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catalytic converter repair?

M

madore9

New member
got another code the other day, autozone said its for my catalytic converter. so I am wondering a few things, is this something i can replace by myself if I get a vehicle specific cat (as I'm terrified of the cost)? and is there a possibility that there could be something else wrong, hopefully less expensive, causing the computer to think the cat is having a problem?
 


It would help greatly if you could supply the code and the year/model of your car along with any mods you might have.
 
It may be cheaper to find somone selling their bolt in downpipe with high flow cat. Get it for $150 or under shipped and usually can get it bolted in yourself or a shop for around $50 and get the extra performance/flow.
 
Infact therwe is someone selling one now in the for sale section believe it was a 3" catted DP bolt on for 150 IIRC
 
i believe it is the P0420 code (will confirm after work) and is completely stock...and these high flow cats, will they still allow me to pass emissions? i live in massachusetts
also its an 02 gt
 
Most of our car have no issue with the high flow cats. I think its the 04+ cars that sotimes shoot codes. Not 100% on that tho your gonna have to have somones confirm that. Im cattless and Im just going to get the codes deleted so emissions wont matter.
 


GM put stricter parameters into the pcm's starting in 2000. A high flow cat with typically cause a code. If you have a universal or high flow cat, that's likely what is causing the P420 which is an inefficient cat code.
 
around lowell. you from the area?

i believe i have a universal cat, i bought the car with about 120k and the guy before me had a cat replaced at sullivan tire (repair was about $900!!!). i believe in mass they stick something over the exhaust to test emissions, so a high flow cat wont cause any problems with this?

-also guys thanks for all the help and quick replys, it is greatly appreciated
 
BillBoost37 said:
GM put stricter parameters into the pcm's starting in 2000. A high flow cat with typically cause a code. If you have a universal or high flow cat, that's likely what is causing the P420 which is an inefficient cat code.
Click to expand...

Thanks for clearing that up man. $900 for a new cat is retarded tho. Buy a cat from rockauto.com and have a general exhaust shop weld it in if you dont want to go the high flow route
 
I would love to get a highflow cat (to hopefully increase performance a bit?), i just wonder if those pass emissions here in mass. i believe they test the actual emissions and not just the computer codes, can anyone confirm this?
 


If you want to increase performance at the same time as keeping the car legal to pass emissions...ZZPerformance sells some pretty decently priced catted downpipes, that are larger than stock...gets rid of the factory u-bend as well...which is HORRIBLY restrictive...and have cats that don't fail...or any that I have seen for that matter. Most any cars after '01 have issues with the SES light tripping because of HF'ing converters...but I don't believe ZZP's trip the SES. If your worried moreso about the SES light being on over a tailpipe test...then get a rear o2 simulator...that plugs into the rear o2 sensor and tells the PCM your cat is there and in working order...they are like 30 or 40 bucks.
 
bluegtp91 said:
If you want to increase performance at the same time as keeping the car legal to pass emissions...ZZPerformance sells some pretty decently priced catted downpipes, that are larger than stock...gets rid of the factory u-bend as well...which is HORRIBLY restrictive...and have cats that don't fail...or any that I have seen for that matter. Most any cars after '01 have issues with the SES light tripping because of HF'ing converters...but I don't believe ZZP's trip the SES. If your worried moreso about the SES light being on over a tailpipe test...then get a rear o2 simulator...that plugs into the rear o2 sensor and tells the PCM your cat is there and in working order...they are like 30 or 40 bucks.
Click to expand...

Always get a tune too and get that code deleted. Even more umph. Still need the downpipe tho. and there around 150-200 just dont get ZZPs Tuned PCM there downpips are great tho
 
Tune really isn't going to do much...the extra "oomph" your feeling is the higher rev limit, no speed limiter, and skip shifts removed.
 
bluegtp91 said:
Tune really isn't going to do much...the extra "oomph" your feeling is the higher rev limit, no speed limiter, and skip shifts removed.
Click to expand...

How so? More timing also. Or are you getting at the fact that he wont really have many mods with the tune? I have a open cone, 3" dp and PLOG. Are you saying I wont see to much difference then?? I know you know your s^!t soooo. Im staying stock pulley more timing per your advice. So how would him getting a tune be any difference than me?
 
I'm pretty sure they don't tailpipe test. Because there's a lot of guys sliding through on reprogrammed pcms. I'll ask though.
 


chevyy1212 said:
How so? More timing also. Or are you getting at the fact that he wont really have many mods with the tune? I have a open cone, 3" dp and PLOG. Are you saying I wont see to much difference then?? I know you know your s^!t soooo. Im staying stock pulley more timing per your advice. So how would him getting a tune be any difference than me?
Click to expand...

Your boosted.

This guy is not.

Also...most box tunes don't screw with timing that much anymore from what I've seen. Stock is 16*...most companies are just removing some TQ management...richening up fuel tables...changing shift points, transmission line pressure, fan turn on points, and skip shifts(40mph kick down to 1st vs. 2nd gear)...the less stuff changed in the box tunes, the better IMO...every car is different and tuning needs to be tailored to each car specifically...while an aftermarket PCM is a nice upgrade...it isn't really a HP/TQ gainer...it just changes some factory parameters that suck.

Also...your right...you'll still notice a difference, but my GT just has an open cone and a few other odds and ends...and I have a DHP Tune in it...didn't really make much of a difference other than the higher shift points and lower temps like I stated. If I were the OP...I'd get a bolt-in 3" catted downpipe and be done with it.
 
alright i like what you guys are telling me! looks like i can turn this negative into a positive. so say i order a cat converter and ubend delete from zzperformance, i then just go to a local exhaust shop and have them weld it on for me??
 
madore9 said:
alright i like what you guys are telling me! looks like i can turn this negative into a positive. so say i order a cat converter and ubend delete from zzperformance, i then just go to a local exhaust shop and have them weld it on for me??
Click to expand...

Here ya go...
http://zzperformance.com/grand_prix/products1.php?id=551&catid=110

3" bolt-in WITH a cat...$189.99 + S&H.

To have an exhaust shop bolt it in for you...probably 20-40 bucks...I wouldn't pay more than that.

Worthwhile upgrade too...as you'll notice gains not only in performance, but MPG's as well.
 
bluegtp91 said:
Your boosted.

This guy is not.

Also...most box tunes don't screw with timing that much anymore from what I've seen. Stock is 16*...most companies are just removing some TQ management...richening up fuel tables...changing shift points, transmission line pressure, fan turn on points, and skip shifts(40mph kick down to 1st vs. 2nd gear)...the less stuff changed in the box tunes, the better IMO...every car is different and tuning needs to be tailored to each car specifically...while an aftermarket PCM is a nice upgrade...it isn't really a HP/TQ gainer...it just changes some factory parameters that suck.

Also...your right...you'll still notice a difference, but my GT just has an open cone and a few other odds and ends...and I have a DHP Tune in it...didn't really make much of a difference other than the higher shift points and lower temps like I stated. If I were the OP...I'd get a bolt-in 3" catted downpipe and be done with it.
Click to expand...

Oh well.. You win again lol. Im gettin a custom tune anyway no box tune so hopfully my timing will be higher. As for the OP I didnt realize he wasnt boosted so that kills qwite a bit on my end. I just shot the tune out there as another option to the O2 eliminator even tho it is more. Since he is N/A tho shouldnt he go with the 2.5" DP?
 
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