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Old 07-24-2011, 02:58 PM   #1
Awyman18
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Default cat converter causing lower boost?

So...I was driving my 1990 toyota supra turbo, and my friend who was driving behind me said that he could smell rotten eggs. So I'm guessing the cat is bad. Also, I'm only boosting around...5lbs..could a bad cat effect the boost this much? Stockk boost is supposivly around 6.7-6.8ish
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Old 07-24-2011, 04:09 PM   #2
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well yes. the material in the catalytic converter may have melted over in places causing a severe restriction to exhaust flow and preventing boost from developing.


I would check for any vac leaks first, its ez enough. When your boosting do you see you needle dropping even with pressure on the throttle? thats one ez way to check for a major vac leak.
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Old 07-24-2011, 04:21 PM   #3
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No the needle never drops when on the throttle. So I don't think its a vac leak
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Old 07-24-2011, 07:38 PM   #4
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A bad cat can definately cause problems. If it has to be replaced I'd recommend a hi-flow cat. Magnaflow has a good one that I'm running.
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Old 07-24-2011, 07:54 PM   #5
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Yea I plan on just buying a test pipe because I'm getting a new exhaust here soon. 3" pipe, the whole shabang. And I live in ohio and the emmission rules are lax
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Old 07-24-2011, 09:47 PM   #6
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I took off my Cat from my supra mk3 7m-ge. i really felt the difference when i took it off compare when i actually had it
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Old 07-25-2011, 02:13 PM   #7
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Lax laws or not, doing the right thing would be replacing the cat, not just removing it. A good quality cat would still allow for good exhaust flow.
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Old 07-25-2011, 06:28 PM   #8
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Using a test pipe is a good idea. They were designed to prevent expensive catalyst damage during tuning and racing and are not intended to replace the cat permanently. They are technically only legal off road regardless of state emission testing. Once the car has been tuned well, you can install a good hi-flowing catalyst. You should notice little to no decrease in power and the cat should last awhile.
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Old 07-25-2011, 08:46 PM   #9
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hmm well I agree with all the above statements. I would recomend running a highflow cat If you decide to put a new one back on. Altho that is entirely up to you. I'm not going to be as presumptuous and tell you whats right and whats wrong. A high flow cat from magflow will give you the same gains as running one w/o. If money is tight and you choose to run the test pipe till you save up, you still have an option of just going straight 3'' all the way back. Either choice is yours. Hell, I ran mine with just the downpipe for about 3 days while my exhaust was being fabricated. Altho I wouldn't recommend it I'm not going to tell you it's wrong. The thing with just deleting the cat all togather is the fabrication will probably run you about the same as a high flow (maybe.) and yes running the test pipe as a permanent solution isn't really worse off then running cat delete. if you want to take the risk, but again these are just options of what is available to you.
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Old 07-26-2011, 05:29 AM   #10
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well...thanks for the advice, and...we shall see on the cat lol
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