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Discussion Starter #21
Thank you. The p0420 code has come on then gone then come on again. We are trying the upstream o2 sensor to start. Hope that fixes or helps. Once all said an done this thing will drive like it’s new. Some of these codes are being read on the code reader with no check engine light on. To night we taped the o2 sensor ( was changing it but had wrong socket) the car coughed and ran slightly bette, and noises were gone. Fingers crossed this works. tomorrow.
 

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Discussion Starter #22
Well still no luck. We are at a loss put in almost 1000 dollars and still not running good.
 

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2012 Forester 4 speed auto
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1,010 Posts
Check the engine to chassis ground wire and the chassis to negative battery terminal. If you cannot find them temporally make one and see if it runs better.
 

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Discussion Starter #24
We will try that. So just took it for an 8 mile ride it does seem to be a little better we still hear like air is escaping from some where near driver side.
 

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Discussion Starter #25
Update these are the things we have done
Plugs,wires,coil pack, alternator, oil change, cleaned maf sensor, 02 sensor upstream also put dry gas and fuel injection cleaner in.
Still can not find the psst noise, car running a little better but still boggy you can tell it wants to go but can’t. Also cleared all codes and none are listed now.
 

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2014 Forester 2.5 Premium CVT
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If you are still hearing that whooshing of air noise, I would think maybe to check all the air intake tube from the filter to the intake manifold. If the wooshing air is a leak messing with the maf sensor reading, it would make the car run bad. Double check each connection point. That noise is coming from some where, it might be the cause of the other issues due to running rich/lean because of a bad sensor reading.
 

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Since your Subie is 10 years old, I'm assuming you must be hitting 100,000 miles on your car. At that point, once you get the misfire resolved, I would replace all of the sensors. They do wear out over time. Doing so may save your cat.
Just a suggestion.
Good luck.
 

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Discussion Starter #28
As far as we can tell all vacuums hoses seem ok. They did spot a slit hole near a gasket in exhaust. They are checking grounds wires today and trying to take better look at all hoses. As of now car runs great at 20-30 mph try to go higher and she seems to sputter a little and slow or slipped shift. If you feather the gas going 30-40 it seems to run smoother.
 

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Discussion Starter #29
So today it is raining car running like crap. Does any one have a vacuum diagram for this model? We have no cel light and can’t find what’s wrong.
 

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Just an idea from the web...
Make vacuum leaks hiss-tory. Vacuum leaks can be located with spray carburetor cleaner or a can of WD-40. If the area is obstructed by linkage or hoses, use an extension nozzle to pinpoint the area of the vacuum leak. If the engine speeds up when an area is sprayed, you are close to finding the leak.Jan 29, 2019
 

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Discussion Starter #31
Just an idea from the web...
Make vacuum leaks hiss-tory. Vacuum leaks can be located with spray carburetor cleaner or a can of WD-40. If the area is obstructed by linkage or hoses, use an extension nozzle to pinpoint the area of the vacuum leak. If the engine speeds up when an area is sprayed, you are close to finding the leak.Jan 29, 2019
Thank you. We have decided to take the car to a Subaru specialist garage. With two adult children with muscular dystrophy we can not wait any longer trying to find this. When we do get it fixed I will update so it may help others. Fingers crossed it doesn’t cost a fortune to fix.
 

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2011 Subaru Forester
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378 Posts
Have them check for an exhaust system leak. If it's after the 02 sensors, it may not cause a code, but it will affect your acceleration. And as others have pointed an air intake leak seems like the likely culprit.

Keeping my fingers crossed for you. I hope it can be resolved relatively cheaply.
 

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2010 Forester
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Have you tried to re-learn the idle. I have had that happen a couple times that after doing work on the car it ran rough until I followed the Idle Re-learn procedure.
 

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‘14 FXTT; '15 Legacy FB25
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If the idle needs to be relearned, then something needs to be cleaned or fixed.
 

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2010 Forester
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If the idle needs to be relearned, then something needs to be cleaned or fixed.
I had a bad gas cap and the car immediately stalled out at every stop. Had the same issue with a very dead battery, the idle got all messed up and I had to re-learn on both issues.
 

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‘14 FXTT; '15 Legacy FB25
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I had a bad gas cap and the car immediately stalled out at every stop. Had the same issue with a very dead battery, the idle got all messed up and I had to re-learn on both issues.
How many miles? Did you clean your throttle plate?

Have you ever had to perform an idle relearn on a new vehicle?
 

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2010 Forester
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How many miles? Did you clean your throttle plate?

Have you ever had to perform an idle relearn on a new vehicle?
I have a 2010 2.5X

I guarantee I know exactly what the issues were. A missing gas cap for a couple days will mess up the idle. As will roll starting on a seriously dead battery, the lower voltage stalling messes up the idle too. Just suggesting a free 15 min fix that is worth a shot.
 

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Right, but my question remains, worded differently: does a new car require an idle relearn after swapping out a battery?
 

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2012 SH Manual Diesel
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Do your brakes work fine? Do they feel normal? as in, you don’t have to push really hard to get them to stop properly.

If your brakes are working well, it’s likely the vacuum brake boost is too. So a vacuum leak from that perspective, is less likely.

If spark plug leads are falling off, you can slightly crimp the metal terminal, so it fits tighter.

Being slow to take off, slow to shift, and won’t rev past certain rpm in Park/Neutral, might suggest lock up converter is not unlocking (faulty lock up clutch solenoid in torque converter).

Whooshing sound could be transmission fluid/pressure.

If 4EAT I believe changing solenoids is easier/possible on the solenoid control module.
 

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2010 Forester
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Right, but my question remains, worded differently: does a new car require an idle relearn after swapping out a battery?
I can't speak to "a new car". I imagine that every manufacturer has their own recommended procedure for battery replacement. Mine required it because of how dead the battery was. I have never heard of idle re-learn being required for my 2010 after battery swaps. But if the car is running like crap after spark plug/ignition coil/battery I would definitely do an idle-relearn, it is a free diagnostic that can be done in the driveway.
 
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