Darren - I've put on over 1500 miles. It has literally been driven every day since this was done.

openclass - It isn't illegal to remove cats in y province in Saskatchewan, its not the shutting off of the light that is the legal issue, it is the removing of the cats that is illegal in many states.

jbrew - Mike is the reason I was in this situation, I asked to have the rear o2's turned off and he never. No, no data logging but I have pulled the plugs on a few cylinders on a few separate occasions and the plugs are burning right where I would like to see them. Those street trucks are running cats to stay legal in their state I would bet. When it comes to high performance most race cars run open headers. In terms of mileage, I went for a 300+ mile road trip last weekend and got 20.25mpg on the way there at 70mph with a rank cross wind and 24 mpg on the return trip at 60mph, with no wind.

 

I'm not really referring to the rears - It's easy enough to wire your eliminators for the 420 & 430 codes

Yea , just the forwards and the way they cipher mixtures. That's not easily overcome. A two valve running the stock tune falls on it's face without HF's - at the least. I tried it and absolutely had NO torque . That's why I ask if you were tuned without cats. At the time, I was running everything stock with the exception of no cats. I also had a Magnaflow cat back installed during this test.

If Troyer didn't tune yours without cats, how did you manage to keep your torque #'s up with that much flow or get your moneys worth out of a tuning ? How did you get her dialed in man ?

 

My tunes are from when I just had my catback. Did you ever unhook your battery when you took your cats off?

 

so does this mod work if you only remove the two rear cats?

 

If you remove the rear cats and it doesn't throw a code then your truck is burning clean enough and your pre cats (front ones) are filtering enough to keep the pcm happy. If the cel does trip then yes this mod will work

 

Yea , my battery was in the Lawnmower when I removed my cats

 

Hey guys, i did this today. truck seems to be running a little lean. its a 98 4.6 5 speed. the valves have started a pretty good ping to them. any ideas on what to do or anything?

 

interesting post, i guess i missed it

Gotts, have you done two consecutive highway trips of atleast 10 miles? That is when its common for 02 monitors to run.

key on, highway speeds 10+ miles, key off, key on, highway speeds 10+ miles, then monitors run....


Jdoss: Did you do this to the rear sensors only?

 

Yes, just to the rears. its kickin' the p0402 code, and nothing else. i know i should get that fixed, but would it cause the pinging?

 

yea it could be causing the ping

could be something else like a bad plug/coil etc

 

I drive 10+miles of highway twice a day, minimum 6 days a week. Drive to school, approx 20 miles, drive home from school 20 miles.


This shouldn't cause you to run lean if you only did it to the rears. The rears only monitor the emissions and that is all, don't have any affect on the air/fuel ratio.

 

well, the ping just started today. it hadn't done it until i did that thing.

 

so it could just be the egr causing that now that it isn't runnning near as rich as it was?

 

Are you sure it isn't an exhaust leak? go under there and tighten them up again after it has warmed and cooled a couple times. i ended up tightening them up another 1/4-1/3ish turn on my after a couple days of driving.

 

well, it just does it at somewhat high rpm's. i'll go under and tighten them though tomorrow i guess.