MC1234 Posted January 17 Report Share Posted January 17 Hello, I recently noticed my TR6 was running a bit 'rough' with some loss of power. It eventually got worse and cut out on me though I managed to re-start and get home. I checked the plugs and injectors and they were broadly OK though one injector was a bit of a dribble to start with but soon improved after I pulled the nipple. I then tested the car again and all seemed fine for 15 mins or so, it was running perfectly but it started to cut out when I pulled up at junctions. It re-started a few times but then refused to and I was towed home. The engine turns over but will not start and I find that there is no spark at the plugs. The HT lead from the coil to the centre of the distributor also does not produce a spark but there is power at both + and - terminals on the coil. To my mind this indicates a problem with the distributor or the wiring from coil to distributor. Is that a reasonble conclusion or am I missing something? It has the lumenition magnetronic ignition fitted so I wonder if that module could that have failed? Any thoughts appreciated and I've attached a few photos of my setup. Please be gentle in terms of advice...I'm at the beginner end of the spectrum though learning fast due to endless problems with this car thanks, Matt 1973 TR6 CR Quote Link to post Share on other sites
RobH Posted January 17 Report Share Posted January 17 This could be a number of things Matt. If you have a voltmeter (preferably an analogue one) you can connect it from earth to the '- ' terminal on the coil - (the one with only one connection). As you crank the engine the voltage should 'pulse' which would show that the ignition module is working. If that is OK the fault may be the coil - if you can do a substitution with a spare or borrowed one you can eliminate that. The 'king lead' from the coil to the dizzy may be faulty - again a substitution can eliminate that. Quote Link to post Share on other sites
MC1234 Posted January 17 Author Report Share Posted January 17 Many thanks Rob. I have only a digital voltmeter. I've just disconnected the black wire from the negative terminal on my coil and then touched one prong of my voltmeter to the terminal and the other to the engine block. It read 12V with the ignition on which dropped to 7 something, and stayed at 7 something, when the engine was cranking. There was no pulsing but have I tested that correctly? Matt Quote Link to post Share on other sites
RobH Posted January 17 Report Share Posted January 17 No you need the black wire still connected Matt. If it's working, the ignition module should switch on and off to earth as you crank, so the voltage on the pin will cycle from 12v to 0v every time a lobe of the distributor cam passes the module. Your meter won't be able to see that accurately as it can't respond quickly enough but you should see the numbers change. Quote Link to post Share on other sites
MC1234 Posted January 17 Author Report Share Posted January 17 ah, yes that makes more sense. I've just tried that and it read around 1.5V once the ignition was on and the engine wasn't cranking (so not zero) but once it was cranking this went up and down rapidly. So that would suggest the ignition module is doing it's job then I guess. I think I need to rule out the coil and the king lead then as you suggest. Thanks again, Matt Quote Link to post Share on other sites
roy53 Posted January 17 Report Share Posted January 17 CHECK CAP / ROTOR and POWER LEAD from COIL to dizzy as it looks as though not fully home just a guess Roy Quote Link to post Share on other sites
RobH Posted January 17 Report Share Posted January 17 It would be a good idea to check that the sprung carbon contact in the centre of the dizzy cap is intact. Also the rotor arm, as those can track to earth through the body - it would probably be worth fitting a new one anyway if it has been in use for a while. The red ones from the Distributor Doctor are recommended. Quote Link to post Share on other sites
MC1234 Posted January 17 Author Report Share Posted January 17 I think all leads and the dizzy cap are on correctly. I've had them all on and off multiple times and have tripled checked everything. I didn't mention but I have changed the rotor arm as the old one was cracked. I had assumed that was the source of the problem but sadly not. The spring and contact in the dizzy cap appear correct though it is difficult to tell if it is actually making contact with the rotor arm once the cap is on. Quote Link to post Share on other sites
Mike C Posted January 17 Report Share Posted January 17 LT feed seems OK. No spark at the HT lead- have a look at the coil. Quote Link to post Share on other sites
roy53 Posted January 18 Report Share Posted January 18 (edited) Double check the rotor arm , old with new as the length could be an issue and not making contact with the posts in the cap Has the lumenition been moved slightly further from the centre Edited January 18 by roy53 add Quote Link to post Share on other sites
Steve-B Posted January 18 Report Share Posted January 18 Whereabouts are you based? I'm sure there's more than a couple of us with a spare coil we could loan you to try. If you remove the leads from your coil/the engine and give it a shake, do you feel fluid moving around in it? What resistance on an ohm setting does your multimeter show for it? Have you tried removing a plug from the engine and having someone turn the ignition key to see if there's any spark (even a weak one)? Quote Link to post Share on other sites
MC1234 Posted January 18 Author Report Share Posted January 18 thanks Roy and Steve for further suggestions. The new rotor arm is identical to the old one (it's one of the black ones). I don't think the lumenition module has been moved in any way. I'm in Leicestershire, but I think my next step is to buy a new coil and set of HT leads. I'm unsure when they were last changed (I've only had the car just under a year) and the coil doesn't look very recent. I haven't physically removed the coil to see if I can feel fluid in it but I'll try that at the weekend. I did measure the resistance a few days ago and from memory it was around 1.5 Ohms. I think that suggests my car is ballasted? I did remove a plug and there is no spark at all when the engine is cranked. Quote Link to post Share on other sites
stuart Posted January 18 Report Share Posted January 18 1 hour ago, MC1234 said: thanks Roy and Steve for further suggestions. The new rotor arm is identical to the old one (it's one of the black ones). I don't think the lumenition module has been moved in any way. I'm in Leicestershire, but I think my next step is to buy a new coil and set of HT leads. I'm unsure when they were last changed (I've only had the car just under a year) and the coil doesn't look very recent. I haven't physically removed the coil to see if I can feel fluid in it but I'll try that at the weekend. I did measure the resistance a few days ago and from memory it was around 1.5 Ohms. I think that suggests my car is ballasted? I did remove a plug and there is no spark at all when the engine is cranked. Get your ignition parts from a reliable source, we all use Martin, Distributor Doctor https://www.distributordoctor.com/ Stuart. Quote Link to post Share on other sites
Cew Posted January 18 Report Share Posted January 18 8 hours ago, roy53 said: Double check the rotor arm , I had a similar problem with a "new" (Chinese, Lucas boxed) rotor arm about ten years ago, changed to a Distributor Doctor one, no problems since. P.S. Had the same thing with the Bentley. Quote Link to post Share on other sites
Steve 286 Posted January 18 Report Share Posted January 18 Hi Matt is the electronic lumenition getting its live from the coil or fuse box as cr cars only give 7/8 volts at the coil and some times run for a while like that without any problems then out of the blue they stop as mine did the car was like it when I got it Quote Link to post Share on other sites
Michael Mckiernan Posted January 20 Report Share Posted January 20 On 1/18/2024 at 5:55 PM, Cew said: I had a similar problem with a "new" (Chinese, Lucas boxed) rotor arm about ten years ago, changed to a Distributor Doctor one, no problems since. P.S. Had the same thing with the Bentley. Same as that !! Quote Link to post Share on other sites
MC1234 Posted January 21 Author Report Share Posted January 21 Hi Steve, it is getting its feed from the coil yes. By way of update, I have now changed the coil and the HT leads and still no spark....which is a bit frustrating to say the least. So that's the rotor arm, HT leads and coil all renewed and I've put new spade terminals on the 3 wires to the coil. This only seems to leave the magnetronic module so I think I'll have to change that next. Quote Link to post Share on other sites
Steve 286 Posted January 21 Report Share Posted January 21 Hi Matt the live feed wants to go to the fuse box not the coil due to the Coil only getting 7or 8 Volts isn’t enough to ignite the ignition hope this makes sense Quote Link to post Share on other sites
MC1234 Posted January 21 Author Report Share Posted January 21 thanks Steve that's interesting. Is that because CR cars are ballasted? It seems strange how it would run perfectly for the 12 months I've had it (and a couple of years prior to that when the magentronic was fitted) and then stop so suddenly. Did you have a similar issue then? Presumably I could take a feed directly from the +ve battery terminal to test it? Quote Link to post Share on other sites
TR Rob Posted January 21 Report Share Posted January 21 9 minutes ago, Steve 286 said: Hi Matt the live feed wants to go to the fuse box not the coil due to the Coil only getting 7or 8 Volts isn’t enough to ignite the ignition hope this makes sense Not sure if this helps , but when fitting electronic ignition to my TR3a I suddenly developed a similar fault. Like you I had been putting new terminals on the positive and negative coil terminals. It was very frustrating and was eventually diagnosed as the power feed to the coil had failed. The outer insulation was OK but the internal copper wire had broken down about an inch from the terminal. After 63 years of engine vibration it had given out. Shortened wire and re crimped terminal and problem went away ! Quote Link to post Share on other sites
RobH Posted January 21 Report Share Posted January 21 15 minutes ago, MC1234 said: Presumably I could take a feed directly from the +ve battery terminal to test it? Easy to do and worth it as a quick check. Bear in mind though that during cranking the ballast is (or should be ) shorted out, so the coil gets the full 12v then anyway as standard. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 21 Report Share Posted January 21 8 minutes ago, RobH said: Easy to do and worth it as a quick check. Bear in mind though that during cranking the ballast is (or should be ) shorted out, so the coil gets the full 12v then anyway as standard. Keep in mind that when you want to stop the engine with a direct coil feed from the battery the only way is to pull the wire off the coil/battery. If you just stall the engine, the coil is still powered. Quote Link to post Share on other sites
MC1234 Posted January 21 Author Report Share Posted January 21 Thanks TRRob and RobH. Yes from the lumenition wiring diagram below it does seem as though my magnetronic unit was wired incorrectly if my car is ballasted. I'm assuming my car is ballasted since the resistance from the old coil is 1.5 ohms. Since this seemed to work perfectly until very recently can I therefore assume that it is ballasted? Later today I will try to run a live feed from the battery rather than the coil, though as Rob says this shouldn't cause a lack of spark when cranking the engine. But maybe long term use at reduced voltage could have damaged the magnetronic unit. Quote Link to post Share on other sites
MC1234 Posted January 21 Author Report Share Posted January 21 8 minutes ago, BlueTR3A-5EKT said: Keep in mind that when you want to stop the engine with a direct coil feed from the battery the only way is to pull the wire off the coil/battery. If you just stall the engine, the coil is still powered. good point Peter, thanks. That is a problem I would love to have Quote Link to post Share on other sites
Steve 286 Posted January 21 Report Share Posted January 21 6 minutes ago, BlueTR3A-5EKT said: Keep in mind that when you want to stop the engine with a direct coil feed from the battery the only way is to pull the wire off the coil/battery. If you just stall the engine, the coil is still powered. 6 minutes ago, BlueTR3A-5EKT said: Keep in mind that when you want to stop the engine with a direct coil feed from the battery the only way is to pull the wire off the coil/battery. If you just stall the engine, the coil is still powered. Yes I had the same problem the car ran fine for the first 12 months of ownership then one day it wouldn’t start that’s when I found the problem I connected the live for magnetronic module to the fuse box just make sure it’s only live when the key is in the on position Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.