Ok - what have I done
Discussion
HC's were high and found HT leads were breaking down. Changed the leads - good quality Bosch - couldn't get the right sized coil to distributor lead though.
Drove the car and acceleration and low rpm running noticeably improved. However, under full throttle there was a massive hesitation and misfire much like a rev limiter.
Drove home and found the coil to distibutor lead warm. Went to pull it out and it disintegrated in my hands !
Put it down to maybe I hadn't plugged it in firmly and had a new one made today as couldn't find an off the shelf lead long enough. Same symptoms although the lead is ok and not getting overly hot.
It seems too much of a coincidence for another problem to have developed at the same time so could it be the coil - maybe unable to deliver a high enough output as the impedance of the new leads is lower than the old ones and hence putting a greater demand on it ?
Don't want to waste money on a new coil if I don't have to, SWMBO doesn't take kindly to any TVR related expenditure, but is there any way to test whether this is the problem and if it is will any coil do or is there a particular rating or spec I need to look out for ?
Any advice much appreciated.
Drove the car and acceleration and low rpm running noticeably improved. However, under full throttle there was a massive hesitation and misfire much like a rev limiter.
Drove home and found the coil to distibutor lead warm. Went to pull it out and it disintegrated in my hands !
Put it down to maybe I hadn't plugged it in firmly and had a new one made today as couldn't find an off the shelf lead long enough. Same symptoms although the lead is ok and not getting overly hot.
It seems too much of a coincidence for another problem to have developed at the same time so could it be the coil - maybe unable to deliver a high enough output as the impedance of the new leads is lower than the old ones and hence putting a greater demand on it ?
Don't want to waste money on a new coil if I don't have to, SWMBO doesn't take kindly to any TVR related expenditure, but is there any way to test whether this is the problem and if it is will any coil do or is there a particular rating or spec I need to look out for ?
Any advice much appreciated.
From deep in my memory banks, i think one way to test for a failing coil is to attach an ice pack to it. Helps cool it down when it starts overheating due to it failing. If this is the problem the ice pack cools it and the problem will temporarily go away.
...or something like that.
Regards
Iain
...or something like that.
Regards
Iain
Thanks mate - trouble is I reckon an ice pack will last seconds under there as it gets pretty hot !
Thinking a bit more its got to be either the coil or fuelling - maybe I set the afm flap spring to get good running previously and now the fuel is actually being ignited courtesy of the new leads then its running lean at full throttle hence the misfire ?
Thinking a bit more its got to be either the coil or fuelling - maybe I set the afm flap spring to get good running previously and now the fuel is actually being ignited courtesy of the new leads then its running lean at full throttle hence the misfire ?
Luckily I have a Disco so could pinch the Bosch coil off of that and try it - worked fine with that.
Purchased a new Bosch high performance coil - coil resistance was 16K ohms whereas the standard Bosch was 12, the one from the Disco 8 and the Lucas one from the TVR 5 so I assume they break down a bit over time and the higher the resistance the higher voltage developed and hence a stronger spark.
Primary coil resistance was a steady 1.3 ohms on the new one whereas both the Disco and Lucas readings wouldn't hold steady but varied between 0.6 and 1.1 ohms- not sure what that says but thought I put the readings down in case they were any use to anyone else.
Purchased a new Bosch high performance coil - coil resistance was 16K ohms whereas the standard Bosch was 12, the one from the Disco 8 and the Lucas one from the TVR 5 so I assume they break down a bit over time and the higher the resistance the higher voltage developed and hence a stronger spark.
Primary coil resistance was a steady 1.3 ohms on the new one whereas both the Disco and Lucas readings wouldn't hold steady but varied between 0.6 and 1.1 ohms- not sure what that says but thought I put the readings down in case they were any use to anyone else.
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