v8 misfire

[burgerman]

Howdy all,  just when you thought every thing was tickety boo with ya motor----------------   popped up to shops today and upon driving home i noticed a slight misfire, gave it a large blip of the throttle , could not syop on road so got it home 2-3 miles, still misfirirng,          

                checked all leads tight, inside dizzy cap, spark on all leads and plugs, plugs out all sparking n nothing unusual to look at with condition,  compression simialr on all cylinders, when running sprayed lots of wd40 around engine bay to check for air leaks,   sounds like just one cylinder to me, but cant work out which one, removed all injector leads and replaced individually, changed plugs, leads, dizzy cap n arm,      now got tooo hot out there and run out of ideas???  p.s all the above made no difference at all at any stage,     any clues/tips? as i have just about run out of them,
  P.P.S    almost forgot, its a 1991 V8 disco manual g/box efi
                               If any one is passing or local i could supply you with tiger tokens (thats showing me age) and or some beer coupons,  many thanks

[bilge rat]

like you say first find out which one its missing on, iff its t/over thal'll help i'd pull each injector terminal off one at a time see which one makes little or no difference to the running. check the plug see what colour it is iff its any different from the others. air leak ?.as your've done spray wd round the manifold see iff the engine revs up. iff it does ya have a leak. have ya changed plugs recently ?.good luck. alan....

[burgerman]

Howdy, yea i think that when i remove the injector lead 2nd cyl from the front n/side  it seems to have the least effeft on any thing, sprayed loads of wd40 around most areas, also tried some easy start in areas away from electrics, no difference,  put a set of second hand pluds in , i only replaced them as matter of course, and swapped around the plugs incase i was lucky enough to have replaced a duff plug with another one,   also all the plugs look ok n similar, blooming frustating as in theory every thing is present???  im kinda thinking injectors ?? blocked? not pulsing??   but getting a tad out of my depth from here,  keep the suggeations coming in please

[bilge rat]

iff that one you mentioned doesnt make a fat lot of difference ,swop the injector for another one say opposite, iff the fault moves . injector. iff the fault stays the same cyl, yourve got to look further. carefull with what your spraying round the hot bits think in this heat oughts possible. alan.....

[Wireless]

I had a similar fault, had to replace Ignition Coil (would get hot and stop working), and both Lambda Sensors.
 :shock:

[Sheddy]

I also had similar ... turned out to be an air leak between the inlet manifold and the plenum chamber.

Probly not that because your plugs are all the same colour.  If it is though, it's easily cured by a take apart and careful application of a smear of Dow Corning.

[Range Rover Blues]

I find I have to pull 2 or 3 injector plugs off before I can tell which one is misfiring (from those left on).  Remember that the negine fires in LH and RH banks soyou can try swapping the harness plugs.  Check to make sure the terminals don't slip out of the back of the plugs too, this can cause you a headache.

[burgerman]

ITS FIXED  =D>  =D>  =D>  =D>   And roaring on all 8 of those lovely cylinders again,    kinda run out of time n skill , so dropped it over to paul @ challenger 4x4, soon worked out and replaced the injector on no1 cylinder, job done, and yet again for a realistic price,   cant wait to go green laning on sunday now :(contented):