Subaru WRX - high, increasing revs when idle in traffic

[Brian]

Hi

My car is a 2005 Subaru WRX Sedan. It has 37000 miles and has had all
the regular servicing.

Last night I did some highway driving (25mins) and then was in city
center stop/go traffic. After about 10 mins in the congestion the revs
started to increase when idling (clutch disengaged and in neutral).
Typically it sits at about 600rpm or so when idling, it was started
out at 1500rpm. After another 5 minutes it had passed 2000 rpm,
another 5 and it was close to 2750rpm. Felt as if I was holding the
accelerator down constantly. I didn't have any engine management or
oil lights showing on the dash, and temperature wasn't any higher than
normal.

Only thing that reduced the revs was to put the car into 1st or 2nd
gears and engage the clutch. Doing this made the car feel like an
automatic - no need to put my foot on the gas. I've probably done some
damage to my clutch, but wasn't sure of possible damage from the high
and increasing revs.

I found somewhere to get my car pulled over and I turned off for
15mins or so. When I started it up, revs seemed normal again, and I
was able to get the car to my mechanic since I was near the highway.
On the highway driving the car performed as it had done earlier.

I've left the vehicle with my mechanic now, and am expecting a big
bill! Anyone have any thoughts on this, or experience anything
similar?

-Brian

 

[JD]

Hi

My car is a 2005 Subaru WRX Sedan. It has 37000 miles and has had all
the regular servicing.

Last night I did some highway driving (25mins) and then was in city
center stop/go traffic. After about 10 mins in the congestion the revs
started to increase when idling (clutch disengaged and in neutral).
Typically it sits at about 600rpm or so when idling, it was started
out at 1500rpm. After another 5 minutes it had passed 2000 rpm,
another 5 and it was close to 2750rpm. Felt as if I was holding the
accelerator down constantly. I didn't have any engine management or
oil lights showing on the dash, and temperature wasn't any higher than
normal.

Only thing that reduced the revs was to put the car into 1st or 2nd
gears and engage the clutch. Doing this made the car feel like an
automatic - no need to put my foot on the gas. I've probably done some
damage to my clutch, but wasn't sure of possible damage from the high
and increasing revs.

I found somewhere to get my car pulled over and I turned off for
15mins or so. When I started it up, revs seemed normal again, and I
was able to get the car to my mechanic since I was near the highway.
On the highway driving the car performed as it had done earlier.

I've left the vehicle with my mechanic now, and am expecting a big
bill! Anyone have any thoughts on this, or experience anything
similar?

-Brian

I am not sure about the WRX, but the STi has electronic throttle control
(drive by wire). If the WRX does, itcould just be a bad sensor. If not, it
can either be an 02 sensor or something wrong with the ECU. If it is the
ECU,it can be expensive. If it a sensor, it probably won't be too bad

 

[bgd]

Does the wrx or sti have an egr implemented?

I am not sure about the WRX, but the STi has electronic throttle control
(drive by wire). If the WRX does, itcould just be a bad sensor. If not,
it can either be an 02 sensor or something wrong with the ECU. If it is
the ECU,it can be expensive. If it a sensor, it probably won't be too bad

 

[Mike]

I get this from my insurance website and it has it listed for my 03 WRX.
Not sure if it specific to the WRX. but may want to look into it.

VEHICLE SPEED CONTROL:CABLES

Recall Number: 04V128000
Dates Manufactured: SEP 2000 to FEB 2004
Number of Vehicles Affected: 127580
Date Owners Notified On: Unavailable
ON CERTAIN PASSENGER SEDANS, WAGONS, AND SPORT UTILITY VEHICLES, THE CRUISE
CONTROL CABLE COULD COME OUT OF ITS TRACK ON THE CRUISE CONTROL LEVER AND
LODGE ON THE CONTROL LEVER TAB WHEN THE ACCELERATOR PEDAL IS RELEASED. IF
THIS CONDITION OCCURS, THE THROTTLE WILL NOT RETURN TO THE IDLE POSITION AND
WILL REMAIN IN AN OPEN POSITION.

 

[Blair Baucom]

My 2005 Forester XS did the same with me twice. Then I figured out my foot
was pressing the brake pedal, and would overlap the accelerator. So the
harder I applied the brake, the higher the revs.

I have now gotten use to the small distance between them, and now at 37000
miles, it doesn't happen much.

If this is not the case, then as others have posted, it is most likely the
TPS (throttle position sensor) for the throttle by wire system. I am
wondering what their life span will be, and I try to use cruise control as
much as possible.

Blair

 

[Stoneman]

Hi

My car is a 2005 Subaru WRX Sedan. It has 37000 miles and has had all
the regular servicing.

Last night I did some highway driving (25mins) and then was in city
center stop/go traffic. After about 10 mins in the congestion the revs
started to increase when idling (clutch disengaged and in neutral).
Typically it sits at about 600rpm or so when idling, it was started
out at 1500rpm. After another 5 minutes it had passed 2000 rpm,
another 5 and it was close to 2750rpm. Felt as if I was holding the
accelerator down constantly. I didn't have any engine management or
oil lights showing on the dash, and temperature wasn't any higher than
normal.

Only thing that reduced the revs was to put the car into 1st or 2nd
gears and engage the clutch. Doing this made the car feel like an
automatic - no need to put my foot on the gas. I've probably done some
damage to my clutch, but wasn't sure of possible damage from the high
and increasing revs.

I found somewhere to get my car pulled over and I turned off for
15mins or so. When I started it up, revs seemed normal again, and I
was able to get the car to my mechanic since I was near the highway.
On the highway driving the car performed as it had done earlier.

I've left the vehicle with my mechanic now, and am expecting a big
bill! Anyone have any thoughts on this, or experience anything
similar?

-Brian

Odd you should mention this. My base Impreza (2007, 2.5i with manual
transmission) was revving very high one morning (3,500 rpm at a stop
light). revving it "up" to kick the idle "down" (like you do in older,
carb'ed cars), did nothing but increase the idle. My car was at ~4000
when I shut the engine off, put the 4-way hazards on, and popped the
hood. No throttle control cable anywhere. It's drive by wire. I fired
it up, problem went away. I moved the floor mats back just in case
(away from the pedals).

1200 km's and it's ok so far.
Stoneman

 

[Brian]

I am not sure about the WRX, but the STi has electronic throttle control
(drive by wire). If the WRX does, itcould just be a bad sensor. If not, it
can either be an 02 sensor or something wrong with the ECU. If it is the
ECU,it can be expensive. If it a sensor, it probably won't be too bad

Thanks for the replies. The throttle control valve/sensor had a lot of
carbon according to my mechanic. He tried to do some diags on the
computer but it had been reset. No idea how this happened as I have
never had battery/power problems. He'll have the part tomorrow and I'm
going to drive it for a week to test the computer.

-Brian

 

[dg]

It never hurts (well, not that I can think of) to remove the negative
battery cable for a few minutes. I used to have a 98 ford expedition that
one time started having similar symptoms. A reset of the ecu or whatever by
way of removing the battery cable fixed me right up, never had the problem
again.

--Dan

 

[Jim Stewart]

It never hurts (well, not that I can think of) to remove the negative
battery cable for a few minutes. I used to have a 98 ford expedition that
one time started having similar symptoms. A reset of the ecu or whatever by
way of removing the battery cable fixed me right up, never had the problem
again.

At the risk of stating the obvious,
make sure the engine is *not* running
when you do this. Load dump is a
bad thing for automotive electronics.

 

[m]

I have a 2003 wrx I am having the exact same problem too. its getting
worse every year since i owned it. the only time i notice the cooling
fans coming on is when i have the defroster on or the ac. If you
noticed under the hood when it is revving it is really hot. i think it
is revving to keep the coolent flowing to keep it cool. If you find
out what the problem is with yours could you let me know too

 

[Mike]

Mine does the opposite. My 03 will idle fine then dip. Sometimes it feels
like is about to stall. I'm going to try cleaning out the IAC valve,
probably should change my pcv valve too. I know its not time but i may pull
my plugs and see what they look like. I dont have a CEL.