Thread: Lucas ignition amplifier replacement by Bosch 024

Thanks for the suggestion and write-up bee utey.

Replaced the remote ignition module and coil with BIC290 and BIM024 units
on my Rover SD1 (Lucas 35DM8) today after issues with weak spark and eventual cut-out in hot weather. The car fired up first crank (once I got the polarity right) and ran as sweet as candy through to the end of a very spirited run.

Existing module was a new "Standard" brand unit (eBay link here) which turned out to be absolute tripe. It's Bosch or bust for me now.

Cheers mate,

Tom

Thanks for the write up bee utey.

Currently chasing intermittent random engine stops. Thinking I had classic symptoms of immobiliser failure I spent the afternoon removing the centre console only to discover that the spider had already been bypassed, and the immobiliser module not plugged in. ****stix.

So off to my local spares shop before it closed and purchased a BIM024 and MEC717 coil, then reassembled the centre console only loosing one screw.

Now I think I have my head around the required wiring. What I am not clear on is why there are two Lucas RD953066 resistors poking out of the end of the coil wiring harness, connected to the White Blue and White Black wires that just return into the harness. Some Internet delving suggests these are to reduce the coil operating voltage, although why there are two connected separately I don't know and I can't find the ignition circuits in Rave to check out what might be going on. Does the BIM024 and MEC717 Coil combo function happily on an constant 12V supply ?

Originally Posted by jonse

Thanks for the write up bee utey.

Currently chasing intermittent random engine stops. Thinking I had classic symptoms of immobiliser failure I spent the afternoon removing the centre console only to discover that the spider had already been bypassed, and the immobiliser module not plugged in. ****stix.

So off to my local spares shop before it closed and purchased a BIM024 and MEC717 coil, then reassembled the centre console only loosing one screw.

Now I think I have my head around the required wiring. What I am not clear on is why there are two Lucas RD953066 resistors poking out of the end of the coil wiring harness, connected to the White Blue and White Black wires that just return into the harness. Some Internet delving suggests these are to reduce the coil operating voltage, although why there are two connected separately I don't know and I can't find the ignition circuits in Rave to check out what might be going on. Does the BIM024 and MEC717 Coil combo function happily on an constant 12V supply ?

The white/black stripe wire returns via a short loop to the negative side of the coil, the white/blue stripe wire takes the coil pulses to the ECU after passing through the resistors. The Bosch coil and module are designed to connect to straight 12V via the plain white wire at the (+) terminal at the coil, exactly like the original Lucas electronic ignition system.

Originally Posted by bee utey

The white/black stripe wire returns via a short loop to the negative side of the coil, the white/blue stripe wire takes the coil pulses to the ECU after passing through the resistors. The Bosch coil and module are designed to connect to straight 12V via the plain white wire at the (+) terminal at the coil, exactly like the original Lucas electronic ignition system.

That made perfect sense. Thanks again. Got it all back together now and it fired up first time and seems smoother than before. The acid test will be SWMBO's commute to work tomorrow morning - see if it has cured the random / intermittent engine stop. If this doesn't cure it I am stumped having already ruled out the immobiliser (Spider already bypassed)

IMAG0412[1].jpg

Re using the existing bracket meant the Bosch ignition amplifier sits a bit closer to the air intake bellmouth than I would have liked - couldn't mount it on the other side of the bracket like the original as the connections point the wrong way and would hit the front panel. Suppose the extra airflow round the amp will assist in keeping it cool. Found it a bit wierd that the positive connection from the distributor is the blue wire not the red one. See pics in Davo's post No. 133 in this thread.

I had a look, and it seems that the red wire is positive, according to the diagram I put up. Or did I miss something?

Originally Posted by Davo

I had a look, and it seems that the red wire is positive, according to the diagram I put up. Or did I miss something?

Without using an oscilloscope it probably makes little sense to assign positive and negative to the pickup wires, just connect them in the direction they work best. One day I might even do the investigation for my own interest.

I think I see what you mean. The distributor is just switching, isn't it? I went by the diagram I posted here: Lucas ignition amplifier replacement by Bosch 024 but now that I think of it I don't know why I went with red to #7 and blue to #3. So what would happen if these two wires were swapped around?

Originally Posted by Davo

So what would happen if these two wires were swapped around?

The ignition module triggers on a later section of the pulse generated by the pickup and massively retards the timing. The rotor button may no longer aim at the relevant ignition lead and cause loads of backfiring, especially with the vacuum advance hooked up. The signal as viewed on a CRO might look like this: