Dying idle when hot and poor pickup off idle

This motoring year is going from bad to worse, first my electrical gremlins and now a new issue!

The car starts easily and runs happily for a few minutes on choke, then I drive away and all seems fine. For the first mile or so the car needs a bit of choke when pulling away from a junction but the choke can then go off and the temp gauge starts to register. The idle in neutral or park is up around 900 to 1000RPM (I have it set this high as I thought maybe I had it too low before when it would die after decelerating to a stop). In this warming up state this leads to quite an urge to go which I have to hold with the brakes.
I can then motor around and all seems fine but when I get into a bit of stop/start traffic and the engine is good and hot the idle in Drive drops to 500 or so and not very smooth. Also pick up is very poor and it seems reluctant to take off.
Once I am running over 1500 to 1800 RPM everything seems fine again with good performance.
I can’t find any air leaks and my initial thought was that the engine was running too lean but I have tried the “lift the air valve” method and it seems to be OK. Maybe I should find a shop that can measure it and get a professional tune up but finding one seems to be difficult these days.
… and then just to make my day complete the starter motor has started to misbehave just giving me a clack, clack, clack sound and not spinning the engine!
I’ve had to walk away!

Mike Badger
(1973 DDS S1)

Just been searching archives on the use of E10 petrol as this is one of the changes that “may” be a cause factor in my dying idle post above…

Has anyone else here with a carbed V12 had any issues with this E10 petrol leaning out the mixture ???

Cheers,
Mike
(1973 DDS S1)

It does sound as though it is retarded. If you have a timing light, check how much (if any) ignition advance you have when you rev it when hot.

You can rule out “leaning out the mixture” theory by applying a bit of choke.

kind regards
Marek

Hi Marek,
I have recently checked the ignition timing (albeit not when fully hot) to set the idle timing at 8 deg BTDC and to check that the advance at 2200RPM was 25 deg BTDC to see if the centrifugal advance was working properly and not sticking.
Because the problem doesn’t seem critical when the engine is cold or warm, and only when fully hot I will revisit these measurements on a hot engine (after I resolve the starter issue !)

… and I’ll try your choke application idea too.

Thanks,
Mike
(1973 DDS S1)

Check the CTS on the water rail on the front left. This will give you choke problems via the ECU.
The clack clack can be simply the battery being down or as I had experienced… the starter throw gear jams on top of the ring ear. I removed the ring gear cover plate and with a long screw diver and a hammer freed the starter gear and then squirted some lube into it and it never happened again.

Re. starter motor :- Suggest that you check that the battery is fully charged.

also worth checking the earth straps between engine and chassis, as bad connection here would limit the voltage to the starter, and mess the ignition

You get the gold star for that suggestion as that is exactly what I found (whilst in the latter stage of engine extraction). Now it’s out I have confirmed my starter is dead (solenoid works but motor doesn’t rotate even on a bench test!).
I also plan to check the distributor whilst I am about it.
Many thanks and well done for putting your finger on the poor running issue.

Cheers,
Mike
(1973 DDS S1)