[Biturbos4] HELP!!! Troubleshooting DTCs w/ EPC light
adlere at sourcecodecorp.com
Sun Nov 28 10:07:19 EST 2004
Two things - fuel trim codes can indicate a bad MAF. One thing to try is
to unplug the MAF and see if the car drives better. Secondly, I believe
B1 is the passenger side - I have a B1 S1 sensor on its way out so I
have done some research on the issue. Still, consult a more qualified
source before yanking parts. I would also check the o2 and egt wiring,
as was already mentioned. You seem to have a lot of codes from the rear
of the engine so maybe they'res some damage back there.
> Ahh, something I have some experience with ( I was about to write
> "know something about, but that may be overstating the case a bit....).
> Let's start with EPC and what it is. EPC is "electronic pedal
> control". The 00+ S4s are "fly by wire" cars which transmit pedal
> angle (from a sensor) to a throttle body stepping motor which in turn
> controls the butterfly angle and opening. The EPC light indicates
> that your problem is within this system. I've had the same gremlin
> and, at least, had the "pleasure" of chasing lots of false problems.
> Given the above, I'd speculate that a large number of your codes (all
> the O2 and mixture stuff) are related to a different problem (probably
> O2 sensor). But the last code:
>> "17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
>> P1171 - 35-10 - - - Intermittent"
> Is exactly the one that I got (and occasionally continue to get).
> What it means is that the sensor sends back a butterfly angle that
> seems impossible given the throttle position, load, etc. It can
> actually be either the pedal sensor or the throttle motor. I never
> found out *for sure* the source of the problem, but I'd bet heavily on
> the following culprit, and I bet it will affect all of us sooner or
> The scenario:
> The throttle body is dirty. The butterfly, as it wipes back and
> forth, slowly builds up a ridge of dirt in the throttle body, which
> the butterfly subsequently "catches" on - either in the forward or
> reverse direction. I speculate ( as does on of Audi's regional
> training techs) that this is partially caused by a limited throttle
> angle in normal driving. (e.g.: the car is very powerful and/or I'm a
> wussy). If the butterfly rarely gets past this point, a ridge of
> fairly hard dirt builds up and you're on your way to trouble. I got
> to the point where this happened daily, or at least weekly.
> A new TB, Audi's suggestion (gee, thanks Audi) was $1000 + install,
> which made me hesitate and figure all the above out. I did talk to
> several audi techs, but the only real proof I have is that I made the
> problem go away on my car and one other.
> The solution has two parts:
> 1) Move the butterfly through its motion several times. In general,
> you get to have fun doing this part (yes, I mean go out and stomp on
> it - but the goal is butterfly motion, not engine revving, so high
> loads at low revs are actually best). Make sure you move the
> butterfly through its motion and back several times, and do this on
> occasion just to keep it "swept out".
> 2) If you can, get some gummout into the TB and clean it. The trouble
> here is getting access to the TB. You need to remove the two snorkels
> that come up from he intercoolers, and one of them is a bear to get
> out, due to a snap-fit in a plastic track. I'd hate to break
> something in there (maybe have your local, friendly garage do it). If
> you decide to do it, you might look at the "throttle body boot
> replacement" instructions posted on the tech part of AudiWorld as a
> sort-of guide to removal.
> I've had one recurrence after ~ a year, whcih was quickly exorcized by
> a deep exploration of pedal travel later that day. Feel free to email
> me with questions, and don't panic. Very likely its not $1000, but
> rather 2 hours, gummout, and a heavy right foot.
> On Nov 27, 2004, at 9:39 PM, Adam Jansen wrote:
>> As I was driving over the Cascades to visit family for the holiday,
>> the EPC light comes on the the power cuts out (not fun coming up
>> Snoqualmie Pass!)
>> I dont have my Bently or family albumn with me, but luckily I did
>> have the laptop and pulled these codes:
>> 17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit
>> P1118 - 35-00 - -
>> 17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
>> P1114 - 35-00 - -
>> 16524 - Oxygen (Lambda) Sensor B1 S2: No Activity
>> P0140 - 35-00 - -
>> 17866 - Exhaust Gas Temp Sensor 2 (G236): Short to Ground
>> P1458 - 35-10 - - - Intermittent
>> 17536 - Fuel Trim: Bank 1 (Mult): System too Lean
>> P1128 - 35-00 - -
>> 17538 - Fuel Trim: Bank 2 (Mult): System too Lean
>> P1130 - 35-00 - -
>> 17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
>> P1171 - 35-10 - - - Intermittent
>> I am replacing the O2 sensor in the morning (driver's side rear
>> correct?) but I am worried about the Throttle Actuator and the System
>> running lean!
>> I stopped when the light came on and then started off again as the
>> light turned off... it seems that the EPC light with the above codes
>> (expect the O2 sensors readings) come on only after the engine has
>> been running on the highway for 30-45 mins, which just adds to the
>> frustration of trying to fix it!
>> ANY help would be appreciated!
>> 00 S4
>> Spokane, WA but current stuck in Olympia and hesitant to crawl over
>> the cascades under limited power
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>> Biturbos4 at www.audifans.com
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