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Old 09-10-2011, 03:57 PM   #1
peytonracer4
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Hesitation/bucking between 1k and 2k rpms. HELP!

As I was going to work today my car started doing this. In every gear under decent load my car bucks forward. It's very noticeable. It's not just a slight hesitation. It almost feels like the clutch slips and grabs again. But it only happens at this rpm. Between 2k and 3k
What could this be
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Old 09-10-2011, 08:33 PM   #2
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Old 09-10-2011, 08:59 PM   #3
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possibly a MAF issue
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Old 09-10-2011, 09:17 PM   #4
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Does it happen under load or coasting?
Do you have a Check Engine light?
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Old 09-10-2011, 09:20 PM   #5
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It only happens under load. It happens in every gear and only between 1 and 2 thousand rpm.
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Old 09-10-2011, 09:25 PM   #6
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Quote:
Originally Posted by peytonracer4 View Post
It only happens under load. It happens in every gear and only between 1 and 2 thousand rpm.
Codes? As stated above.

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Old 09-10-2011, 09:25 PM   #7
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Oh sorry
No. No codes.
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Old 09-10-2011, 09:30 PM   #8
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How many miles you have. When did you get it and what do you drive like?

Could it be your clutch slipping? Sure. Park in front of a wheel chock and try to start off in fifth gear. If you stall, your clutch is fine. If you don't stall, I guess you'll start loosing your clutch. If it's clutch.

I'm not sure how sure you are this is a clutch issue though. Intake boot or other major intake leak would make you feel a sudden loss of power while the car tries to figure things out. If this disappears when you drive without the maf, that narrows it down to maf or intake leaking somewhere...in the intake or in a vac line.

I'd start there, but if you have more details about your sense of things, I'll try to make up more stuff for you!
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Old 09-10-2011, 09:41 PM   #9
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I got it two years ago. I drive... Normal. I'm honestly a pretty conservative driver but I'll definitely get on it every once and a while.
I only said it sorta feels like a clutch slipping then instantly grabbing. I can still burn rubber though. So I feel like if the clutch is strong enough for that then it should be a clutch. Correct me if I'm wrong.
I replaced the upper intake boot recently. Soon after I got an even louder intake whistle. I looked at the lower one yesterday the best I could without taking anything out. I touched it and moved it around. This could've caused a rip or something. I was really messing with it. It felt new.
So I have to have a vacuum leak somewhere. It's possibly the lower one and I just missed something. After I messed with the lower boot I drove for close to 70 miles without issues. The bucking just started today.
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Old 09-10-2011, 09:49 PM   #10
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If your lower boot is moving around, that could be your issue and you might as well get a new boot and replace it. For $12, you'll be there anyway.

Also, you might broaden your work a bit and clean up things like the icv and TB with appropriate cleaners. I wrote about all the work I did to take care of my idle surging. Search for me and 'maf disa icv tb grommet'

It shouldn't be loose, and that could certainly be your issue. The maf doesn't know about the air coming in past it, so the fuel isn't what it's supposed to be. Eventually, the O2 sensors seem to catch up and call for more gas.

It's not so out of range yet that you haven't thrown codes. If it gets worse, you have too much air and won't be able to get the mixture right...then it seems you would get a code. I'm not positive, but I think you'd get either a maf code or an O2 code.

Sorry...I think you need to go deeper.
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Old 09-10-2011, 10:07 PM   #11
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Can you get your hands a a scan tool to look at fuel trims? This would tell you if you had a vacuum leak, MAF or o2 problem.

Sound more like an ignition problem, but hard to say without driving...
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Old 09-10-2011, 10:45 PM   #12
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Well I'll run it without a maf tomorrow. This will tell me if it's due to a vacuum leak or something of that sort.
Is it possible that it could be a fuel filter? Maybe sorta clogged? I've read that a new fuel filter changes performance.
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Old 09-11-2011, 05:55 AM   #13
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If it runs better without a maf, that means it's either a maf or intake leak issue. One of the two. But, clean the maf and it's electric connections first before buying a new maf ...and don't buy a maf without checking back here.

It doesn't sound like a fuel filter, but if you haven't replaced yours in years, it'd be a good idea anyway. I got an extra 1.5 mpg or so when I did mine...just by doing that one thing!

I reread what you did with the lower boot...and I guess you moved it, it wasn't moving around loose...is that right? If you moved it, you may have cracked the elbow to the icv to slipped it out of its proper orientation, but if it was on tight, you shouldn't have been able to really move it at all. If you moved it without loosening up the clamp, then we're back to that as a likely suspect again.
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Old 09-11-2011, 08:10 AM   #14
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When I say I moved or messed with the intake boot. I was squeezing it and really just feeling all around it for leaks. It's definitely on the icv and tb tight.
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Old 09-12-2011, 02:43 PM   #15
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update: i just drove it with the maf plugged in and unplugged. it's the same both ways. the bucking doesn't go away with the maf unplugged. i did notice that it only does this when the engine has warmed up. i couldn't make it hesitate with a cold engine.
so does this rule out a vacuum leak causing this?

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Old 09-12-2011, 03:16 PM   #16
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update: i just drove it with the maf plugged in and unplugged. it's the same both ways. the bucking doesn't go away with the maf unplugged. i did notice that it only does this when the engine has warmed up. i couldn't make it hesitate with a cold engine.
so does this rule out a vacuum leak causing this?

help
I think you've only ruled out the maf at this point. The maf goes to factory settings, so would run better if the maf is bad/dirty. But, given your symptoms, especially the hesitation only when warm, it makes me think an intake leak is likely.

That said, there might be other things I don't know of that are 'warm related.'

I believe the computer takes in temp readings from the outside air temp sensor, the intake air temp sensor at least in calculating the right amount of fuel; I don't know that they'd cause hesitation if they're 'off' but maybe.

You specified an rpm range for your symptoms. Have you checked to see whether you still have the issue when accelerating hard in third, say, from 3-4K rpms?
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Old 09-12-2011, 03:37 PM   #17
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The hesitation is only from 1k to 1500 rpm. At no other time does it occur. I'm actually in the process of taking the lower boot off now to check it. It's a pain
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Old 09-12-2011, 03:42 PM   #18
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The hesitation is only from 1k to 1500 rpm. At no other time does it occur. I'm actually in the process of taking the lower boot off now to check it. It's a pain
I think it's a 6mm socket that fits on the screw clamp...if you haven't figured that out yet. Just loosen it up a turn or two then rotate it to the top of the boot.

I hope you find a crack...and hope you won't hate me if you don't! You shouldn't trust people on the Internet, you know...especially me!
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Old 09-12-2011, 03:48 PM   #19
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Ok well it's out. Took me a few tries but I got it. It's in perfect condition. So what now?
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Old 09-12-2011, 03:49 PM   #20
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I assume it threw a code when you ran it without the MAF?

It sounds similar to the problems I was having when I forgot to reconnect my intake cam sensor, but that failing should throw a code too.

Would a bad PCV valve cause enough of a vacuum leak to cause a problem? (thinking of that whistling problem)
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