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A slight over-rev upon gear change

agrippa

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Location
Solihull, West Midlands.
Car
Type S 2.4 2007
Hello everyone,

I'm driving a 2007 Honda Accord Type-S (2.4), which I got a month ago. I'm fairly sure that, on gear change, the engine ever so slightly over-revs itself in between gears. First I thought it was my own sloppy gear work. So I decided to pay attention to my gear changes, and slicked them up for the avoidance of doubt. I also kept an eye on the Rev meter. Sure enough, the engine over-revs ever so slightly upon a gear change. I can observe it at low revs and low gears, for example gears 1-4 during town driving. I have not seen any threads on this subject, so was just wondering if any other Accord Type-S drivers had encountered this?

Kind Regards,
Agrippa.
 
Mine does this too. I think it's normal.

The nature of the car seems that there's a tiny bit of latency between putting your foot down and the engine responding. I think it's something to do with the VTEC mechanism and the drive-by-wire etc. I think it's a bi-product of that. You know, like you lift off and it takes the engine a moment to respond, just like it does when you put your foot down in the first instance. Try lifting off the accelerator a second before you change gear, see if it still does it.

But hey, maybe it's just us. See what the other 2.4 owners say.
 
Mine does this too. I think it's normal.

The nature of the car seems that there's a tiny bit of latency between putting your foot down and the engine responding. I think it's something to do with the VTEC mechanism and the drive-by-wire etc. I think it's a bi-product of that. You know, like you lift off and it takes the engine a moment to respond, just like it does when you put your foot down in the first instance. Try lifting off the accelerator a second before you change gear, see if it still does it.

But hey, maybe it's just us. See what the other 2.4 owners say.
 
Hello Steve,

Thanks for the reply, glad to hear I'm not alone. I've just sold my ATR and it didn't do it. So, I'm used to revs dying off the moment I come off the throttle. I will try what you suggest to see what happens. I'm happy to accept it's the nature of the car, but if I were a Honda test driver (and I am far from that) it would be an obvious point to raise with the engineers. Maybe they did and the engineers said, "Well you see, it's like this ... ".

Kind Regards,
Agrippa.
 
So there you go, an interesting alternate take on it. It helps with down shifting ;) .
 
I'm sure mine does this but only in Vtec
 
Hello Gentlemen,

Steve - I did as you suggested (come off the throttle a second before de-clutching) and ... it's still doing it.

A quick Google for "Honda Accord over rev gear change" found a website with the following thread (edited by me for relevance):

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OK, so with all my prior cars, I have never experienced this behaviour and wondered what you guys thought of it.

I'm changing gears (usually more noticeable when going up) and I can hear the revs rise for a split second. Annoying because it makes me sound like a P-Plater
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When you depress the clutch, the ECU rises the revs in order to keep the catalytic converter temperature at a given level (really high, that is). This is supposed to raise its efficiency and, at any given output, keep the toxic substances levels in exhaust emissions low.

Or, put another way, it is used to keep the combustion optimum so that the petrol-oxygen mixture can react at the right temperature.

Why does it do this? It is necessary to reach the EURO 4 emission-standards which in turn benefits you by lowering your tax band.

So, all in all, you always seem to look like inexperienced driver
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My email to dealer:
After driving my New Vectra for almost a week now I have noticed that when I change gear (when the engine revs build up to around 2 -2.5k) the engine revs rise up by around 300 rpm when I dip the clutch. The revs fall to the idle speed after a second or so. Is this normal behaviour? Surely the engine revs should start to fall as soon as the clutch is disengaged? (My foot is off the throttle by the way).

Their reply:
I've looked into the problem you have described and after speaking to our Master Technician, he has ***ured me this is a design feature of the Vectra 1.8 VVTi engine. When you dip the clutch, there is a sensor which increases the revs temporarily to allow a purging of the catalytic converter.

However, be rest ***ured this isn't a problem with the engine. To put your mind at ease, I am more then happy to take you out in another 1.8 VVTi Vectra which will display the same characteristics.
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Non of my previous cars have done this but my Honda Accord does. Instead of simultaneously taking your foot of the accelerator and pressing the clutch, take your foot off the accelerator a split second before. I find it helps to stop people looking and thinking I'm ***** at gear changes.
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It's not when all the time when idling, it's temporary when foot on clutch. Confirmed with Honda that it's designed to do this (apparently) although they were a bit vague as to the exact mechanism (whether it's for cat "purging" as Vauxhall do or aiding the synchromesh or something else).
Had a drive in my sis' Jazz which does the same thing....so it appears to be inherent in the overall design.
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Kind Regards,
Agrippa.
 
Interesting stuff man. Thanks for researching and sharing with us. It's nice to know it's not a glitch/bug/problem and a conscious design aspect.
 
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