catalatic converter


jweb6769
10-27-2004, 05:19 PM
Does anyone know what effect it would have if you cleaned out the converter on the exhaust and ran it like that. Would it affect the post o2 sensor and what it reads back to the PCM?Mine is plugged and i am fixxing to get it replaced.I know on the older models you could clean them out with no problems.I have a 2000 model chevy truck .4.3 V-6.It has 2 converters.The one that is plugged is the passenger side.The truck has been bogging down when you punch it.I did a pressure reading on it today thru the pre o2 sensor hole.Had 15 psi at 2500 rpms.1.5 psi at 2500 rpms on the driver side converter.I believe this will correct my problem.

jeverett
10-28-2004, 06:41 AM
I've heard it will mess up the air/fuel mixture, but I'm not sure. Mine are stopping up as well, they are starting to smell really strong.

internic
10-28-2004, 12:21 PM
it is my understanding that removing the converters will not alter your fuel/air mixture. Specifically on my 99 4.8, there are four o2 sensors, two on each side, before the converter, and after. The pcm uses the pre-converter sensors to actively monitor the f/a ratio and adjust injector pulse accordingly, and it uses the post-converter sensors to monitor catalytic converter efficiency. If you remove the converters and keep all the o2 sensors, it will throw the check engine light cause the post-converter sensors are now way off, but it just turns the light on, it *shouldnt* change the fuel air mixture? hope this helps

-nick

jeverett
10-28-2004, 12:52 PM
I think this is a case when the "02" simulators would come in handy. They trick the computer into thinking the sensor is getting a correct reading and all is well.

vnotaro
10-28-2004, 03:21 PM
Removing or boring out the converters could be a problem if your state does emmisions inspections. NY is a pain in the ass as far as all that goes. You fail automatically if the check engine light is on.

jweb6769
10-28-2004, 04:49 PM
thanks for the reply.Just got back from the muffler shop.Had the plugged converter changed out.$130.00 bucks.It has a lot more power but something is still not right.It seems to be surging at low speed.It will get up to speed but sl;owly.I live in Texas so I could do without it.We dont do the emissions testing at this time.Thanks for the replys I'm going to go do some more checking.I had about 15 psi backpressure on the one I had replaced and 1 psi on the other.I sure thought I had found the problem.Looks like that was part of the problem but not all of it.I'll let you know what i find.

Slowprocess
10-28-2004, 05:17 PM
I think this is a case when the "02" simulators would come in handy. They trick the computer into thinking the sensor is getting a correct reading and all is well.

Hey jeverett, do you still have your cats? I know Allen cut off my rear 02s so I could take them off. The truck sounds alot deeper now without them. My front 02s are mounted in my headers, so they're still on. I also made plates to plug up my EGR system, and had Allen turn it off as well.

grego12r
10-28-2004, 10:10 PM
the catalatic converters are an waranty up to 80.000 mils and 8 yers
an all chevy silverado

jweb6769
10-29-2004, 11:30 AM
Grego thanks for the reply.I was aware of the warranty but guess what? I have 84,000 on the truck.That's the way my luck usually goes.Nick,Thanks for your reply.This is the second converter to be changed on this truck.The first one was changed under warranty.Did'nt have but 25,ooo miles on it at that time.Like I said previously,It helped after replacing it but it still is not right.Runs better but has a bog when accelerating.Idles real good.Sometimes when you barely push the gas it jumps like it is getting more fuel than your giving it.Anyone know of any other problems related from having a plugged converter?I'm fixin to go do some more checking and I'm going to check to see if I have any backpressure on the muffler.I'll let you know what I find out.Thanks.

jweb6769
10-29-2004, 01:04 PM
Just checked the pressure on the other converter.Readings are 6.5 to 7psi at 25oo rpms.Thats from the pre o2 sensor hole.I cant believe these would go out at the same time.The book says 1.5 psi at 2500 rpm is normal.Would the backpressure that this one have cause it to run sluggish?I getting ready to check from the post o2 sensor to see if I have a restriction in my muffler.

jweb6769
10-29-2004, 10:10 PM
well I had the other converter changed out and it runs like it did when it was brand new.Amazing what a little back pressure on the engine will do to it.If you ever have a engine that boggs down when you accelerate it ,I suggest checking the back pressure on the pre o2 sensors.Had a mechanic friend tell me that anything over2-1/2 to 3 psi will greatly affect the way the engine runs and will also make the PCM go crazy.Sure did on mine.Thanks for the reply's.Later

grego12r
10-30-2004, 12:41 AM
my went out arund 66.000 mils got new from deler for free
im thinking about hi flow cats what you thing thanks

jeverett
11-02-2004, 09:09 AM
Hey jeverett, do you still have your cats? I know Allen cut off my rear 02s so I could take them off. The truck sounds alot deeper now without them. My front 02s are mounted in my headers, so they're still on. I also made plates to plug up my EGR system, and had Allen turn it off as well.

Yeah, I do still have my cats. I was worried about taking them off b/c of the loss of backpressure and maybe some low end loss, but I think they're hurting more being half stopped up. I didnt even think about Allen being able to disable them. Do you think it would make much difference if I cut them off?

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