View Full Version : C5 A4 Idle tuning issues- TOO RICH

09-28-2005, 01:13 AM
Back in august on a trip out to michigan I burned up a O2 sensor. I got if fixed but the car still wasn't running right. When I got home and went to park the car, my low oil level light came on. Reset the light and it went away. After this point the car has not been the same.
I came to find out after replacing my sensor and connector( oil level sensor) that the wires had been burnt completely threw by the header. So I got them free and soldered good wires in between and heat shrinked the new connection.Then tucked the group of wires far away from the headers. I also replaced both O2 sensors with brand new AC Delco sensors.
I've yet to be able to get the car to run like it did before these two issues. I've added a ported TB and it only seems like it has worsened the issue. Opon start-up the cars IPW's are around 6-7ms, once into closed loop they come down to around 3.1ms, yet my LTFT's are negative 18 and my STFT's go negative and max out then kick off and start over to then max out again negatively. After the ported TB installed after a few minutes of driving the car dips way lean it seems and starts boggin on all the extra fuel its dumping. If I get on the throttle a little it clears out and everything is fine.

My VE tables from 0-2000 have been modifed many times to try to help lean out the idle, but it never seems to get better. Hopefully someone has some

Tonight we attempting to decrease the MAF freq. by 10% and once flashed into the car it would not go into closed loop. That was the only change between flashes, is there a reason for this?

The car is a 99 A4 C5,
TSP 233/239 cam
LS6 manifold
160 tstat
vararam intake
LG headers
3.90 gears

Thats the main mods, like i said before the weird fried O2 sensor, and oil level sensor everything was great. I'm swapping out the AC delco O2's for Bosch 13111 sensors this week and we'll be attempting to tune more this weekend, any direction would be great.



09-28-2005, 12:32 PM


Ragtop 99
09-28-2005, 01:29 PM
If the O2's don't work and you correctly fixed the wires, disconnect your MAF and run the car. If it is way rich and you have fixed the VE tables, it must think more air is getting in than really is.
Are your MAP readings normal?
Did you look at all the plugs to see if one cylinder wasn't firing?

Did you look for a leak in front of your O2 sensors or in the O2 sensor bungs? This normally causes a lean condition but is worth checking while you are it.

09-28-2005, 02:03 PM
Dunno what happened to my post, but...

Look at your O2 voltage waveforms and see whether
they look like "sleepy" or "happy":