Fangio2 Posted October 23, 2007 Share Posted October 23, 2007 Loud pop and bang from exhaust when lifting off gas sharply. Quite good when going through a tunnel, quite fun anyway. Nonetheless, probably doesn't do whats left of silencer much good so, is it likely to be a timing issue? Advance or retard please? Neil Link to comment Share on other sites More sharing options...
Pew Posted October 24, 2007 Share Posted October 24, 2007 Have you checked for leaks in the exhaust? Link to comment Share on other sites More sharing options...
Fangio2 Posted October 24, 2007 Author Share Posted October 24, 2007 Don't think it leaks, the join seems sound. Read some back issue Posts and it could be running a bit lean i suppose, may have a fiddle with the idle mixture screws to richen it up a little, see if that makes a difference. Otherwise, what the hell, lots of them seem to do it. Link to comment Share on other sites More sharing options...
Martin Keene Posted October 24, 2007 Share Posted October 24, 2007 Pops and bangs on the overrun are *generally* caused by a leak in the exhauts and running rich. The rich running provides the fuel, the leak provides the oxygen and the exhaust provides the heat. Hence small fire/explosion in the exhaust. Link to comment Share on other sites More sharing options...
Fangio2 Posted October 25, 2007 Author Share Posted October 25, 2007 That makes sense, thanks. Shall check it over. Link to comment Share on other sites More sharing options...
Tubs Posted October 25, 2007 Share Posted October 25, 2007 I remember that this has been discussed before and with little convergence on the reasons i.e. some saying too rich and others too lean. The too rich argument is that there is fuel left over after the power stroke which, when it meets the air, ignites. The too lean brigade, of which I'm one, state that when running too rich, although there is obviously fuel to burn, the temperature of the exhaust gasses is much lower and, in fact, not hot enough for combustion when it meets the air. However, when the fuel is too lean, you still get unburned hydro carbons (this is why modern cars are fitted with a catalytic converter) which are leaving the exhaust environment at a much higher temperature, which then ignite causeing the popping and banging. I believe that, for both cases, timing is less of an issue. I hope that this has confused you completely. Tubs. Link to comment Share on other sites More sharing options...
Fangio2 Posted October 28, 2007 Author Share Posted October 28, 2007 Thanks Tubs, no, not confused can see the logic in both so it helps. Shall have a twiddle and see if either adjustment to rich or lean has positive effect and get back to you if there is a significant change. Interested in you view about ignition timing, shall leave that alone as in other respects it seems fine. Neil Link to comment Share on other sites More sharing options...
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