'Unplugged' my cat (track test)

[tann3r]

I recently started getting a p0420 code (no p0300, so coil packs are still good thankfully), and decided to see what the power change would be by simply gutting the cat. Finally got out to the track this weekend and wow what a difference.

According to the Traqmate data, I picked 10 mph down the front straight 118 mph vs 108 mph (a hair over 0.5 miles long) even with a worse entry 54 mph vs 59mph (5 mph slower, cold drying track). I'm usually flat out through turn 1 but since the track was just getting dry I ended up braking before turn 1 (~500 feet of sooner than usual), so there even more of a difference. Only change from last month was gutting the cat.

Granted that my cat was deemed inefficient by the OBD2 system, theres no real way to know how blocked it was. I had gotten 2 p0420 codes in a 1200 mile period. Yes the car is a bit louder, but it is still quieter than my bike (SV650S). current exhaust is a ebay header (w/ custom 'relief'), ebay muffler, gutted stock mid-pipe.

One question, is there a way to simulate the rear O2 signal or stop the CEL associated with it with the PCPro's? I tried the stacking spark plug non-foulers, but it still throws a code. I may pick up a pair of longer ones and try them if there's no electronic solution. Worse case I'll have to soder up a O2 sim.

[fourwhls]

http://www.o2simulator.com

[Tom @ Fast Forward]

Put a voltmeter on wire pink/yellow from the PC-Pro if it is not already connected to something. if it oscillates and is not already connected to something, cut the wire in the PC-Pro harness that is for the rear O2 and connect the PC-Pro wire to the ECU side of the wire you just cut. Tape the other end of the cut wire to prevent it from touching anything.

Could be I already thought about this potential problem. :-)

[Tom @ Fast Forward]

You have evidently released a plug and allowed a lot more air to flow. Be sure that your A/F is still good. Before, you would have had high boost and low flow. Now you will have lower boost and higher flow. That will make a significant change to your A/F.

[tann3r]

You're the man Tom! I thought I had read somewhere that someone (Chuck?) had this feature back in development, but I haden't heard anything about it recently. Thanks!

[Tom @ Fast Forward]

Let me know if that wire is already in use on your car. Recently, I switched from using VCB for the TPS signal to using VCA (on your PC-Pro, you will see an "A> and A<" and a "B> and B<". These are circuits I can program to do all kinds of neat things. :)). However, when I did that, I moved the Rear O2 signal to the VCA. That means that, if the pink/yellow is already in use and connected to the TPS wire, you will use the purple/yellow wire instead.

I removed my cat a long time ago and tried the spacer that worked for others. My conclusion is that the spacer works for high flow cats but, with no cat, there is simply too much gas. You still need to leave the O2 in place because the ECU also does a "heater" check on warm up and I can't simulate that signal.

[tann3r]

I have been keeping an eye onthe AFR and it did require an adjustment. The area i noticed the largest change was 5000-7000 rpm range, which makes sense.

Also, a the track, Many people dropped wondering what was screaming under the hood. Everyone was amazed how clean the kit installed. I even had a BRP hotside owner drop by and say he wished his engine bay looked as tidy as mine. A few asked if it was a factory special edition. Thanks for a great kit Tom.

[tann3r]

Just ran down and ckecked, found both wire you are referring too. I'll pull the harness this evening.

[Tom @ Fast Forward]

Yep. That makes sense. 5000+ is where the cat would cause the most harm. Glad it is working well now.

"Special Edition". You should just tell them it is what should have come from the factory. :)


I have been keeping an eye onthe AFR and it did require an adjustment. The area i noticed the largest change was 5000-7000 rpm range, which makes sense.

Also, a the track, Many people dropped wondering what was screaming under the hood. Everyone was amazed how clean the kit installed. I even had a BRP hotside owner drop by and say he wished his engine bay looked as tidy as mine. A few asked if it was a factory special edition. Thanks for a great kit Tom.

[tann3r]

Well that was a nice and easy fix. I spent more time waiting for the sodering iron to heat up that it took to pull the harness, soder, and reinstall. Great job on the patch harness, made this infinately easier.

[Tom @ Fast Forward]

I gather it fixed your problem then? ;)

[tann3r]

I'll know in 60 or so miles, but I have high hopes :).

[99mx5]

Post some engine pics of that bad boy in the picture thread :)

[tann3r]

Great news, it worked! :)

and as requested pics and a bonus video here (http://www.fastforwardsuperchargers.com/forum/showthread.php?p=11334#post11334)