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Guest tmp123

99 Subaru Outback Hesitation/fuel mixture problem...help

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Guest tmp123

Hello, what a great board this is....lots of good info

 

 

I have a problem.....My 99 Outback is acting strange. Here are the symptoms:

 

1.Rough idle(engine vibration) from 600Rpm to 2500rpm very bad when engine cold. feel it less after 2500RPM

 

2. Sometimes car hesitates from takeoff or jerks when driving/stopping down hill.

 

I brought it to a dealer with no results.(tried 2 different dealers). Both give me the same lame excuse"no engine code evident, therefore no problem".One mechanic thinks it is a fuel mixture problem.....

 

I replaced all injectors, wires, plugs, fuel filter and checked timing marks.....and no positive results.

I read some previous posts and some people experienced similar problems with a bad oxygen sensor. Also some people claim that the 99 outback is very very picky on the type of fuel it likes.......MTBE additives may damage oxygen sensors. Is this true?

Did anyone experience the same problem? Please feel free to give me some input on this.

 

Thank You............

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Guest Legacy777

If you've replaced fuel injectors, that's one good step in eliminating things. The old ones were probably ok.

 

How many miles on your car? An O2 sensor may be beneficial. The newer OBD2 cars are more sensitive to a faulty O2 sensor.

 

Other thing you might want to do is run some fuel system cleaner/dry gas to get rid of any water or other crud in the tank/lines.

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Guest tmp123

The car has 40,000 miles on it. I will replace o2 sensors on it...It has 2 oxygen sensors!!??? This is getting expensive...........

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Guest Frag

Replace only the first one (upstream). The other

has no impact on drivability and, contrary to the upstream one, rarely goes bad without giving a CEL.

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Guest Commuter

Before you go to the expense of O2 sensors etc, you might want to investigate whether it is a carbon build up.

 

I had this happen on my 97 2 years ago... and am battling it again now. And I do 90% plus highway driving!

 

The 2.5L DOHC phase I engine is noted for running rich and occasionally having this problem. A weakening O2 sensor may just aggrivate the problem. (I'll let you know shortly on that one. I just changed mine.)

 

My symptons were exactly like yours. Started off as a slight hesitation at idle, eg, starting off from a light. Feathering the throttle (eg for parking) became more and more difficult. As the problem progressed, the symptons kept climbing higher and higher up the revs. I would feel it while loafing thru town with the engine turning over 1500 rpm. Felt like a slight miss. Idle itself was never bad for me... just when I wanted to "go" that it acted up.

 

The dealer did a MotorVac on my car. When things get carboned up bad, the off the shelf stuff won't really help much. The MotorVac solved the problem. If I detected it coming back (usually every 3 or 4 months), I would run some gas cleaner or higher octane gas thru it, and then usually be fine for another while.

 

Lately, the gas cleaners etc haven't done the trick anymore. As my car is 6.5 yo and with over 200k miles on it, I decided to change out the O2 sensor. The dealer said it checked out ok...little sluggish. My understanding is that their 'test' does not check if its generating the 'correct' signal, only that it 'is' producing a signal. *shrug* I'm waiting to see what happens. I still might have to do something to get rid of the carbon that's in there.

 

I never got a CEL with any of this.

 

Commuter

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Guest spagemurray

Commuter

Get youself 2 bottles of Auto-Rx and give the engine internals a real clean (It's not a solvent type flush). http://WWW.AUTO-RX,COM or http://WWW.BOBISTHEOILGUY.COM forum for info. Amazing what it does for any vehicle particularly high mileage like yours. I have 2nd bottle in my Outback 2.5 now and the difference is not subtle!

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Guest TinyClark

You shouldn't need any gas additives in your tank, except for some drygas in the winter months. Major oil companies already use cleaning solutions in their gasolines.

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Guest remarcable

Sometimes the sugar pill works. I've never had any luck with the gimmicky additives, but your mileage may vary.

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Guest Cougar4

I would check the intake manifold for an air leak and also the vacuum hoses for a problem. Spraying some WD-40 around the intake manifold gaskets while the engine is idling may show up something.

 

Glen

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Guest scoobtech

If your going the carbon cleaning route , remove the IACV & give it & the passage a good cleaning . This is often overlooked & can cause your complaint . I would not trust any "mechanic in a can " stuff . You would do just as good stuffing dollar bills into the gas tank . :cool:

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Guest tmp123

After cleaning the IACV valve and checking the Oxygen sensors, replacing the injectors,plugs, wires, timing belt. All produced no results.....

After doing some research on the Web I noticed that some people report 99 and up outback Subarus with the 2.5 liter engine are having same problems (engine vibration from 2200RPM to 3200RPM)20-30MPH.

 

Evidently the problem is with some unballanced engine components in the 2.5 liter engine. Some dealers are admitting this others are not. If you happen to get a bad one than you have to live with it...........I found about 10 posts about this on the web.

 

Does anyone think they have the same problem?:lol:

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Guest lazyNorm

Yes I have the engine vibs at 2000 and up RPMs. It didn't do it when I got the car at 32K miles. It started shortly there after. I think mine is due to a slight misfire. I've tested the coil pack and according to my DVM the coil is off spec. I don't have a check engine light but when I get some $$$ I'll try changing it and see what happens.-------------Dave

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