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Old 03-22-2012, 08:11 PM   #1
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Engine Studder 3000-4000 RPM

94 2.5 auto. Idles fine, feels to fall on it's face if I floor it from a stop then revs fine to 3000 then studders until 4000 then runs out great. Any Ideas? I did do the fuel lines on the tank but they are not binding anywhere.
Thanks in advance

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Old 03-22-2012, 11:01 PM   #2
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Ttt!

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Old 03-23-2012, 07:58 AM   #3
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Obviously

Obviously it is telling you "DON'T DO THAT"!

How would you feel? Your sitting peacefully at a stop light, probably eyeing that catchy looking Miata next to you, and all of a sudden somebody kicks you in the ass as hard as they can?

I mean, come on,, you'ld give quick look, then a heck of a jump, then maybe a few steps and look back to see what that was all about. Then run like hell to get away before it happens again.

Obviously I don't have anything of substance to offer. In the "day" (carb) that would have been the accelerator pump. Fuel Injection, don't have a clue.
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Old 03-23-2012, 07:44 PM   #4
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Ballistix, I litterally laughed out loud.
I did some diagnosing and if I unplug the brake booster vac line it run out great. Any ideas. I pulled the TB and cleaned all the carbon out. Ran Seafoam through the vac system. New injectors.
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Old 03-24-2012, 08:19 AM   #5
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vacuum leak

Could be a vacuum leak in the brake booster. That would seem the most likely. Did you plug the vacuum line from the booster, or just leave it open? If you plugged it, then likely a leak in the brake booster. If you left it open, then it is running better with a vacuum leak. Not sure what that means but there are a lot of people on this forum that are much more familiar with that issue than I am.
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Old 03-24-2012, 08:33 AM   #6
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please understand am shooting in the dark...any chance it is "dirty" up in throttle body/ air intake? besides something along those lines I would look for a vac leak or something plugged restricted that is "bypassed" at higher revs?
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Old 03-24-2012, 10:47 AM   #7
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Well im guessing here, if you pulled the break booster line out and it ran better. I would think that a increase in air from the open brake booster line would mean that it was previously runing to rich? Or perhaps the timing is off?
I can't recall exactly how the brake booster ties into the whole vacuum so I could be totally off here.
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Old 03-25-2012, 08:04 AM   #8
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It smells rich. I'm wondering. Can you time the 2.5 TBI. I hear you can't. Also I don't really know how the brake booster works but if I ran some sea foam in it would it hurt anything.

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