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Discussion Starter #1
Hi All

My car has been doing a wierd idle ever since i almost got the car a couple years ago. At first i thought it was the nature of the car, but now it is getting a little old and annoying.

I have a MY00 2.5rs sedan. The only mods are an exhaust and DIY indtake, and DIY 5pt grounding mod, car has about 50,000 miles.

Here is the issue, when im decelerating (coasting to a complete stop), and it doesn't matter which gear or neutral, as the engine gets to a low RPM (2000 and below) it sounds like its misfiring, and the engine bogs a bit (I don't let it die of course), but the bucking is getting soooo OLD. Forget about stepping on the gas when it is in this state, it will hesitate and then go.

This is something i can replicate and it doesn't matter on the weather conditions.

Tried the searches but nothing quite specific to this comes up.
Anyone have any ideas.

thanks

jt
 

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I had that problem with a DIY intake that was sucking in too much water vapor from under the fender, AND with the Cobb intake as well. Consider replacing the stock air box and see what happens.
 

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Discussion Starter #3
Sounds probable, however, im not sure where the vapor would be coming from. The intake that i have uses the stock airbox with a KN filter, and it has a 3" in diameter aluminum tube that stops just before the hole in the engine bay that leads to the fender well, looks like a short ram kit only it goes very close to the fender well hole. I had some pics but i lost them.

jt
 

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That's very similar to the Cobb.... So... can you switch it back? What's it going to hurt?

Otherwise... maybe a clogged filter? Bad spark plugs? Bad fuel (dirty fuel filter, defective pump [low pressure]) or ... got me. :(
 

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Discussion Starter #5
I took off the short ram piece that i have and i noticed a slight improvement, (the lurching and bucking has stopped, it just decelerates normally now)

however my butt dyno tells me that there may have been a pony or two that went along with the intake tube. Is that possible

jt
 

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Generally speaking the DIY intakes lose low end torque when installed, and don't do much for HP. However, if you can tell the difference of 1-2 HP then you've got the most sensitive Butt Dyno in the world. I bet most people could not tell the difference of 10 HP, so I think it's your imagination. Besides, 1-2 hp is completely negligible in terms of performance. You'd never know it was gone.
 

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Discussion Starter #7
That butt dyno is sooo unreliable,
maybe it was my imagination, but when i reached 3500rpm it seemed to take a little bit longer to get to 5000rmp. Again it could be my imagination. I did this in every gear and it almost feels the same as before only without the bucking. So i guess this case can be closed.

thanks for the help

jt
 

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Ver 7 STi GC, elderly L
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Would you also so this problem with a dirty filter in an OEM air box?
 
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