BRINDUS44 Posted June 15, 2021 Report Share Posted June 15, 2021 Hi All, My CP engine developed a worsening misfire following a 100 mile mainly motorway drive. Especially noticeable and worsening when pulling away from standstill. I expected to find dribbling injectors but all was good. More in hope than anything else I put some new plugs in and the car is dramatically improved , though not perfect. Pic of removed plugs attached. They are NGKBP6ES done only 3000 miles . All same colour, but does anything look wrong ? Any ideas what might cause plugs to degrade like this ? Many Thanks Ian Quote Link to post Share on other sites
Mk2 Chopper Posted June 16, 2021 Report Share Posted June 16, 2021 I had a similar thing with initially what seemed to be an injector problem, and turned out to be plugs. Some have reported after some plugs have got wetted they don't seem to recover. You say it's not running perfect, do you have another issue that's lead to a plug fouling or something? Gareth Quote Link to post Share on other sites
Nigel Triumph Posted June 16, 2021 Report Share Posted June 16, 2021 There are plenty of fake branded spark plugs for sale online. Try another set from a reputable source e.g. Green Spark Plug Co. Nigel Quote Link to post Share on other sites
Hamish Posted June 16, 2021 Report Share Posted June 16, 2021 15 hours ago, BRINDUS44 said: Hi All, My CP engine developed a worsening misfire following a 100 mile mainly motorway drive. Especially noticeable and worsening when pulling away from standstill. I expected to find dribbling injectors but all was good. More in hope than anything else I put some new plugs in and the car is dramatically improved , though not perfect. Pic of removed plugs attached. They are NGKBP6ES done only 3000 miles . All same colour, but does anything look wrong ? Any ideas what might cause plugs to degrade like this ? Many Thanks Ian apart from being too clean - is it a little lean ? but as gareth says NGK's don't like getting wet (fuel) i had this with my 3a too much cranking without ignition kna***red a set and even burning off with a blow torch didn't bring them back. H Quote Link to post Share on other sites
Michael Mckiernan Posted June 16, 2021 Report Share Posted June 16, 2021 Ian , is the engine missing on all the cylinders ? Run the car then pull off each plug lead in turn , you should get a drop in rpm roughly the same on them all. At the moment it could be anything ( lead breaking down/ injector spray "above" tickover/ tight tappet ) If its on one cylinder you can swap bits over to see if it moves the miss. Good luck Mick Quote Link to post Share on other sites
Tim D. Posted June 16, 2021 Report Share Posted June 16, 2021 Also worth considering that it could be an ignition problem which is degrading the spark energy which you partially rectify with new plugs. If you are running points check the condenser and points gap. If you have a timing light you can put the probe on each HT wire in turn and work out whether a specific one is not firing or whether it is just a random mis-fire. I have also had issues with coils, so if you have a spare, swap it in and see if it is any better. Cheers Tim Quote Link to post Share on other sites
BRINDUS44 Posted June 17, 2021 Author Report Share Posted June 17, 2021 Hi All, Thanks for your comments. I am away on holiday in the car, so I have limited spares and tools on board. So far I have changed plugs, points, rotor, condenser and coil - which is all the believe good used spares I have with me ! Still the misfire , worst under load pulling away. I took a short drive to fuel up this morning and suddenly far worse misfire - permanent 5 cylinders. Injectors all OK at idle. Removed plug leads one at a time, cylinder 2 not firing. Swapped lead 2 with lead 1, cylinder 1 not firing. If I hold the plug cap close to the plug I cannot hear the click of the spark on the non firing plug. Removed valve cover - all valves moving freely and closed at TDC. Checked compression with thumb over plug hole - all sucking and blowing. It looks like a duff HT leads and they are only 3000 miles old. New parts coming by courier tomorrow- fingers crossed ! Ian Quote Link to post Share on other sites
Hamish Posted June 17, 2021 Report Share Posted June 17, 2021 looks like issue is following the plug lead well done mick (above) fingers crossed for you so difficult whilst on the road and it affects your enjoyment H Quote Link to post Share on other sites
BRINDUS44 Posted June 18, 2021 Author Report Share Posted June 18, 2021 To close the topic - new HT leads fitted today , car running as it should again . Great service from TRGB to send a box of ignition stuff on next day courier. Now I can hopefully enjoy the drive home. Thanks to all Ian Quote Link to post Share on other sites
Hamish Posted June 18, 2021 Report Share Posted June 18, 2021 Great result ian Quote Link to post Share on other sites
Nigel Triumph Posted June 18, 2021 Report Share Posted June 18, 2021 3 minutes ago, Hamish said: Great result ian +1. Have a great run home! Nigel Quote Link to post Share on other sites
Mk2 Chopper Posted June 18, 2021 Report Share Posted June 18, 2021 Thanks for coming back to update us, that's great news. Gareth Quote Link to post Share on other sites
Michael Mckiernan Posted June 19, 2021 Report Share Posted June 19, 2021 Well done Ian. Great that you let us know the outcome , enjoy the trip home. Mick. Quote Link to post Share on other sites
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