2003 Audi A6 2.7t with a mild performance tune.
The tune is designed to increase the boost pressure and increase timing/fuel to match, increasing the power by ~60hp. It is doing just that, but for some reason it thinks it is always running rich (at idle and under load). I did post about this a while ago, but I have new info now and am hoping someone can solve the mystery.
I had sent the ECU back to the tuner so he could reporgram again and rule out human error, and it came back with the same problems. So I believe the tune is good.
I can drive the car about 10-15 miles before it hits the max of how much fuel it can pull, and then it sets the CEL and power is reduced but not into a limp mode failsafe. It actually drives about the same as it did without the tune, which is still pretty good.
I've done the simple things like check the coils, replace the plugs with stock, replace the plugs with one heat range colder, and run diagnostic tests on the MAF and EGT sensors. The MAF and EGT readings are just where they should be for the tune. I even unplugged the MAF and ran without it last night and it seems that it would get to the maximum much faster than before, after about 3-5 miles. I don't know if that means that it's on its way out or not.
The strange thing is that the two sets of plugs I pulled out were not black and/or fouled, so I'm not convinced that it is really running rich. I monitored the O2 operations, and the voltage bounces around between 0.89v and 0.11v and the short term fuel trim is always trying to pull fuel.
Anyone have any other ideas for what I can check besides what I've already done? The O2 sensors are somewhat easy to get at, so I could replace them if need be but they are pricy so I'd like to do that only if they are the problem.
Thanks in advance.
The tune is designed to increase the boost pressure and increase timing/fuel to match, increasing the power by ~60hp. It is doing just that, but for some reason it thinks it is always running rich (at idle and under load). I did post about this a while ago, but I have new info now and am hoping someone can solve the mystery.
I had sent the ECU back to the tuner so he could reporgram again and rule out human error, and it came back with the same problems. So I believe the tune is good.
I can drive the car about 10-15 miles before it hits the max of how much fuel it can pull, and then it sets the CEL and power is reduced but not into a limp mode failsafe. It actually drives about the same as it did without the tune, which is still pretty good.
I've done the simple things like check the coils, replace the plugs with stock, replace the plugs with one heat range colder, and run diagnostic tests on the MAF and EGT sensors. The MAF and EGT readings are just where they should be for the tune. I even unplugged the MAF and ran without it last night and it seems that it would get to the maximum much faster than before, after about 3-5 miles. I don't know if that means that it's on its way out or not.
The strange thing is that the two sets of plugs I pulled out were not black and/or fouled, so I'm not convinced that it is really running rich. I monitored the O2 operations, and the voltage bounces around between 0.89v and 0.11v and the short term fuel trim is always trying to pull fuel.
Anyone have any other ideas for what I can check besides what I've already done? The O2 sensors are somewhat easy to get at, so I could replace them if need be but they are pricy so I'd like to do that only if they are the problem.
Thanks in advance.
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