davidbek95 Posted June 28, 2014 Report Share Posted June 28, 2014 Got a small backfire in the exhaust when turn the engine off.I am sure that unburnt fuel doing this.I am using a v88,engine is a 4g63 engine,what's best way to cure this problem. regards david Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted June 28, 2014 Report Share Posted June 28, 2014 Hi David, Is your idle mixture rich or are you running aggressive camshafts. When the ECU is turned off, all outputs are switched to ground. If there is any unburnt fuel there is a chance that an ignition O/P fires due to being switched to ground, any excess fuel/air mixture left in the cylinder may get a partial combustion event. What ignition system are you running, COP, Ignition module or CDI system. Heat can contribute to this also with fuel vapour left in cylinders from rich mixtures. I have also seen some customers cars do this when they have the incorrect trigger edge selected. Regards Dave. Quote Link to comment Share on other sites More sharing options...
davidbek95 Posted June 28, 2014 Author Report Share Posted June 28, 2014 david, using ls1 coils,cam is standard,when the engine is hot,I will check afr reading,I am the autronic gas analliser B.As I changed the throttle body the otherday,there not different. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted June 28, 2014 Report Share Posted June 28, 2014 Hi David, just double check the ignition feed 12 volt supply to the coil +ve goes to 0 volt when the Ignition is turned off. Regards Dave. Quote Link to comment Share on other sites More sharing options...
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