven it has too, echoing complaints that the X3 accelerates either one of two ways: too slowly or with your head jerking back. We've also seen comments on numerous BMW forums saying the same thing, all stemming from new BMWs equipped with the new eight-speed automatic transmission.
I believe it's a result of programming, not the transmission itself. Even so, a trip to the dealership resulted in an unsatisfactory "operating as designed" prognosis and no change in its behavior. This month, we strapped our test gear to the X3, and took a closer look.

Findings: During low-speed acceleration from rest, like on a stop-sign punctuated residential street, the X3 exhibits repeatable throttle delay and very non-linear acceleration. Applying a normal level of throttle results in essentially zero forward movement for over half a second. Then, it feels like a gear engages, and then normal acceleration begins. While we expect some delay in throttle application (and miss throttle cables dearly), the X3's is noticeably longer and it makes driving smoothly difficult.

How we tested: At our test track, we strapped in a Racepak data recorder that uses accelerometers and GPS information. It is a system primarily designed for drag racing classes like Pro Mod, Pro Stock, and Super Stock; essentially overkill for this test. We then restricted the movement of the gas pedal with tape so the pedal could be treated like an on/off switch, but would be limited to the low-speed acceleration one would experience on a residential street. Doing so eliminated any wavering a foot might do on the throttle; when it's on, it's on completely. We then wired a trigger that would mark the data whenever the throttle was applied. We then simulated stop-and-go residential street driving, doing both complete stops and "California" stops.

Results: The graph above shows one near stop and start. Time is on the X-axis, mph (orange) is on the left Y-axis, and longitudinal (acceleration) g is on the right Y-axis, in green. This shows a "California" stop where the X3 decelerates to 0.6 mph (longitudinal g jumps to 0 when the brake pedal is lifted). At this point, the throttle is applied to its set point -- seen by the white spike -- and the X3 begins to slowly accelerate. After 0.6 second, the acceleration rate increases substantially, evident by the change in mph and longitudinal g, and then normal acceleration begins. Keep in mind that throughout this change in acceleration, the gas pedal input hasn't changed.

This half-second delay phenomenon was evident throughout our testing. In the five-run sample above, there is a noticeable change in acceleration behavior despite an unchanging pedal input. In 10 tests, we saw an average 0.5-second delay from the time that the throttle was applied to the time normal acceleration began, counting the time from the trigger mark to the jump in longitudinal g.
We believe this half-second delay is the culprit of all the complaints. But now that we've found it, we have more questions: Why is it there? One theory suggests that BMW might be trying to curb quick, "jackrabbit" starts to save fueleconomy, but that's just a theory. We also want to know what's causing it. But, most crucially, can we get rid of it?


Solution...

A new software calibration was just released for this engine:
SIB 24 02 12
Subject:
N52T/N55 with 8HP45: Delay in Engine Response
Model
F25 with either N52T or N55 engines and 8HP45 transmission up to 1/16/2012
Situation
When slowing down to lower suburban road speeds and then reaccelerating, a delay in engine response may be experienced
Cause
Unfavorable EGS and DME software calibration
Correction
Program the vehicle using ISTA/P 2.46.0 or higher

CaliRubicon 04-20-2012 08:34 PM

So is this saying that it only effects vehicles built before 1/16/2012?

TJPark01 04-21-2012 06:37 AM

Quote:

Originally Posted by CaliRubicon (Post 6784944)
So is this saying that it only effects vehicles built before 1/16/2012?

that's how I interpret it.

Evlengr 04-23-2012 03:15 AM

Quote:

Originally Posted by TJPark01 (Post 6785295)
that's how I interpret it.

This sounds like a lesser version of the great transmission debacle you can read in the older X3 of 2007 on up. You are correct in presuming it is designed to save gas. I literally have a binder now over an inch thick of affadavits from other owners when I was trying to make BMWNA admit and fix the problem.

I can go on for hours on this, but most drive by wire systems suffer this symptom to one degree or another.

I am betting once Dinan releases the "Chip" for the N55 egine that they currently use in the 335 it will erase this issue completely. I have spoken to Steve and his staff and unlike the earlier X3's engine which was just for the X3 they are going to develop one for this MY as it is used in other BMW paltforms and therefore a good ROI for their reaserch and development.

Thank you for a very definitive perspective on this new car issue with drive by wire acceleration issues. :thumbup:

TJPark01 04-23-2012 06:23 AM

@Evlengr
I don't think this is a transmission issue. It's definitely related to DME programming.

JupiterX3 04-23-2012 07:18 AM

Quote:

Originally Posted by TJPark01 (Post 6788862)
@Evlengr
I don't think this is a transmission issue. It's definitely related to DME programming.

Evlengr doesn't either... I think he was just saying that its a similar situation...

Quote:

Originally Posted by Evlengr (Post 6788717)
This sounds like a lesser version of the great transmission debacle

Personally, I am yet to get home and drive our new X3, but my wife has mentioned the delay. From what Evlengr says, I'm sure trying to get BMW to admit a problem will be tough.. And from what you have said, it sounds like a few 'fixes' will be on the way to release soon... Personally, I would love a Dinan chip upgrade that also takes care of this completely... Either way, thank you to you BOTH for the great info thus far! :thumbup:

lbjgh 04-23-2012 07:34 AM

If BMW doesn't resolve the design flaw a third party might... Check out these guys. http://www.bimmian.com/65/SPB/

jdavid2 04-23-2012 10:13 PM

I know some of you are sceptical, but it looks like the fix for this is out. I had the update installed two weeks ago on my 2011 35i and it has been great so far.

Sent from my Galaxy Nexus using Bimmer App

JupiterX3 04-24-2012 07:53 AM

Quote:

Originally Posted by jdavid2 (Post 6790838)
I know some of you are sceptical, but it looks like the fix for this is out. I had the update installed two weeks ago on my 2011 35i and it has been great so far.

Sent from my Galaxy Nexus using Bimmer App

Please explain... Direct from BMW or from a 3rd party? Did they give reasoning as to the fix?

lbjgh 04-24-2012 09:47 AM

... and there were a bunch of 'skeptics' on this and other forums that recommended that we had to "learn how to drive a BMW" :dunno:

leighton 04-24-2012 11:10 AM

It is not about "skeptics". The point is that you could learn how to drive to compensate for the lag but that doesn't make it go away. There is only one EPA test for each model and year for which BMW wants so set DME programming in a way that they believe will maximize mpg. After the test and the published mpg results BMW has more flexibility to respond to owner complaints. Even though the lag extended through two model years, it ws only 10 calendar months from F25 initial introduction to the production change.

jdavid2 04-24-2012 10:23 PM

Quote:

Originally Posted by JupiterX3 (Post 6791396)
Please explain... Direct from BMW or from a 3rd party? Did they give reasoning as to the fix?

The detailed info on the fix is in the first post. It is a system update that was recently released by BMW and installed by the dealer. You have to bring in your car for warranty work and describe the lag issues that you have when trying to accelerate from a stop or when slowed down almost too a stop.

TJPark01 04-25-2012 06:16 AM

Quote:

Originally Posted by jdavid2 (Post 6793236)
The detailed info on the fix is in the first post. It is a system update that was recently released by BMW and installed by the dealer. You have to bring in your car for warranty work and describe the lag issues that you have when trying to accelerate from a stop or when slowed down almost too a stop.

Correct. You can't just call or walk up and say, hey I need this software update. You have to speak "Service". The service advisers are basically sales and customer service reps, they aren't technicians. So if you go there and ask about SIB 240212, they have no idea WTF you're talking about.
You have to tell them,
"Hello SA, I'm having a delayed throttle issue where, when slowing down to lower speeds and then re-accelerating, a delay in engine response is experienced."
The SA writes down your comments then the tech looks it up in the BMW BatComputer against your VIN. That is where they will see this SIB.

dandanio 04-25-2012 01:31 PM

My 35i was produced in 08/2011. I just sent an email to my service dept. and will report back when done.

AutoUnion 04-25-2012 02:33 PM

I don't understand how BMW seems to be having this problem.

Audi uses the same 8 speed throughout their whole lineup matched up to the 3.0T, 2.0T, 3.0TDI, etc and none of them have any throttle lag at all

lbjgh 04-25-2012 03:17 PM

I suspect the throttle issue was a design flaw. That or BMW intentionally incorporated the delay to artificially inflate the MPG numbers for the regulators. :angel:

Quote:

Originally Posted by AutoUnion (Post 6794761)
I don't understand how BMW seems to be having this problem.

Audi uses the same 8 speed throughout their whole lineup matched up to the 3.0T, 2.0T, 3.0TDI, etc and none of them have any throttle lag at all


datrobmw 04-25-2012 03:49 PM

I'm still confused. I have a new custom ordered 2012 X3 28i that I picked up from the dealer on March 12, 2012. I definitely notice the throttle delay in this vehicle, but from what I've read in this thread the fix should have already been installed. So do I qualify for this programming udpate or not? I guess I'll need to contact BMW Service to be sure.

Dave

TJPark01 04-26-2012 09:25 AM

Quote:

Originally Posted by datrobmw (Post 6794921)
I'm still confused. I have a new custom ordered 2012 X3 28i that I picked up from the dealer on March 12, 2012. I definitely notice the throttle delay in this vehicle, but from what I've read in this thread the fix should have already been installed. So do I qualify for this programming udpate or not? I guess I'll need to contact BMW Service to be sure.

Dave

Depends on your build date not when you picked up the car.
F25 with either N52T or N55 engines and 8HP45 transmission up to 1/16/2012

dandanio 04-30-2012 07:01 PM

Just came home from a 40 miles trip back from work/dealer. I had the work performed and the the jerkiness is all gone. Granted, they removed all the transmission adaptation but even without it the power delivery from dead stop or just a slow rolling stop is buttery smooth and there is NO noticeable lag/throttle hesitation. Good job BMW!

lbjgh 04-30-2012 07:08 PM

:beerchug: for both you and BMW!

Quote:

Originally Posted by dandanio (Post 6805932)
Just came home from a 40 miles trip back from work/dealer. I had the work performed and the the jerkiness is all gone. Granted, they removed all the transmission adaptation but even without it the power delivery from dead stop or just a slow rolling stop is buttery smooth and there is NO noticeable lag/throttle hesitation. Good job BMW!


CaliRubicon 04-30-2012 10:11 PM

I haven't had time to get in to the dealer but would like to know if anyone has taken their x3 built after date in the bulletin in for this service. Defiantly have this problem and would like to know if there is anything the dealers at doing for this. Thanks.

cadman50 05-01-2012 06:15 AM

Quote:

Originally Posted by dandanio (Post 6805932)
Just came home from a 40 miles trip back from work/dealer. I had the work performed and the the jerkiness is all gone. Granted, they removed all the transmission adaptation but even without it the power delivery from dead stop or just a slow rolling stop is buttery smooth and there is NO noticeable lag/throttle hesitation. Good job BMW!

what do you mean by: "Granted, they removed all the transmission adaptation" ?

dandanio 05-01-2012 06:50 AM

Quote:

Originally Posted by cadman50 (Post 6806593)
what do you mean by: "Granted, they removed all the transmission adaptation" ?

Well, your transmission learns your driving patterns and adjusts to your driving style with for example shift points. After this service has been performed, the shifts became a bit on the rough side, signalling that the adaptation was gone. Not a big loss, it should learn again in the next few hundred miles...

lbjgh 05-01-2012 02:16 PM

I've found no reference of that in the manual.

Can you post a link verifying this cybernetic skill? :)

Quote:

Originally Posted by dandanio (Post 6806659)
Well, your transmission learns your driving patterns and adjusts to your driving style with for example shift points. After this service has been performed, the shifts became a bit on the rough side, signalling that the adaptation was gone. Not a big loss, it should learn again in the next few hundred miles...


snowboardjoe 05-01-2012 02:55 PM

Quote:

Originally Posted by lbjgh (Post 6807634)
I've found no reference of that in the manual.

Can you post a link verifying this cybernetic skill? :)

I don't think they spell that out in the manual anymore. My 2003 has the adaptive function as well and was standard on all automatic transmissions. Over time it does adapt to your driving habits (spirited vs. easy going, etc.). Adjustments are pretty subtle over time.

In my first year I had an igniter problem causing multiple cylinder misfires. I limped into the BMW to fix the problem. To get there I had to apply a lot more gas to get reasonable acceleration. After I picked up the car the automatic was completely out of adjustment with the restoral of normal engine power. It was quite jerky the first 5 miles and then it adjusted itself to more normal shift points and throttle response. Took several days before it was back to normal. Disconnecting the battery for a few minutes would have reset this back to factory defaults and made things smoother.

Trust me, it's there. :) I think they called it Adaptive Automatic Transmission. I'll see if it's in my old manual.


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