I think but could be wrong!?

[413mk3]

Alright so I bought my car and knew my cat was going because you would get on it, it would smell like rotten eggs. But out of know where it stated to run really rough and almost want to bog down. Then today it shut down on me. Tonight on my way home from work it started to idle all over the place and it bogged the entire way down my street. Basically I'm asking if my cat is clogged and making my car to run like sh*t?!? Please help?

[smokeytom]

cut that b*tch out! even if it doesnt cure the problem it'll sound good
does sounds like a potential clogged cat tho, i had an old jeep once and it died on me on the highway and when i looked under it to see wtf, the cat was glowing lol had to get it towed and cut out...

[413mk3]

I planned on cutting it out lol. Make the vr even louder, my neighbors must hate me haha

[smokeytom]

i see your a 98 vr6 tho (obd2) ? if thats true, when you cut out your cat you'll throw some engine codes and i think the car goes to a more factory setting since your cutting out two o2 sensors. if you do this you NEED to LEAVE the first 02 sensor and cut just after it and before the cat and take the second 02 sensor out and secure it to the underside of your car somewhere so the car can still read the sensors and not throwing codes. anyone back me up? i think im right? this is my plans soon anyways... sometimes i wish i had an older vr (obd1) they have no sensors in there so you can just cut the cat and put a pipe up there and get away with it without any engine codes

[Nico.]

i see your a 98 vr6 tho (obd2) ? if thats true, when you cut out your cat you'll throw some engine codes and i think the car goes to a more factory setting since your cutting out two o2 sensors. if you do this you NEED to LEAVE the first 02 sensor and cut just after it and before the cat and take the second 02 sensor out and secure it to the underside of your car somewhere so the car can still read the sensors and not throwing codes. anyone back me up? i think im right? this is my plans soon anyways... sometimes i wish i had an older vr (obd1) they have no sensors in there so you can just cut the cat and put a pipe up there and get away with it without any engine codes

OBD1 still has an 02 sensor.
You cut out the cat and you'll throw codes. You remove the second 02 and you'll still throw codes.

[51mg-TD]

OBD1 still has an 02 sensor.
You cut out the cat and you'll throw codes. You remove the second 02 and you'll still throw codes.

OBD1 o2 sensors are pre-cat, cutting the cat will do nothing to throw a code.

[builtvw]

OBD1 o2 sensors are pre-cat, cutting the cat will do nothing to throw a code.

this is this kids first post, and he just showed you whats up....cause hes correct

[Spiller337]

this is this kids first post, and he just showed you whats up....cause hes correct

[Nico.]

this is this kids first post, and he just showed you whats up....cause hes correct

I had two separate statements. He said OBD1 Vr's had no 02 sensors. I said OBD1 Has 1 sensor.

2nd statement was in response to the OP's OBD2 VR which has a pre and post cat 02 sensor. You remove the cat you'll throw a code. Remove the 2nd 02 sensor and you'll get "an "implausible value" code. I'll be more clear next time?

[smokeytom]

What I meant by my statement was I've heard where people on obd2 cut after the pre cat 02 and then unscrew the second 02 that's post cat and just tape it or secure it to the underside of your car and leave it plugged in and you won't throw codes since there will be fresh 02 for it allday errrday?

[smokeytom]

I've honestly read it more than a couple times in my searches for straight piping a vr... anyone back me up? Why do you think this won't work? What do 02 sensors do then if its not checking for emissions? If its not in there and getting constant fresh air all it'll do is be like dam I'm runnin clean today and be happy?

[aphythiate]

OP, your symptoms seem consistent with a failed cat. Bogging, not being able to go over a said rpm or speed, that's typically what happens.

Now, to prove this, there are two ways.

-Jack up the car, whack the cat with a hammer. If you hear junk clanging around inside it, it's trash. Replace it.

-If the "smack test" fails to bring you closure on your diagnosis, you'll need to have a mechanic perform a "back-pressure test." This is a procedure wherein the pre-cat 02 is temporarily removed, and a pressure tester is screwed into it. Above a certain threshold of pressure, the mechanic will rule your converter to be obstructing the exhaust passageway.

However, you're just going to have to go on test one, as your pre-cat O2 sensor on this vehicle is in a tight spot, on top of the end of the downpipe. Not that easy to get to.

As far as O2 sensors, you need both on an OBDII car. If you remove the cat, the post-cat O2 will throw a P0420 or something similar for cat efficiency. If you remove the pre-cat O2, your car will be stuck in open loop. This will result in less-than optimal air-to-fuel ratios, greater pollution, and lowered fuel economy. It may even risk damage to your engine, due to not being able to sense an overly lean condition that could cause piston-melting fun.

Do it nice, or do it twice.

[smokeytom]

We've established bad cat, and i never did say to take the second one out and throw it away... there a simple sensor, clean air makes it happy obviously and leaving it plugged in and where fresh air is would be no different then a very clean running vr... they don't measure airflow so I've still yet to see you prove me wrong?
lol I said leave the first one, don't even touch it, cut AFTER it.. how would cutting after it all of a sudden change it?

[aphythiate]

We've established bad cat, and i never did say to take the second one out and throw it away... there a simple sensor, clean air makes it happy obviously and leaving it plugged in and where fresh air is would be no different then a very clean running vr... they don't measure airflow so I've still yet to see you prove me wrong?
lol I said leave the first one, don't even touch it, cut AFTER it.. how would cutting after it all of a sudden change it?

I misread your sentence. Sorry. It still is not what you do. That would result in an "out-of-range" reading. The proper way to delete a cat, if there is such a thing, is to either get a chip that edits out the post cat 02, then you can do what you want with it. Or, you can space the post-cat O2 with a wayne-angle block or a pair of spark plug defoulers.

You want to move the O2 away from the exhaust stream, not totally out of it. Apologies for misunderstanding.

I know they don't measure airflow. They chemically determine the oxygen content of the exhaust stream. Having no heat at all on the sensor would be incorrect. Spacing it out will fool it into thinking the cat is working.

[smokeytom]

No worries! But yes that's the proper way of doing it, buying a c2 chip or something like it. I like the idea of the c2 since you get the sai deleate aswell! I've done alot of picking and poking around trying to be cheap and not chip my obd2 vr but have it with no cat and the best I found was to secure the second 02 to the underside of car outside of exhaust but I never knew it would throw that other code? Thanks for the Info!

[aphythiate]

Scan it, it may have a code it's not showing a light for, or your bulb may have burnt out. I don't see how that wouldn't throw a code. I've heard of this, but never tried it. If it's working for you, then great. Never heard of someone doing that to a VR.

I ran a test pipe for a while, and thought, damn, no CEL. Well, my CEL bulb was dead.

Just hanging the rear O2 is going to throw a P0140 or something similar.

[v-dubkyle]

im going to say, check for vaccum leaks.

[413mk3]

brand new vacuum lines all over, it has to be a bad cat, i hit it with a hammer and it didnt make any noise. im just going to cut it out and replace it with a 42 drafts test pipe when i get paid. Anyone running one now? would like to see if they like it.

[aphythiate]

I had a 42DD test pipe, and it was more than adequate at what it did, until I had a shop do some exhaust work and they lopped off the flanges. Next time, I'll just buy my own torch and welder.

42DD makes high quality stuff. I may also note that they make a highflow cat for your car as well. Haven't used one, but I'd suspect nothing less than top notch. Just something to note if you want to clean up your exhaust. (I had terrible guilt running catless.)

[smokeytom]

i havent actually done this i still have a cat, im hoping to do it soon but might actually go the 42dd route. is that test pipe more for obd1 or does it have a spot for both 02's? i looked at there site but only see one spot for an 02?

[will_t]

i havent actually done this i still have a cat, im hoping to do it soon but might actually go the 42dd route. is that test pipe more for obd1 or does it have a spot for both 02's? i looked at there site but only see one spot for an 02?

that's because the first o2 sensor is on the downpipe. if you're going to run the test pipe on an obd1 car, where there is only 1 o2 sensor..you can simply plug the bung.

[smokeytom]

on the dp? never knew lol thanks man