I have bad catalytic converters on my car. I was wondering would it be cheaper to just get straight pipes or go with high-flow cats again? Could I even run straight pipes without any problems, or would it throw off sensors? Basically how hard would it be to get straight pipes working correctly on the car?
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slp longtube headers, slp y-pipe, high-flow cats, superchips programmer, slp 85mm air sensor, slp loudmouth exhaust, ws6 hood, slp cai, kn air filter, slp high-flow lid, smooth bellows, tb bypass, subframes, lca's, panhard bar, torque arm. -
How do you know the cat is bad?2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen" -
Are you getting a cat specific code? What led you to believe you had a bad cat? Not saying we don't trust your judgement, just trying to better help you.
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The car was tested by a local dealership, and I was told that the cats are bad. If anybody has helpful information please chime in on the subject.slp longtube headers, slp y-pipe, high-flow cats, superchips programmer, slp 85mm air sensor, slp loudmouth exhaust, ws6 hood, slp cai, kn air filter, slp high-flow lid, smooth bellows, tb bypass, subframes, lca's, panhard bar, torque arm.Comment
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You have a 5 year old car with aftermarket cats that are less than 5 years old and they are already bad? I question the diagnosis from the mechanic. Why does he say it is bad? Did it not pass emissions? I kind of doubt that since you are asking about going with a straight pipe.2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen"Comment
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If you are looking for a power gain by going with a straight pipe in place of the cats, there ain't much there if any at all.
Lots of people also regret getting rid of the cats because of the raspiness of the exhaust and the sulfur odor in the exhaust. The smell doesn't bother me but the raspy exhaust note does.Comment
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I do not have to pass emissions here in florida. I appreciate the other input, but lets try and stick to the original question please.slp longtube headers, slp y-pipe, high-flow cats, superchips programmer, slp 85mm air sensor, slp loudmouth exhaust, ws6 hood, slp cai, kn air filter, slp high-flow lid, smooth bellows, tb bypass, subframes, lca's, panhard bar, torque arm.Comment
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It won't adversely affect the "pre" cat o2 sensors, but you will have to run o2 simulators for the "post" cat sensors if you don't want to set a code for the rear 02 sensors.
The rear o2 sensors only tell the PCM how effectively the cats are working. They do not control fuel trim like the "pre" cat sensors do.
Thunder Racing sells the o2 sims.Comment
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I still question if yours are bad. I have a hard time believing they are bad.Originally posted by smokin2001Formula
Cheaper? Not if you get caught having removed them.
If you remove them you will have to get O2 sims or get the PCM reprogrammed to remove the rear O2s. Compare that to the cost of just replacing them.2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen"Comment
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How many miles on your car? It may still be under emissions warranty, and the cat replacement would be free.... can't get any cheaper than that.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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His sig says "slp longtube headers, slp y-pipe, high-flow cats". It would be a mfg warrantee from the cat mfg rather than a GM warrantee but it's worth a try.Originally posted by Injuneer2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen"Comment
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I'm not sure why I even posted.... he seems like he's already made up his mind and just wants someone to tell him to put in a straight pipe.
A buddy of mine had a 98 T/A with LT's, and straight pipes. He replaced the straight pipes with CarSound cats (Mufflex did the install to check the CarSound cat performance) and he picked up a consistant 1 to 2/10ths. And the car sounded a lot better. LS1's with straight pipes do not sound very good at low RPM.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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I have to agree. I've heard an LS1 Z28 with straight pipes. To me, it sounded like an old truck with a bad exhaust leak.... Especially at idle. A bit louder? Sure. However, louder isn't necessarily better.Originally posted by InjuneerI'm not sure why I even posted.... he seems like he's already made up his mind and just wants someone to tell him to put in a straight pipe.
A buddy of mine had a 98 T/A with LT's, and straight pipes. He replaced the straight pipes with CarSound cats (Mufflex did the install to check the CarSound cat performance) and he picked up a consistant 1 to 2/10ths. And the car sounded a lot better. LS1's with straight pipes do not sound very good at low RPM.SOLD: 2002 Trans Am WS.6 - Black on Black - 6 Speed
SLP Loudmouth Exhaust
17K Miles
2005 Acura TL - Silver on Black
Navigation - Surround Audio - Bluetooth
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Well thanks for all of the replies first of all. Secondly to answer injuneer's question the car has 48,000 miles on the clock. I also have the car being checked out as we speak at a different reputable shop besides the dealer that I took it to already. These are not stock cats as well. They are high-flows that I replaced when I had the lt headers put in to replace the stock ones. I switched the headers and cats out about a year to a year and a half ago. Besides the cat ordeal I had also posted about a week ago about my ls1 possibly being in trouble. People told me to chek connections on the batterty and other minimal things which were all normal. It was runing funny like bogging down in the morning for a short period (5 seconds), then after I let off the gas it would run fine again. Also I had a weird problem with all of the guages flat-lining on me a few times. The car also unusually runs at 3,000 rpms at 70-80 mph in regualr Drive with the a4. The car also seems to start off like a real dog almost as if it were starting off in 2nd gear. Then also the car drops off in rpms immediately to the neutral level for rpms at any speed when driving it and I let off of the accelerator. Then when I accelerate the car picks up in rpms as if it were at the rpm point already. Where to begin with your analysis? I don't even know. It seems like everything is going wrong. Please help out. Injuneer I know you have quite a bit of experience with f-body's, and I'm hoping you will continue to chime in. As do I hope others will as well.slp longtube headers, slp y-pipe, high-flow cats, superchips programmer, slp 85mm air sensor, slp loudmouth exhaust, ws6 hood, slp cai, kn air filter, slp high-flow lid, smooth bellows, tb bypass, subframes, lca's, panhard bar, torque arm.Comment
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Well, I think you would really benefit by monitoring the PCM with a laptop. Get a interface cable and some software for a laptop and log some data. You can then post it here and have the members provide feedback on it.
If your cats are shot after such a short time, I'd say there is a problem. Getting a log of the data from the PCM would be a solid first step in getting an answer. Anything else is just speculation.Tracy
2002 C5 M6 Convertible
1994 Z28 M6 Convertible
Current Mods:
SLP Ultra-Z functional ramair, SS Spoiler, STB, SFCs, Headers, Clutch, Bilstein Shocks, and TB Airfoil. 17x9 SS rims with Goodyear tires, 160F T-Stat, MSD Blaster Coil, Taylor wires, Hurst billet shifter, Borla catback with QTP e-cutout, Tuned PCM, 1LE Swaybars, 1LE driveshaft, ES bushings, White gauges, C5 front brakes, !CAGS, Bose/Soundstream audio, CST leather interior, synthetic fluids
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