slight backfire when downshifting in second gear
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- 356 Fan
- Posts: 98
- Joined: Fri Dec 31, 2010 12:49 pm
- Tag: shore bird
- Location: south orleans, MA 02662
slight backfire when downshifting in second gear
Just took my 356C out of storage and drove it less than 100 miles so far. Today I noticed a popping or slight backfire when I downshift to second gear and it doesn't seem to matter what the rpm's are. Several years ago I had a very loud backfire issue when downshifting and it was an exhaust manifold gasket. This is nowhere near that but I am wondering what people may think is the problem. No performance issues with acceleration - just this new noise. Possible air/mixture issue with the Webers?
- VinceFinaldi
- 356 Fan
- Posts: 107
- Joined: Fri Mar 14, 2014 10:29 pm
- Location: Ladera Ranch, California
Re: slight backfire when downshifting in second gear
That popping is usually when unspent fuel ignites in the exhaust...not a true backfire. In order to do that it needs oxygen. Thus, when you have an exhaust leak (bad gasket, cracks) it introduces oxygen and boom. Classic example is a bad air check valve on early cars w smog equipment. Check the exhaust first. If that's not it, then it could be a carb issue (too much gas getting in on decel)