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Thread: Loss of Power past 4000 RPM

  1. #1
    GUEST DaHonda's Avatar
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    Loss of Power past 4000 RPM

    Hey TPC,

    need some help diagnosing my problem. I was driving on the 401E yesterday and all of a sudden I wasn't able to go any faster than 120 km/hr. The tachometer maxed out at around 4000 rpm and any gas given to it after that point I would feel a loss of power and the engine would sound like it'd be doing 7-8k rpm. I pulled over to the side of the street after taking the first exit and I could hear rattling and as if there were little pieces flying around inside the exhaust system as I was revving the engine in neutral.

    I'm thinking most likely its my catalytic converter dying out on me as my mechanic had told me before that the honeycomb inside was probably disintegrating. As a temporary solution do you think it'd be a good idea to find a mechanic to gut the cat just so I can drive back to Toronto and put on a new exhaust system?

    Would it be possible that the cat is clogged and creating back pressure in the exhaust system causing it to lose power at 4000 rpm? The check engine light turned on shortly after this but I have not checked the codes yet. I have replaced my spark plugs and distributor less than a year ago. I'm 430 km away from Toronto so any help or input would be much appreciated!

  2. #2
    Just some guy Grant's Avatar
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    Re: Loss of Power past 4000 RPM

    Clogged exhaust might do this....

    but it might be something worse.. did you check your oil level?

    Grant
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    Black 1995 SR <><

  3. #3
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    Oil levels were fine last time I checked...

  4. #4
    Gate 7 Ultras Fan OUZO Power's Avatar
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    Re: Loss of Power past 4000 RPM

    My money is on a clogged cat or bad injectors.

  5. #5
    GUEST Metz's Avatar
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    Re: Loss of Power past 4000 RPM

    so what happened???

  6. #6
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    I was just driving on my way to Cornwall and near Trenton I felt a sudden loss of power and it felt like I wasn't able to rev past 4000 rpm although the engine sounded a lot louder.
    When I pulled off to the side of the road I could hear rattling like little rocks moving around from under my feet in the exhaust.

    I just went to like 4-5 shops and no one will punch the catalytic converter out for me...

  7. #7
    GUEST 92siR's Avatar
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    Re: Loss of Power past 4000 RPM

    Try to find a test pipe?

  8. #8
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    Re: Loss of Power past 4000 RPM

    I think its to late now for any ideas,but you could've gone to a muffler shop and ask them to put any straight pipe,clamped thow,not welded.

  9. #9
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    They were all being uptight stating that having no catalytic converter is illegal blah blah blah but I just said I need a cheap temporary solution so I can drive back to Toronto safely. Fuuuu

  10. #10
    Man Made. Woman Broken. Lord Dragon's Avatar
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    Re: Loss of Power past 4000 RPM

    can you still call on vtech after 4200RPM?

  11. #11
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    I didn't want to push it, the engine sounded like it was in overdrive mode past 4k.
    My Vtech at home worked fine though.

  12. #12
    The Doctor is in drjless's Avatar
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    Re: Loss of Power past 4000 RPM

    you need to do a compression test bro. a burnt valve could be your issue. plugged exhausts dont happen instantly. valves do snap instantly. checking the cat is easy. undo the three bolts and let it hang. the hangars on the midpipe will hold it up. it will be loud but if it is the problem, theres your workaround. the compression test is easy. buy a tester at C-tire and its simple to do. just need a spark plug wrench. if an exhaust valve broke, you wont have any compression in that cylinder and parts of valve that would have been mangled by your piston will be floating around in the screen of your cat.
    The only true wisdom is in knowing you know nothing

  13. #13
    Man Made. Woman Broken. Lord Dragon's Avatar
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    Re: Loss of Power past 4000 RPM

    Quote Originally Posted by DaHonda View Post
    I didn't want to push it, the engine sounded like it was in overdrive mode past 4k.
    My Vtech at home worked fine though.
    haha - nice

  14. #14
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    Re: Loss of Power past 4000 RPM

    If you have no problem starting your car and Idling, im willing to bet it is the cat, usually engine issues are pretty obvious when they fail, loss of oil pressure, oil in coolant, Car on fire, etc etc

    I've had a cat plug on me in my rx7 same thing, cept I couldn't do better than 110 km/h lol

    unfortunately 99% of shops won't do it its a $50,000 fine for them to do it.

    Be careful driving it, the cat is probably Glowing red hot under your car and its very possible it can catch fire.

    You don't mention what year the car is but if it's a newer Lude there are 2 O2 sensors and if the cat has failed you should be throwing a CEL for it

  15. #15
    TPC Shooter Lude Awakening's Avatar
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    Re: Loss of Power past 4000 RPM

    Can't believe no one has suggested checking the CEL since it came on after the problem. This is easy to do with a paper clip and might help diganose the problem.

    http://www.hondaprelude.to/articles/...ck_engine.html

    Ive had a spark plug wire come loose at the distributor and have a similiar effect to what your describing. Perhaps check all the spark plug wires and ensure there on tight at the plug and dist.

    If it is the catalytic converter, you should be able to get any exhaust shop ( midas, crappy tire etc ) pick up a universal high flow cat and have the flanges from your OEM one cut and fit to the new one.

    However, a rattling sound might be indictive of another serious problem though. Check the CEL and let us know the code

  16. #16
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    OK well I was finally able to talk my way into getting an exhaust shop to remove the cat.
    They cut off piping a little before and after the catalytic converter and welded in a straight pipe.
    Cost me a good dime but if it means I can drive back to Toronto to put on my 2.5" exhaust then it's worth it.
    Didn't check the CEL codes but I'm pretty sure it's just from the O2 sensor readings.
    The cat was pretty bad, a piece broke off and rotated around and blocked off almost everything but now I can feel a little bit of extra power so I'm glad.

    Thanks for all the input though guys.

  17. #17
    Just some guy Grant's Avatar
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    Re: Loss of Power past 4000 RPM

    Sawzall, a pipe and a couple clamps from CanTire probably would have worked no?

    Grant
    Chairperson,
    Toronto Prelude Club
    Black 1995 SR <><

  18. #18
    GUEST DaHonda's Avatar
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    Re: Loss of Power past 4000 RPM

    I don't have a lift and they welded it pretty good so it'll do for now.

  19. #19
    GUEST Northern Sun's Avatar
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    Re: Loss of Power past 4000 RPM

    burning up O2 sensor, can do weird shiet when combined with working A/C

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