Ghionw Posted January 30, 2020 Share Posted January 30, 2020 Good Afternoon guys, I have a 10' GT that is throwing a P0420. I switched the O2 sensors when it first happened a few years back, but now it is coding again. My mechanic said it is more than likely that the Cat is on it's way out. My question is, should I simply get a new Cat (~$1100) or get a new catted downpipe ($600 Invidia) and go from there? I've read that most have overboost issues when they upgrade their downpipe. Looking for advice/suggestions. Currently OTS Stage 1 with an Invidia catback. Link to comment Share on other sites More sharing options...
mcg_ Posted January 30, 2020 Share Posted January 30, 2020 In brief, according to this forum, overboost issues from the invidia catted DP seem rare (maybe even non-existent). Nonetheless, if overboost occurs, porting your WG would very likely take care of it. Upside is that you could get a stage 2 tune! The vast majority of the overboost issues occur in (a) non-catted downpipes or (b) nameless (the brand) downpipes. Link to comment Share on other sites More sharing options...
Ghionw Posted January 30, 2020 Author Share Posted January 30, 2020 Sounds like stage 2 is more cost effective Link to comment Share on other sites More sharing options...
FLlegacy Posted January 30, 2020 Share Posted January 30, 2020 Sounds like stage 2 is more cost effectiveNot really, a tune is another $4 to 500. Then all the other mods you will need. The bpv, ebcs, clutch, clutch fork, tsk-3 kit...head gaskets, new shortblock...[emoji2369][emoji1787] Sent from my SM-G965U using Tapatalk Link to comment Share on other sites More sharing options...
Ghionw Posted January 30, 2020 Author Share Posted January 30, 2020 Not really, a tune is another $4 to 500. Then all the other mods you will need. The bpv, ebcs, clutch, clutch fork, tsk-3 kit...head gaskets, new shortblock...[emoji2369][emoji1787] Sent from my SM-G965U using Tapatalk lol. Well, I already replaced my clutch last year with a South Bend stage 2, or was it stage 1. I'd have to double check. I have the racer X charge pipe with a bpv. For a mild tune, what else would I need for supporting mods? Not looking to maximize power. Link to comment Share on other sites More sharing options...
FLlegacy Posted January 30, 2020 Share Posted January 30, 2020 lol. Well, I already replaced my clutch last year with a South Bend stage 2, or was it stage 1. I'd have to double check. I have the racer X charge pipe with a bpv. For a mild tune, what else would I need for supporting mods? Not looking to maximize power.I was mostly kidding, but now I hope you replaced your clutch fork, those have seemed to fail quite suddenly especially with an aftermarket clutch. Sent from my SM-G965U using Tapatalk Link to comment Share on other sites More sharing options...
Ghionw Posted January 30, 2020 Author Share Posted January 30, 2020 I was mostly kidding, but now I hope you replaced your clutch fork, those have seemed to fail quite suddenly especially with an aftermarket clutch. Sent from my SM-G965U using Tapatalk Mine did fail and my housing was even damaged in the process. So, yea, had to replace that as well. Link to comment Share on other sites More sharing options...
FLlegacy Posted January 30, 2020 Share Posted January 30, 2020 What exhaust are you using now? That seems to be where the overboost comes in. The stock midpipe really helps keep the turbo in check. Sent from my SM-G965U using Tapatalk Link to comment Share on other sites More sharing options...
Ghionw Posted January 30, 2020 Author Share Posted January 30, 2020 What exhaust are you using now? That seems to be where the overboost comes in. The stock midpipe really helps keep the turbo in check. Sent from my SM-G965U using Tapatalk Invidia catback Link to comment Share on other sites More sharing options...
FLlegacy Posted January 31, 2020 Share Posted January 31, 2020 Invidia catbackYou can always try it on a ots stage 2 map. If it's going to overboost it will do it on any map. Sent from my SM-G965U using Tapatalk Link to comment Share on other sites More sharing options...
Ghionw Posted January 31, 2020 Author Share Posted January 31, 2020 If it overboosts, I'll probably go back to the stock exhaust. Do I need upgraded fuel pump? And is the EBCS needed for a mild setup? Link to comment Share on other sites More sharing options...
FLlegacy Posted January 31, 2020 Share Posted January 31, 2020 If it overboosts, I'll probably go back to the stock exhaust. Do I need upgraded fuel pump? And is the EBCS needed for a mild setup? It shouldn't overboost with the catted dp, the ebcs is up to the tuner some like the control of the aftermarket ones better. Fuel pump would be worthwhile if your due for a filter change anyway, every 60k miles. I plan on doing mine around the time I do my timing belt and clutch. Link to comment Share on other sites More sharing options...
coco26 Posted January 31, 2020 Share Posted January 31, 2020 For reference, I have an invidia catted downpipe, magnaflow catback, and bpv. I had pre-stage 2-tune overboosting issues (likely more due to the bpv than the downpipe). I exceed the capabilities of my southbend stage 2 with my stage 2 tune... so you don't need anything more than those three parts if you don't want it. Link to comment Share on other sites More sharing options...
stewdogg Posted January 31, 2020 Share Posted January 31, 2020 What are your short and long term goals for the car? Are you keeping it for a while? Are you willing to blow it up and build it up again? Are you hard on the car? Building these cars can get expensive real quick. I just keep throwing money at mine. It was once my daily (for a very short period of time) and is now my garage queen summer car. Link to comment Share on other sites More sharing options...
Ghionw Posted January 31, 2020 Author Share Posted January 31, 2020 It shouldn't overboost with the catted dp, the ebcs is up to the tuner some like the control of the aftermarket ones better. Fuel pump would be worthwhile if your due for a filter change anyway, every 60k miles. I plan on doing mine around the time I do my timing belt and clutch. Yea, I did my timing belt/water pump end of last spring and then my clutch fork went shortly after. So I opted for the South Bend Stage 2. For reference, I have an invidia catted downpipe, magnaflow catback, and bpv. I had pre-stage 2-tune overboosting issues (likely more due to the bpv than the downpipe). I exceed the capabilities of my southbend stage 2 with my stage 2 tune... so you don't need anything more than those three parts if you don't want it. Thanks. Going for a simple setup. What are your short and long term goals for the car? Are you keeping it for a while? Are you willing to blow it up and build it up again? Are you hard on the car? Building these cars can get expensive real quick. I just keep throwing money at mine. It was once my daily (for a very short period of time) and is now my garage queen summer car. It is my daily driver. I am willing to keep the car but I am not looking to build a high power car. A simple stage 2 setup would probably be the extend of my mods until some time way down the road. I really don't want to blow it up, which is why I would go with a conservative stage 2 setup/tune. More about reliability and smoothness over power. Link to comment Share on other sites More sharing options...
dgoodhue Posted February 1, 2020 Share Posted February 1, 2020 This has come up a couple times recently about checking the catalytic converter by data-logging, so I tried it on my 121k mile LGT with a Cobb AP. The parameter to log on the AP is 'AF Sens 3 Voltage'. Instead of logging it, you can also display the parameter on the AP gauges screen. The pictures are of steps 2 and 3 of the P0420 code in the FSM, the 2nd wave form in each is what a bad catalytic converter would look like. I didn't do the 50-70mph log step 2 with my car (I suspect you would want to do this in steady state/speed) but I did step 3 with my car warmed up. My car mostly stayed 0.75V and every once in awhile went to 0.8V or down 0.6V for reference. Link to comment Share on other sites More sharing options...
Ghionw Posted February 5, 2020 Author Share Posted February 5, 2020 Thanks for this. I am in traffic most of my commute but I will see if I can get some readings at 50-70 mph. Hopefully my APv2 has the required monitor. Link to comment Share on other sites More sharing options...
Ghionw Posted February 6, 2020 Author Share Posted February 6, 2020 Of course my APv2 doesn't have the 'AF Sen 3 Voltage' monitor. Strangely enough, the code cleared itself last week and stayed cleared for a few days and returned. And then it cleared itself again yesterday. Link to comment Share on other sites More sharing options...
dgoodhue Posted February 8, 2020 Share Posted February 8, 2020 Of course my APv2 doesn't have the 'AF Sen 3 Voltage' monitor. It may have a different name. My other scan tool referred to it O2S12. Strangely enough, the code cleared itself last week and stayed cleared for a few days and returned. And then it cleared itself again yesterday. IIRC The sensor logics is that it needs to meet the threshold 3 times before it sets a check engine light. If the code is reset, it will need to meet the threshold 3 more times. Link to comment Share on other sites More sharing options...
Ghionw Posted February 9, 2020 Author Share Posted February 9, 2020 It may have a different name. My other scan tool referred to it O2S12. IIRC The sensor logics is that it needs to meet the threshold 3 times before it sets a check engine light. If the code is reset, it will need to meet the threshold 3 more times. I'll check. The code cleared itself. I didn't reset the ECU. But I've seen it clear itself and come back, so I'll continue to monitor it. Link to comment Share on other sites More sharing options...
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