RPM float when shifting - Hyundai Performance Forums

hondakiller · 11-27-2002, 03:16 AM

I've noticed that when shifting in my 99' tiburon(manual) it seems like the ecm is keeping the engine RPM's up (I guess to help out slow shifters). Whenever I double clutch, I have to wait forever for the RPM's to drop to the correct RPM for the next gear. Is there any way to disable this inexpensively, without modifying the ecu? I think that the vehicle speed sensor might have something to do with it because it happens when the car is moving. Maybe a switch to cut off the IAC valve would eliminate it, but then the engine would stall if the RPM's got to low. Any suggestions would be helpful.

mouse · 11-27-2002, 03:35 AM

I'm not sure what causes it, or if there is a way to change it... but I have noticed it as well. Mostly I think just the ECM waiting for you to grab another gear.

**i8acobra** · 11-27-2002, 03:53 AM

This is for emissions. It's even worse on the Ford Focus.

richard734 · 11-27-2002, 05:03 AM

It is one of those inventions designed to aid smooth driving

Read the old double-de-clutch posts, but basicly the original reason behind DDC'ing was to keep the revs up between gear changes. ECM's allow the engine to take that function over.... Syncromesh and ECM's remove the need for DDC'ing in most cases, and I think it is more of fashion statement to talk about/do it on the street and is very F&F wannabee:lol:
But if you are using it properly and for good reason, the last comment was not aimed at you:duh:

joonie78 · 11-27-2002, 10:50 AM

hmmm, i don't know how serious your problem is...
but is it actually a problem?
just like richard said above, it helps smooth shifting in normal driving conditions
in sporty driving, the rpm drops slower so you are getting almost hill and toe effect
unless your rpm stays up for like 2 seconds or more, then it is a problem
my ecu, i set it up manually for that setting
my rpm drops a lil after a pause...it becomes a longer pause with A/C on..
so try to utilize it and i hope it's not a serious problem but a little advantage

:

peter.weedy · 11-27-2002, 07:52 PM

can some one explain (v. quickly) exactly what double clutching is.....i just dont know!

hondakiller · 11-27-2002, 08:46 PM

Hey guys, thanks for the replies. I disconnected my IAC valve today and despite the fact that it stalls if not revved, the idle falls much faster. Since I don't have A/C and am going to remove my power steering anyway, I guess I could just take out the valve. Do any of you know what would be the easiest way to get some air to the engine with the throttle plate closed. Should I just try to adjust my throttle cable to directly allow some air in, or would I need to do something more serious like drill a hole in the throttle plate?

P.S.- peter.weedy: Here's an article on double clutching:

http://www.urs4.com/technical/miscellaneous/Igor.html

ZX2GUY · 11-27-2002, 10:55 PM

yes your wasting your time double clutching with a sync. tranny.
unless you drive some old car without sycros
just upshift the floating rpms wont hurt anything
the year is 2002 get with the times double clutching is dead on production cars

[Edited by ZX2GUY on Nov 27, 2002 6:59 PM]

peter.weedy · 11-29-2002, 10:15 AM

dont think its necessary after reading about it......

Useless · 11-30-2002, 02:00 AM

O.K. maybe I'm an idiot, but why would you want ever double clutch on an upshift. If your involved in a race of any type, wouldn't double clutching cause a violent jerk? I understand that it raises your rpm's to reach your ideal hp/torque rpm, but in our cars, (my tib) won't that just lessen my available rpms caussing me to shift sooner?

Like I said I may just be an idiot, but please someone explain the logic in double clutching on an upshift!?!?