I noticed today that when I shift gears my rpm does not drop right away when I step on the clutch like it should. When you step on the clutch , the rpm should drop down until you put it in gear and step on the gas . I do know that when your clutch goes out this can also happen , but my clutch feels good and does not slip. My car is a 99 Accord Lx sedan 5 spd. Thanks in advance.

 

my 92 prelude does the same thing i dont know why but it takes a sec to drop down maybe somethin to do woth compression or something idk

 

IS this normal on these cars?

 

sounds not like a good thing.

 

its called rotational mass, think of it, your flywheel is heavy and its still spining. so when you put the clutch in for a second it will stay till it loses forward velocity.

 

i have a lightweight flywheel and my still does it

 

thats not good, flywhee;s are supposed to make the revs more responsive

 

it may be the way you shift... if your foot never comes completely off the gas if may give it just enough to keep the rpms up for that second.

 

I'd look for a sticky throttle cable, then a sticky throttle body (throttle shaft bushings).

Maybe your IACV is sticky & doesn't close like it should?

 

Mine does it a little but it's not nearly as bad as my last car. I think that part of it has to do with emissions control, which prevents the throttle from slamming shut to prevent...something. I think it's trying to eliminate backfiring from a suddenly rich mixture due to an instantaneous loss of airflow. That was the explanation given to my by my Volvo mechanic when it was driving me nuts.
As others have mentioned, shifting technique can help. Taking your foot all the way off the gas before clutching results in a quicker loss of RPMs than if you start to clutch and lift off the gas at the same instant. Fractions of a second can make the difference.

 

p.s. keeping your rpms up when you shift should be considered a bonus, higher rpms means a harder shift, which means faster accel.

 

Ok, a little help for you guys. In our day and age most auto manufactuers are trying to make their parts last longer. In the old days when you shifted, 9 out of 10 times, unless you knew what you were doing, you ground gears. then came the glorious invention of the synchros. These little bastards stick out a little to keep contact with your flywheel (no I'm not 100% sure they stick to the flywheel) and keep your gears in the proper RPM for good shifting. One way they do this is with the symptoms you are describing.

When you go from 1st gear to 2nd, your rpms in the gear housing will drop lower, say from a 4-1 ration to a 3-1 ratio, meaning your engine will turn less rpms for the same amount of rpms from your transaxle. When you shift, your motor is designed to turn rpms at the previous RPM for a second or two to help with the shifting into the next higher gear. This helps for two reasons (that I know of)

1. It helps you so that you don't have to slam gears like a mad man. You can take your time so you can shift from 2nd to 3rd without worrying about getting 5th or even 1st gear.

2. When you release the clutch after selecting your gear, the higher rpms help it go more smoothly.

The main thing they are shooting for here is the average person shifting gears. The time it takes for the rpms to start dropping should be perfect for the timing of the driver's foot to release the clutch, equaling a perfect shift. This helps for their wear and tear and ultimatly, saves the manufactuer money.


Yes I know there may be a few things wrong with my post, and by all means correct them, but I'm trying to help someone out who think's there is something wrong with his/her car when there is nothing wrong at all.


PS: May car does NOT do this, I think the primary reason is because I changed my pulley's, intake, and exhaust. All meaning less pressure for the engine and easier to fall RPM's. My other car, the Escape does take forever to lose RPMs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Obsidian &raquo;</TD></TR><TR><TD CLASS="quote">In our day and age most auto manufactuers are trying to make their parts last longer. In the old days when you shifted, 9 out of 10 times, unless you knew what you were doing, you ground gears. then came the glorious invention of the synchros.</TD></TR></TABLE>Hey, I'm more than twice your age & when I learned to drive (before you were born) it was pretty hard to find a non-synchronized car...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Obsidian &raquo;</TD></TR><TR><TD CLASS="quote">
These little bastards stick out a little to keep contact with your flywheel (no I'm not 100% sure they stick to the flywheel) and keep your gears in the proper RPM for good shifting. One way they do this is with the symptoms you are describing.</TD></TR></TABLE>Ummm, NO.
Synchros are like little clutches inside the tranny. Nothing sticking out. But I don't believe that's got anything to do with what's going on.

In the old days ('60s) when you lift the gas pedal to shift, your carburator goes really rich for a moment. Maybe you get some popping in the exhaust from the rich mixture igniting.

In the '70s they had to do something about that. Some clever & some stupid ideas to handle that. Mostly there was mechanical doodads on the throttle, to let it close slowly instead of just snapping shut. With oil, dirt, & drivers who didn't know how to use a screwdriver, that stuff would get funny & then the RPM would hang up.

Eventually, with the engine controls we're used to these days, it's just some software to completely turn off the fuel injectors during this short moment when the throttle snaps shut. That stuff started in the late '80s. Peja (original post) has a '99 Accord. There shouldn't be anything to prevent the throttle from closing.

 

Well then I am corrected. I know the syncros stick out to act like little clutches but I wasn't 100% sure. I am sure, however, that I read in a tech magazine that the main reason for the throttle hang, especially, in manuals is to help with the shifting. I've heard people ask this question many times and when it gets down to it, the answer I just gave, (not about the syncros part) about the hang to help for shifting, is the one they normally get.

I work on a lot of motors (not too many trannys) so I'm always open minded as to what can cause something. I'm still learning a lot and I plan to keep on learning, but this is what I was taught so I'm learning different.

 

Yeah, the throttle hangup was a kind of multi-purpose feature; or maybe that story just sounded better than saying it was just for EPA emmissions. I personally found that it made it a little harder to shift smoothly.

When people say 'THE OLD DAYS' was the '80s, now THAT makes me feel old! So I was kinda glad to hear that the old days was actually before MY time!

The synchros act against the gearset that they're attached to. So when you push the gearshift lever from neutral towards the gear, you press that clutch/hub against it's gear. This sorta 'persuades' the gear to spin at the same speed as the synchro hub, allowing the hub to engage into the gear.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">
The synchros act against the gearset that they're attached to. So when you push the gearshift lever from neutral towards the gear, you press that clutch/hub against it's gear. This sorta 'persuades' the gear to spin at the same speed as the synchro hub, allowing the hub to engage into the gear.
</TD></TR></TABLE>
the hub also being known as the collar.

 

One of the most informative threads I think I've seen on here in a while. And I haven't seen the occasional ****** running around putting everyone down yet. Good stuff to learn here buddy.