AEM Air/Fuel 30-0300 gauge reading 15.8-16.4 @ idle

[cbehr]

Hello,

I just installed a new AEM 30-0300 A/F gauge and it seems to be reading a bit lean at idle? I'm about to work on a customer tune with 04Sleeper but want to make sure the readings are squared away so I'm not wasting his time through the process. 03 Cobra w/ 2.7" upper pulley, idler set, exhaust & intake.

I had the bung welded about 18" downstream of the factory headers at a slight angle as instructions state. This model is not supposed to need a calibration but does have an open to open air calibrate. I'm thinking perhaps:

- Open air calibration
- Exhaust leak on Mac H pipe to factory header although the driver side does not have a gasket, just the flange where if it's tightened proper I'd think there wouldn't be an exhaust leak. Not sure how to check for exhaust leak other than just loosening bolts and re-tightening. Bung appears to be fully welded with no gaps for air.
- factory tune it just lean at idle?

Any ideas or suggestions?

Chris

 

[MG0h3]

Pull it out and calibrate and report back before doing anything.


Sent from my iPhone using svtperformance.com

 

[01yellercobra]

If there's an exhaust leak you can usually see black soot around the joint. Some of the pipes have a small cone that fits inside to seal better on the driver side. Are you running the X series gauge?

 

[cbehr]

If there's an exhaust leak you can usually see black soot around the joint. Some of the pipes have a small cone that fits inside to seal better on the driver side. Are you running the X series gauge?

I'll look under tonight but I put a used H-Pipe in the same time as the gauge and only have 10 minutes of run time, it may be hard to see soot around the joint at this point?

It is the X-Series yes.

 

[01yellercobra]

It'll show up quick. I have a leak on my passenger side and it shows up in my wideband readings.

The instructions I found online mention a free air calibration. Do that as mentioned and see how it reads afterwards.

 

[cbehr]

I pulled the sensor and did a fresh air calibration. On startup it was mid 15's then dropped more to the 13's after idle settled down. However after 10-20 seconds it creeped back up to high 15's low 16's. I looked at the connection between the header & H-pipe and didn't see any soot but it's hard to see up there and only can see about 2/3 of the way around the pipe. I'll try to loosen and re-tighten the bolts tonight, was too hot to work on last night.

I should also note that the h-pipe I installed is catless and for whatever reason the option to turn off rear 02 sensors is all of sudden missing from my sct livewire ts? could the rear 02 sensors be causing an problem?

 

[01yellercobra]

They got rid of the option to turn off the rear O2's because of the EPA. They won't cause an issue. If you can datalog it's worth checking what the STFT's are doing. You might also have a vacuum leak that's affecting it.

 

[cbehr]

So I figured out at least one problem. Stuck the ole shop vac up the tail pipe and found a decent air leak at the h-pipe to header driver side flange. After numerous attempts to realign and torque down I can’t get the leak sealed...is there any sort of gasket I can use or what do I do?

 

[olympic]

Take out the H pipe and check if the flange is bent somehow, then clean both surfaces with a wire wheel. Run a bead of Permatex Ultra Copper RTV around the flange before re-assembling.

 

[SVT_Nthn]

for reference, i run a 14.6/14.7 on idle (intake and catless exhaust i think) just got the car so not sure on the tune. hopefully gonna get it retuned soon