george Posted April 3, 2022 Report Share Posted April 3, 2022 Hi all first time posting here. I have a Vitesse 6 that runs fine at low RPMs (up to 3.5K) or when cold. Once the car warms up or the revs exceed 3.5k or so the car develops an aggressive misfire/ splutteing and refuses to rev any higher. The misfiring continues to get worse as the car warms up to operating temperature, eventually causing it to stall even under no load at idel. To try and diagnose this issue: I have set the timing at idle with a timing lamp to 10° BTDC. Both the mechanical and vacuum advance work. I’ve also checked the mixture on the carbs (Stromberg 150CD without emission control); with the lifting pin, the revs increase briefly and then go below idle speed, but the misfire still persists. To see if the misfiring was caused by a lean mixture; whilst the car was misfiring I pulled out the choke, but this only made it splutter harder. Checking if the misfiring was caused by a rich mixture I made the mixture intentionally lean but this had no impact on resolving the misfire. I then moved onto the plugs, I found that they were sooty so I cleaned the soot off but the problem still persisted so I retried making the mixture richer or leaner, but had similar results. Thinking the problem was fuel related I took apart the fuel pump to see if the diaphragm or valves were clearly damaged, they weren’t. I have also checked the operation of the fuel pump when hot by lifting the priming lever, but fuel still came out of the pump. I then checked if fuel was getting into the bowls, expecting it to be a vapour lock issue on the carbs I removed the brass mixture adjuster on the bottom, there was plenty of fuel in the bowls, which were also cold. I then wondered if the misfire was caused by some kind of blockage between the fuel tank and pump so I ran the car off a fuel cell that used the cars mechanical fuel pump but the problem still persist. I then wondered if the problem was caused by a head gasket failure (at this point I’m clutching at straws) but there wasn’t any oil in the radiator or water in the oil. At this point I am stumped so would appreciate any help from anyone. Link to comment Share on other sites More sharing options...
johny Posted April 3, 2022 Report Share Posted April 3, 2022 To me it sounds more electrical like the coil or an electrical breakdown somewhere. You could try running it in the dark, carefully, to look for sparks and/or spray WD40 on components but substitution of items might be the only solution (they are always useful to have as spares)... Link to comment Share on other sites More sharing options...
NonMember Posted April 3, 2022 Report Share Posted April 3, 2022 I agree, likely ignition rather than fuel. What distributor do you have? Points or electronic? Link to comment Share on other sites More sharing options...
Iain T Posted April 3, 2022 Report Share Posted April 3, 2022 Cracked dizzy cap or rotor arm? When I took my Vitesse to a rolling road he found my rotor arm was cracked. A cheap fix if it works! Link to comment Share on other sites More sharing options...
george Posted April 3, 2022 Author Report Share Posted April 3, 2022 Thanks for the suggestions, I have ordered a new dizzy cap and have a new spare rotor arm to put on once the new dizzy cap arrives Link to comment Share on other sites More sharing options...
Sparky_Spit Posted April 3, 2022 Report Share Posted April 3, 2022 Just one tip, if I may..... don't change more than one thing at the same time, as you may then not know which thing was the cure. The golden rule is change just one thing at a time and test each change. Good luck! 1 Link to comment Share on other sites More sharing options...
Peter Truman Posted April 3, 2022 Report Share Posted April 3, 2022 I had a similar problem eg it’s my Sprint it has graphite or something ht cables and the distributor end the cable is held/connected with little pins/needles these burnt around there connection point cut the cable and traffic all ok for a few days then again. solution was some new cables made by the local ignition people Link to comment Share on other sites More sharing options...
Wagger Posted April 3, 2022 Report Share Posted April 3, 2022 I would change the condenser first. That has always been my first point of call since my first motor bike. 90% of the time since, this has always been the cause. The condenser works when cool but breaks down as it heats up. Tell tale sign is blackened points. Link to comment Share on other sites More sharing options...
george Posted April 3, 2022 Author Report Share Posted April 3, 2022 2 hours ago, NonMember said: I agree, likely ignition rather than fuel. What distributor do you have? Points or electronic? It’s running a delco 212873r distributor with an AccuSpark electric ignition kit Link to comment Share on other sites More sharing options...
george Posted April 3, 2022 Author Report Share Posted April 3, 2022 31 minutes ago, Peter Truman said: I had a similar problem eg it’s my Sprint it has graphite or something ht cables and the distributor end the cable is held/connected with little pins/needles these burnt around there connection point cut the cable and traffic all ok for a few days then again. solution was some new cables made by the local ignition people Good to know someone else has had a similar problem, I’ll definitely try new leads if the dizzy cap/rotor arm doesn’t change anything. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 3, 2022 Report Share Posted April 3, 2022 i would suspect the accuspark unit you wont have a condenser which was my first thought do not discount fouled plugs are now stuffed cleaning wont help these days Pete Link to comment Share on other sites More sharing options...
Wagger Posted April 3, 2022 Report Share Posted April 3, 2022 I had not realised that you had electronic ignition. Inside the module, there will be a solid state switch. many components including capacitors. (Called Condensers prior to 1960's) These do not last for ever. I always arrange to be able to convert back to a points operated system if possible when using electronic ignition units. They are not all what they are cracked up to be and you cannot 'See' symptoms easily. Link to comment Share on other sites More sharing options...
johny Posted April 4, 2022 Report Share Posted April 4, 2022 My experience of this type of electronic ignition is that they work or dont so in Georges's case probably the last item to swop out? Link to comment Share on other sites More sharing options...
NonMember Posted April 4, 2022 Report Share Posted April 4, 2022 Not my experience, johny. I've seen a fair few electronic units develop intermittent or partial faults. Misfires are not uncommon. There was a Vitesse at the start of the 2004 RBRR which revved cleanly up to 3000RPM then cut out completely; putting it back to points solved the problem. Link to comment Share on other sites More sharing options...
johny Posted April 4, 2022 Report Share Posted April 4, 2022 Would have thought it unusual with micro electronics used in Accuspark types as any failure is normally catastrophic. The older remote type electronic ignition units with circuit boards can have tracking or components breaking down to give intermittent problems... Link to comment Share on other sites More sharing options...
Chris A Posted April 4, 2022 Report Share Posted April 4, 2022 49 minutes ago, NonMember said: There was a Vitesse at the start of the 2004 RBRR which revved cleanly up to 3000RPM then cut out completely; putting it back to points solved the problem. 2004, quite a while ago now plus I imagine the electronic system was a few years old when it failed. Twenty year old technology, surely even the cheap Accuspark systems have better technology now. My 13/60 has an Accuspark unit in the distributor, fitted in February 2015. Yes one day it will fail but with all the comments on forums about the poor quality of condensers I'll fit the same again. Link to comment Share on other sites More sharing options...
johny Posted April 4, 2022 Report Share Posted April 4, 2022 Its quite a tough environment for electronics with heat, vibes and HT sparks but yes I wouldnt dream of going back to points now... Link to comment Share on other sites More sharing options...
NonMember Posted April 4, 2022 Report Share Posted April 4, 2022 19 minutes ago, Chris A said: 2004, quite a while ago now I've worked in automotive electronics - specifically engine control - since 1990. Very little has changed in how ignition coils are driven. I doubt the aftermarket has changed much, either. And a well designed EI should last - my GT6's Lumenition is over 20 years old and still going strong. Anyway, that's all irrelevant. Electronics does fail and NOT always catastrophically. It can go in surprising and weird ways. An intermittent misfire - especially one that's temperature and revs related - could well be a failing EI unit. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 4, 2022 Report Share Posted April 4, 2022 and dont discount the problems of modern made plugs and dont use any plugs with an R in the suffix with std ign coils Link to comment Share on other sites More sharing options...
PeteH Posted April 4, 2022 Report Share Posted April 4, 2022 The Sooty Plugs?. Might point to an issue with the grade/heat/age of the plugs themselves?. Pete Link to comment Share on other sites More sharing options...
Badwolf Posted April 5, 2022 Report Share Posted April 5, 2022 This is a slight drift, so apologies. My antique Sparkrite SX1000 electronic ignition unit died the other year as some of you will remember and the car is running with it still incircuit but set to conventional. Now, obviously this unit is old skool electronics, so the question is, has anyone opened up one of these and repaired it? I don't want to go inside without having a chance of fixing it. I did try the modern Sparkrite 4000 unit without success. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 5, 2022 Report Share Posted April 5, 2022 if the sx1000 runs std points there is little to gain , maybe less load across the points so may i suggest you mend it to destruction and tell us all about it Pete Link to comment Share on other sites More sharing options...
Wagger Posted April 5, 2022 Report Share Posted April 5, 2022 On 04/04/2022 at 08:57, johny said: Would have thought it unusual with micro electronics used in Accuspark types as any failure is normally catastrophic. The older remote type electronic ignition units with circuit boards can have tracking or components breaking down to give intermittent problems... I am a retired Electrical and Electronic Engineer. Believe me, Potted or Integrated circuit components still fail AND it is not possible to find out which component is faulty without access to every NODE. At least one can fault find a points system in a layby. I made my first system with descreet components and could fix that, but only on the bench. Link to comment Share on other sites More sharing options...
Badwolf Posted April 5, 2022 Report Share Posted April 5, 2022 I think that I'll just leave it as it is, but thanks for the observations. I was hoping that I might be able to replace a fried capacitor or something but no, I'll just leave it as it is. Link to comment Share on other sites More sharing options...
Chris A Posted April 5, 2022 Report Share Posted April 5, 2022 29 minutes ago, Badwolf said: I think that I'll just leave it as it is, but thanks for the observations. I was hoping that I might be able to replace a fried capacitor or something but no, I'll just leave it as it is. There is a simple piece of test equipment you could try. It may not work but it might make you feel better Link to comment Share on other sites More sharing options...
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