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Old 06-23-2006, 11:56 AM   #1
sregger
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Default slight hiccup and sound

For the past week my car has had a slight hiccup problem. Periodically i will hear a quick "chk" sound that i *think* is coming from towards the front of the car, and the car will hesitate just slightly for a split second. It is slight enough that i don't think anyone who isn't driving the car would notice, and it is very quick. But i know i am not making things up, because it happens often. I haven't been able to pin it to a specific RPM, and it seems to do it under soft and hard acceleration, and cruising, though maybe the most often under soft acceleration. The best example i can think of is that it almost feels as if the wheels hit gravel and lose traction for half a second. I don't lose control of the car or anything, but the slight hiccup in acceleration feels like that.

My first thoughts are that i have a plug or wire that is failing. I haven't checked these yet, but wanted to see if anyone else had any ideas or suggestions for what this problem might be. Am i right about the plugs and wires or does this sound like something else all together?

Thanks,
Sean
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Old 06-23-2006, 02:28 PM   #2
yarrgh
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is your A/C on at the time? mine does that when the compressor kicks on.
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Old 06-23-2006, 02:41 PM   #3
sregger
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i am not sure if the AC has been on every time, but i am sure it has been on at least some of the time it happens. But this has never happened before when i was using the AC, and it happens several times during a drive.
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Old 06-24-2006, 02:13 AM   #4
83Rabbit
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or the defroster can cause that too, check your motor/tanny mounts, throttle cable, axles, and other drivetrain components.
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Old 06-26-2006, 10:40 AM   #5
sregger
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can you be a bit more specific 83Rabbit? What exactly am i looking for? Thank you for the suggestions though.

And i am not 100% certain yet, but today i had a long drive, and half of it i used AC and half i didn't, and i don't remember it happening when i had the AC off, so it is definitely something i will look into now.

Any other suggestions?
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Old 06-28-2006, 09:54 AM   #6
sregger
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looks like you were on to something yarrgh. I never realized it before you mentioned it, but this only occurs when the AC is on.

Since you said you experienced this before, what exactly was the problem and how did you fix it?

Anyone else have any suggestions now that we know it has to do with the AC unit?
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Old 06-28-2006, 12:06 PM   #7
83Rabbit
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it is normal, the AC system cycles on and off I suppose to save on fuel efficiency from having the compressor cycle all the time if it doesnt have to.

Things you can do to alleviate the situation is again check your throttle cable and motor mounts, worn mounts will cause the engine to dip forward or backward when driving it once the compressor kicks on and off, especially changing gears when this happens... trust me, mine is that way and was worse before I changed my tranny mount.

maybe you could find a relay to replace the stock one that will allow the compressor to stay active all the time to take out the cycling on and off?
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Old 06-28-2006, 12:07 PM   #8
83Rabbit
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oh yes and check on belt tension it may alleviate the chirp or belt noise when it first engages.
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Old 06-29-2006, 10:10 AM   #9
sregger
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thanks 83rabbit for the info. I had heard that the cycling of the AC compressor was a normal thing, but what my car is doing now is definitely not normal. I have never felt it before, and it is bad enough now that i can't miss it when it happens. i am hoping it is as simple as getting the belt tightenned or replaced. I don't know much about AC units though, so i may have to take it to a shop here soon if i don't see anything obviously wrong.
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Old 06-29-2006, 09:24 PM   #10
83Rabbit
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check the vacum connections to the solenoid for the AC.
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Old 07-02-2006, 05:23 PM   #11
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will do thank you.
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Old 07-02-2006, 09:53 PM   #12
dknc
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I have this AC related hiccup problem and then I get a sound much like a BOV, but it of course is not from a BOV cuz it's a NA. So what can I do to get rid of this hiccup? Compressor problem? I can see why that makes the car jerks a bit because the engine is driving the compressor belt, but is that solely a compressor design problem, or the compressor is bad? thanks
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Old 07-03-2006, 12:21 PM   #13
83Rabbit
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the hiccup is normal think about it when the compressor kicks in it puts extra tension/strain on the belt, the hiccup your hearing is from those 2 factors, theres not really all that much you can do that hasnt been mentioned in the thread already. Check the vacum connections at the solenoid, check your motor mounts, throttle cable, belt tension and such and it will alleviate alot of the issues revolving around the AC cycling and being jerky.
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Old 07-03-2006, 02:00 PM   #14
grifter
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Quote:
Originally Posted by dknc
I have this AC related hiccup problem and then I get a sound much like a BOV, but it of course is not from a BOV cuz it's a NA. So what can I do to get rid of this hiccup? Compressor problem? I can see why that makes the car jerks a bit because the engine is driving the compressor belt, but is that solely a compressor design problem, or the compressor is bad? thanks
It's not a design fault or a bad part. That noise is the clutch on the compressor engaging and is completely normal. The compressor pulley spins free until the clutch engages, then it makes the noise, and you can feel the sudden extra drag on the engine. The only way to stop it is don't run the a/c.
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Old 07-03-2006, 04:52 PM   #15
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I have notice on my NA 05 RS, when the A/C kicks on, I can hear it kick on and feel it slightly. Then the cooling fans kick on too. Could it be the cooling fans that you are noticing. Sometimes the A/C and the cooling fans kick on at the same time and it takes the car a second to increase the rpm's a little bit because of the drag from the compressor.
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Old 07-03-2006, 05:55 PM   #16
sregger
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Quote:
Originally Posted by grifter
It's not a design fault or a bad part. That noise is the clutch on the compressor engaging and is completely normal. The compressor pulley spins free until the clutch engages, then it makes the noise, and you can feel the sudden extra drag on the engine. The only way to stop it is don't run the a/c.

I know that AC puts an extra load on the engine, but whatever my car is doing is definitely not normal. it is very noticeable now, and i have never noticed it before. people outside the car can hear it when it happens. I still haven't gotten a chance to get it to the shop yet, so i don't have any updates. but i will post when i do.
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Old 07-07-2006, 06:01 AM   #17
dknc
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sregger, could you record the sound and post it? I'll try to post mine too. but as grifter discribed, it's probably nothing we can do? Or maybe your case is a bit different from mine?
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Old 07-07-2006, 11:16 AM   #18
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my car always reacts worse to the AC kick when it's a little low on oil, so make sure you check the basics! my dad just bought a 97 Legacy GT (ej25) and when the AC compressor clicks on you can definately hear the AC clutch engage outside the car, it's not as loud in my car but i have an ej22 and i'm not sure if it's a different compressor/clutch system. you could always just remove the compressor and cut the belt off... that way you lose some weight in the front and your car will drive better! (mythbusters prooved that driving with your windows down is more fuel efficient anyways... and before someone chimes in with a "no, they proved that the AC is more efficient through computer testing!" did you watch the rest of the show???)
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Old 07-27-2006, 01:56 AM   #19
Husky07
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Any news on this problem, I think I have the exact same problem, came up after my 60k mile service, so my own prediction is on the loose belt. It's not only with the AC either. I also get a squeal on cold starts.
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Old 07-27-2006, 10:35 AM   #20
sregger
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i got a chance to have this looked at the other day, but haven't had a chance to get at the forums until now. It looks like the AC compressor is slowly dieing. The clutch is slipping which is making the sound and causing the hesitation. The big clue was when i really started looking at the compressor and clutch and noticed slight rusting round the edges of the clutch, meaning it had been slipping and getting really hot. I should have it fixed within the next week, depending on how quickly i can find the parts i am looking for and for what price.

and funny enough, i was low on oil, but when filled back up, it didn't fix the problem.
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