Car runs better after ECU reset

[gibson981]

Car seems to run alot better for a short period (day or two) after the ECU is reset. Less vibration at idle, improved acceleration, etc. If I understand it right, when the ECU is reset, it runs off the stored defaults and then air/fuel is trimmed based on input from the sensors. So I need to find out what is throwing off the mixture...right? Whats the best way to isolate what is causing the problem. I assume I should be looking at the O2 sensor and MAF (tried cleaning it and no change). Thanks.

[bez101]

fault code read ?

[gibson981]

Sorry, should have specified in original post ** no CEL light or fault codes when scanned.

[schmally]

boost or vac leaks!

[gibson981]

boost or vac leaks!

I would expect the opposite to happen as a result of leaks....car would run worse when running off the default setting, then O2 sensor would adjust based on engine running too lean (assuming sensor is working properly) and improve it. I'm going to check for leaks this weekend using the a4mods method and see what I come up with.

[cdn20valve]

check block 032 with vag com, and report back.

[gibson981]

check block 032 with vag com, and report back.

Is there anyway to get this without buying the full version of the software? I have the cable and have been using the VCDS lite, but when I tried to check block 032 it said I needed fullversion.