CalG

Yes, I agree with your position.

At this moment I question the exact timing of the status display offered via the VAG-COM software. The most recent Block 7 and block 9 (engine load and throttle pos.)log has many illogical data points. aquisition rate perhaps

I have tried to minimalize trailing throttle conditions, although that is significant in driving the local hilly landscape.



In a private correspondence with Gabor, the idea of a NEW valve body in effort to dispel the mystery has been considered.

This may be something I will try in pursuit of Knowledge.

Regards

CalG

CalG

Any recommendations on a creditable source for a Good" VB.

Certainly paying "extra" is not a noble act ;-)

I'm on this page

CalG

CrazyINP-12V Ivan

Sorry but where can I read about the hunting ? now how can I check that with my S8

skiwi

"Infineon Technologies AG aims to broaden its automotive reach by entering the transmission side of powertrain applications. The German chipmaker, which already has a presence in engine controllers, hopes increased growth in six-speed transmissions will create an opening for its expanded focus. Though some manufacturers have already adopted six-speed automatic transmissions, the company is among those who expect far more growth in the near term.

"Some observers predict that the drive for fuel economy will prompt U.S. car makers to shift to six-speed automatic transmissions, which offer from 3 to 8% better mileage than four-speeds," said Chris Wunderlich, Senior Staff Applications Engineer at Infineon Automotive Microcontrollers' Automotive, Industrial and Multimarket (AIM) Business Group.

That means transmissions will need more than the 4-6 solenoids to help control fluid flow so the clutches work properly. "In six-speeds, you need one PWM and as many as seven constant current of variable force solenoids," said Joe Funyak, Infineon's Global Product Marketing Manager for Transmission ICs (integrated circuits).

That in turn creates a need for more microcontrollers. Those controllers must provide far more precise control of the fluid flow. "For four-speeds, you don't care about accuracy, it's more on and off," said Shawn Williams, AIM Senior Staff Engineer, Automotive. Resolution of around 5% used to meet all requirements, but six-speeds require at least 2%, he added.

Infineon's TriCore line is being upgraded to address this market. In addition to providing speed and high resolution, the line is being augmented with more channels. That lets transmission engineers use a single processor to control many PWMs or variable-force solenoids, reducing parts counts.

The controller comes in plastic packages that can be mounted on or near the transmission as well as on a bare die that can be packaged for use inside the transmission casing. Infineon also offers switches and other devices that augment the controllers.

tozoM8

<ul><li><a href="http://www.levelten.com/">http://www.levelten.com/</a</li></ul>

gtreng1

...I was told I needed a fluid change, did the change, shutter decreased but still occurs (at higher rpm now) They must be related somehow.

gtreng1

would do something if we have 100 signatures or so or more.

gtreng1

Calling all A8/S8 doctors! Acceleration mystery
Posted by: SteveIAS8 on 2006-09-16 07:31:40
Account #: 22450



The "patient:" 2001 S8

"Vitals:" 76k miles, 100% compliance of service intervals. Plugs last changed at 40k. NEW transmission at 40k (i bought car at 38k.. Audi replaced tranny under warranty.)

"Symptom:" Car runs perfectly fine, except for one condition.... Under moderate to heavy acceleration, as the tach sweeps through the 3000-4500 rpm band (with CONSISTENT and STEADY throttle position), i experience hesitations or surges, then it returns to smmooth normal operation past 4500 rpm.

It is quite noticeable in 3rd and 4th gear. i assume it happens in all gears, however the car revs too quickly through the band in 1st and 2nd gears to get the full effect, and 4500 rpm in fifth is a little bit "fast" on the highways.

The car idles fine, acceleration is normal under 3000 rpm, no transmission thumps of any kind, no tranny hunting...

The dealer is also stumped (and they are a "very good" service department---a breath of fresh air...)- i had a tech road test with me- he noticed it as well, and had his "computer" hooked up to the car to read the car as we were driving it...

Your thoughts, doctors.... Mass airflow sensor? Plugs? Fuel filter? Fuel pump?

Thanks for your thoughts....

tozoM8

variable length intake. It sounds like it was switching over too slow.

ryoung

Depending on rpm, the S8 switches between three different intake manifold lengths. Check that the vacuum lines to those two diaphram valves in front of the intake manifold are in good condition. With the motor not running, you should also be able to move the valves easily and smoothly by hand. I believe the A8 switches between only two <a href="https://forums.audiworld.com/a8/msgs/79585.phtml">Intake Manifold Lengths</a>.

<img src="http://www.vboston.net/a8_engine/images/a8_engine_05.jpg">