New Exhaust OBX RACING

[cali yaris]

yes, as discussed the 2nd sensor must be AFTER the cat.

[CTScott]

Originally Posted by cali yaris

^ The two sensors are not the same. Technically, the first one is more of an air/fuel sensor (though it's kind of a weird hybrid design by the way the ECU reads the voltages) and the second one is an O2 sensor to monitor the cat. Pretty sure that's all it does.

Why would you move it downstream?
And why would you want it to be "warmer"?

They are both platinum coated zirconia sensors, but the Air/Fuel sensor has the ability to detect the ratio over a wide range (i.e wide band sensor). The heated O2 sensor can only detect that the AFR is at stoich or is rich or lean - It can not detect how rich or lean it is.

So, the air/fuel sensor before the cat allows the ECM to precisely control the ratio and the heated O2 sensor after the cat allows the ECM to monitor that the fuel ratio is properly adjusted to allow optimal operation of the 3 stage cat (which performs best at an AFR of 14.7).

[07stlYaris]

So, after moving the O2 sensor to after the Cat I still have the lean condition. (Light pinging). Should it correct itself or should I disconnect the battery and clear the ECU? If this continues, what would happen if I upgraded the injectors (cart before the horse??)? By the way, no CEL for 3 days so the lean condition just seems to be what the engine wants??? Fricken weird if you ask me.

[1.5]

I thought with our "smart" ecu's that kinda stuff would be auto corrected by the car and have more fuel dispensed to meet the demand the increased air creates.

[07stlYaris]

I agree but i still hear a little pinging and power is down a little too.

I'm going to do a little research on injectors and see if I can fool the ECU a little bit. if not, I might go with 1 extra injector and go analog on the control.

All I can say is DAMN COMPUTERS. I miss my 1967 Porsche 912. 2 carbs, 1 coil and the most electronic part of the car was the radio. Don't ask.

[cali yaris]

Definitely disconnect the battery and force a relearn. I would do this anytime any change is made to an engine/performance part on the car.

[Jason@SportsCar]

Just ordered this... Noticed over the weekend that we have a leak where one of the hangers is welded on the custom exhaust on the 99. The off-track excursions have also crushed the tubing in a few spots. So it was time to rebuild it, and this is way less than the custom setup. We will just hack off the OBX muffler and use our Coast Fabrication race muffler.

[Jason@SportsCar]

Have not had time to put the new exhaust on, but did start the prep work - we are not using the heavy OBX muffler, we will use a Coast Fab lightweight muffler, so I went at it with the plasma cutter.

They put a lot of fiberglass in the case.


Not so sure how the Scotch tape is going to hold up in there.


Not much of a heat barrier between the tube and first layer of fiberglass. And the perforated section is only 6" long, not much sound going into the case, but a lot of it going out the back.

[07stlYaris]

And for some reason, that mess doesn't quiet things down nearly as well as it looks like it would. I replaced mine as well with a Monza resonated tip and a baffled glasspack-style muffler. Waaay better sound and no sharp rasp.

[Jason@SportsCar]

So after a few months of looking at the OBX sitting in the corner of the garage I took some time today and tried to install it... I say try because it turns out the header on the 99 car is not an exact match to the production DC Yaris header (the first clue is the fact is has no O2 bung, we think this may have been the prototype), the exit of the collector is at a different angle than the OE and DC header so the OBX will not line up with my headers outlet.

Rather than mod the OBX we are just patching up the exhaust that is already on the car.

Kind of wish I had not cut off the OBX muffler before the test fit. Oh well. If anyone using a OE/DC/WR headers wants the start to a killer custom setup I will make you a great deal. Just install your favorite race muffler (I recommend Coast Fabrication) and you will be ready to rock.

[4/20 NEVER FORGET]

I ended up buying this exhaust off of amazon for $175 shipped. Since it's 2" I plan on cutting it and welding it onto the stock exhaust right at the end of the resonator where the diameter reduces to 1.75". If figured with the time and cost to have a shop make me a crush bend mid-pipe I could get this and have them cut and install it instead.

[TPA5]

Originally Posted by 4/20 NEVER FORGET

I ended up buying this exhaust off of amazon for $175 shipped. Since it's 2" I plan on cutting it and welding it onto the stock exhaust right at the end of the resonator where the diameter reduces to 1.75". If figured with the time and cost to have a shop make me a crush bend mid-pipe I could get this and have them cut and install it instead.

A video would be nice if you do get that done, this may be an interesting exhaust option, provided it doesn't sound buzzy.

[4/20 NEVER FORGET]

I'll post a video after I get this installed tomorrow. Also to clairify, I measured the inner diameter at 2.25".

I don't think it will be too loud since it will still have both cats and the stock resonator. I had a Megan axle back before that was very quiet, but I ended up taking it off because i have my car quite low and it was hitting the suspension.

[4/20 NEVER FORGET]

I got the exhaust installed today. Like I said previously I had the factory and OBX exhausts cut to meet just after the factory resonator.

I took a picture of the inside of the resonator so you all could see that is straight-through in design. I was going to have it changed out if it wasn't, but looking at it there didn't seem a reason to have it replaced.

Some work was required to make the muffler fit into the space available under the car, we had to take a sledge hammer and hammer the spare tire well in a bit as well as bend the toe-hook out a half-inch so that the muffler could be fitted nice and tight under the car. With the factory hangers it wanted to hang pretty low, we used the OBX back mount that holds onto the pipe next to the muffler and the exhaust shop welded a hanger to the top of the muffler, just out of sight.

The muffler is quite loud compared to the Megan axle-back I had before. I'm going to give it a week before I make a final decision but I might have it cut off and changed out with a Magnaflow or some other exhaust. I do really like the way the muffler looks though, the tips look nice tucked up right under the bumper.

Here's a video, I should have revved the car up a bit more but it's what I have for now. I'll take another one and post it when I get a chance.

http://www.youtube.com/watch?v=niZYgO0vvrU&feature=plcp

And to respond to TPA5, while loud, there is no buzz or rasp that you sometimes get. I've had a lot of Honda cars so I know what you mean about buzzy or raspy. If this car was a bit faster I could justify the sound it makes, but for now I would like it a bit quieter.

[yak]

You want loud...then try this thing
Holy crap this bugger is loud, I cant imagine what this would be like as bolt on.
I just had the same OBX system installed but spliced in a hi-flo cat & a resonator (both Vibrant parts)...Pictures to follow

Can anyone please suggest a quieter muffler cos this one has gotta go

[bebeelo]

Originally Posted by yak

You want loud...then try this thing
Holy crap this bugger is loud, I cant imagine what this would be like as bolt on.
I just had the same OBX system installed but spliced in a hi-flo cat & a resonator (both Vibrant parts)...Pictures to follow

Can anyone please suggest a quieter muffler cos this one has gotta go

tanabe medallion touring.....or stock

[cali yaris]

I had a Vibrant that was reasonably quiet. Which one did you get? You can't miss with Magnaflow, it will be very deep and warm.

[ezhacker1]

Originally Posted by cali yaris

it will be very deep and warm.

TWSS

I do prefer the deep bass growl of the exhaust. I can live with what i have, its as loud as I want it, with no highway drone, just lacks the depth and warmth. Time to do some more research.