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Discussion Starter #1
So i havent posted much but ive done a good amount of reading, and im pretty sure i already know the answer, but, i have a '03 zx3 and when i accel then push in the clutch to shift the revs jump about 200-400 rpms. likewise when i come to a stop (holding the clutch in or neutral) the idle sticks at about 1200 and it takes 3-8 seconds for the idle to come down to the regular 900rpm level. from what ive read this sounds like a vacuum leak but i figured i would get some opinions. if its not a vacuum leak its the throttle body (which i dont really wanna go through replacing if i dont have to...)

thanks in advanced,
zakk

edit------
i also have been looking for a strut bar for ages and cant find one, anyone know any aftermarket sources for one?
 

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Look at what Massive & CFM offer for the bar, links in their vendor sections.

RPM bump when shifting sounds in the normal range, get off gas a little sooner when shifting.

Slow drop when stopped could be a vac leak as mentioned, seldom see a SLOW IAC response but it's possible.
 

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Discussion Starter #3
Thanks for the input, in every other car I've driven stick in (jetta, Kia soul, wrx, Evo, and honda fit) it's never rpm bumped that's why I figured I would ask if it is a vacuum leak (referring to the latter of your reply), do you suggest carb cleaner checking? Or just replacing throttle body? If I do replace the throttle body, should I take the time to port it as many others on here have done?
 

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Why a throttle body?

Did you find a sticking problem there that wasn't mentioned?
 

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Discussion Starter #5
ive dug around on multiple threads and alot of sticking issues pointed to throttle body, under that reference thats the first assumption. only way to for sure know is leak test it. which i plan on doing hopefully soon, as if its the fuel vacuum line, its a much cheaper and easier fix.
 

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You're lost, leak checking a TB does nothing to unstick it. It can sticking leaking or not depending on how it's been treated (overtightened or misadjusted).
 

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Lost me, only testing for sticking TB that I know of is to move the butterfly & see if it sticks anywhere.

Is there confusion between checking for vacuum leaks vs. checking for a sticky TB?
 

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Discussion Starter #9
to clarify, im not checking the butterfly valve itself. but to see if there are any cracks in the housing, sealing around connections, and the fuel vacuum line. all those could attribute to a sticking idle. if none of those seem to be the issue, then ill then inspect the butterfly valve.
 

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If you want to check for unmetered air leaks (which it sounds like you are) get some starting fluid and spray around all cracks and crevices. If there is a leak the car will rev.



Don't spray anything hot like your header or the block directly. Starting fluid is very flammable.
 
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