Phil Read Posted January 2, 2020 Report Share Posted January 2, 2020 I have an intermittent misfire on my TR6. It is worst at revs below 2000 and when on light throttle. When you go to full throttle it pulls away fine once over @ 2000 rpm. My first though was ignition but i have a new electronic distributor, new plugs and new plug leads. Do injectors give the same symptoms as you would get with an ingition problem or do they go off and not work at all? Quote Link to post Share on other sites
Peter Cobbold Posted January 2, 2020 Report Share Posted January 2, 2020 PI can do that - the clue is the light throttle misfire. There may be an air bubble in a the fuel somewhere. Italian tune up would be my first action. Peter Quote Link to post Share on other sites
Paul Hill Posted January 2, 2020 Report Share Posted January 2, 2020 1 hour ago, Peter Cobbold said: PI can do that - the clue is the light throttle misfire. There may be an air bubble in a the fuel somewhere. Italian tune up would be my first action. Peter In other words give it a good thrashing. Quote Link to post Share on other sites
Phil Kirk Posted January 3, 2020 Report Share Posted January 3, 2020 Phil, What fuel are you using? Quote Link to post Share on other sites
Rogcastle Posted January 3, 2020 Report Share Posted January 3, 2020 Phil I would look first at the bits that you have recently changed before doing anything else. Start with easiest to check first, leads/plugs and then electronic distributor. Best of luck Roger Quote Link to post Share on other sites
Mike C Posted January 3, 2020 Report Share Posted January 3, 2020 2000 rpm and a trailing/closed throttle (decelerating) ? Mine does that, always has - maybe the cam profile or unburnt fuel in the intake manifold being vaporized by the suddenly closed throttle causing a vacuum. Quote Link to post Share on other sites
Phil Read Posted June 14, 2020 Author Report Share Posted June 14, 2020 I have been working on this problem now for a couple of weeks. Changed all the ignition system back to original, fit a new fuel pump, changed a couple of injectors and voila, I notice that there is no fuel coming to No2 injector at tick over and very little when reving. I tried injecting fuel back up the pipe but it did not cure it. The car had a reconditioned metering unit fit before I bought it a couple of years ago, its done less than 3000 miles since. It goes like a rocket once you get over 2250 rpm. Any ideas would be useful, how complicated is it fitting a replacement pump? Quote Link to post Share on other sites
Peter Cobbold Posted June 14, 2020 Report Share Posted June 14, 2020 Give it full throttle up a long hill to get #2 working properly, it may be air trapped and you need foot-to-floor, not mere rpm, to get fuel flowing as fast as possible to free off a stuck non-return valve in the MU. Peter Quote Link to post Share on other sites
Phil Read Posted June 17, 2020 Author Report Share Posted June 17, 2020 Thanks Peter it worked. I took the car out last night to the nearest long drag. Flogged it up in top overdrive at full throttle and only changed down when the engine was labouring, it did'nt work first time so I did it again and it cured it. Now I can drive at 30mph without having to change down. I realise that is is very rare that I drive it at full throttle for any period. Only problem now is the overdrive stopped working. Quote Link to post Share on other sites
Mike C Posted June 17, 2020 Report Share Posted June 17, 2020 TR6's need to be run close to full throttle fairly often to prevent problems with the PI. I'm lucky to have a mountain range with good roads close to where I store the car. Almost certainly the OD problem will be electrical- its so prevalent that I installed a green "OD" light from a Landrover to confirm that the the OD solenoid is getting power from the OD switch. Quote Link to post Share on other sites
Peter Cobbold Posted June 17, 2020 Report Share Posted June 17, 2020 2 hours ago, Phil Read said: Thanks Peter it worked. I took the car out last night to the nearest long drag. Flogged it up in top overdrive at full throttle and only changed down when the engine was labouring, it did'nt work first time so I did it again and it cured it. Now I can drive at 30mph without having to change down. I realise that is is very rare that I drive it at full throttle for any period. Only problem now is the overdrive stopped working. Phil, Modern fuel is very different from when Lucas designed to PI...no lead, ethanol etc. When mine wasa daily driver the PI was exceptionally reliable over 150k miles. I suspect a combination of more aggressive fuel and long periods of lack of use cause many PI gremlins. Good that yours has an easy cure. Peter Quote Link to post Share on other sites
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