Turbo 1gr-fe AFR sensors can anyone help?

So im hoping someone might be able to help with the AFR o2 situation. Currently both AFR sensors are plumbed pre cat and both rear o2 sensors are plumbed post cat in the same dump pipe. It seems having the sensors installed this way in the same pipe is causing fuel trim havoc and eventually a bank 1 rich and bank 2 lean hard fault. At the time I wasnt fully aware that the front afr sensors sense currant and not voltage directly. Im not ready for a stand alone replacement ecu, is there anything else i can do in the mean time? Im a little stumped.

 

What is your current EMS solution? Also looks like this might be a Hilux instead of a Tacoma, is that the case?

 

Yes you are correct its a 2008 hilux. Im currently using an AEM fic 6 for timing control and fuel via maf control. Also im running 4psi boost

 

If you're trims are so far out that you're triggering CEL's for them, You've got either significant vacuum/boost leak(s), fuel pressure issues/leaks, or a leak in the exhaust pre-O2 sensor(s) that is quite sizable. Or the tuning in your AEM is just not appropriate for your setup. Lots of variables, and without more testing/troubleshooting anyone would just be stabbing a the problem blindly.

Start eliminating variables to isolate the issue is my suggestion.

I'd start with refitting the factory injectors and zero out your fuel/ignition mapping in the AEM. If you do that, and you're still having issues, you can rule out tuning as the culprit.

 

Thanks for the reply. I had a feeling that the AFR sensors would fight each other if mounted in the same pipe but finding information on it was proving difficult. Theres no leaks, but as soon as the vehicle is in closed loop one bank will lean and the other will run rich. It does this on the stock tune with the AEM removed (completely stock). Sensors worked fine prior to the turbo being fitted.

So it seems these sensors cant be used in this way or at least in the way i have them configured. I have removed them and will freshen the tune via the AEM/wideband and simply run without them.

Very happy with the way the build turned out otherwise.

 

Also, what size is your a/r exhaust housing? If it’s too small and causes back pressure, it can cause the sensors to read all skewed because of the mixed gases caused from
The back pressure.

 

0.63 A/R. It is on the small side.

 

Yea then that will probably cause the readings to get mixed up, especially if you’re using the stock sensors. They’re very sensitive and will cause it to run like crap if readings are crap which is happening in your case. Could probably try a turbo with a bigger housing or use another type of tuning that will use A wideband sensor.

 

Interesting, I never would have thought that might be an issue. Wideband it is, toyota afr sensors are truly a pain in the backside. Thanks for the help gentlemen, appreciate it.

 

Swing by here when if you haven’t yet

https://www.tacomaworld.com/threads/turbo-bs-thread.481844/unread

 

Or you could run twins which would eliminate the problem all together