99accord lx 4dr 5spd, When i'm shifting gears when i push the clutch in, the rmps go up just slightly then down slowly even though my foot is off the gas before i push the clutch in, what's going on? if the car is in neutral and i hit the gas and push the clutch in it does nothing.

 

i got a 99 accord 2dr 5spd and sometimes when i shift it does that to me too, i believe thats normal because your accelerating, and when you push the clutch in the rpms should go up a tiny bit becase you just let go of the gas and put in the clutch. are you putting in the clutch right after you let go of the gas? b/c it should be normal, unless it jumps up the rpms largely

 

well i own a 90 crx, been driving it for 8 years and over 100k miles and it's never done that(maybe the crx is screwy). yes, right after, the rmps don't go up very high, maybe 200 at the most, i just thought it was weird that the rmps were still going up when my foot was off the gas.

 

yeah, does it constantly do it?

 

yes, it's most notable in switching from first to second gear

 

well i think i found the answer

To try to get around this upshifting problem, auto engineers added what is called a "dashpot" to the throttle system. This causes the engine to not slow down so quickly when the throttle is released - essentially, if you take your foot off of the gas pedal quickly, it causes the engine to think you are taking your foot off much slower. If you are in neutral and rev the engine to 3000 rpm, then suddenly take your foot off the gas pedal, you will notice it takes a second or two to return to idle. This is the work of the dashpot. However, this does not help us at all when downshifting.

from...http://www.nerocam.com/ManTrans.asp

 

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Those 2 engine-control systems are very different from one another. I thought they haven't used those dashpots for quite a few years. The ECU controls the IACV to sorta do that job.

Besides, throttle dashpots were more important on carburators & early injection systems. Now there's smarter ways to avoid the rich-mixture when you suddenly close the throttle.

 

so do i actually have a problem with my accord? So the IACV is causing the rpms to hover and sometimes go up instead of just dropping like in the crx?

 

Depending on how severe it is, maybe it's not normal. Our '98 has an auto.trans, so I can't really compare.
Maybe the IACV is sticking, or maybe the base idle isn't set right?

 

base idle is fine, it's not that bad, i think it just might be that im used to driving the crx. Ill test drive a honda accord of the same year to see if it does the same thing. Thanks for the replies.

 

It's not for fuel effieciency or anything like that. It's mainly for people who have a stick shift. It keeps the rpm higher for a second longer so that it should be in a good rpm range when you let off the clutch in the next gear.

Mainly just for people driving a stick so that the clutch doesn't burn out from being at 700 rpm when you're doing 60 in 2nd gear and shifting to third. Better to have your RPM at 6000 and drop to 4500 to be in the 4000 RPM range than to have it be at idle and your car surging forward...


Did I make any sense of this at all?

 

yeah it makes sense, it was my second car with a manual i've driven and it was very different, thought it was broken