knocking or popping sound at start up
 

Every so often I get a popping sound from the exhaust when I start the car and accelerate. Almost like a hesitation. What I have to do is accelerate hard a couple of time and it goes away. Any ideas???

Jteixidor, please list your:

Year
Mileage
Engine/Model
And any codes if you have them

Car
 

2001 Porsche Boxster
31K
just recently did the 30K service with Porsche
2.7 engine and I dont get any lights on the dash (if that is what you mean by codes)

Joshua

Anyone have this happen????

Hi,

Is it Knocking or Popping? Two completely different things.

Knocking would indicate something mechanical, such as an engine internal or even a loose exhaust component.

Popping would seem to indicate a problem with the A/F Mixture causing unburnt fuel to ignite in the exhaust, this could be either a Rich or Lean condition caused by anything from a bad MAF to an Air or Vacuum leak. No Codes?...

Happy Motoring!... Jim'99

Not sure
 

Not really sure, Sounds more like a pop in the exhaust. If you mean lights on the dash by codes, I dont have any lights coming on. Any ideas?
Joshua

Did you ever find out what the problem was or is? :confused:

I think I know what you mean and mine does this from time to time. (2001 S, 6 speed.)

I'd say it's more like an air "burping" or "gulping" sound, which could be described as a muted/muffled/soft popping or knocking.

I've always assumed it was just some normal intake noise -- never noticed any problem.

popping and hesitation
 

Mostly when cold, if I have to stop in traffic right after starting, then tremendous hesitation. Sometimes 1-2 seconds before engine speeds up. Then hesitation at 2800 RPM and it lasts for a day. Overnight, restart and drive and about 5-10 miles later all is okay again until the next time. No codes and no pending codes. 2001 5 speed. New MAP, new air oil separator and rubber boot.

"Every so often I get a popping sound from the exhaust when I start the car and accelerate. Almost like a hesitation. What I have to do is accelerate hard a couple of time and it goes away."


Mine does not really pop, but you can hear the exhaust gurggle, not when I accererate, but when I let off the gas. It does sound like unburnt fuel igniting, but just checked my mixture last week and its right on the money. I suspect it is just my exhaust system allowing you to hear more of what is going on. Anyone else with headers 100-cell cats and a high-flow muffler hear that sort of thing?

Ed

:cheers:

Ed-
I have a stock '99 w/ the 2.5 monster ;) but had a similar gurgle sound when I let off . It went away when I replaced my AOS which I had a feeling was going bad. Not sure when/if you last inspected your AOS, but I'd pull the j-tube and also inspect your throttle body for more than a light misting of oil. Otherwise, you could be right and it might just be your headers.

Ed, my '02 S did this too. I checked the AOS, and it was fine. It kept getting worse until I ran a bottle of Techron thru... Amazingly easy fix, car runs like new now. Gas mileage dramatically improved too. My car is stock.

Ok guys, what is the deal with Techron ?

Does this stuff really work, or is it snake oil ?

If it is worthwhile, where can I get it ( I don't see any Chevron stations listed in Illinois on their website ) ?

Thanks,

Nick

Nick, I have used it. About once per year. You can buy at any of the better auto parts stores. It's a black bottle. They have it pre-measured for 12 gallons and 20. I use the big one. Cost about $11.

Techron is good.. I've seen the results first hand tearing down a 911 motor that I ran Techron through with every oil change.

HOWEVER.. I have seen a more direct improvement in my Jeep and my 951 using the Lucas products. I highly recommend the Lucas fuel additive (http://lucasoil.hodgsoncorp.com/lucas_fuel_treatment.htm

It solved a bouncing idle issue in my Jeep, and marginally improved throttle response in the Boxster.