Sporadic Air/Fuel Ratio.

[94'TSI'AWD]

Hello I installed my AEM Uego A/F gauge today and upon starting the car the A/F ratio was jumping between 13.0 and 15.0 after driving it for a while it became more sporadic jumping everywere and sometimes even so far rich/lean it couldn't even process it on the gauge. As I come to an idle after driving it is registering super lean at 17.0 - 17.5. Could I have had the 02 Bung installed too close to the turbo? I had it welded right in between the motor and firewall on the downpipe. Are they normally quite sporadic on an untuned V3 ecu? Mods are in profile. And for basic fuel tuning as par adding more fuel for idle do I tune with a cold sensor or warmed up sensor? (Due to the fact of the difference in A/F at idle before and after driving) Thanks!

 

[EvoRage]

What was it reading while you were driving? During idle it can possibly jump around but what really really matters is what it's doing while you are in gear and driving. Just cruising around you should be close to 14.7, under throttle you should be seeing lower numbers hopefully around 12, if you are seeing higher you should take it easy until you tune it.

 

[94'TSI'AWD]

What was it reading while you were driving? During idle it can possibly jump around but what really really matters is what it's doing while you are in gear and driving. Just cruising around you should be close to 14.7, under throttle you should be seeing lower numbers hopefully around 12, if you are seeing higher you should take it easy until you tune it.

But what would cause the drastic difference in A/F from the idle before and after driving it?

 

[EvoRage]

Because it's up to running temp. And you want to tune your car with everything up to temp.