SIMON64 Posted March 21, 2009 Share Posted March 21, 2009 hi my 93 RRC 3.9 v8 has developed a backfire it does it on lpg or petrol but only if i go over 4000rpm any ideas regards simon Quote Link to comment Share on other sites More sharing options...
SIMON64 Posted March 23, 2009 Author Share Posted March 23, 2009 hi whats happening why has `nt any one replied has everyone jumped ship Quote Link to comment Share on other sites More sharing options...
SteveRK Posted March 23, 2009 Share Posted March 23, 2009 Being as it mis-fires on both fuels it could be an ignition related mis-fire at higher RPM or valve train problems. It could be a large air-leak that comes into effect at higher RPM but i cant think how this would only occurr at higher RPM - a tear on the air intact tube perhaps between the AFM and inlet manifold Quote Link to comment Share on other sites More sharing options...
steve_d Posted March 23, 2009 Share Posted March 23, 2009 I'll have a go then. If it is happening on both fuels then it could be an air leak causing both fuels to go lean. have a good inspect of all the hoses etc related to the plenum, breather from rocker cover, stepper motor hoses. Or It could be ignition related. The prime suspect here would be the ignition amplifier or the coil. Is there a time element to this as in it only shows after the engine has really warmed up. Steve Quote Link to comment Share on other sites More sharing options...
SIMON64 Posted March 24, 2009 Author Share Posted March 24, 2009 thanks guys i will take a look at air hoses and see what i can see will let u know how i get on thanks again regards simon Quote Link to comment Share on other sites More sharing options...
shazrange Posted March 27, 2009 Share Posted March 27, 2009 hi i have a range rover 1999 4.6 petrol and runs rich and miss fires on petrol but runs perfect on lpg any ideas wot could be the fault? Quote Link to comment Share on other sites More sharing options...
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