1jz dumps - effect of oxy sensor on one pipe?

**Z2TT** · 28-12-2009, 08:55 PM

Hello.

I have noticed many 1jz dumps have a provision for the oxygen sensor on only one of the runners, so it would only give outputs based on the gas coming from three cylinders.

I am wondering what effect that would have on closed loop operation, and would it be better to have the oxygen sensor placed after the merging section.

Thankyou.

**JZA70 R** · 02-01-2010, 02:31 AM

Originally Posted by Z2TT

I am wondering what effect that would have on closed loop operation, and would it be better to have the oxygen sensor placed after the merging section.

Providing your engine, ignition and fuel delivery system is in perfect working order, closed loop will work as normal. obviously its much more preferable to have the oxygen sensor reading from all 6 cyliders...

**DrNick** · 02-01-2010, 04:18 AM

Are the 1JZ similar to the 2JZ and run leaner in the rearmost cylinders? If so I suppose you would be safer if your O2 sensor is in that bank, but not the other way around. Still, having it read them all would be better I suppose.

**Z2TT** · 02-01-2010, 04:24 AM

Yeah so i guess if any cylinder gets a bad mixture it gets picked up?

**JZA70 R** · 02-01-2010, 12:30 PM

it wont be picked up as an isolated cylinder but the o2 sensor will detect an overall higher/lower average reading over all cylinders. in other words the other cylinders will mask the bad cylinder.

**Z2TT** · 02-01-2010, 01:26 PM

Ah Allright,

So it would only detect differences if there was a big change in fueling?
In saying that then I assume it's allright to have only 3 cylinders being read by the o2 sensor with aftermarket dumps?

**JZA70 R** · 02-01-2010, 04:20 PM

like i said, if your motor, ignition system and fueling system are in good working order you will be fine. its a risk you will be taking at the end of the day...