By on October 28, 2015


Joel writes:

Hello Sajeev,

I am having an issue with my 2008 Honda Accord EX 5MT. I bought it with about 90,000 km (less than 60,000 miles) from a Honda dealer nine months ago. It was in good shape but was not babied. On the upshifts, there is a momentary … what could I call it … overrun? overspeed? Clutch in, accelerator off, the revs don’t drop right away; they almost seem to increase, but only for a moment.

On the downshifts, blipping requires more than a stab; I would call it a prod, a sustained stab of the accelerator.

The clutch take up is mysterious. I can tell it’s loading up in the bottom two inches of travel; yet I can be near the top and not fully engaged. It sometimes seems to differ from gear to gear. The number of times I’ve done 1-2 without issue, then, using the same clutch-accelerator motions, ground the gears on 2-3, is embarrassing.

Full disclosure: I’ve driven many manual transmission cars; owned two manual Jettas previously, driven sports cars, heavy trucks, and never had the issues keeping my shifting consistent that I’ve had with this Accord. Yet, when I raised this issue with my trusted mechanic, he drove it and said all was well.

Obviously, a guy doesn’t buy an Accord for thrills, and this Accord doesn’t disappoint in that department — it is singularly dull. But everything you hear about Hondas is how great their drivetrains are. What gives? I had a theory that the flywheel is too heavy, but it’s only a theory.

Sajeev answers:

You say the car was not babied before you bought it, so that always changes the discussion. My thoughts are as follows:

  1. Clutch: they don’t normally fail at this mileage, but yours sounds toast. The rate of engagement along the pedal is a dead giveaway. Perhaps the last owner constantly, mercilessly rode the clutch when in traffic. Do it over the course of seven years and, yes, it will be a goner by now.
  2. Rev Hanging between Gear Changes: this is likely built into the computer’s tune to ensure smoother up/downshifts, and possibly better emissions as the fuel injectors have time to react to a change in revs. Computers are smart enough to make life easier, even if that kind of defeats the purpose of driving a manual transmission in today’s auto-erratic gearbox world. Perhaps Hondata has the cure for what ails ya?
  3. Dull Driving: a direct correlation to #2. Hondas are not immune to market demands. Most people don’t give a crap about “our” need for computer calibration worthy of a performance driving piston head. People have complained about the watering down of Honda products for years decades now, and it’s true: the days of the CRX, the Civic Si, the Integra, and even the smaller, nimbler Accords of yesteryear are gone. The only conciliation prize? Every purist says the same thing about their preferred brand.

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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33 Comments on “Piston Slap: Rev Hanging on the 5-speed Manual Accord?...”

  • avatar

    A well known ECU issue. I don’t know if Hondata has cracked the Accord ECU but they’ve fixed the issue on countless other K series equipped cars. FWIW I don’t think I have it on my Civic, which is every bit as quick as a same year 4 banger Accord while being 500-600lbs lighter….

    • 0 avatar

      C/Net complains about RPM float on the 2012 Civic Si.

      It’s built-in.

      • 0 avatar

        Those CNET reviews are normally alright, but it bothers me when they do them and spend 80% of the time on infotainment and 20% on the part about driving the car.

        IIRC they did that on the 2012+ Acura RL review and it annoyed the crap out of me.

    • 0 avatar

      I have an ’08 Civic with the same rev hanging bewteen gear changes. Would love to get that fixed.

      No clutch problems though. 86k on the clock.

      • 0 avatar

        I have it fixed on a 08 Si with hondata. There’s essentially a checkbox to turn the rev hang ‘feature’ off. This alone was worth the pirchase price for me. The other benefits are being able to create my own linear throttle map and lowering the vtec point for more tq and a better noise at mid rpms.

        I’m not exactly sure why it is there. It is not for drivabilty. The suspicion is emmissions. Either extending the cat life (by not dumping excess fuel) or keeping emissions low (nox or whatever) to pass the epa tests.

        The other sorta fix is to turn the ac on. That extra load will help make it less noticeable.

      • 0 avatar
        Kosher Polack

        Same here, same car, same problem since day 1…It’s annoying when you really need to get moving, but at least it’s been consistent!

  • avatar
    87 Morgan

    I have noticed the rev hanging on mine as well. I don’t have the clutch issues though. It seems to occur randomly in my end or more to the point I notice it randomly.

  • avatar

    Biggest problem with it is the lack of an automatic transmission.

    • 0 avatar

      While it’s true that an automatic transmission can mask driveability issues, there’s no reason that this car should behave this way. My previous ride had an MT, and while the revs didn’t fall quite as quickly as I’d like (that was the emission control talking), it didn’t accelerate the engine when I used the clutch either.

  • avatar
    bumpy ii

    Re the clutch: make sure the master and slave cylinders aren’t leaking anywhere. Master in particular can be tough to catch, as it leaks out of sight down the firewall and under the carpet.

    • 0 avatar

      More often than not, they leak internally. You don’t see any fluid anywhere, it just leaks past the internal seals.

      This is also where I would start. The slave cylinder is external, and both are relatively cheap. Replace those before going any deeper. Also not a bad idea to change out all the brake fluid, since debris and old fluid for the clutch likely caused your issues.

    • 0 avatar

      The input shaft cover that the throwout bearing rides on can get gummed up with old grease or even gouged/scored. If you end up replacing the clutch check the shaft cover for wear, clean it well, and grease it with good grease.

      Also, clean your throttle plates. It sounds like your rev hanging is programmed in, but clean throttle plates are important to prevent sticking.

  • avatar

    I don’t know abbout the Accords, but the Honda Fit 5MT definitely has a Clutch Delay Valve, which in concert with the ECU allows “rev hang” in the interests of managing emmissions, or something to that effect. The Fit forum even has a DIY on how to remove the CDV. I’ve driven manuals for years and at first, I thought I was losing it!! :-)

    • 0 avatar

      This is exactly right. Check for a how-to on the clutch delay valve delete. It is a check valve typically installed in or near the slave cylinder. The inconsistent shifts are 100% attributed to it. My e36’s and e34’s had this, it is made for old grandma driving.

      The rev hang, as Sajeev and Sporty stated, are built into the tune. The only way I know to disable it is using Hondata. Another method is to “power shift” but most people are not keen to it nor can they execute it.


    • 0 avatar

      BMW uses clutch delay valves but does not have the programmed-in rev-hang that Hondas do. It really took me a while to learn how to drive it smoothly.

      I think the BMW CDV is there to protect the clutch and drivetrain during hard shifting.

      • 0 avatar

        I agree, the CDV on BMW’s are there to protect shock to the driveline, no matter how hard or fast you “drop” the clutch, the engagement is nearly always the same. It does throw your timing completely off. I believe the clutch will prematurely wear at the expense of say carrier bearings or guibos. I always deleted mine, 10 minute job with a pressure bleeder.

        True, rev-hang is “new” and I’ve only seen it applied on cars equipped with throttle-by-wire. It definitely has something to do with emissions, I don’t know the science behind it but it sucks.

        • 0 avatar

          CDV delete is on my short list as it really does $h!t up the driving experience. I’d never ground gears in my Miata, but I’ve done it a few times in my e60. Not sure why anyone thinks this a good idea. If I wanted help shifting, I would have gotten an automatic!

    • 0 avatar

      I believe Honda must have added this valve to the 04 Acura TL as well. I test drove a new TL when I was in the market in 05 and the clutch takeup mysteriousness really turned me off. Sometimes I almost killed it, other times I way overrevved it. I’ve only had manual transmission cars since I was 16, so my capability wasn’t the issue. It was an embarrassing test drive for me.

    • 0 avatar

      Yep — I test drove a new 5MT Fit a few years ago because I thought it would be a fun commuter but immediately noticed the rev hang and CDV. It totally killed the driving experience for me.

      • 0 avatar

        Wish I had researched the car—my 2nd gen US Fit was a blast to drive, except for 2 years I had it, I never was able to shift it consistently smoothly. Stupid rev hang. Takes all of the joy out of shifting yourself. One of the reasons I got the DSG with my CC. Well, that and they were looking to move inventory, and all they had on lot were DSGs.

        I hear the newer Mazda6 MT are almost like old manuals with almost no rev hang. Will definitely have to test one when I go shopping again.

  • avatar

    Sounds like its a known problem from the OEM, but I’d give the TPS and the MAF a check for proper operation. Depending on the ECU software, if the TPS fails the MAF will take over, but it will lag a bit.

  • avatar
    heavy handle

    Generic Honda advice: replace the O2 sensors, or at least Bank 1/Sensor 1, which is the pre-cat sensor on 4 cylinder Hondas. Use an OEM part.

    It sounds silly, but it’s been known to fix most oddball driveability issues on Hondas.

    In this case, it seems like your clutch is sticking, but you probably still need to replace the O2 sensor.

  • avatar

    I’d suggest a combination of all three of Sajeev’s answers. Most particularly, I would have the clutch inspected–nay, overhauled–as I ran into a similar situation with my ’97’ Ranger’s clutch despite only having 20K miles (actually less) when I took possession. Apparently a leak in the slave cylinder rusted a spring and prevented full engagement (hydraulic clutch in that case.)

    I’d also suggest looking into having the car’s computer re-flashed to factory stock. I’m betting the previous owner purposely reprogrammed the computer for high-performance speed-shifting. A full diagnostic wouldn’t hurt, either.

  • avatar

    165K on my v6 6MT Accord Coupe. Only issue I’ve had is the occasional rejection of trying to grab third gear. Sigh. Dammed syncro.

    • 0 avatar

      I’m envious of your ride – I’d love to have one … sigh.

      That 3rd gear syncro problem is a known problem and you should pester
      your local dealer about fixing it. I’ve heard of instances where a
      Honda dealer refuses to fix the problem but Acura dealers are willing
      to fix it – for free, of course.

  • avatar

    Manufacturers are really taking the fun out of manuals (or more accurately, regulators are)

    More and more it seems like modern stick shifts are just about creating the illusion of a manual transmission.

  • avatar

    Clutch is FUBAR.

    Previous owner probably rode around with their left foot resting on the clutch pedal wondering at the end of their drive what that burning smell was.

    As for the dull and rev issues – it’s built that way. You’ve gotten solid advice above – but I see a new clutch in your immediate future.

    I haven’t had to do a clutch in a “newer” car but I would ASS-U-ME that the general rules of doing the throw out and bearing and slave at the same time likely applies.

    • 0 avatar

      If the clutch isn’t chattering or slipping under high torque conditions (full throttle in 3rd or 4th gear at around 4k RPM or so), then it probably isn’t bad yet (at least not FUBAR). Hydraulic clutches are self-adjusting, so even when they reach the end of their life they should be engaging relatively consistently.

      This is probably the delay valve as mentioned earlier.

  • avatar

    Well, at least it seems like it’s not just me. I’ve driven MT my entire adult life and I have had more trouble getting my 10 month old Accord to shift consistently than any other car I have owned. I don’t really want to mess with a tune, but if removing a valve is a simple fix I’m willing to give it a shot.

  • avatar

    I found a way to fix annoying rev hang in my 2012 Accord Euro (K24) 6M/T.
    I looked into the issue of rev hang in some depth and published my findings here:

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