The cause for rev-hang

[anavrin351]

This hasnt been brought up in a while, atleast that i have seen, but today i was thinking that the revhang and the DBW delay had something in common. I tested the theory today while driving around.

I found out that if the clutch is pushed in while releasing the gas, (like a normal shift) the rev hang is there. When i let off the gas and waited to push in the clutch until the motor started to slow down the car, there was no rev hang.

Now when i am driving and traffic slows down a little bit, not enough for brakes, the car doesnt start to slow down for about 2-3 second. Thats the DBW causing that. So the rev hang is caused by the DBW not letting off the accelerator for a delayed period of time. This could be a total coincidence, but i thought i would post this up, and let you decide for yourself. I hope this isnt a repost that has already been figured out, if so.........oops

[I Vtec, do you?]

No I think you're right.. someone posted this in the last thread about DBW lag I made. If you let off the gas before the clutch, there is practically no hang. My shifts = buttery smooth now. Ok not really, but they're better. 2nd gear still gets me!

[opticpursuit]

is there a fix for rev hang besides hondata reflash?

[AllShowNoGo]

dont let this one turn into a "bitch post" like the other "rev-hang" post turned out to be....

[nayilsi]

2nd gear is frraaaakin shiiaatt

its only smooth when im driving slower than a reg civic.

[anavrin351]

^^thats because your trying to fix it before the ECU has caught up to the peddle position. Push in the clutch, put the gas peddle to the floor and let off. Do that in a fast motion, and you will watch your RPMs only jump to about 2k. Do it in any non DBW car and the rpms jump almost immediatly, and go high. It acts the same way with the clutch out, while you are trying to get rid of the jittery feel, the ECU is still catching up to the position the gas peddle was at before you started to adjust.

[07mugencivic]

[radiocontrolhead]

This has been covered multiple times.

[Agnt004]

So is the ECU computer just not quick enough to realize the throttle has been lifted? Maybe Honda needs to upgrade the RAM.

[volvo9]

Originally Posted by opticpursuit

is there a fix for rev hang besides hondata reflash?

Hondata fixes rev hang?

[onequickfamilysedan]

rev hang is common in alot of cars and is for emissions. It keeps the car from dumping excessive fuel, and there by running overly rich

[Tastycakes]

The delay between when you take your foot off the gas and the butterfly on the TB closing is minimal. Go into your garage and turn the key to on and floor it, then back off, then floor it again (w/ the engine off of course ) . You can hear the motor on the butterfly closing and opening depending on the gas pedal. It is quick enough, it just chooses not to be .

[divinebarrel]

Originally Posted by onequickfamilysedan

rev hang is common in alot of cars and is for emissions. It keeps the car from dumping excessive fuel, and there by running overly rich

i had slight rev hang in my 04 1.8 sentra it wasnt as bad as the si but it was 100% there

[Tastycakes]

I'd take a guess to what happens. I think it might cut the fuel but leave the butterfly open for a second to lean it out for less emissions?

[07LX]

I don't have a problem with rev hang in my LX, and I usually am on the gas before I let off the clutch when I shift.

You want rev hang my 06 1.8S sentra was horrid not to mention that the shifter was like 6 ft tall, not literally.