O2 Sensor Replacement, Intake & Downpipe
 

I am the happy owner of a Vintage Red Touring '93. I have been making mostly reliability mods (New front A-arms, 5th gear synchro, new clutch, boost guage, Fuel/air guage, plugs, wires, all fluids changed) and have a few questions.

1. Does anyone have any recommedations for O2 Sensor replacement? I have 58K on the car and just want to replace it with a better one. My Fuel/Air ratio guage jumps around a little and reads steady only on WOT.

2. I have an excellent mechanic at my Mazda dealership who works on the car for me. I asked about replacing the pre-cat with a downpipe. He did not recommend it. He said in Illinois the emissions standards got tougher in Feb 2001. He said, it is tough enough now on an RX-7 to pass. He thought it would not be able to pass. Anyone in Illinois have any experience to dispute or support what he said?

3. I also purchased a used PFS intake. After removing the stock airbox and brackets, I found the intake could not be installed because a main radiator hose runs under the air box. This prevents the PFS intake from seating properly against the frame. Anyone have any experience installing one?:p

the O2 sensor is a sensible upgrade. I have a 3 wire heated O2 sensor from Pettit Racing. But the A/F gauge should wander around, swinging back at forth. I believe that the most crucial reading is at wide open throttle, where it should stay at least above .82v.

As for the pre-cat., I would assume that it would be standad protocol for RX-7 owners to install a downpipe, as it reduces the engine temps. It's a must-have reliability mod, and the pre-cat is necessary to pass emissions anyways because I did. (At least b4 my midpipe was installed :)

I'm not sure about the intake though....

I hope this helps.

Hey thanks for the info!!!

Did you put in the O2 sensor yourself? Was it hard to do?

is it possible to knock out the insides of the precat instead of installing a downpipe?

You mean gutting the cat??

If your worried about the emissions test, gut it, but I would just throw a dp in there for a couple hunderd bucks.I they use an eye test then your straight with gutting it, If they use the sniff then you won't pass.

It's my understanding that the two pre-cats which the dp replaces are only for start-up emissions. As long as you have the car good and warmed up before you take it in, you should be fine. MO uses the sniffers now, and I've been told people have passed even though they have dp's. And looking at my numbers from my last inspection this past spring, they are almost microscopic compared to what is considered the acceptable level. All I did was drive it around doing errands that day, then headed to the test center.

I'm getting a dp in a few weeks, so I'll find out in two years when I have to be tested again :)

And if all else fails, buy a bottle of that Emissions Passer stuff at Autozone or someplace. :D