To anyone with potential Rich or Lean conditions read this!!!

SlvrBullet Unloaded · 06-06-2002, 07:29 PM

as many of you know i have removed my mass air meter and use a programmable fuel computer for my fuel curve. Now I have the thing tuned in pretty damn well but about 2 weeks ago i started getting dark soot in my tail pipe...I looked at my fuel program as well as doing diagnostics w vag tool, yeah the car was running richer(data block 1) than normal by 5-7% but no check engine lights and also no DTC's, turns out it was the coolant temp sensor, audi has superseded this sensor with a new part #. Only $5 and 5 minutes and the car was back to being perfect! Guys although the damn mass air meter sucks A$$(in 2000 S4's)the coolant temp sensor can also cause fueling fluctuations without giving you much of a heads up! these rich conditions can lead to cat as well as O2 sensor fouling and failure and can put the car in failsafe mode further heightening the already rich conditions!

***things to look for***
1) erratic coolant temps on your gauge
2) high or low coolant temps on vag tool (data block 1) especially on cold start up(I believe the default value is 189 degrees for the sensor but this will not show up on your instrument cluster gauge)
3)too high or too low fuel trim(data block 1) I believe anything +/- 10% under idle and part throttle is a red flag!(if you have this and its not the coolant temp sensor you can also look at mass air levels at idle(i believe 4.8-6.3 g/sec is a good range**its been a while since i had a mass air**(data block 2) and also make sure your primary O2 sensors are trying to maintain stoichiometry(sorry i dont remember the data block)

BaysideRS4 · 06-06-2002, 07:31 PM

KAOS, AZ (Papa Smurf) · 06-06-2002, 07:37 PM

Sounds like some good news. Hope to meet up with you guys this summer out on the east coast.

SlvrBullet Unloaded · 06-06-2002, 07:45 PM

SlvrBullet Unloaded · 06-06-2002, 07:46 PM

anyway i cured the problem the very day of the "GAS INCIDENT"

Nick Gustas · 06-06-2002, 07:47 PM

-15F indicated coolant temp whens it's really 100F out is bad

DarinS4Turbo · 06-06-2002, 07:50 PM

SlvrBullet Unloaded · 06-06-2002, 07:54 PM

This little bugger is tricky to figure out as the sensor will give Vag/ecu a default value rather than tripping a code!

Nick Gustas · 06-06-2002, 08:03 PM

Normally the temp data was fine but if I watched it with a vag it would suddenly dip way down, and my power would drop, then it would snap back up and everything felt fine. I got stranded a few days later since I was going to wait till the weekend to replace it. I drove straight to the dealer to buy the sensor after that. :/ not fun.

LCP · 06-06-2002, 08:39 PM

...it took a few trips to the dealer and the condition worsening before it was diagnosed and replaced. I wonder if I got the revised part? <90 second delay while I look for my receipt> Sure enough, back in Nov. 2000, that is the part number I got!

06-06-2002, 07:29 PM	#1
SlvrBullet Unloaded Member Account #: 2711 Join Date: Mar 2000 Posts: 3,175	To anyone with potential Rich or Lean conditions read this!!! as many of you know i have removed my mass air meter and use a programmable fuel computer for my fuel curve. Now I have the thing tuned in pretty damn well but about 2 weeks ago i started getting dark soot in my tail pipe...I looked at my fuel program as well as doing diagnostics w vag tool, yeah the car was running richer(data block 1) than normal by 5-7% but no check engine lights and also no DTC's, turns out it was the coolant temp sensor, audi has superseded this sensor with a new part #. Only $5 and 5 minutes and the car was back to being perfect! Guys although the damn mass air meter sucks A$$(in 2000 S4's)the coolant temp sensor can also cause fueling fluctuations without giving you much of a heads up! these rich conditions can lead to cat as well as O2 sensor fouling and failure and can put the car in failsafe mode further heightening the already rich conditions! *things to look for* 1) erratic coolant temps on your gauge 2) high or low coolant temps on vag tool (data block 1) especially on cold start up(I believe the default value is 189 degrees for the sensor but this will not show up on your instrument cluster gauge) 3)too high or too low fuel trim(data block 1) I believe anything +/- 10% under idle and part throttle is a red flag!(if you have this and its not the coolant temp sensor you can also look at mass air levels at idle(i believe 4.8-6.3 g/sec is a good rangeits been a while since i had a mass air(data block 2) and also make sure your primary O2 sensors are trying to maintain stoichiometry(sorry i dont remember the data block)

06-06-2002, 07:31 PM	#2
BaysideRS4 Member Account #: 10509 Join Date: Sep 2000 Posts: 4,589	have the part numbers handy? __________________ ----------

06-06-2002, 07:37 PM	#3
KAOS, AZ (Papa Smurf) Member Account #: 1134 Join Date: Mar 2000 Posts: 3,237	And here I thought that piss gas you putin the car did it :P Sounds like some good news. Hope to meet up with you guys this summer out on the east coast. __________________ EVERYTHING POSTED HERE BY ME IS OF PERSONAL OPINION

06-06-2002, 07:45 PM	#4
SlvrBullet Unloaded Member Account #: 2711 Join Date: Mar 2000 Posts: 3,175	sensor-059-919-501A $3.85/O ring-N 903-168-02 $1.10

06-06-2002, 07:46 PM	#5
SlvrBullet Unloaded Member Account #: 2711 Join Date: Mar 2000 Posts: 3,175	That crap is finally out of my tank---BOOST BABY! anyway i cured the problem the very day of the "GAS INCIDENT"

06-06-2002, 07:47 PM	#6
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	If it's bad enough it can leave you stranded for a few minutes with a flooded car. -15F indicated coolant temp whens it's really 100F out is bad

06-06-2002, 07:50 PM	#7
DarinS4Turbo AudiWorld Senior Member Account #: 16111 Join Date: Feb 2001 Posts: 2,174	Yeah, constant warm-up (rich) mode = burned out cats, washed out cylinder walls, etc. Eek

06-06-2002, 07:54 PM	#8
SlvrBullet Unloaded Member Account #: 2711 Join Date: Mar 2000 Posts: 3,175	cold start is where most of the potential problems occur... This little bugger is tricky to figure out as the sensor will give Vag/ecu a default value rather than tripping a code!

06-06-2002, 08:03 PM	#9
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	In my case power was inconsistant from moment to moment, and I had a few implausable temp faults Normally the temp data was fine but if I watched it with a vag it would suddenly dip way down, and my power would drop, then it would snap back up and everything felt fine. I got stranded a few days later since I was going to wait till the weekend to replace it. I drove straight to the dealer to buy the sensor after that. :/ not fun.

06-06-2002, 08:39 PM	#10
LCP AudiWorld Expert Account #: 125 Join Date: Mar 2000 Posts: 26,557	Mine went south over a year ago... ...it took a few trips to the dealer and the condition worsening before it was diagnosed and replaced. I wonder if I got the revised part? <90 second delay while I look for my receipt> Sure enough, back in Nov. 2000, that is the part number I got! __________________ "I can't stop apexing" 2000 S4 :: Nogaro Blue :: 6-spd :: AWE RSK04 :: AP Racing 13" 4-pots STaSIS Tracksports 550f/600r + 19mm rear sway bar :: APR Bipipe RS4 ICs :: Forge BPVs :: Autospeed DPs :: Borla :: Aquamist 1s UUC 40% short shifter w/spacer mod :: AWE center vent boost guage Lightweight flywheel :: 18x8 Ronal LZ's :: 235/40-18 Toyo T1R's 2002 allroad :: Atlas Grey :: Tip :: 245/50-17 Dunlop SP5000's Looking for tires? See My review of all of the tires I've had on my S4 Need info? See Everything anyone needs to know about their S4 Help our troops protect their heads: Donate to Operation Helmet Rest In Peace Matthew Ammon a/k/a O.W. Kenobi. May the Force be with you as you keep on apexing. Read his funniest post here.

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