[Biturbos4] Throttle position sensor problem

Grant Lenahan glenahan at vfemail.net
Sun Oct 26 14:30:29 PDT 2008

For the record, i used gummout carb cleaner which is much safer ( i  

As a lubricant, WD40 is pretty bad. never intended to be a lubricant,  
it was developed as a water displacement agent in a light evaporating  
oil carrier. Hence its designation, "WD". I'd prefer something like  
super lube.

Has anyone considered the virtue of "dry" lubricants that will not  
contribute to sludgy buildup?  Several companies sell aerosol dry  
lubes.... just wondering.

On Oct 26, 2008, at 4:24 PM, Tony Hoffman wrote:

> Richard,
> I've also dealt with this on customer cars, but never a v6tt. I've had
> to clean the TB's on the 1.8T's and the 30V 2.8 and 3.0's. Do it just
> like Grant described. I use Brake parts cleaner, then WD for a
> lubricant. However, if you use brake parts cleaner, be very careful
> where you spray it. i can melt/eat certain sorts of plastic. Only
> allow it inside the throttle body itself.
> Tony
> On Sun, Oct 26, 2008 at 10:17 AM, Grant Lenahan  
> <glenahan at vfemail.net> wrote:
>> BTDT on my 2000 S4.
>> here's what I found.
>> The typical fault you will get is called "epc" and a light should
>> come.  epc is electronic pedal contgrol, or drive by wire.
>> When a fault in the fly by sire system is detected the system goes
>> into limp mode, which you experienced. It was happening to me every
>> day. It resets with an ignition cycle.
>> What i found is that the throttle butterfly, which is controlled by a
>> stepper motor, slowly builds up crud inside the TB, much like an old
>> carbon composition potentiometer in a hifi. I posited that thsi was
>> the case, and tried the same old cure:
>> 1. clean with carb cleaner by spraying inside the TB
>> 2. loosen/clean the TB inside by exercising the butterfly completely
>> through its angle of motion, several times, quickly. This creates a
>> wiping action.
>> It worked.
>> You can infer that one of the problems I had run into was that teh S4
>> basically had too much power for normal driving, and i almost never
>> went WOT.  So junk built up.  Its another case of cars must be driven
>> as intended, at least occasionally.
>> Hope this helps,
>> Grant

Grant Lenahan
glenahan at vfemail.net
(201) 602-4702 mobile

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