The Lotus Grand Tourers

Hi all,
Was out yesterday and did around 40 miles, all running sweet then out of the blue ignition seemed to fail and engine stopped.
Pulled up, went to restart and it fired up and ran up to about 3k revs in a couple of seconds and stopped. did the same again with same result. third time it didnt fire up at all.

Have checked fuel , thats ok, pump runs fine plugs nice and wet but no spark.

checked the ohms across the coil and getting nothing between coil tower and +
getting around 1.4 ohms resistance between + and -
anyone got thoughts on if its looking like the coil has packed up?
It a lucas coil so I guess a replacement part will be easy to get?
looks like there are plenty on ebay etc.

However if its not the coil I fear it might be the immobilizer - I didn't get the plug in for it when i got the car

Check your dizzy cap and rotor arm. Rotors are renowned for being poor quality.

My usual answer to these kind of problems. Disconnect the rev limiter. Only takes seconds and could save you a lot of time. Wish I had done this when I had the same problem.

viewtopic.php?f=27&t=8349&p=61107&hilit ... ter#p61107

Hi all,
disconnecting the immobilizer didn't work

Looks like its carbs off to get to the distributor and rotor

If im doing that im thinking of an upgrade to electronic ignition.

any tips or advice on this?

Now looking on line at options for electronic ignition

Can anyone confirm its a lucas distributor with negative earth please?

Its looking like 123 ignition is the correct unit to buy. anyone bought this option?

It's a Lucas 45 IIRC and 123 is a usual replacement option.

Take the air box off for better access.

Rotor arm rivet - check

Coil - check

Coil connections usually drop off - check

Dizzy king lead (black) - check

keith rhodes wrote: ↑

Sun Apr 11, 2021 10:27

Hi all,
disconnecting the immobilizer didn't work

....

Do you mean the rev limiter here?

I have the 123 bluetooth one fitted to mine - fitted by previous owner trying to cure a problem with running which was actually nothing to do with distributor. There is no preset map for the Excel, you have to load your own. This was not very good when I got the car, but now set very close to factory specs.

Have you disconnected the Rev limiter as advised?

You don’t need to remove carbs to get to distributor, just air box - held in by trumpets. Again, as said check rotor arm - the rivet that holds the metal bar can break through on the inside and short to the shaft.

Have you checked electrical connections to coil from ignition switch and between coil and amplifier module?

Hi Guys, thanks for the responses;

I thought the immobilizer was the rev limiter - i read that somewhere on here.

it the rev limiter item the lucas ignition amplifier ?
or the smaller module next to it which does not have any indication of what it is?

ahh - i just found another module with speed limiter written on it - it this the one I should unplug?

I have the 123 bluetooth one fitted to mine - fitted by previous owner trying to cure a problem with running which was actually nothing to do with distributor. There is no preset map for the Excel, you have to load your own. This was not very good when I got the car, but now set very close to factory specs.

Thanks Alan, can you elaborate on how I would find and load my own mapping?

keith rhodes wrote: ↑

Sun Apr 11, 2021 11:39

I have the 123 bluetooth one fitted to mine - fitted by previous owner trying to cure a problem with running which was actually nothing to do with distributor. There is no preset map for the Excel, you have to load your own. This was not very good when I got the car, but now set very close to factory specs.

Thanks Alan, can you elaborate on how I would find and load my own mapping?

With the Bluetooth one you load the map via the app on a phone or tablet. I used the details from the WSM to set mine. If you get one I can share what I have loaded. With the non bluetooth one you do it via laptop usb.

Sounds like you have now found the Rev limiter. Has unplugging it helped?

Hi Alan, Just tried the engine with the rev limiter unplugged - still no go

regarding taking the sir box off the access the distributor - the back end of the box looks like its bolted onto the inlet trumpets - i thought it might just be simpler to unbolt the whole inlet manifold and ease it out of the way?

I'll try taking the back box off and see if i can get my large hands in!

keith rhodes wrote: ↑

Sun Apr 11, 2021 11:36

Hi Guys, thanks for the responses;

I thought the immobilizer was the rev limiter - i read that somewhere on here.

it the rev limiter item the lucas ignition amplifier ?
or the smaller module next to it which does not have any indication of what it is?

The Lucus Amp is the AB14. Most people hate them and blame it for everything else.
We have previously sampled a small number of AB14's previously discarded using a Lucus test set and all passed IIRC. So the bad name for the AMP appears unwarranted.
The rev limiter in just forward of the AB14 as you have found .