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Discussion Starter #1
i brought home my gto on 12/16. so far, i'm extremely pleased, as this car is seriously FUN to drive. at first, i thought i'd never use the cruise control. but after driving on the highway for about 5 minutes, i looked down and saw that i had let the speedometer creep up to about 95 without noticing. so, on second thought, i should probably use the cruise merely to avoid speeding tickets.

to my question... i've noticed that when i'm idling, i feel a little shake/rumble which i assume is caused by the engine. is anyone else experiencing this? and is it normal?
 

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i feel the same rumble also. but i am pretty sure its the massive v8 under the hood. this is my first v8 and i love it. previous car was an acura tls. love this car.


brimm
 

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yup. it's that fatty LS1 under the hood, which I would fathom would rumble even more w/ headers or an aftermarket exhaust...
 

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I have a bit of a rumble coming through the gas pedal. Something I do not have in my LT1 powered Z28 so the massive V8 argument doesnt fly.

Since I leased the car, I dont care that much, but if it does get on my nerves at 7500 miles when I bring it in for its first oil change (right after it gets its first car wash) I will probably say something.

This renting and not shiving a git is great!! When my RX7 convertible had 700 miles on it I had the oil changed. My then girlfriends father knew a place open on labor day weekend on the Cape. My girlfriend wasnt too pleased I was hanging out with her dad at a gas station during our vacation.

He wasnt a car guy, but....
 

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My GTO shakes and rumbles as well. Sometimes when I am sitting at a stoplight I can feel the car sway. Maybe it is not the "massive V8" but the shaking and rumbling is a charactaristic of the GTO.
 

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rwilson831 said:
My GTO shakes and rumbles as well. Sometimes when I am sitting at a stoplight I can feel the car sway. Maybe it is not the "massive V8" but the shaking and rumbling is a charactaristic of the GTO.
in 1984 i had a 1985 RX7. I would blip the throttle and let off the gas. as the motor was going down to idle at about 1200 rpm the car would shake. i took it to the dealer. he said I could start as many of the new and used RX7s on the lot and he guaranteed me that every one did the same thing.

If GTOs rumble then GTOs rumble. it just seems odd that such a refined car would allow the vibration in the gas pedal. if others have the same vibration then there is no issue.
 

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My LT1 in the 95 Impala SS has never shook or rumbled. NO problems at all with that LT1.

My 02 Z06 shook some at the red light but it was the LS6 engine and i was told they shook some at idle.. kinda felt like it was a MEAN motor and a side to side feeling.

Now my 04 Z06 hasnt never shook at red lights or anytime.

I wonder if its how you break the car in? For one thing i broke the 02 Z06 in harder, i mean i went thru the gears and drove it alot harder and it was because they told me at the dealership to break it in the way i wanted it to run later. I never had any problems out of the car, but when i got the 04 Z06 most of the guys on the corvette forum were saying to break it in by the manuel, not hard but to do this and that at certain mileage. So i went by the book and the result seems to be a smoother idle at redlights and stops. Car runs very good and fast also. So you got me, may be the way you guys are breaking in your cars. they say the first 500 miles is very important on the brakes and getting everything settled and balanced in the whole drivetrain, then you can step it up some from 500 miles to 1000 miles BUT still not too hard ( NO redlines) lol..and then after that you can get more aggressive and so on. Read your manuel on break in. All i can say is i have no rough idle in the 04 and never any problems out of either Z06 breaking them in differently. Although the idle in the 02 was sorta cool in a way. HAHA!

Good luck, lets hear how your breaking in your new GTO's.

see ya.. T.
 

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Tom said:
it just seems odd that such a refined car would allow the vibration in the gas pedal.
i'm not sure that i feel the vibration in the gas pedal, but i was thinking the same thing about just being in park. because when i'm accelerating or coasting, it feels strong and smooth. it's just when i'm stationary or when i'm in park that i feel the car shaking a bit. some have said that the rumble is good, but why is that good? i do admit though that the shaking does give a "muscle car" feeling more so than a refined one, which i suppose is the whole point. i'm trying to break the goat in properly, but that muscle car feel just begs the driver to punch it. it's killing me.
 

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skibum100_777 said:
Tom said:
it just seems odd that such a refined car would allow the vibration in the gas pedal.

i'm not sure that i feel the vibration in the gas pedal, but i was thinking the same thing about just being in park. because when i'm accelerating or coasting, it feels strong and smooth. it's just when i'm stationary or when i'm in park that i feel the car shaking a bit. some have said that the rumble is good, but why is that good? i do admit though that the shaking does give a "muscle car" feeling more so than a refined one, which i suppose is the whole point. i'm trying to break the goat in properly, but that muscle car feel just begs the driver to punch it. it's killing me.
A rumbling engine is bad? If so, then you bought the wrong car.
 

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My 2001 Corvette didn't shake at all--it had a very smooth idle. It idled at 550 rpm.

The GTO shakes a bit and idles at 800 rpm. I think the LS1 in the GTO has a higher lift cam than the LS1 in the Vettes--if so, that would account for both the shake and the higher idle RPM.

I broke in both cars the same. No full throttle to redline blasts, but many moderate throttle applications followed by cool-down periods. No sustained running at any particular PRM.
 

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Discussion Starter #12
djdub said:
A rumbling engine is bad? If so, then you bought the wrong car.
no, i'm not trying to incinuate that a rumbling engine is bad, i'm just asking what makes it good? since i'm new to the gto, i'm taking a neutral stance. just trying to learn. should the engine rumble to the point that it shakes the car at idle?

I DON'T WANT ANY TROUBLE FROM YOU DJDUB!!! :)
 

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Discussion Starter #13
Duck916 said:
The GTO shakes a bit and idles at 800 rpm. I think the LS1 in the GTO has a higher lift cam than the LS1 in the Vettes--if so, that would account for both the shake and the higher idle RPM.
ok. so, if this is the case, then the shake isn't indicative of anything that is malfunctioning or balanced improperly?

sorry if this issue sounds elementary, just wanna make sure.
 

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Hello- I just brought home my new 2004 last night (Got a GREAT deal!), and yes, there is a little bit of rock from my engine at idle. I'm sure that's just the nature of this engine. I don't have what I would call a rumble or any extra vibration through the gas pedal. The engine is actually pretty quiet at idle, but there is a little bit of shake at idle.
 

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skibum100_777 said:
ok. so, if this is the case, then the shake isn't indicative of anything that is malfunctioning or balanced improperly?

sorry if this issue sounds elementary, just wanna make sure.
I guess my reputation preceeds me. :)

When my GTO was brand new it rumbled and shook a little bit, but nothing that I wouldn't expect from a big V8. Keep in mind I've only ever owned V6s and one I6, and I still didn't think the shake was abnormal. As the cars gets a little more broken in, the rumble and shake seems to subside and only return on ice cold starts.

Come to think of it, I do remember quite a bit of shake when I first brought the car home. I reved the engine for a buddy of mine in my driveway, the day I got it, and it sounded like sh*t. But since that day it has gotten smoother and smoother (or I got used to it) and it doesn't seem to shake that much at all, any more.

Remember these cars made a long trip, by boat, without being started for long periods of time. Also, if you just got the goat, it probably sat on the lot for a long while without being started.

I say give it time.
 

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skibum100_777 said:
ok. so, if this is the case, then the shake isn't indicative of anything that is malfunctioning or balanced improperly?

sorry if this issue sounds elementary, just wanna make sure.
Don't be sorry. Any question is good.

I don't know for a fact that the GTO motor uses a different, higher lift cam, but I am pretty sure it does. I have a lot of experience with modified and built V8s--with high lift or big overlap cams, you will get some rock and roll at idle. This smoothes out at higher RPMs.

If there were a problem with the engine's balance, it would be just the opposite--it would get worse at high RPMs. Since that isn't the case with mine (and yours, I suspect), I don't believe anything is wrong.
 

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shaking...

I have read that the shaking is also partly due to no X-over pipe in the exhaust. They are 2 separate pipes all the way back so there is no way for the exhaust pressure to equalize at idle. Not sure how accurate this is, but sounded plausible to me.
 

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shake

I read on a Corvette website that the engineers who built the LS1s went to great lengths to minimalize the "Shaking" that the engines do. The fact that the blocks and heads are aluminum alloy and lighter than cast iron means that there is less weight in the assembly to "smooth out" the shakes. I found the information on the engineering that went into the engines by doing a google search on LS1 engines. I recommend doing a little research in this area, as I gained some respect for the engine that is the heart of my new car. I'll try to add the link here : http://www.idavette.net/hib/ls1c.html I hope it works.
I haven't read anything about what kind of piston rings are in our LS1s, but I suspect that part of the reason they are running progressively smoother, is that the rings are breaking in and the compression is coming up to the range where it is supposed to be, this would also explain why we are getting progressively better gas milage as we log more miles on the engine.
Another thing I have wondered about is the quality of the stock spark plugs. It is my suspicion that the spark plugs may be contributing to the shakes through random misfires at idle.
Sometimes my engine doesn't seem to shake at all, and at other times it is very pronounced. However, it does seem to like being taken out for a hard drive, as it seems to run smoother afterward.
The quality of the gas you use can also play a huge role in whether you will get misfires. Cheap gas is not worth the savings. You get what you pay for, especially when consumers aren't kept informed as to what additives are being used by what gas companies at which times of year, etc.. Some companies are giving us "Gasahol," without letting us know what we are getting. What is in fuel can change constantly, if you can find a gas station that consistently delivers the fuel that your car seems to like, my advice is to stick to that station.
A great deal of money, talent, and technology went into the design of the LS1, but they are not the "Perfect" engine.
These are my thoughts on the subject. You are welcome to take what makes sense to you. I don't think it would be possible to eliminate the shaking all the time, as there are too many variables to keep up with.
I hope you enjoy your car as much as I do mine. :cheers

Maximental
 
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