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Hi peeps, just bought a TR6 PI CP in germany RHD ( I converted to LHD in 4 days) I wasn't really looking but something about this car pleased me, apart from the colour it looks as though somebody has spend some money on the TR in the past, the guy told me he couldn't find a garage capable of starting it.. I got the car home and compression tested 125/130 on all 6,I would have liked 150 but OK for an original engine. I put in a bosche pump, new pressure relief valve, cleaned the tank, new injectors and metering unit. couldn't find a spark with the petronix system so reverted back  to good old points and condenser, and bingo a spark, after insisting for about an hour, and  bleeding the injectors she started in a plume of grey smoke and no rumblings down below. I rechecked the points, plugs, and static timing 10° BFTDC. And took the car for a drive, great drive above 3000 RPM amazing acceleration but rough running and smoking below 2500, the plugs aren't oily but black. I have driven for about 5 miles at over 80MPH but drop down to 40 and the rough running starts, any ideas guys ???....

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Hi, The black plugs point to over fuel-ing. are you sure you have the correct metering unit for your CP engine?, you said the metering unit was new, .... check that the choke/over fuel lever on the metering unit is returning properly, .... then you need to check your manifold vacuum, ..... you're looking for 8 to 10 inches of mercury, any less and you need to find out why.

Check:- all the hoses to and from the throttle bodies, the vac hose to the metering unit, the vac diaphragm in the metering unit, that the throttle butterflies are closing and the engine is running on the throttle bypass valve, that the inlet manifold gasket is sound for each throttle body, ..... and finally the compressions are rather low, and you need  well sealing rings to develop any vacuum, a work around is to adjust the metering unit to cope with the lower vacuum, but it's a compromise, and would invalidate any guarantee you have on the new unit.

Good luck, nice looking car.

Cheers Rob     

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2 hours ago, Rob Salisbury said:

Oh I nearly forgot, also check the fuel pressure from your new pump and pressure relief valve, 106 to 110psi is what you are looking for.

I didn't check the fuel pressure the pressure relief valves are apparantly preset but will check tomorrow, I bought an improvement kit for the throttle linkages, all the butterflies are closing, the car is running rich. It could be the PRV will check fuel pressure tomorrow, I thought the compressions weren't too bad. The car pulls well I hope its the PRV fingers crossed. Cheers

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4 hours ago, Rob Salisbury said:

Hi, The black plugs point to over fuel-ing. are you sure you have the correct metering unit for your CP engine?, you said the metering unit was new, .... check that the choke/over fuel lever on the metering unit is returning properly, .... then you need to check your manifold vacuum, ..... you're looking for 8 to 10 inches of mercury, any less and you need to find out why.

Check:- all the hoses to and from the throttle bodies, the vac hose to the metering unit, the vac diaphragm in the metering unit, that the throttle butterflies are closing and the engine is running on the throttle bypass valve, that the inlet manifold gasket is sound for each throttle body, ..... and finally the compressions are rather low, and you need  well sealing rings to develop any vacuum, a work around is to adjust the metering unit to cope with the lower vacuum, but it's a compromise, and would invalidate any guarantee you have on the new unit.

Good luck, nice looking car.

Cheers Rob     

Someones a dick head, and forgot to put the vac hose on the metering unit, its midnight and I have just been into the garage and checked, the hose actually fell off. Could well be the problem

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As suggested above, your symptoms are consistent with the metering unit enrichment lever not being fully home.

You need to get your finger in between the block and MU and really push the lever home. If it moves a couple of mm that will be at least part of your problem.

Edited by John McCormack
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Absolutely, the vac operates on a calibrated fuel cam within the metering unit and controls precisely the volume of fuel fed to the injectors.      Google Lucas Pi Mk11 for the definitive description of the whole system and how it's supposed to work along with a full workshop guide of each component plus fuel calibration curves against vac for each model of metering unit.   

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6 hours ago, Rob Salisbury said:

Absolutely, the vac operates on a calibrated fuel cam within the metering unit and controls precisely the volume of fuel fed to the injectors.      Google Lucas Pi Mk11 for the definitive description of the whole system and how it's supposed to work along with a full workshop guide of each component plus fuel calibration curves against vac for each model of metering unit.   

Hi Rob, done it and thanks:) put the vac tube on and little smoke.. a slight misfire at lower revs but I noticed the HT lead from the dizzy was split, so replaced that and will drive tomorrow..  Thanks again Rob 

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