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Kevin C.
Kevin C., Subaru Master Tech.
Category: Subaru
Satisfied Customers: 1727
Experience:  34 years of Subaru service experience, ASE Master Technician.
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My 2004 forester has been accelerating by itself. I can fix

Customer Question

My 2004 forester has been accelerating by itself. I can fix this by stamping on the gas pedal, but it can be scary. The tachometer has been as high as 4 rpms with the car in park. I have replaced the throttle assembly and the entire line from gas pedal to throttle, but the car will still start zooming at random moments. I need help!
Submitted: 9 months ago.
Category: Subaru
Expert:  david craig replied 9 months ago.

Hi my name is ***** ***** check engine light on?

Customer: replied 9 months ago.
no
Expert:  david craig replied 9 months ago.

was the throttle position sensor part of the throttlebody that you replaced?

Expert:  david craig replied 9 months ago.

it should have come on the throttlebody assembly

Customer: replied 9 months ago.
checking with the mechanic that did the work. no answer, left a message, waiting for response.
Expert:  david craig replied 9 months ago.

ok thanks

Customer: replied 9 months ago.
Still no response to my phone message, I believe the garage has closed for the day at this point. I'll have to wait until tomorrow for an answer to your question.
Expert:  david craig replied 9 months ago.

ok thank you

Customer: replied 9 months ago.
Hi David, Just heard from the garage. They have replaced everything from the gas pedal through the throttle body.
Customer: replied 9 months ago.
The only other suggestion they had was to disconnect the cruise control. Didn't make sense to me since the car isn't in cc when this happens.
Expert:  david craig replied 9 months ago.

well the cruise control is cable operated i believe and is attached to the throttle linkage, which can get stuck and hold the throttle open on occasions....

Customer: replied 9 months ago.
Can the cruise control activate when I haven't engaged it? Only one of the racing episodes (and there have been several) occurred when I was in Cruise control. Set for 65, zoomed up to around 80!
Expert:  david craig replied 9 months ago.

no it can not engage itself. it is a throttle problem possibly caused by a sticking cruise control cable. even if its not engaged. disconnect the cruise control cable from the throttle linkage and see if that cures it.

Customer: replied 9 months ago.
Thanks, I'll try that. I can sometimes drive for a month or more without it happening so it may be quite a while before it happens again. I've had the car 8 months and it has only happened a half a dozen times.
Expert:  david craig replied 9 months ago.

please let me know how it turns out. then we can take it from there

Expert:  david craig replied 9 months ago.

please dont forget to rate my service....thanks

Customer: replied 8 months ago.
Hi David, It's me again with the self accelerating Forester. I had the cruise control disconnected last Friday. Today the car took off on me again... When I put it in neutral and gave it some gas a big black cloud of smoke blew out the tailpipe and the the car stalled out. It took me four or five tries to start it again. It finally started when I gave it some gas as I turned the ignition. I then drove another 90 miles or so, started it 3 times , no problems. Any further suggestions? ( I haven't rated you yet. Waiting for the problem to be resolved.) Thanks, Keren
Expert:  david craig replied 8 months ago.

Sorry to hear you're still having problem. allow me to get home from my shop and get back to you in a bit. thanks

Expert:  david craig replied 8 months ago.

black exhaust smoke can be caused by one or more leaky fuel injectors, too much fuel pressure (sticking fuel pressure regulator), a faulty MAF sensor or Oxygen sensor, or a engine computer fault. the black puff of smoke is rom the computer dumping too much fuel into the system because it think the car is running lean(not enough airflow) I would suggest looking at your air filter to make sure its clean, cleaning the mass airflow sensor also would be a good idea. maybe pull the vacuum hose off of the fuel pressure regulator to make sure no fuel is present on it.

Expert:  david craig replied 8 months ago.

I contacted Subaru about your acceleration issue and its a chronic problem with the foresters that no one has figured out. They have a few successful cases of reprogramming the computer and a couple more of replacing the computer. That seems to be what the problem is. But there is not one thing that they pinpointed to be the definitive culprit.