Test!
http://www.dsmtuners.com/forums/newbie-forum/334225-testing-o2-sensor.html

Did it suddenly do this or ever since you installed it? Putting the sensor in the rear O2 spot won't effect A/F ratio reading, it's just thought to produce a "lag" between what the A/F ratios are in the engine versus in the pipe.

Mine did that until I fixed my little exhaust leaks.

It is a bran new gauge. It has been like that since it was installed. Which was only a couple of days ago.

68442 said:

Mine did that until I fixed my little exhaust leaks.

Click to expand...

I suspect I may have a little exhaust leak but I can not find it, and I am not 100% sure I have one.

I would have to say an exhaust leak.

Was thinking of getting some Seafoam and seeing if it will come out anywhere that it shouldn't.

Yeah that would work. Usually you can carefully put your hand down by the exhaust manifold and downpipe and feel gases coming out. If it pegs all the way lean I would imagine you have a bigger leak. Seafoam would do the trick though.

IMO that probably not the best spot anyway. I would either weld a bung in the dp or run it in the front o2 and simulate NB via link, but that's just me. I would deff take it back out and test it, after all it is still a electric sensor so they can be doa just like any other electronic. There is a vid on YouTube that shows you how you can test it easily in about 5 mins uninstall and reinstall included, and all you need is a can of break cleaner.

Well I just ran some seafoam through the intake via the bov line and I would say I have an exhaust leak.
It is coming from under the exhaust manifold but I can not tell where. There is a big cloud of smoke and it isn't coming out in any particular area that I can see. Doing it myself. But I just put on a brand new OEM exhaust manifold gasket, new oem exhaust manifold studs to head and new OEM manifold to turbo bolts and washers while I was doing my build the past month.

I have an Evo 3 16g turbo and a 2g o2 housing. The gasket that is between the evo 3 and o2 is the 2g gasket and I had to cut it so the gasket whole would line up to the evo 3. It got quite thin. Maybe this is my issue? Maybe it is my exhaust manifold to turbo gasket or turbo to 3" exhaust pipe gasket which also had to be cut to fit the exhaust pipe hole.

Any idea where I can get these gaskets in the right size? Possibly from napa or O'Reilley? If so what would I ask for.

thank you

For the gaskets I would say one of our supporting vendors, IE ExtremePSI, JNZTuning, STM, etc. (Those are just the 3 I deal with the most) And you might be better off with the EVOIII gasket Why not just install the sensor in the front O2 and run narrowband sim? I have my Innovate set up like that using the built-in sim and my car actually runs better with it

Exhaust leak can cause it to show lean but shouldnt stay pegged on lean unless the leak was fairly large but should still change when you get on and off the gas. You may just have a bad sensor, mine went bad, but when they go bad they just show lean as an indicator of needing replaced. If in fact it is bad, Autozone sells the wideband sensors much cheaper than AEM, Part Number: 17014, just cut and crimp the plug over, the one i got had a different plug so i had to cut n crimp the wires to swap the plug over. Its very simple.

It changes when I give it gas or driving just at idle it sits full lean.

Then sounds like an exhaust leak. You said you found one so fix it and go from there.

I understand it's an older thread, but I've had this recurring issue. I've tried several injector scalings and sizes. It must be something mechanical. Mine reads full lean and doesn't have any type fuel issue. Any ideas come to mind? Also it does scale the afr with a little bit of throttle.

Check for exhaust leaks, when I put mine in it did the same thing until I went through the entire exhaust. Fixed the leaks and problem solved

Can also be a post-maf, pre-turbo leak. Car will run, not great, but be lean on anything w/o throttle.