Honda Fit rev hang issue

Hi all,

We have a 2010 5 speed Honda Fit. Bought it for my 16 year old's first car and a family project. 

I have noticed when shifting that the revs hang for a second or so after the clutch is depressed. This adds pretty makes you have to slow down the shifting process if you want a smooth shift.

I have read in a few places that this is intentional on Honda's part for emissions reasons. 

Is this something others have noticed? Maybe in other Hondas or even other makes. Its a little annoying and I would like to understand whether the car is behaving normally or there could be some issue we need to resolve.

Thanks

Rev hang is real. It's been a thing for about 2 decades now.  I remember my 2002 elantra having it and that body style started in 01. 

Heavy flywheel + clutch delay valve probably. 

I can't speak to the Fit directly, but every modern manual transmission car I've driven does this for the same reasons.  It's usually only noticeable on full throttle acceleration, and you can usually mitigate it a bit by lifting to half throttle and pausing for a split-second before the shift.  If I'm trying accelerate quickly, I end up just dumping the clutch and letting it slip.  I assume that the only actual fix would be an aftermarket ECU, but would love to hear if there are other options.

Slippery said:

Heavy flywheel + clutch delay valve probably. 

I would bet it's ecu programming.  Throttle plate held open after shifting.  If it's not a TBW car, they usually accomplish this with the idle air control circuit. 

ProDarwin said:

Slippery said:

Heavy flywheel + clutch delay valve probably. 

I would bet it's ecu programming.  Throttle plate held open after shifting.  If it's not a TBW car, they usually accomplish this with the idle air control circuit. 

Its mostly this. Its common for people with Ktuner software to remove it. Not sure if thats available for your Fit or if you would want to do that though.

If it is getting worse start by smoking the car.  Even the smallest of vacuum leaks can start to screw with idle quality.  

ProDarwin said:

I would bet it's ecu programming.  Throttle plate held open after shifting.  If it's not a TBW car, they usually accomplish this with the idle air control circuit. 

Emissions tuning, specifically. Snapping the throttle shut means there's a big puddle of raw fuel in the intake tract (may be less of a problem on DI motors) and the engine will run rich for a second or so. So many stock tunes cut fuel while backing the throttle down more slowly so there's enough airflow to draw in the fuel puddle.

Throttle closes too quick, puff of unburned hydrocarbons out the tailpipe, don't pass emission testing.

Learn to live with it.

My 2011 Accord K24 did the same. There's a company selling some gas peddle plug in magic that solves it, I think......

The GD delay valve can be deleted by running a new clutch line from the master to the slave... step in the right direction

Can confirm its real on my 08 fit, best way to deal with it is to speed shift...

During my brief somewhat hateful ownership of the same generation Fit, I got rid of the clutch delay valve and shifted as fast as I wanted.  It didn't seem to bother anything. 

Slippery said:

Heavy flywheel + clutch delay valve probably. 

We ditched the clutch delay valve already.....

In reply to RonnieFnD :

"smoking the car" sounds interesting. How would I do that?

Thanks for all the responses!

As noted, the clutch master has been replaced with a non-delay valve replacement we got from Seb's Garage.

The vacuum leak idea had occurred to us. Very curious to hear about "smoking the car".

The KTuner path sounds interesting for all kinds of reasons.

I was hoping to eliminate any issues before modding things to improve the situation. It sounds like the behavior is built in.....

It is surprising that Honda built that into the thing.

TLDR

The short story on the car: I bought it for my oldest son, now 16, to learn to drive a stick and use as needed for being mobile and hauling his younger sibs places. Then he can pass it down to his sister, next in line for a DL and so on. I also want the kids to have a lash at autocross. I would be happy for them to do some track days if they are so inclined. Because I will be doing a bit of that in the Fit.

I had heard they were pretty high on the fun scale from various mags, etc. Its a riot to drive, partly because its slow and you can run it through the gears without anyone noticing. ;-)

It has the basic sports car qualities of being small and light. 

Thanks again for the responses! 

douglasddm said:

Thanks for all the responses!

As noted, the clutch master has been replaced with a non-delay valve replacement we got from Seb's Garage.

The vacuum leak idea had occurred to us. Very curious to hear about "smoking the car".

The KTuner path sounds interesting for all kinds of reasons.

I was hoping to eliminate any issues before modding things to improve the situation. It sounds like the behavior is built in.....

It is surprising that Honda built that into the thing.

TLDR

The short story on the car: I bought it for my oldest son, now 16, to learn to drive a stick and use as needed for being mobile and hauling his younger sibs places. Then he can pass it down to his sister, next in line for a DL and so on. I also want the kids to have a lash at autocross. I would be happy for them to do some track days if they are so inclined. Because I will be doing a bit of that in the Fit.

I had heard they were pretty high on the fun scale from various mags, etc. Its a riot to drive, partly because its slow and you can run it through the gears without anyone noticing. ;-)

It has the basic sports car qualities of being small and light. 

Thanks again for the responses! 

 

Just to confirm, most cars I know do the rev hang via ecu programming by holding the throttle open. You can easily confirm this by flooring it in 1st gear, clutch in and going into second gear and wait. If the RPMs rise even if your foot is off the throttle, its the ECU programming that needs to be removed via Ktuner. I don't have experience with the Fit but this has been my experience in a decent bit of other cars I've co-driven at autocross and owned myself.

There are a few places on the Internet that have some good instructions but basically you use some PVC pipe to make a pot to hold mineral oil, some vape wire wrapped around a tiki torch wick to pull up the oil and make smoke when connected to a 12V power source, some clear tubing to push smoke out, and an air fitting to connect to your compressor to put 3 or 5 psi in to make the smoke go.  For about $20-30 you can make a really decent smoke machine that is amazing for finding vacuum, boost, and exhaust leaks.

In reply to wae :

So, if I already have a smoke machine........

In reply to Ryan Greener :

This is precisely the behavior we are seeing.

This has been a very educational morning!

douglasddm said:

In reply to wae :

So, if I already have a smoke machine........

In reply to Ryan Greener :

This is precisely the behavior we are seeing.

This has been a very educational morning!

100% needs to be software/ecu tuned out.

Let us know if you get it tuned out with a reflash/software fix. I absolutely hate rev hang and would love to know it can be fixed.

Very common, especially on the 2000's era non-direct injection cars. The thought process is that the vaporized fuel condenses on the cool walls of the intake manifold, and by cutting fuel and allowing air flow to continue momentarily it helps to evaporate that fuel and ignite it instead of spitting unburned hydrocarbons out the tail pipe between shifts. 

I have no clue why it still exists on DI cars. 

Rev hang used to be quite easy to tune out, but unfortunately the government has cracked down on off-the-shelf tuners messing with emissions protocols so it's not as easy an endeavor to defeat it anymore.

douglasddm said:

In reply to RonnieFnD :

"smoking the car" sounds interesting. How would I do that?

You have a 13 year old car so first thing is to just make sure everything is working as it should be.  Where I would start is to cap the intake at the airbox (assuming factory intake), pick any random port on the intake manifold and attach a smoke machine.   Start filling up with smoke a looking for leaks.  Air leaks usually start to show themselves as a hanging throttle so when cars come in at work with this concern this is the starting point.  Always make sure everything is working as is should be before changing anything. 

In reply to RonnieFnD :

Totally agree with trying to make sure its working right as the first step.

The method you describe is the inverse of what I have done with old mx bikes. We were usually spraying various flammable liquids around the carb at idle to see if the idle bumped up a little.....

Will let you know.

In reply to CyberEric :

Will do.