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mvvette97

Gutted stock cat on 02 vfr. Don't do it

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Hey guys I has a spare stock header for my 02 vfr800 so I thought I would try gutting the stock cat on the spare system. Got it done to swapped the headers lastnight and was able to take it for a spin thismorning. Sounds pretty tough but it killed the power. The two short wide open bursts I did it felt like a dog and would not even rev past 10k. I do have a power commander coming in the mail but I'm going to put my original header with the cat back on. I'm sure may have wondered how it would run without the cat on stock tuning and now I can telll you. haha. Glad I only paid 20 bucks for the spare header. It was worth it just to see what it would do. I'm sure tuning it on a dyno would probably fix the issue but to me it's not worth the cost. So if you want to gut the cat I would say don't do it unless you have a spare header around that you got for free or little to nothing. Stock going back on so I hope this info will help others that was wondering the same thing as I was. Cheers.    

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I put my stock exhaust back on. It still doesnt run right. It's like the vtec doesn't kick in. I read somewhere that the coolant temp has to be so high or it won't work. Is this true? It's about 40 degrees here so it's pretty cold. My coolant temp was running about 135. Is it just not warmed up enough since it's so cold outside? 

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yeah, something's not right about that temperature.  even with a stuck-wide-open thermostat VFRs run warmer than that.

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well it was fine the other day when it was 60 out. I just looked at the temp outside now and it 34 degrees. I went for a drive again and this time let it warm up by driving slower and it got to 165. Now it runs fine. I let it cool off a bit to see at what temp the vtec will kick in and it looks about 150 degrees. I feel stupid now. Didn't know it had to be a certain coolant temp to allow vetec to work. This is my first Honda I have ever owned and just bought it last week. I guess this is how ya learn. haha   

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4 Valve = RPM greater than 6,800 and coolant temp greater than 149degF.

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yea that's what my problem was. Just wasn't warmed up to temp. I didn't think anything about the temp being to low for the 4 valves to kick in. My zx14 doesn't have all that.

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So are you going to put the gutted headers back on and try again with the engine at the correct temp?

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On 3/23/2018 at 9:49 PM, Marooncobra said:

So are you going to put the gutted headers back on and try again with the engine at the correct temp?

Yes I put it back on and ran it longer to get the engine up to temp better. It was so cold that day the bike had trouble getting up to temp at highway speeds. It ran great! As for power gains I have no idea but I can say it didn't lose any. It seemed to pull a bit harder in the upper RPMs. The best part is that it sounds so deep through the exhaust. Not alot louder than before but deeper. Almost like an old big block chevy or ford V8. I have the mufflers gutted as well. Currently still running the O2 sensors as well with no FI light or anything.

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