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Gusu
User
Oct 17, 2008, 3:11 AM
Post #1 of 6
(1817 views)
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inconsistent RPMs
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I have a 91 honda civic.
When I am driving at constant a constant speed my car seems to bog down but the RPMs do not change. If I am stopped my car will sometimes want to stall when taking off. Recently it has had an issue where I slowly accelerating from a stop light where my car went from not moving at all to 3000RPMs and a little roll to instantly shooting 6000 RPMs spinning the tires then right back to normal. Some days it will be totally fine and others it is horrible. From time to time unless I am accelerating a little bit it will start to bog down.
I had my clutch replaced about 4 month ago and my car ran great. I also changed spark plugs and the wires.
Any ideas as to what it would be?
Oh if this is in the wrong section sorry. I wasn't really sure where to put it since I'm not really sure what is causing it.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 17, 2008, 4:13 AM
Post #2 of 6
(1809 views)
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Re: inconsistent RPMs
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Guessing: This just happened AFTER the clutch job?
It can rev to 3,000 and barely move the car with foot OFF the clutch pedal? Then up to 6,000 and take off?!
Need to know what you are doing with the clutch pedal when this happens. This is all screwed up seemingly with clutch linkage or clutch itself not moving freely as told by pedal request if I'm reading into this right??
T
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Gusu
User
Oct 17, 2008, 5:50 AM
Post #3 of 6
(1803 views)
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Re: inconsistent RPMs
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Sorry I guess I could have gave you more information.
My cars clutch needs to adjusted so keep that in mind. It does nothing until about being let out about 70% from there, there is about a 5% difference from engaged or not.
I will do the same amount of clutch every time about 67% before applying about 20% gas for a slight roll and then go to about 35-40% gas for some moderate acceleration while letting the clutch out evenly and smoothly as possible. My shift times are good and I know I am not riding the clutch while I am shifting.
The clutch will be fully let go while i am taking off and the car will jump up almost to the redline instantly for no reason at all.
Its almost as if the power of the car is just not there then suddenly there is WAY to much power. Almost as if I were trying to launch my car or something.
While driving at a steady speed my car will bog down and seem as though it is losing power. Not something to terrible maybe a 10-15 HP lose on a civic.
My RPMs also rev up and down in neutral totally out of gear with the clutch engaged or disengaged it does not matter. Giving it gas will cause this to stop though.
If it is doing this before I take off my car will roll smoothly until about 10mph and then almost seem like it is stalling.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 17, 2008, 6:20 AM
Post #4 of 6
(1801 views)
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Re: inconsistent RPMs
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 Ok - I'm sufficiently confused. Does this clutch "slip" when your foot is off the pedal?
There's no adjustment for how well a clutch grabs just WHERE it grabs and some aren't adjustable. This should be a hydraulic clutch linkage which must be known in working order no matter what type of linkage is used. If this job was done just four months ago why does it need adjusting in your opinion? You can only adjust linkage not amount of grab as said.
Note: Improper adjustments or incorrect use of clutch can make a new one fail in short order.
Engine doing things on it's own is a separate issue from the clutch,
T
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Gusu
User
Oct 17, 2008, 8:16 AM
Post #5 of 6
(1798 views)
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Re: inconsistent RPMs
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When I first got my car the clutch needed to be pushed in farther and gradually needed to be let out more for a shift. The guy who installed it said that would happen and if I wanted I could have it adjusted so it would be needed to be pushed in all the way and let off very little so I'm not sure.
I am almost positive it is not the clutch slipping though. I have had a few bad clutches and I am pretty good and determining if that is happening or not.
I have had some friends tell me that it could be a fuel pump/filter, transmission needs flushed, vacuum leak and a few others I just don't recall at the moment.
I did find a vacuum leak and replaced the hose but could not find another leak anywhere and it is still acting the exact same way.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 17, 2008, 9:18 AM
Post #6 of 6
(1793 views)
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Re: inconsistent RPMs
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Two issues going on here. Your clutch doesn't care if the engine is running or not for all intents and purposes. This change you note is not normal and must be corrected at once.
A clutch will self destruct in certain conditions if linkage can allow it to drag,slip etc even it you aren't touching the pedal. Just the motion of the engine under certain loads changes the adjustment of "freeplay" needed that you feel at the top of a pedal where nothing happens and you can move that with a finger.
I just don't know what the heck is happening to you with the RPMs changing and vehicle surging. I'm about certain this is a hydraulic linkage to clutch. That is that it uses a master cylinder like brakes do thru lines, a flex hose and to a slave cylinder to apply the pressure you request. If there's a problem - even air in that it will misbehave erratically. Perhaps if there's air in lines at just the wrong place it can get hot and expand in the lines with perhaps being close to engine/exhaust heat and do really funky things.
Know this: When clutch is "disengaged" as in foot to the floor it has essentially disconnected the engine from the drivetrain. If there's some residual connection it's the fault of linkage usually or maybe the clutch parts have broken such that they are jammed up - dunno.
Gotta have a known good running engine first or last - your call. You could know a clutch is behaving while coasting engine off down a long hill but that isn't practical for most folks.
Maybe it's me but so far this is like trying to fix or diagnose a handling or aligment problem with a flat tire.
Perhaps it's best if you get this checked out by a shop familiar with both clutches and engine operations to clear this up. I apologize but I'm lost??
T
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