Ernest Posted June 15, 2021 Report Share Posted June 15, 2021 Out for a run in 6 today - and found that the car is running 'lumpy'. It started fine, but once warmed up it ran what I can only describe as 'lumpy' until revs. get up to about 3,000 rpm then all fine and goes well. My first thought was petrol supply (had a new Bosch pump fitted about 300 miles ago) but ruled this out given how well the car ran when more petrol (higher revs) required. Any ideas? Ernest Quote Link to post Share on other sites
Peter Cobbold Posted June 15, 2021 Report Share Posted June 15, 2021 I'd check the points gap first. Peter Quote Link to post Share on other sites
Mk2 Chopper Posted June 15, 2021 Report Share Posted June 15, 2021 Look at your plugs too, might have a misfire from a dirty plug. Also check your injector lines for pulsing. Gareth Quote Link to post Share on other sites
Ernest Posted June 15, 2021 Author Report Share Posted June 15, 2021 Thanks Peter and Gareth It looks like: check points and plugs then, if still poor running, check the P.I. system. I would be relived but disappointed if it was plugs or points as a new set of each was fitted during a recent service carried out be a respected TR garage (about 50miles ago). Thanks again Ernest Quote Link to post Share on other sites
Peter Cobbold Posted June 15, 2021 Report Share Posted June 15, 2021 1 hour ago, Ernest said: Thanks Peter and Gareth It looks like: check points and plugs then, if still poor running, check the P.I. system. I would be relived but disappointed if it was plugs or points as a new set of each was fitted during a recent service carried out be a respected TR garage (about 50miles ago). Thanks again Ernest Ernest, Points can wear that fast, especially plastic ones if lacking a small smear of molygrease on the cam. Peter Quote Link to post Share on other sites
Macleesh Posted June 16, 2021 Report Share Posted June 16, 2021 Has it ever run smoothly since fitting the Bosch pump? They are quite demanding of their power supply in my experience, I had a marginal Alternator and my idle and pick up improved significantly when I upgraded it. Thanks Sean Quote Link to post Share on other sites
Ernest Posted June 16, 2021 Author Report Share Posted June 16, 2021 Thanks Peter I will check points for wear and if greased. Sean The Bosch pump was fitted by Maidstone Sports Cars (this was not the garage who did the recent service noted above) and the car has run realy well since then (approx 300 miles). Indeed the guys at Maidstone Sports said that as a driver this 6 was about the best they had driven. Thanks Ernest Quote Link to post Share on other sites
John L Posted June 16, 2021 Report Share Posted June 16, 2021 (edited) I would suspect throttle balance, check to see when the throttle cable is lifted, do all three arms lift at the same time? This tool would be very useful, but prices do vary for the same item at different places. https://www.amazon.co.uk/Deluxe-Carburetor-Airflow-Latest-Rage/dp/B00CMC57R0 John Edited June 16, 2021 by John L Quote Link to post Share on other sites
Ernest Posted June 16, 2021 Author Report Share Posted June 16, 2021 Hi John That's an interesting suggestion - I have checked the plugs and all clean and set correctly - and no points (electronic ignition). So I am thinking something to do with P.I. system, which would be beyond my technical ability, but I can at least check the throttle cable as you suggest. Thanks Ernest Quote Link to post Share on other sites
Mike C Posted June 16, 2021 Report Share Posted June 16, 2021 +1 on the PI. Was the petrol tank nearly empty when this occurred? If not may be a sticking PI system PRV . Quote Link to post Share on other sites
Ernest Posted June 17, 2021 Author Report Share Posted June 17, 2021 Hi Mike Thanks for the suggestion but tank over half full of petrol. Ernest Quote Link to post Share on other sites
Rob Salisbury Posted June 17, 2021 Report Share Posted June 17, 2021 Hi Ernest, You could try this, with the engine running remove each injector in turn from the throttle bodies and check that each gives a fine cone of petrol sprayed from the tip (care needed here, into a small jam jar or similar), any injector with failed flow, dribbling, or large droplets will be the culprit, and sometimes a bit of gentle persuasion can bring a failing injector back to life, ie tapping or gently pulling out the fine tip with a pair of small pliers, simple job you just need a 1/2"AF socket or spanner to remove the three keeper plates then the injectors just pull out. Cheers Rob Quote Link to post Share on other sites
Ernest Posted June 18, 2021 Author Report Share Posted June 18, 2021 Hi Rob Thanks for this suggestion - I am wary about tinkering with the P.I. unit but I will consider the action you suggest. I was thinking of taking the car to Sanspeed in Bexleyheath to let see if they can identify, and hopefully resolve, the problem. They have tuned a 4a for me in the past and the improvement was marked. Thanks again Ernest Quote Link to post Share on other sites
michaelfinnis Posted June 18, 2021 Report Share Posted June 18, 2021 Further to Rob's suggestion, misbehaving injectors can sometimes be cleared by blowing through with air. A bike pump will do. mike. Quote Link to post Share on other sites
astontr6 Posted June 23, 2021 Report Share Posted June 23, 2021 On 6/16/2021 at 11:08 AM, John L said: I would suspect throttle balance, check to see when the throttle cable is lifted, do all three arms lift at the same time? This tool would be very useful, but prices do vary for the same item at different places. https://www.amazon.co.uk/Deluxe-Carburetor-Airflow-Latest-Rage/dp/B00CMC57R0 John +1 and check that the black injector pipework has no air in them and enquire bleeding by checking them for pulsing. Bruce. Quote Link to post Share on other sites
Steves_TR6 Posted June 23, 2021 Report Share Posted June 23, 2021 If the injectors are quite old then for a very modest cost they can be refurbished and will perform well for many years thereafter mine were refurbished in 2013 by Neil Fergussen and have been faultless ever since. steve Quote Link to post Share on other sites
John McCormack Posted June 24, 2021 Report Share Posted June 24, 2021 On 6/18/2021 at 6:45 PM, Ernest said: Hi Rob Thanks for this suggestion - I am wary about tinkering with the P.I. unit but I will consider the action you suggest. I was thinking of taking the car to Sanspeed in Bexleyheath to let see if they can identify, and hopefully resolve, the problem. They have tuned a 4a for me in the past and the improvement was marked. Thanks again Ernest Unfortunately clearing injectors is a must know for PI owners. It will happen occasionally that the car will be running on 5 cylinders. It is usually 2 or 5 and can be ascertained by feeling each injector tube in turn and the faulty one will have very weak or no pulses through the tube. Bleeding isn't too hard as described above. Just be careful not to damage the injector tip. It may take a short while to clear but be gentle with the injector tip. Quote Link to post Share on other sites
Ernest Posted June 24, 2021 Author Report Share Posted June 24, 2021 Thanks Bruce, Steve, John For these further sugestions - I took it out agan yesterday and problem continues - bit weird as it idles fine and once above 2000 rpm it goes as good as ever. The lumpy ruinning happens between about 800-2000 rpm. Ernest Quote Link to post Share on other sites
John L Posted June 24, 2021 Report Share Posted June 24, 2021 That now sounds a bit like the lean spike that the metering unit has if its set too lean. As the metering unit doesn't have an accelerator pump, that's what happens. A small adjustment to the metering unit to make it a bit richer would fix it. Find a club member to make an adjustment, where are you? John Quote Link to post Share on other sites
Rob Salisbury Posted June 24, 2021 Report Share Posted June 24, 2021 I ran a Triumph 2.5Pi saloon for around 25 years and during that time became very familiar with all aspects of the Pi system, the car was and Auto and as you can imagine it needed a smooth tick over and pick-up from idle, I found that if the throttle bodies were very slightly mis-aligned then the transition from 800 to 2000 would be, shall we say, uncomfortable .... Triumph produced a jig for correctly mounting the TBs, but using a solid straight edge across the airbox spigots works, although it's somewhat fiddly to get right, ........ it seems to me that if the TB spindles are not directly in line then the inter connecting levers and screws can't cope and give a slightly different opening to each TB as they move and consequently a slightly different airflow through each, ...... if all else fails then worth a check. Cheers Rob Quote Link to post Share on other sites
Ernest Posted June 24, 2021 Author Report Share Posted June 24, 2021 Thanks John and Rob I am really wary about tinkering with the P.I. I live in Hayes, Bromley, south London (about 3 miles from Biggin Hill airport) and would appreciate if a club member living nearby would be prepared to adjust the metering unit - very happpy to make a donation to a charity if this can happen. Best Wishes Ernest Quote Link to post Share on other sites
stuart Posted June 24, 2021 Report Share Posted June 24, 2021 1 hour ago, Ernest said: Thanks John and Rob I am really wary about tinkering with the P.I. I live in Hayes, Bromley, south London (about 3 miles from Biggin Hill airport) and would appreciate if a club member living nearby would be prepared to adjust the metering unit - very happpy to make a donation to a charity if this can happen. Best Wishes Ernest As your in London, take it to Enginuity https://www.enginuity.co.uk/ Stuart. Quote Link to post Share on other sites
Ernest Posted June 24, 2021 Author Report Share Posted June 24, 2021 Hi Stuart Thanks for the suggestion, I understand that they have a good reputation. I don't know how well you know London but the journey from here to west London would be awful - I would think that the car would be running between idle and 2000 rmp for most of the run, so pretty uncomfortable for the TR and for me re. 'lumpy running' for pretty much the whole 2-3 hour journey. I was down in Cornwal for a week recently (Polruan nr Fowey) and the roads were lovely and clear, if a little narow in places! I envy you having access to these driving conditions Best Wishes Ernest Quote Link to post Share on other sites
stuart Posted June 24, 2021 Report Share Posted June 24, 2021 1 hour ago, Ernest said: Hi Stuart Thanks for the suggestion, I understand that they have a good reputation. I don't know how well you know London but the journey from here to west London would be awful - I would think that the car would be running between idle and 2000 rmp for most of the run, so pretty uncomfortable for the TR and for me re. 'lumpy running' for pretty much the whole 2-3 hour journey. I was down in Cornwal for a week recently (Polruan nr Fowey) and the roads were lovely and clear, if a little narow in places! I envy you having access to these driving conditions Best Wishes Ernest Yes I know London very well so do understand but Im sure if you asked they would happily collect it which would be a lot easier. Next time your down come and say hello Stuart. Quote Link to post Share on other sites
Ernest Posted June 24, 2021 Author Report Share Posted June 24, 2021 Hi Stuart Yes of couse...... I did not think of using a car transport - I guess my mind is focused on obtaiing more local help. It would be lovely to come along to your garage, and to view any current restorations, so thanks for the invite - I will bring half a dozen of the lovely saffron buns to share with you and your staff! Best Wishes Ernest Quote Link to post Share on other sites
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