TR6 - Problems with No 1 and No 2 Cylinders

[russellbaldwin]

Looking for some inspiration!

 

The TR (125 model) has been lumpy, especially on start-up which has been exagerated since fitting a Phoenix manifold - i think the problem was there before-hand.

 

With engine running and insulated pliers took each of the spark plug leads off. Pots 3-6 noticed a cylinder going 'off' but 1 and 2 made no difference. Used a different HT lead on pot 1 and no change - so thought it must be a worn distributor cap/rotor.

 

Replaced the cap (couldn't get the rotor arm off so left it as-is for now), spark plugs, LT and HT leads - but to no avail!

 

I've since tried taking the plug out and leaving in the HT lead and I do have spark on pots 1 and 2 when it arcs to the cylinder block.

 

I've looked at fuel - good pulse coming through the injection pipes and took the injectors out and have a reasonable spray pattern.

 

Might be worth noting that the car is running very rich with plugs sooting which I was going to look at after getting pots 1 and 2 back on-line.

 

Any ideas?

 

[Steves_TR6]

Well if it's sparking and squirting fuel you have the basics covered Russell !

 

I still suspect the pi system.

 

Try swapping injectors and see if the problem moves with the injectors.

 

Also try the same with spark plugs, swap working ones to eliminate.

 

Then maybe have the rocker cover off to check nothing untoward on valves for Cyls 1 and 2

 

Did this come on suddenly !

 

Steve

Edited June 6, 2016 by SDerbyshire

[boxofbits]

Hi Russell

 

I'd say a compression check would be your next stop.

 

But if you say it is running rich you might find cleaning the plugs will rule out a shorting plug electrode. They are difficult to get clean when sooted as it gets up into the stem of the electrode and creates a short.

 

You will need to clean them ideally with a proper sand blast type of cleaner. Also check your air filter and tappet clearances.

 

Regards

 

Kevin

[RogerH]

Hi Russell,

even though the plugs spark when removed they may not spark under compression.

What does the spark look like compared top say #5 or 6 plug when removed.

 

Have you got a colour tune - this may give an insight to whether sparks are happening or not.

 

Have you swapped the p[lugs around? Or simply try new plugs

 

Roger

[barkerwilliams]

Russell,

 

You mention lumpy running, is that at tickover or at any revs?

 

If only at tickover I would suspect the butterfly synchronisation, with cylinders 1 & 2 completely closed at tickover so they contributed nothing to engine -just a very rich, airless mixture that cannot ignite (black plugs). When the spark plug lead is disconnected it makes no difference as the fuel/air mixture is not igniting with any oomph anyway. Another symptom of that would be for example, pulling away from traffic lights after ticking over when the throttle is opened and the clutch starts to move the vehicle the car staggers, perhaps stalling. But car will seem good over perhaps 12-1500 revs.

 

 

Alan

[peejay4A]

"Couldn't get the rotor arm off". Something is wrong there, it should pop off easily. Wrench it off and replace with a quality red rotor arm.

Edited June 6, 2016 by peejay4A

[DaveN]

+1 replace the rotor arm and cap for quality items from The Distributor Doctor.

Check the valve clearances.

Do a compression check.

As for the very rich running:

Remove the cavity drain from the MU and check the return to the tank is clear (a favourite place to block is a short piece of 'rubber' hose located in the l/h wheel arch area!

Check the choke is fully returning at the MU. (The excess cable can contact the bulkhead!)

Remove the vacuum hose that goes to the MU from the inlet manifold.. Suck on the pipe and block it off with your tongue check it holds vacuum.

Check the throttle butterfly's..... On the CR engine especially the designers must have been on drugs with the linkages!

[russellbaldwin]

Thanks all - lot's to go on. I'll have a look at the compression and tappet clearances and be more persuasive with the rotor arm.

 

Alan - it souds like you've described the problem and air for cylinders 1 and 2 is a common source. I've taken off the air mainfold and visually inspected the operation of the butterflys and they look consistent across all six pots. I guess it could be in the fine adjustment. The manual says getting the timing and fuel metering right needs to be done first - more investigations required!

[russellbaldwin]

one other thought - should the engine timing change from standard given the phoenix stainless exhaust mainfold?

[barkerwilliams]

Russell,

 

You cannot "see" if the butterflies are sync'd.

 

Could obviously be a number of things but if it's a balance or air leak problem then:-

 

 

Basic test :-

 

Will the engine tick over with the large Air screw fully screwed in? If so then the there is an air leak somewhere - butterflies or manifold.

 

Test 2

 

engine ticking over, air manifold off.

 

Close each of the 6 intakes off one at a time. (I used palm of hand - probably not a good idea) perhaps with a rubber glove.

 

If butterfly is fully closed then no "suction" no, or little change to engine revs.

If the butterfly is slightly "open" then the blanking hand slammed into manifold and the engine stalls.

 

On my car it originally ticked over on two cylinders, the other four just marking time. Not particularly rough just down on power at low revs. A little odd at tick over but nothing dramatic.

 

A very easy and quick couple of tests. All cylinders need to be singing from same hymn sheet.

 

If not all very similar then buy or borrow a Delltoro Carb balancer about £35 ebay etc. This is an essential PI tool. If just plugs into each of the 6 intakes and you take a reading at tick over. Get all six with a similar reading - it's harder than it seems but tremendous benefits in engine smoothness and power/economy.

 

I have Phoenix no timing change - but if you have disturbed the inlet manifold during fitting then could easily be an air leak.

 

Alan

Edited June 6, 2016 by barkerwilliams

[russellbaldwin]

Alan

 

Test 1 failed, so must be an air leak

 

Test 2 there was a little suction on cylinders 3-6 but lots on 1 and 2 - so looks like this could be the problem

 

The CR linkage seems different to the one in the brown book and haynes manuals I have and there's more slack than a slack thing there. Noted comments on BL being on drugs when they did this - have many converted to a CP linkage to improve matters?

 

But at least I know where the problem is and can start fettling

 

Thanks everyone for all your input - a massive help!

 

Russell.

[barkerwilliams]

Russell,

 

What part of the world are you in?

 

Alan

[russellbaldwin]

Alan

 

I'm on South Coast so I've asked the guys at Southern Triumph to take a look to finish tuning the car as I'm running out of time for a trip and work (and lack of skill) is getting in my way!

 

thank again

Russell.