Puffing noise when revving engine


#1

Hi,
Was hoping I could get some help from you experts.
When in idle the car is fine, however when revving the engine up to 2500-3000 rpm there is a puffing noise from the exhaust pipe area.
Any idea what this could be?
There is only on puff when reaching 2500 rpm… When I asked mechanic he said "it’s because there is a small engine…"Sigh.
Please help!


#2

@ Sannis86
Please… Make, Model, Model-Year, Engine ?

Also, why are you revving the engine to 2500-3000 rpm?

CSA


#3

Hmmm only between 2500-3000, and I thought those Model T’s puffed at just about any RPM.


#4

^
I was working on the assumption that the car in question is a Hupmobile from the late '30s.

Quien sabe?


#5

1918 Stanley Steamer?


#6

If your vehicle is a 1996 or newer, the computer has what is called a Rev Limiter.

This means that if the vehicle is in park/neutral, and you try to bring the RPM’s up too high, the computer see’s no reason for that high of an RPM when the vehicle is not in gear or moving. So the computer cuts back the fuel delivery to the engine and that causes the sputtering out the exhaust.

Tester


#7

In my limited experience puffing usually comes from an exhaust leak. Or a very tired muffler whose innards have given up the ghost.

But, let’s face it, on an Isetta anything is possible.


#8

@the same mountainbike

Wow! That brings back memories. When I managed a body shop (unfortunately) once, for a couple of years, our painter bought and restored an exact duplicate of that Isetta. It basically needed only new paint. Whenever anybody mentioned, “Isetta,” anybody within hearing range responded with, “You said-uh what?”

CSA


#9

I had the honor of driving one a few times in the very early '70s (1971 or '72 I believe). A buddy had one. It’s a really weird experience.


#10

@TSM do you remember if the gear shifter on the left side panel had a shift pattern or was it progressive ala motorcycle transmissions? I was too young to drive one but I rode shot gun in a yellow one for a few years. The Isetta was always in the shop to replace the rubber donuts which acted as universal joints between the transmission and the final drive ala BMW drive shafts.


#11

It had a pattern.
However, versions of the Isetta were built under license by numerous manufacturers in numerous countries. The car was originally designed by a company named Iso who made refrigerators and scooters. I’ve always wondered if the refrigerators were the inspiration for the opening front.


#12

I had a head gasket leak that only manifested itself as a “puffing” sound in the exhaust at WOT…and it would pop the breather off the block. Maybe that’s what OP’s getting at with puffing at mid revs.


OP, fill in the blanks: “I drive a 20[xx] [Brand] [Model] with [n] miles.”


#13

Its a cheverolet cavalier 2001…


#14

It’s been a very, very, very long time since open-air breathers were replaced with PCV systems. That must have been a while ago… or at least an old car.

But it does suggest something having popped off the valvecover (like perhaps a PCV valve) as a possible source of puffing sounds. As a matter of fact, it’s a very good suggested possibility to look into. I probably would not have thought of it.


#15

To some extent your mechanic is correct, that could be entirely normal. First off, the faster you go the more exhaust gasses have to pass down the tailpipe. And they do exit the tailpipe discontinuously, in spurts , hang a dollar bill over the tailpipe and watch what it does at idle for example. See it move back and forth? So it would make sense there could be a sound like that, and the sound would get louder at higher rpms.

Second off, it’s pretty common when you are going pretty fast, then you let your foot off the gas slightly a put-put-put sound will come out the tailpipe. Even a backfire could happen. Has to do with a vacuum build up in the intake manifold. Some cars have deceleration valves to minimize that effect.

http://www.autozone.com/repairguides/GM-Celebrity-Century-Ciera-6000-1982-1996-Repair-Guide/ELECTRONIC-ENGINE-CONTROL-SYSTEMS/Deceleration-Valve/_/P-0996b43f8039383e


#16

Mechanic said " it’s because there is small engine " I can’t imagine a real mechanic making that statement.


#17

Smaller engine displacements tend to sound different than bigger ones for some reason.