mpbarrett Posted August 17, 2018 Share Posted August 17, 2018 I am getting some pinging from my Herald, its a 1500 engine just rebuilt with 20thou rebore and new Newman (PH1). Its running Megasquirt with ITB and wasted spark ignition. Before I rebuilt the engine there was s no sign of pinging, as the engine has run in (now up to 1000 miles) I have noticed it starting to ping under load. I have adjusted the timing to retard it slightly but its still pinging under load, usually at low rev high gear. So am not sure whats going on as its only started in the last 200 miles. Could it be that as the engine runs in the compression ratio is improving and that's why its started to ping? I don't think the basic timing has changed but will check that this weekend with a timing light. The mixture is not lean when it pings if anything its a bit rich (going by the AFR readout). I don't think I really understand what causes the engine to ping! Is it just the timing or can other things cause it? Also how harmful can it be, its only happening at certain loads and revs. Cheers mike Link to comment Share on other sites More sharing options...
JohnD Posted August 17, 2018 Share Posted August 17, 2018 (edited) Are you still on the tankful of fuel from before the engine was rebuil t? Modern unleaded fuel loses the octane boosting components on storage, so old fuel may be much lower octane than you think! Fill up with Shell V-Plus or similar 98 octane fresh. If you have a lot of old fuel, consider draining it, and donating to the lawn mower.! If you didn't run on 98 octane, consider it. John Edited August 17, 2018 by JohnD Link to comment Share on other sites More sharing options...
Nick Jones Posted August 17, 2018 Share Posted August 17, 2018 John may well be onto something. Fuel is suprisingly variable. The Vitesse never pinks (except when fed rural French 95 piss which is 20% water) but the PI was quite fussy about it's 95 (10.5:1 CR!). Some was ok, some was not. Source didn't seem to make much difference. On one or two occasions I was actually moved to top up with the good stuff to shut it up. Low rpm /low load shouldn't do much hard unless severe. Any deposits on the plugs? What plugs are you running? Nick Link to comment Share on other sites More sharing options...
mpbarrett Posted August 17, 2018 Author Share Posted August 17, 2018 7 hours ago, Nick Jones said: John may well be onto something. Fuel is suprisingly variable. The Vitesse never pinks (except when fed rural French 95 piss which is 20% water) but the PI was quite fussy about it's 95 (10.5:1 CR!). Some was ok, some was not. Source didn't seem to make much difference. On one or two occasions I was actually moved to top up with the good stuff to shut it up. Low rpm /low load shouldn't do much hard unless severe. Any deposits on the plugs? What plugs are you running? Nick will try some better fuel! Running NGK multi electrode plugs, cant remember the number used them on my TR6 and like them a lot, nice grey colour not overheated. Going out in her tomorrow so will have a play. Its not too bad, was thinking about adding a knock sensor but that does not help understanding whats going on! cheers mike Link to comment Share on other sites More sharing options...
Nick Jones Posted August 17, 2018 Share Posted August 17, 2018 Only started in last 200 miles...... could represent last fill up? Must be getting upper 200s to a tank? Plugs are BUR6ET I expect. Heat range 6 should be fine. Anyway, plugs problems usually show up at high rpm, high load. Knock sensors are tricky things to get working well I understand, but reckon you may well have the expertise so would welcome a tutorial! Nick Link to comment Share on other sites More sharing options...
JohnD Posted August 17, 2018 Share Posted August 17, 2018 Knock sensor usual with moderns, but their ECU can fiddle with retarding response. If you can do that, fine! Also, IMHO, multi electrode plugs are only a fleet managers wet dream. A plug an only fire one one electrode, with those once that wears the next takes over. Less need for servicing, but we service our vehicles! John Link to comment Share on other sites More sharing options...
Nick Jones Posted August 17, 2018 Share Posted August 17, 2018 MS can be configured to retard the ignition based on knock sensor output (difficulty is tuning the knock sensor system for meaningful response), inlet air temperature (which might be relevant here also) and engine temperature. Completely agree re. only one spark at a time John. Not much fussed about the life either - though what's to complain about 30k miles plug life? However, I firmly believe that the Triumph engines love the triple/quad electrode plugs. I think it's because they are a side-electrode design and the spark is directly exposed to the chamber. Have you not tried them yet? I've been banging on about them for years...... decades even! Nick Link to comment Share on other sites More sharing options...
RichardB Posted August 18, 2018 Share Posted August 18, 2018 I've spent quite a bit of time figuring out where to put a knock sensor but it seems a bit of a dark art. There's a chunky flat on the 1500 block towards the rear of the inlet side that might work well? Last thing you'd want is to end up with a useless hole that needs plugging, or even worse ruin the block with a very badly placed one. Link to comment Share on other sites More sharing options...
spitfire6 Posted August 18, 2018 Share Posted August 18, 2018 Hi, mpbarrett, remember to change your plugs around as you run wasted spark. I have my wasted spark coil connected 1& 6, 2 & 5 and 3 & 4. I swap from front to back every time I take the plugs out. Cheers, Iain. Link to comment Share on other sites More sharing options...
JohnD Posted August 18, 2018 Share Posted August 18, 2018 Why swap them Ian? I respect your endorsement, Nick, but happy with stand plugs! John Link to comment Share on other sites More sharing options...
Nick Jones Posted August 18, 2018 Share Posted August 18, 2018 6 minutes ago, JohnD said: Why swap them Ian? On the wasted spark system, one plug in each pair (1/6, 2/5, 3/4) runs the opposite polarity, so wears in the opposite direction. Swapping them balances this out. Be even happier with triples (or quads) John..... Nick Link to comment Share on other sites More sharing options...
JohnD Posted August 19, 2018 Share Posted August 19, 2018 AaaaaaaaaaaaaaaaaaaaaaaaH! So! See this NGK video, with ridiculously dramatic soundtrack!: Link to comment Share on other sites More sharing options...
spitfire6 Posted August 19, 2018 Share Posted August 19, 2018 Hi, is that video correct? I would have sworn that electrons jumped from centre to earth on a conventional system? Confused, Iain. Link to comment Share on other sites More sharing options...
zetecspit Posted August 19, 2018 Share Posted August 19, 2018 Iian, but negative earth. So electrons will head to the positive electrode. Or am I going rusty on this stuff? Link to comment Share on other sites More sharing options...
spitfire6 Posted August 19, 2018 Share Posted August 19, 2018 (edited) Hi Zetecpit, But the coil voltage is reversed when the primary coil current stops. Centre electrode is hot to emit electrons & a precious metal if you want it to last long. The video goes against everything I thought. I'm not going to argue with NGK though! Still confused, Iain. Edited August 19, 2018 by spitfire6 Removed: Somebody want to tell me the video is correct and I'm wrong? Link to comment Share on other sites More sharing options...
oldtuckunder Posted August 19, 2018 Share Posted August 19, 2018 Just to confuse on Wikipedia The central electrode is usually the one designed to eject the electrons (the cathode, i.e. negative polarity[12] relative to the engine block) because it is the hottest (normally) part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces (see thermionic emission).[13] In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, from a sharp point or edge rather than a flat surface (see corona discharge).[13] Using the colder, blunter side electrode as negative requires up to 45 percent higher voltage,[13] so few ignition systems aside from wasted spark are designed this way.[14] Waste spark systems place a greater strain upon spark plugs since they alternately fire electrons in both directions (from the ground electrode to the central electrode, not just from the central electrode to the ground electrode). As a result, vehicles with such a system should have precious metals on both electrodes, not just on the central electrode, in order to increase service replacement intervals since they wear down the metal more quickly in both directions, not just one.[15] Link to comment Share on other sites More sharing options...
spitfire6 Posted August 22, 2018 Share Posted August 22, 2018 Hi, Just spoke to NGK about plugs and mentioned the video. They are aware of the video that NGK Germany produced. They were not 100% happy with it.. I have been sold on BPR6EIX plugs. Multi-electrode plugs getting replaced. Cheers, Iain. Link to comment Share on other sites More sharing options...
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