Cat sensor?

[TurboToy-R]

Hello,

I just installed a full 3.5" exhaust on my JDM 1JZ car and during the exhaust removal I found a sensor in the back of the catalytic converter. I was curious what this is.. it looks like a long slender rod, similar to the diameter of a pencil and roughly 3 inches long. It was inserted into the back of the cat. I know this is not the 02 sensor as it is located in my Y-Pipe. Is this an EGT sensor? (seems kinda too far back to be that) The cable length of the sensor will only allow me to move the sensor 6 inches either way on my exhaust (need to make a new mounting hole for it). I have run for the past 3 days without it, but my concern has been due to the following:

-a noticable increase in fuel consumption (may be due to now boosting more freqently due to better exhaust system)
-seems my car warms up noticably faster now (am i running lean??)
-slight smell of gas at idle (makes me think im running rich, contradictory to being lean and warming up faster)

Thanks.

 

[Stanzaspeed]

its the cat temperature sensor. when i did my exhaust i just unplugged the sensor and put a body plug in the hole.

 

[TurboToy-R]

so it pretty much just makes sure the exhaust temp doesnt max past the cat's abilities? well if thats all, i guess my other symptoms are my paranoia. should I add other monitoring devices to my exhaust for safety measures? i hear about these wideband sensors, they sound pricy

 

[Rich]

Wideband is for monitoring A/F ratio's.
If you go up in performance, you will get closer to the max. temps parts of your engine can sustain before failing, you will want to keep an eye on that. On an EGT (exhaust gas temperature) meter you can monitor these temps. Most ideal would be six of those; one for each runner with the sensor mounted as close to the head as possible. But I haven't seen anyone do that.
If you have a big single the best place would be to put the sensor in the flange of the exhaust housing of the turbo. If you're on stock twins you're best of putting it in the flange of the rear manifold; the rear cylinders are the hottest because they're furthest away from the radiator.

 

[becauseican]

Yes it is an EGT (exhaust gas temp) sensor. It is just hooked up to the warning light on your dash. It shouldnt affect milage or anything. Most 1jz swap guys here run without them with no negative effects. I have heard of some people installing a resistor inplace of the sensor so that the ECU/ light will think everything is normal.

 

[garagefujimoto]

Cut it off and run without it. It turns on a light in the dash for "hot cat"

And although it shouldn't affect the engine, I ran mine with the sensor dangling under the car in the winter, so it was measuring extra cold.

I went through $25 in gas in 47 km before correcting the issue.

Continued driving like that for a few weeks would wash out the rings and dilute the oil, resulting in engine failure.

 

[TurboToy-R]

Continued driving like that for a few weeks would wash out the rings and dilute the oil, resulting in engine failure.

:aigo: Engine failure! There are contradicting views on here.

So after I unplug it, how do i get rid of that dash light?

 

[OneJoeZee]

:aigo: Engine failure! There are contradicting views on here.

Well not having it and leaving it dangling to pull a very cold ambient temp are two different things. Had he removed it completely, his end results would probably be different.

Probably every 1J swapped US car does not have the sensor. I've never seen one. Never even heard of it. Just a guess.

 

[TurboToy-R]

Well not having it and leaving it dangling to pull a very cold ambient temp are two different things. Had he removed it completely, his end results would probably be different.

i agree, i think that the best solution would be to weld in a bung and re-install it where it was along the exhaust, eventhough there is no cat now, and the sensor is quite a ways down the pipe, it will still read a temp, and thats better than ambiant temp, or wind factor temp driving down the road, or oopse, i just drove through a puddle temp...

 

[lagged]

If you're on stock twins you're best of putting it in the flange of the rear manifold; the rear cylinders are the hottest because they're furthest away from the radiator.

actually if you want to get picky the number 1 cylinder would be the leanest because it is at the end of the fuel rail. therefor, an egt probe might get the hottest reading from the number 1 exhaust runner.

me personally, id just look for a nice flace space in either of the exhaust manifolds. you cant tune by EGT anyway so its just really to let you know if something goes very wrong.

with that said, EGT sensors are slow to react so you might have already done serious damage to your engine if you see high temperatures.

moral of the story? While an EGT sensor is not a bad thing to have, just put it anywhere pre turbo and be done with it.

 

[IJ.]

 

[garagefujimoto]

Well not having it and leaving it dangling to pull a very cold ambient temp are two different things. Had he removed it completely, his end results would probably be different.

Running with it connected, but not in the exhaust stream caused a terrible rich mixture.

Having it in the pipe only turns on the light if the in-pipe temp gets excessive.

Having no sensor, no wiring to or from it, and nothing to take it's place causes no light because there is no voltage reading to trip it, no rich problem as the sensor isn't false reading, and allowed me to get typical fuel mileage and run a 13.9 on stock boost...so I don't think it's a problem. :icon_bigg

Cliffs: Cut the fucker off and forget about it and the idiot light it was hooked to.

 

[Rich]

actually if you want to get picky the number 1 cylinder would be the leanest because it is at the end of the fuel rail. therefor, an egt probe might get the hottest reading from the number 1 exhaust runner.

me personally, id just look for a nice flace space in either of the exhaust manifolds. you cant tune by EGT anyway so its just really to let you know if something goes very wrong.

with that said, EGT sensors are slow to react so you might have already done serious damage to your engine if you see high temperatures.

moral of the story? While an EGT sensor is not a bad thing to have, just put it anywhere pre turbo and be done with it.

From all the failed engines I've seen due to too hot temps, including two of myself, I've never seen damage at #1 cylinder, #5 cylinder is the first to go, #6 will hold a little longer because the coolant flow at the back of the block is more than what #5 gets.

I have an Apexi egt meter and it moves up and down faster than my rev meter...
But like you said, it's a warning device, best to have one with peak-hold and a warning light which you can set to a certain temp.

Tuning on egt's is for the stupids.

 

[garagefujimoto]

Wonder why they sell the Night Pager waterline kit?

It puts cool water at the back of the head. They didn't just build it because they were bored.

 

[TurboToy-R]

Just a quick follow up to this problem, I just dis-connected the sensor at the location right under the drivers (RHD) seat and seems to be running just fine.. Hoping to install some gauges to tell me exactly how its running now, but for the meantime, I am happy.

 

[OneJoeZee]

Your avatar is funny.