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Rough Acceleration


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9 replies to this topic

#1 R2 Subaru

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Posted 24 April 2007 - 07:51 PM

Ok so the 'preza is running great and seems to be pretty happy.

Except, often when cold the car has jerky acceleration when going slow. Not hesitation but accelerates a little and then a lot. Also the car sometimes feels like it wants to keep going after I have let off the accelerator. I notice it most when I am paralell parking or sitting in traffic. Once the car is going I don't notice it at all. It almost feels like its trying to find the gear.

The car is 98 Impreza Sedan 2.2 with AT 184k on it. The car idles very smoothly and has good power.

I looked into the throttlebody and it looked really dirty.

Do you think I chould try cleaning the throttlebody with throttlebody cleaner or carb cleaner (is there a difference?)

I read in another thread that it is bad to clean the TB. is that true?

Do you guys think it could be the AT starting to go?

#2 nipper

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Posted 24 April 2007 - 08:01 PM

Start with basics...

A tuneup

OE wires
The recomended plugs
fuel filter
air filter
PCV Valve

O2 sensor (if its the original).

It sounds like to me you can have spark degredation under load, which can be plugs or wires or both.

nipper

#3 R2 Subaru

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Posted 25 April 2007 - 10:40 AM


It sounds like to me you can have spark degredation under load, which can be plugs or wires or both.

nipper


See, I wouldn't have thought of that.

Thanks. I'll let you know how it goes.

#4 porcupine73

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Posted 25 April 2007 - 11:11 AM

Do you have any stored codes or CEL/MIL? Any good size vacuum leaks?

If you clean the throttle body you want throttle body cleaner not carb cleaner. Some manufs don't want the butterfly cleaned if they have put some kind of special coating on it that could be damaged or rubbed off by cleaning.

It also depends if you plan to remove the throttle body to clean it. Cleaning it in place pretty much means all the gunk and junk you clean off is going into the intake. If there are chunks that could get stuck between the valve and seat, etc.

#5 R2 Subaru

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Posted 05 May 2007 - 06:09 PM

So just to follow up for the other s00b n00b's out there:

So I did an ATF flush and the wierd accelaration thing went away! :clap: I thought my fluid was Ok but then I saw what some fresh fluid looked like on a friends car and I was blown away! :lol: I felt like such a dumb@ss! My fluid looked like old motor oil! I don't know why I thought it was red.

For the record, ATF fluid is RED! Red like Robitussun, like cherry pie!

One thing that was weird was that I thought I would have to do the flush in stages, three quarts at a time . So I drained the transmission while it was cold, expecting three quarts to come out. Then I would drive it around the block to get it warmed up and do it again. But, it almost all came out. Like 7-1/2 quarts. I had the car up on a jack on one side and it had been sitting for a weeks or so, so maybe it all settled down while sitting?:confused: Do you guys think this could be a problem?
Anyways, replaced it all and it looks and feels great. I guess getting it hot first would have gotten a lot more crap out but what-ever's clever.

I also repacked the inner CV's while replacing torn boots. Which was a PITA but I think will keep these axles going for a while and was cheap. I have lots of time and elbow grease, not so much $$$. Those three-pot bearings are really cool looking too. On the other hand, I could have done without looking for the needle bearing I dropped for an hour!) Doing the inner CV's also seemed to really clean up the clunky steering I had in tight corners. Once I remembered to reconnect the stabilizer bar that is! Ha! :lol:

Oh yeah, per Nipper's instructions I am still going to do the plugs and wires, PCV, fuel and air filter. O2 sensor is a bit pricey for now and I smogged with flying colors so I am going to leave it. :headbang: :headbang: :headbang: :headbang: :headbang: :headbang: :headbang:

#6 nipper

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Posted 05 May 2007 - 08:20 PM

YAY

Dont question the mechanic gods about the tranny fluid and rough idle fix.

Glad it all worked out. There may have been a gummed vlave in the tranny that was doing odd things. 2.5L auto is 10 qts, just an FYI.

nipper

#7 R2 Subaru

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Posted 05 May 2007 - 09:18 PM

YAY

Dont question the mechanic gods about the tranny fluid and rough idle fix.

Glad it all worked out. There may have been a gummed vlave in the tranny that was doing odd things. 2.5L auto is 10 qts, just an FYI.

nipper


You know I am think maybe it was more of searching for the right gear thing and less to do with idle...who knows. I have a 2.2 isn't that like 9 qts ? Anyways the level is fine and the color is RED!
:burnout:

#8 porcupine73

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Posted 05 May 2007 - 09:23 PM

I wonder if your ATF was overfilled. Generally you'll get 4-5 quarts from the drain plug.

#9 nipper

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Posted 05 May 2007 - 10:04 PM

Here is a longshot, but what condition is your radiator fluid in? It's a longshot but the internal cooler may be leaking.



nipper

#10 R2 Subaru

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Posted 06 May 2007 - 02:32 AM

Here is a longshot, but what condition is your radiator fluid in? It's a longshot but the internal cooler may be leaking.
nipper


The ATF fluid was real dark brown but didn't smell burned. I did top it off about a week ago because I had pulled the radiator. I added 2 quarts when I did this and I don't think much more then a quart came out... but the level looked good when I did it. But say I get 5 quarts out on the drain normally and then an extra quart and a half or so because I over-filled it. Plus I had the car jacked up on the passenger so maybe i got an extra 1/2 quart out...That could account for 7-1/2 quarts right?

Basically it seems to be happy now. I'll keep an eye on the dip stick and maybe do another drain and fill in the next couple of weeks. are there any other symptoms of an over filled tranny besides the dipstick?




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