Remote diagnosis: Try your hand!

sligh93 · 05-23-2005, 03:25 PM

This is an emissions issue. One that I thought I had rectified two years ago but has reared its head again.

Two years ago: The S4 failed the HC test at idle, passing everything else. It was determined (somehow) that the issue was an exhaust leak, failed cat or both. In any case, I replaced the center section of the Stromung and the emissions issue went away.

Fast foward to present: The S4 failed both the HC idle and HC 2500rpm test, passing everything else. It seems to me that the problem that caused the initial emissions failure wasnt solved, or was solved temporarily but replacing the cat section.
(FYI, idle limit: 125 idle measured: 320, 2500 limit: 125 2500 measured 300)

Now, from what i understand of an HC failure, too much unburned fuel is exiting the engine. This is most commonly caused by a misfire yet none is detected. Not only that, the mileage has been a steady 19-20mpg (mostly highway). Prior to the emissions test, the plugs had been recently replaced as have the boots, the fuel filter, and the oil has recently been changed (amsoil 5w-40).

Whats left?

Wont a fouled O2 sensor reflect in the mileage?

If my cat is fouled again, what fouled it in the first place?

Any ideas, thoughts, BTDT's welcomed

Sandy

Julian_B · 05-23-2005, 03:42 PM

In class, one of my teachers caused a missfire on a toyota camry and told us to look at the cat. It was glowing red.

sligh93 · 05-23-2005, 03:47 PM

So, what i want to find out is what could cause improper fuel metering at idle... is that ONLY the O2 sensor?

4Driver4 · 05-23-2005, 03:50 PM

High HC is often the result of dirty oil. Change oil just prior to testing.

Whose software are you running?

sligh93 · 05-23-2005, 03:59 PM

26psi Bob Pastore brand.

The oil is less that 500 miles old AMSOIL 5w-40.

05-23-2005, 03:42 PM	#2
Julian_B Junior Member Garage is empty, add now Join Date: Dec 2002 Posts: 2,653	Unburned fuel will damage the cat.... In class, one of my teachers caused a missfire on a toyota camry and told us to look at the cat. It was glowing red. __________________ **RIP Bill Perron** You wont be forgotten... 1995.5 UrS6 EPL stg.1(beta) w/ stiffer WG spring, FMIC,Stromung 3" exhaust, Hyperboost BPV, Eibach springs, Bilstein shocks, K&N panel filter, Clear corners, McCulloch 5300k HIDs, S6 Plus Tails, CF trim, more mods to come... 1993 90S Dark green,ABT 17x8 A-11 wheels(FOR SALE), 17x7 ADR DV-8 wheels(FOR SALE), Mance's XTB,Home Brew S3 hose Kit, APR snub mount, Billzcat1 SS, B&G springs, Bilstein sport shocks, Intense Performance cone, custom 2.5" exhaust, Catco hight-flow cats, Magnaflow resonator, 8mm Beru ignition wires, lightened flywheel, Sachs clutch kit,UUC Rocknob II, RS2 grille and badges, RS2 Headlights. retired =*( email: julco16@hotmail.com AIM:julco12345 -Keep your GF away from Dubbers from Vortex, they will try and steal her...=/

05-23-2005, 03:47 PM	#3
sligh93 Audiworld Junior Member Garage is empty, add now Join Date: Mar 2003 Posts: 96	Re: Unburned fuel will damage the cat.... So, what i want to find out is what could cause improper fuel metering at idle... is that ONLY the O2 sensor? __________________ 1992 S4 (1993 Canadian model year) RS2: Comp Turbo, MAF, EM, FIs 26lbs Pastore software Stratmosphere bypass Eibach/Bilstein 996tt calipers over 993tt rotors Stromung 3" D585 coil upgrade - awesome 17x8.5 SSR Comps w Eagle F1s

05-23-2005, 03:50 PM	#4
4Driver4 Tech Guru Garage is empty, add now Join Date: Oct 2002 Posts: 32,394	Step one: pull codes. High HC is often the result of dirty oil. Change oil just prior to testing. Whose software are you running? __________________ 4Driver4 Growing old is mandatory; growing up is optional. 2005 A6 Sedan Q 3.2 (wife's whip) 2000 A4 Avant Q 2.8 (daily driver) 1980 VW Scirocco (mid-life crisis car) 1983 Mazda RX-7 (revolutionary sports car) 2003 Mini Cooper S (just because) 1995 Mazda Miata, Superdupercharged(anti-Audi) 1999 Mazda Miata SSB (track beotch, no plate) 2003 GMC Yukon Denali XL (the anti-earth) 2004 Dodge Dakota (hey, at least it's stick and 4x4)

05-23-2005, 03:59 PM	#5
sligh93 Audiworld Junior Member Garage is empty, add now Join Date: Mar 2003 Posts: 96	Re: Step one: pull codes. 26psi Bob Pastore brand. The oil is less that 500 miles old AMSOIL 5w-40. __________________ 1992 S4 (1993 Canadian model year) RS2: Comp Turbo, MAF, EM, FIs 26lbs Pastore software Stratmosphere bypass Eibach/Bilstein 996tt calipers over 993tt rotors Stromung 3" D585 coil upgrade - awesome 17x8.5 SSR Comps w Eagle F1s

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