Martin Barrett Posted July 12, 2004 Share Posted July 12, 2004 I have a 03 Lemans, with 3,800 miles on it just under a year old. Over the last couple of weeks has developed a backfire on a shut throttle. Started as a little puff and now is a good'n. All the exhaust joints have the sooting deposits but appear to be tight. Even where it meets the cylinder head. I have sooty tail pipes and return 33-35 mpg. I haven't checked the valve clearances but sounds tappety so they might not of closed up. Searching the threads show a backfire attributed to lean fueling but I don't think its running lean, I haven't done a plug chop. Hasn't got as bad as my old FJ with its holed collector, which was great for clearing cars out the way on the motorway Which of the above or where else should I start looking in ernest. Is any damage likely to be caused in the mean time? Link to comment Share on other sites More sharing options...
Admin Jaap Posted July 12, 2004 Share Posted July 12, 2004 Did you check the intake rubbers for cracks? Link to comment Share on other sites More sharing options...
HolgerKvD Posted July 12, 2004 Share Posted July 12, 2004 Did your dealer installed the latest ECU software update? Most of the bikes come with an old software version from the factory. The old software runs the engine in a lean fuel/air condition. This causes stumble and sometimes backfire. Holger Link to comment Share on other sites More sharing options...
jrt Posted July 12, 2004 Share Posted July 12, 2004 Check the plugs- that'll tell you straight away. J Link to comment Share on other sites More sharing options...
Martin Barrett Posted July 12, 2004 Author Share Posted July 12, 2004 Did you check the intake rubbers for cracks? Yes sorry they did have signs of cracking but didn't seem to be cracked all the way through Link to comment Share on other sites More sharing options...
jrt Posted July 13, 2004 Share Posted July 13, 2004 Put a wrap of electrical tape around them as either a temporary fix, or a check to see if that's the problem. J Link to comment Share on other sites More sharing options...
docc Posted July 13, 2004 Share Posted July 13, 2004 I actually ran with a few wraps of electrical tape on one of mine for some time waiting for the part to come in. Link to comment Share on other sites More sharing options...
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