Wagoner

Engine over racing/reving

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Hi. First time post. 2 years ago I purchased a manual 2010 Forester. right from the start I found that the engine tends to over rev when changing gear. Instead of the revs dropping , it stays at whatever rpm it was before the change. Also, when crawling in traffic with the clutch depressed (in gear), foot off the accelerator and the car just rolling along, the RPMs rises suddenly to about 2500 then drops down to idle. A few seconds later it does this again. As long as the above conditions are in force it will do this until I put the gear in neutral.or stop completely.

 

Any ideas??

 

Wayne

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I'm not expert on if this could be an issue with the engine somewhere but to me, it sounds like someones played around with the software to get things like auto blep and flat foot shifting but did a weird version of it. 

but I could also be way way off. 

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So with your foot fully on the clutch pedal, the motor is still engaged? 

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"when changing gear. Instead of the revs dropping , it stays at whatever rpm it was before the change. " is that when changing down the revs stay the same, changing up they will stay the same if in the same rpm range

 

"clutch depressed (in gear), foot off the accelerator and the car just rolling along, the RPMs rises suddenly to about 2500 then drops down to idle. A few seconds later it does this again. As long as the above conditions are in force it will do this until I put the gear in neutral.or stop completely. "

 

So you have the car in gear and clutch pushed in .. so the clutch is engaging again, lower clutch fluid/pressure/spring

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When the clutch pedal is depressed, it disengages the engine. I mostly notice the issue when changing into a lower gear. I did mention this issue to my garage last ti e it was in. The tech ad vised that there us a sensor in the transmission which causes the revs to be maintained when changing gear. Basically I inferred from his reply that it really wasn't anything to be concerned about. Today I tried it again while traveling on the M/way. I depressed the clutch pedal in and watched the RPMs cycle up and down as reported (regardless of speed). As soon as I put the gears into neutral, the revs dropped down to idle.

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I've had a similar issue with my car which made changing gear annoying as the rpms wouldn't drop quickly enough when shifting. 

 

Mine turned out to be a vacuum leak. I had blown a small hose off the intake manifold. Put it back and cable tied it and then I had to reset the ecu and it went back to normal

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Are you talking about "rev hang" ?

 

To my understanding this was deliberately tuned in by Subaru on the newer models to help with emissions. With a cable throttle body when the throttle plate slams shut it causing the car to run slightly rich. So with some of the later electronic throttle body cars the throttle doesn't snap completely shut during a gear change. Quite a few of the Americans complain about it in their wrxs.

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Izichard, I am not sure if this applies to my vehicle given that it is only a 2010 model. I have checked all the vacuum hosing on the inlet side as per Firenza's reply but can find nothing wrong there.

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15 hours ago, Wagoner said:

Izichard, I am not sure if this applies to my vehicle given that it is only a 2010 model. I have checked all the vacuum hosing on the inlet side as per Firenza's reply but can find nothing wrong there.

Maybe it isn't relevant to your car. Sorry I do not know too much about the newer cars, I just saw the post and rev hang crossed my mind as I have read about it before. I thought it could potentially be of use to you.

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