stallie Posted December 17, 2017 Report Share Posted December 17, 2017 (edited) TR6 CP PI 1972. It was proving a bugger to start, but once going was running very nicely. I got the RWC (equivalent to UK MOT) at the mechanics last Wednesday and am able to drive it for purposes of testing / maintenance on an unregistered vehicle permit until the appointment for reregistration with VicRoads next Tuesday. Anyway, after the difficulty of starting, she was driving well. Yesterday I drove about 40kms at 90-100kmh in 30+ degree heat to ensure that all the cooling was working as advertised, which it was. Accelerated fairly hard at times. In the afternoon, I did the same, but then accelerating out of one corner, she suddenly became very lumpy under load. No pinking and backfiring, just lumpy. Once up to speed it was OK, but just lumpy low down in the trq band. I got home, pulled each injector and had a nice cone in each into a glass jar with engine running. No problems there (Bosch Fuel pump with separate relay too). I figured maybe the dizzy shifted slightly in some spirited acceleration so timing became my starting point. (In the course of events, I have found why she was being difficult to start - I had one of those screw isolators on the neg terminal and it looks like that it has shorted (not been tight enough) and reducing the current. I replaced it for a normal brass battery terminal and she starts much better now, firing before the key is released! It wasn’t the earth lead in the end, but very closely related!). Anyway today the timing I have adjusted the dizzy all over the place. I’ve tried setting 11° BTDC and setting the dizzy when the light just goes out. I’ve also then tried with the engine running where the RPM rises. Nothing cured it. There’s a back road with two sidings about 500m apart near me so I have been able to go into each to readjust a smidgeon so can test multiple setting sin a short space of time. I’m starting to think that it is something else now. I had recently replaced the capacitor, so put the old one back in. Rotor arm is DD. plugs dry and gaps 0.025. Biscuit colour ends. Points gap is checked at 0.015. Any suggestions please of where to look next? Edited December 17, 2017 by stallie Quote Link to post Share on other sites
John Lewis Posted December 17, 2017 Report Share Posted December 17, 2017 Have you had a look at the distributer cap, is there any sign of the spark tracking along cracks? Another option could be a sticky advance/retard mechanism. Another thought, I had a similar problem a while back and the new contact breakers were sticking and not opening/closing properly. Good luck Quote Link to post Share on other sites
graeme Posted December 17, 2017 Report Share Posted December 17, 2017 I am no expert on PI, but is it possible that the throttle bodies have become unbalanced? Cheers Graeme Quote Link to post Share on other sites
DaveN Posted December 17, 2017 Report Share Posted December 17, 2017 +30 deg heat.....hot fuel causing vapour.... what does the fuel tank feel like? Quote Link to post Share on other sites
stallie Posted December 17, 2017 Author Report Share Posted December 17, 2017 DaveN - It was cool in the afternoon and today. Problem persists, thus it's not heat related. John L - I replaced the dizzy cap with the older one. No change. Contacts are unchanged (as I bought the wrong ones in the last Moss order grr...) Graeme - Not an area that I have yet investigated. Quote Link to post Share on other sites
Mike C Posted December 17, 2017 Report Share Posted December 17, 2017 Plugs look OK ? Quote Link to post Share on other sites
barkerwilliams Posted December 17, 2017 Report Share Posted December 17, 2017 (edited) Your refer to lumpy under load, is that just low revs? My Pi has was very poor at pulling away at low revs from either a stand still or slow corner but OK when above 1500'ish revs. That was throttle synchronisation and needed an air flow meter (£40'ish) to balance the inlets. Had to see why that would suddenly come on if the car was running well. Have you checked that the inlet manifold bolts are tight against the head? They can work loose and allow air in. Does the engine stall at tickover if you screw the idle speed air screw fully in? If the engine keeps going it points to an air leak somewhere. (Manifold, brake servo etc.) or unbalanced throttle linkages. Alan Edited December 17, 2017 by barkerwilliams Quote Link to post Share on other sites
stallie Posted December 17, 2017 Author Report Share Posted December 17, 2017 (edited) Mike, Yep, new plugs a month ago. Gap OK and biscuity brown colour. What would suddenly " let go" that would cause this. As I mentioned, it was working just fine with relatively enthusiastic driving. Then there was a quiet slow stretch (50) for 3 kms through a town and accelerating onto the main road that it started. Edited December 17, 2017 by stallie Quote Link to post Share on other sites
stallie Posted December 17, 2017 Author Report Share Posted December 17, 2017 (edited) Alan, It is lumpy at higher revs too - just when under load. just tried winding the idle screw fully in and it cut out. Edited December 17, 2017 by stallie Quote Link to post Share on other sites
john.r.davies Posted December 17, 2017 Report Share Posted December 17, 2017 (edited) Stallie, Are you saying that the running gets rough as you come out of corners? OK otherwise? How much fuel in the tank? An injection system cannot tolerate air in the fuel line, unlike carburettors where the air is excluded in the float chamber. If your tank is near empty, then slosh in the corner can expose the pickup and the bubbles will go all the way to the injectors, where the fuel will dry up until more comes along. My Pi would not accelerate beyond 3-4K just after I installed it. Turned out to be that the choke cable was jammed, and was holding the lever slightly open. So slightly that it took ages to spot. Worth a check? JOhn Edited December 17, 2017 by john.r.davies Quote Link to post Share on other sites
stallie Posted December 17, 2017 Author Report Share Posted December 17, 2017 In straight lines John, nothing to do with corners. Tank is half full. Choke cable checked, returns to idle just fine. it is a newly overhauled MU installed 2-3 months ago. Quote Link to post Share on other sites
Guest ntc Posted December 17, 2017 Report Share Posted December 17, 2017 Check the small wire on the dizzy baseplate. Quote Link to post Share on other sites
Mike C Posted December 17, 2017 Report Share Posted December 17, 2017 If it's only happening under load and the plugs look OK it's probably related to fuel supply. I know the plugs look OK but check for fuel weeping from under the MU- fuelling diaphragm failure gives a rapid onset of rich running. If a nitrile diaphragm was used when your MU was rebuilt it will only last a few hours on Australian high octane unleaded. However I should note that if this happens the plugs generally carbon up fairly quickly . Quote Link to post Share on other sites
TR5tar Posted December 17, 2017 Report Share Posted December 17, 2017 A few years ago I had intermittent, lumpy acceleration issues which I think I pinned down to a failing coil. Might be worth you testing yours. Cheers, Darren Quote Link to post Share on other sites
Bodiam Posted December 17, 2017 Report Share Posted December 17, 2017 A few years ago I had intermittent, lumpy acceleration issues which I think I pinned down to a failing coil. Might be worth you testing yours. Cheers, Darren +1 for the coil beginning to fail under load, sounds very similar to my friends problem CP which we fixed last year. Good luck, John Quote Link to post Share on other sites
tr6tuga Posted December 17, 2017 Report Share Posted December 17, 2017 Another wiyh thd same scenario, traced to coil intermitent failure until full stop, road side.. Quote Link to post Share on other sites
Tim D. Posted December 18, 2017 Report Share Posted December 18, 2017 Yes had the same thing happen on the way to goodwood this year. Cheers Tim Quote Link to post Share on other sites
littlejim Posted December 18, 2017 Report Share Posted December 18, 2017 (edited) Along the lines of Mike C's reply, is it possible a bit of crud in the tank is interfering with the fuel supply in high demand situations?? I had some problems from this cause in the early days with the 4A. Edited December 18, 2017 by littlejim Quote Link to post Share on other sites
Z320 Posted December 18, 2017 Report Share Posted December 18, 2017 (edited) Has there been actually / direct before any work on the exhaust system? Ciao Marco Edited December 18, 2017 by Z320 Quote Link to post Share on other sites
Mike C Posted December 18, 2017 Report Share Posted December 18, 2017 A Bosch coil is a bit over $40 at Supercheap. Much as I hate swapping over electrical parts to check if they're faulty this may be the cheapest & fastest way out of a coil problem. Christmas is coming and the weather is warm and sunny- not a good time to be stuck in the garage. Quote Link to post Share on other sites
stallie Posted December 18, 2017 Author Report Share Posted December 18, 2017 Thanks for the replies all. I focussed on the coil and did as you suggested Mike and grabbed one on the way home. I replaced both it and the LT wire to the coil. I've taken it for a run through some back roads here in perfect afternoon temperatures after a hot day and it now appears to run just fine... If it's the coil I'll be peeved as it's brand new from Moss (the gold sport coil). I'll test it when I get a chance. It could also be the wire. Quote Link to post Share on other sites
stuart Posted December 18, 2017 Report Share Posted December 18, 2017 The new type "Lucas" gold are well known for being iffy on occasion. Stuart. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted December 18, 2017 Report Share Posted December 18, 2017 In Aus think about a Bosch coil GT40 type for pre '73 non ballast, << http://www.myshopping.com.au/PT--171_Auto_Parts_Bosch_Ignition_Coils__fs_15234_54057_e__ GT40 coil type << https://www.sparesbox.com.au/ignition-coil-gt40-bosch-gt40?utm_source=CommissionFactory&utm_medium=14626&utm_campaign=Sparesbox " Coils came up in TR2-3 recently:- from another thread on this forum" My research says this is the blue coil that will do a TR. Bosch Ignition Coil Pt No 0221 119 027 K spec https://au.bosch-aut...coil-0221119027 More info http://360.haubits.n...ition Coils.pdf This book says SU12 is standard coil (with screwed terminals!), GT40 is performance and GT40T is racing type (all 12 volt) For TR6 with ballast resistor - Add R suffix - SU12R is standard etc. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted December 18, 2017 Report Share Posted December 18, 2017 Thanks for the replies all. I focussed on the coil and did as you suggested Mike and grabbed one on the way home. I replaced both it and the LT wire to the coil. I've taken it for a run through some back roads here in perfect afternoon temperatures after a hot day and it now appears to run just fine... If it's the coil I'll be peeved as it's brand new from Moss (the gold sport coil). I'll test it when I get a chance. It could also be the wire. Simple check - Is the LT wiring the correct way round on the coil top? - ve terminal connected to the distributor LT terminal (white with black trace originally) and + ve the feed from the loom? If not the car will run like a bag of poo when under load.... Peter W Quote Link to post Share on other sites
stallie Posted December 18, 2017 Author Report Share Posted December 18, 2017 I had hoped to get the Bosch, but ended up with some other brand (unballasted) from Repco as Bosch was sold out of there and SuperCheap. No time to source anything else after work, and I if it didn't run tonight, I would forfeit the registration appointment fee tomorrow which at $50 is more than a Bosch coil... Anyway it's running, and I might change the coil down the track. Peter - thanks, yes the LT wiring was correct, I did check that. Cheers. Dan Quote Link to post Share on other sites
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