I have already posted this in the computer and diagnostic forum a couple of days ago and had no responces just wondering if someone can help out thanks in advance.
I am a new user to autotap and data loging in general. I am trying to figure out if I have a sensor going bad also want to make sure I have a good tune. I am currently getting only 12 to 13 MPG 70% highway 30% city with just a baby hotcam while my buddy has a 224/230 XE cam and gets 17 almost all city driving. I am wondering about my o2 sensors and IAC as far as I know the O2 sensors have not been changed, and the IAC I just cleaned 2 weeks ago cause of an chasing idle going from park to reverse to drive, it did not help. If someone wants to look at my log and tell me what you think I can Email the files. Some questions I have are, can data logging tell me if O2's are going bad if so what do you look for? Also, I have suspected that the IAC needs replaced. Could that cause a drop in MPG if it was bad? Some info about the car not in my sig. plugs and wires changed about 3 months ago new MSD coil just added, and just turned 98000 miles today I drive this car daily and I am very easy on it 95% of the time. So if anyone has any sugestions post away.

 

The iac should control idle quality, if iits bad, your pcm would have a hard time maintaining the idle at the speed its set at (I think).

When you data log, you should be able to see the O2 sensor voltage for the left and right sensors (I think you have like 3 or something, left, right pre cat and right post cat - somebody can chime in on this). After a few mins when the car goes into closed loop, the numbers shoudl be all over the place (dancing) from 0.100 volts up to 0.9xx volts and everything in between. If you're o2 sensors are stuck at 1 or 2 voltages after the car has warmed up and switched to closed loop, you have a bad sensor.

 

well should the the O2's be replaced after 98,000 miles?

 

Yes, it's time.

 

Thanks shoebox I will order some tonight.