I have a 2012 Honda Accord EX with a manual trans. It’s a fly-by-wire system. When accelerating and shifting, the tac momentarily jumps various hundreds of RPMs when the clutch is in. That used to mean you weren’t coming off the gas when the clutch was in. I’ve been driving manual trans cars for 45 years. I know how to shift. But, it was a new car, so maybe… I paid close attention and was not screwing up the shifts. Apparently the computer doesn’t realize the clutch is in and the gas pedal has been released. Is this normal for these cars? Is it a problem? (other than wasting a half thimble full of gas and over-reving the engine?)
I would take it to the dealer where you bought it and have the service manager drive it with you riding shotgun. This does not sound even close to normal. Should be a warranty issue.
Back in the '70s carburetors had dashpots on the throttle valve to keep it from closing too quickly, which could cause a spike of tailpipe pollution (hydrocarbons).
My 1975 Civic CVCC would hold ~1500 rpm for a second or so when lifting off the throttle, but only when rolling over 10 mph.
Now many computer controlled engines do the same thing to some extent by blipping the idle air control valve on drive-by-cable throttles or just slowing the control motor down on drive-by-wire.
The air/fuel control has limits of how quickly it can track changing conditions.
My 2006 Toyota Matrix has the same drive-by-wire quirk.
The throttle doesn’t close as quickly as it could and the RPMs jump a little when shifting.
I think I have compensated some by lifting off the throttle earlier.
There’s also a delay between pressing the gas pedal and opening the throttle. Again I’ve had to compensate.
I can blip the throttle in neutral and the RPMs will jump a fraction of a second after I’ve taken my foot off. It’s weird.
I’m with mleich on this. Definitely bring it back under warranty. It sounds to me like the ECU isn;t properly responding to the gas pedal. Specifically also ask him if there are any relevent TSBs. Sometimes there’ll be one that they not yet familiar with. Their database should tell them, but it also never hurts to ask.
I just bought a new 2012 Accord MT with exactly the same problem! I took it back to the dealer the day after and a mechanic drove it. It did the same for him. He said he wasn’t sure if it meant anything was wrong, and said he would contact Honda to see if they had any info. Any developments with yours?