Disco-Ron Posted June 6, 2015 Share Posted June 6, 2015 Have recently finished building my truck around the above engine from a late 200 shape discovery. Have had smooth running issues since. The list of bits I've changed is getting excessive. . lambdas stepper motor temp sensor plugs ngk bpr6es leads genuine Cap lucas. rotor arm lucas. coil bosch. amplifier ecu loom checked for continuity different ecu tried. Its decatted but running cat map as suggested by a well known tuner.. symptoms are. slightly uneven idle. Feels slightly ss if its holding back. .. drives ok ish until its warm then it misses and occasionaly backfires at wider throttle setting. .... always use shell super and it drinks it as fast as you can put it in the tank. ... plugs are sooty. And the timing has been checked. ... have also checked the timing marks are actually in the right place. .... any help appreciated as I'm toying with chucking a match on it!! Quote Link to comment Share on other sites More sharing options...
mad_pete Posted June 6, 2015 Share Posted June 6, 2015 My first thing to say for any engine issue is air flow meter and mine had running issues with a dodgy spade connector to the coil or dizzy. Spade fails as it gets hot. Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted June 6, 2015 Author Share Posted June 6, 2015 Should have added that I've tried another and adjusted the resistance. ..... however I have yet another now so will try that. .... also forgot to say that I fitted a rrc efi pump in the under seat tank Quote Link to comment Share on other sites More sharing options...
mad_pete Posted June 6, 2015 Share Posted June 6, 2015 double check HT leads connected correctly ? Broken spring in the dizzy messing the advance up ? Quote Link to comment Share on other sites More sharing options...
robertspark Posted June 6, 2015 Share Posted June 6, 2015 I'll ask the obvious, but suggest you check again and spend a bit of time to double check.... Plug leads.... are they on in the right order (3 & 5 can be very easily mixed up, and although it will run and tuned to idle it will run rough under load). Rotor arm... lucas is not always the best (it is not called the prince of darkness for nothing!), you just need one that works. (you running it only on petrol I take it? [LPG can make ignition issues very much worse]) swapping out for a new rotor arm does it change anything in the short term? No air leaks between the Manifold and the MAF? (check and check again, nothing perished?) You have got all of the airline hoses connected onto the right sides of the MAF (given if not the ECU won't actually know the right mixture of ai going into the cylinders). All the engine gas scavenge (gas recirculation) ports connected up to the air intake? (rocker cover(s) + rear of engine, on top of bellhousing?) Suggest cleaning the plugs of all the black soot / swapping them out if its caked on (petrol / carb cleaner soak / ultrasonic cleaner?) could be the fuel filter / fuel pump if issues under WOT (too much air, lack of petrol @ the right pressure). Presume you have the bypass / pressure relief return plumbed in for the petrol return to tank from the fuel rail? What's the spark quality like? (have you put a timing light on yeach plug lead to see if you have any intermittent firing?) Check the inside of the distributor, is there much play in the rotor arm under very little force (note the rotor arm is sprung loaded & will have counterweights in the bottom of it, but the springs could be shot), the rotor arm should not be able to flail about (or you'll get erratic running). Rob Quote Link to comment Share on other sites More sharing options...
JeffR Posted June 6, 2015 Share Posted June 6, 2015 My 3.5 had similar symptoms you describe as well as 3 foot jets of flame out of the exhaust , changed dizzy cap, leads, coil,ignition pack in the steering column, rotor arm and still the symptoms remained. Changed the amplifier pack on the dizzy and the symptoms went away. The "old" amplifier was less than a year old! Quote Link to comment Share on other sites More sharing options...
mad_pete Posted June 6, 2015 Share Posted June 6, 2015 new parts not always good parts. Some dizzy caps and rotor arms can be rubbish from new. Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted June 6, 2015 Author Share Posted June 6, 2015 Thanks for the suggestions guys....... everything is connected as it was in the discovery pipe wise etc. I used the discovery fuel lines along the chassis to the defender tank and connected from there. ... This morning I have fitted another set of plugs. Still bpr6es ...... and given it a bit of advance and touch wood after ten miles it hasn't missed a beat..... all very bizarre. .. is it possible that running the engine for short times could kill pugs??..... Quote Link to comment Share on other sites More sharing options...
robertspark Posted June 6, 2015 Share Posted June 6, 2015 Normally its rich running... Check you have a thermostat (its not been removed or is stuck open). Simple check is does it reach temp in a reasonable time because the engine will remain in enrichment mode until it gets up to operating temp. Could be lambda ( but you changed them) besides the obvious that they ain't working they could be coked in carbon or oil which means they won't be working very well Check the condition of the plugs as they will tell you if its a common problem or a cylinder or bank problem. Are they all coked or is there a pattern? Are they oily, are they brownish grey or white? Do they smell of oil or fuel Sometimes it can be useful to get someone to drive behindb and advise if there is any some under deceleration / when to close the throttle after acceleration Rob Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted June 6, 2015 Author Share Posted June 6, 2015 First thing this morning 7 of the 8 were quite dark. And the 8th was fully black. Compression test proved it isn't a mechanical issue. ... decent spark out of the cylinder with another plug. So new plugs and touch wood it seems fine. The thermostat is present and operating correctly. .. I have a capillary temp gauge so I know exactly what it's doing temp wise. I suspect that doing a lot of tinkering in the garage has led to killing at least one of the plugs due to it running in choke mode for too long..... now its hopefully fixed it will get used rather than tinkered with. ... I drove it about ten miles this morning with the diagnostic program plugged in and everything was working fine. ... There's no apparent oil usage. .. so hopefully it will stay that way. ... Thanks for all the input. ... hopefully it'll remain fixed for a while. ... I'll carry a set of plugs. ..... Quote Link to comment Share on other sites More sharing options...
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