Warthog Posted February 20, 2009 Share Posted February 20, 2009 The 4.2 v8 in my RRC has started running at high revs on start up and when idle. It will calm down after awhile but something just aint right. Where shall i start checking to try and sort the problem out? It has an LPG kit on it but it runs the same on Petrol or Gas Cheers for any help, Mark Quote Link to comment Share on other sites More sharing options...
bishbosh Posted February 20, 2009 Share Posted February 20, 2009 There's a sensor wotsit that screws into the back of the plenum. If you stand at the drivers side of the engine bay (RHD) and look at the plenum, the end of the sensor, with connector is at the left hand end of the plenum facing you. Might be that or might be the AFM. At least, that how it is on a 3.9....... Was that any help? Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted February 20, 2009 Share Posted February 20, 2009 There's a sensor wotsit that screws into the back of the plenum. If you stand at the drivers side of the engine bay (RHD) and look at the plenum, the end of the sensor, with connector is at the left hand end of the plenum facing you.Might be that or might be the AFM. At least, that how it is on a 3.9....... Was that any help? Is the LPG kit a multipoint one that takes timing signals from the petrol ECU? If not, that rules the AFM out, as it would only affect petrol. Bish - 'sensor wotsit'. Are you referring to the stepper motor? It isn't a sensor, it's a valve controlled by the ECU which allows additional air past the throttle when the engine is cold. They do fail, but more often just get gummed up. You can unscrew them and clean them up, usually. Quote Link to comment Share on other sites More sharing options...
Fatboy Posted February 20, 2009 Share Posted February 20, 2009 I'd check all of the vacuum hoses and breathers that connect to the plenum and make sure none of them have split or fallen off. Trace them to their other ends as well. Its also worth checking the linkages for the throttle / cruise control / kickdown to make sure they are all okay and "on the stops". Quote Link to comment Share on other sites More sharing options...
bishbosh Posted February 20, 2009 Share Posted February 20, 2009 Bish - 'sensor wotsit'. Are you referring to the stepper motor? Sensor wotsit / stepper motor - close enough!! If you say it fast enough no on ewould notice! Yes, that was what I was referring to. Quote Link to comment Share on other sites More sharing options...
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