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High Idle after muffler "swap/removal"

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Old 09-09-2015, 10:56 AM   #1
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High Idle after muffler "swap/removal"

Hello everybody,

I have a 88 Camaro with an stock LO3 305 TBI, and today I removed my muffler and two tailpipes for just a 2.5" piece of pipe.
I was curious how the car would sound with only the cat being a muffler.

When I started the engine, it would rev up till 2000rpm.
While driving it wants to accelerate to a certain point, until like 30kph.

Also, when I'm driving like 50 kph, put it in neutral, it would idle about 1250rpm, while normal idle would be 750 till 900 ish.

The weird part is, when I'm in gear and completly stop, it idles about 750rpm in gear and when I turn it in neutral its about 850rpm. Like how it normally should.
But when I start driving again, it starts to high idle again.


Does anyone has an idea what this could be?
And, could it hurt my engine?

Cheers,

Tias
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Old 09-09-2015, 05:16 PM   #2
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Re: High Idle after muffler "swap/removal"

Could the lack of a muffler hurt the engine? I don't know how it would. Your description is a bit confusing though. While driving, in gear, the engine doesn't idle...it is now connected via fluid and gears to the wheels... which are spinning. Driving, in neutral, it will idle....roughly the 1250rpm you stated before. I also don't quite understand what you mean by "While driving it wants to accelerate to a certain point, until like 30kph." So then, how did you get it up to 50kph?


Maybe you can clear things up. I can understand if there's a language barrier.
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Old 09-10-2015, 02:15 AM   #3
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Re: High Idle after muffler "swap/removal"

Ill try to make a video and hopefully it will explain the problem.

Althouh I think its the lack of backpressure.
But who knows
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Old 09-10-2015, 04:06 AM   #4
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Re: High Idle after muffler "swap/removal"

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Originally Posted by aliceempire View Post
Could the lack of a muffler hurt the engine? I don't know how it would. Your description is a bit confusing though. While driving, in gear, the engine doesn't idle...it is now connected via fluid and gears to the wheels... which are spinning. Driving, in neutral, it will idle....roughly the 1250rpm you stated before. I also don't quite understand what you mean by "While driving it wants to accelerate to a certain point, until like 30kph." So then, how did you get it up to 50kph?


Maybe you can clear things up. I can understand if there's a language barrier.
Driving in neutral means.
You are in gear driving till 50, then put it in neutral and just let it roll.

My bad for the word choise.
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Old 09-10-2015, 05:42 AM   #5
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Re: High Idle after muffler "swap/removal"

The weird thing is, when I took it for a drive today, it has only a high idle because the engine is still cold. But the rpm of that idle was lower then the first time I started the car without the muffler.

And after a while , when the engine is warmed up, everything is normal .

Cars are like weird magical creatures.
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Old 09-10-2015, 07:59 AM   #6
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Re: High Idle after muffler "swap/removal"

It's only going to hit the 750 idle at a complete stop in gear. It will be around 1000 or so in park or neutral at a complete stop. Rolling at any speed in neutral the engine does not have any resistance from the transmission and will run at a higher rpm.

Also these cars run at a higher rpm when cold and slowly drop to a lower rpm at idle as the car warms up.

To help with some of the laguage barrier, the term idle only applies to the car being at a complete stop in any gear or park or neutral.

If the car is still running smooth. As in no misses or stumbles, and it sounds good to you now, I would say that you are okay.
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Old 09-11-2015, 05:45 AM   #7
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Re: High Idle after muffler "swap/removal"

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Originally Posted by Wife'sCar View Post
It's only going to hit the 750 idle at a complete stop in gear. It will be around 1000 or so in park or neutral at a complete stop. Rolling at any speed in neutral the engine does not have any resistance from the transmission and will run at a higher rpm.

Also these cars run at a higher rpm when cold and slowly drop to a lower rpm at idle as the car warms up.

To help with some of the laguage barrier, the term idle only applies to the car being at a complete stop in any gear or park or neutral.

If the car is still running smooth. As in no misses or stumbles, and it sounds good to you now, I would say that you are okay.
I guess the car is doing fine then.
Thanks for the answers.
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Old 09-11-2015, 07:38 AM   #8
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Re: High Idle after muffler "swap/removal"

No problem! Glad to help!
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