Finally broke down and bought myself a header for my 87 sr5 22re. I found the OBX header with headpipe on ebay for 179 plus shipping and decided to go for that one since it had the thickest flange and it was stainless steel. We spent over two hours fitting the header in the truck as one of the pipes near the collector was binding against the bell housing. We finally got that taken care of and stopped the leaks and as i was driving home, the truck lost its ability to idle smoothly. It runs/drives great for the most part until you slow down. The company claims the header will work for the 22re but the o2 sensor bung was moved from near the head to the end of the headpipe near the front of the catalitic converter.

Im wondering if moving the o2 sensor that far away from the head is causing the engine to run poorly since the exhaust gas is cooler than it should be.

Any thoughts, or ideas would be greatly appreciated. if I need to, I will move the bung from the headpipe to the header. Would like to confirm this before i move anything.

Also, does anyone know how to "reset" the engine's computer? I tried removing the ground cable from the battery for over an hour hoping that something would change. I have heard that touching the positive battery cable to the negative battery cable while disconnected from the battery will do it.

Thanks for the help.

 

O2 sensors do like to run hot... so that might have something to do with it

 

To reset the computer pull the efi fuse for 30 sec., or disconnect the battery for the same amount of time.

 

on the 94 22re the O2 sensor is under the drivers seat area, so heat cant be that much of an issue.
No Codes??
Pull the + battery cable off for 1 hour. check the wiring to the O2 sensor if you had to extend the wires, they might have come undone.

Maybe the O2 sensor died? But a code would be present

 

When I replaced my exhaust manifold I had to re-time the motor and reset idle. I would also make sure there are no leaks.

 

What codes are coming up? At what point does the CEL come on?

Double check the plug wires and make sure one didn't get knocked a little loose or broken when the header was installed.

 

does the 94 have a heated O2 sensor? the 87 more than likely doesn't

 

Thanks for the replies. I got a CEL on two separate occasions but for a split second only and did the jumper wire and it showed no codes at all. I double checked the plugs, wires, and distributor cap with no abnormalties. I disconnected the battery for well over an hour last night while replacing the new bosch O2 sensor with the old toyota sensor. This morning the truck still ran like crap but was more stable. Ran more like a v8 with a lopey cam. Exhaust is very rich smelling.
After some research, It looks like the O2 sensor is the culprit. The single wire sensors are supposed to be located near the head where the exhaust gasses are hottest. Multi wire sensors are "heated".
I suppose it could be a timing issue, which would explain the issues, although Im struggling to figure out why changing an exhaust setup would require a change in timing.

 

It could also be your air filter. With easier air flow leaving your engine you want easier air flow entering your engine

 

Ah, Just put a new filter in the truck the same time I did the header...

 

the O2 sensor theory makes sense as the ECU is getting inconsistent (wacky) readings from the sensor and the ECU is metering incorrect fuel... what you might want to try is to throw the ECU into limp mode, it might run better than having bad O2 readings... disconnect the O2 and see what happens

if it runs better, then that's what the problem is... the O2 isn't getting hot enough

now there's 2 fixes to this, first the obvious one is relocating the O2 closer to the engine (like stock)... the other is to install a heated O2 sensor in its place... I guess it's not a common mod with the yota trucks because nobody has mentioned it yet, but it can be easily done with some basic electrical skills... people in other forums such as miata ones have successfully done this conversion... all that needs to be done really is to wire 12 volts and a ground to the heater circuit and then hookup the sensor wire to the existing wire... I think I recall seeing such a guide on a miata website years ago, so you might want to check it out

end result will cost about the same as far as money goes, but it's just the matter of which is easier for you to do

 

On my header the O2 bung is down by the collector next to the frame rail..probably moving it away 7 or 8 inches. It idles fine like it is, but occasionally while driving it will throw a lean mixture code for a few seconds.

How much of a difference do you get when you changed out the O2 from the BOSCH to the OEM? Try what the The MAN said and put it it in limp mode and go from there. It could just be a bad OEM O2 sensor and since most people on here have problem with the aftermarket ones that could be it too. I would just take the BOSCH one back and get one from the dealer and see how it runs then.

 

no need to waste money on buying the one from the dealer... get an aftermarket denso, same EXACT thing (denso makes the OEM toyota sensors)... it'll save you a good chunk of money

 

Or that! I couldn't think of the brand name when I last posted lol

 

Well, I thought I would try sending it into "limp mode", so I unplugged the O2 sensor and got no change...really. The truck ran the same and no codes, that lasted longer than a second, ever came up. Im starting to wonder if there isnt a problem with the computer now since the CEL isnt coming on and staying on.

Shouldn't the CEL come on and stay on when the 02 sensor is unplugged?

 

Is there a break in the wire that goes from the ECU to the O2 sensor?

 

good question.... that should also be checked... disconnect the ECU and probe one lead of the multimeter to the O2 sensor pin and the other should go to the O2 sensor connector... if there's not enough reach, there's always the jumper wire trick

 

I know in the Honda world that Bosch O2 sensors never seemed to play well with the car, maybe that's something to think about.

Did you touch the probe? I've always read that touching the probe can damage it.

 

that's what she said!

 

why not try putting the stock header back in and see if the problem goes away.

how long did you let it run with the o2 unplugged