Thread: lumpy acceleration on LPG between 1000-1500rpm

Here’s a picture of the Lucas amplifier module that I replaced the third party version with (bottom) 3 years ago

I gave up years ago using those modules, they're marginal at best.

Lucas ignition amplifier replacement by Bosch 024

Not to say that yours isn't working. Try undoing the distributor cap and leaving it to air in the sun for an hour after getting the engine warm. Use a hair dryer if no sun available. There may be slight traces of moisture condensing inside the distributor cap. Polish the cap inside and out with a soft cotton cloth.

double post

Originally Posted by bee utey

I gave up years ago using those modules, they're marginal at best.

Lucas ignition amplifier replacement by Bosch 024

Not to say that yours isn't working. Try undoing the distributor cap and leaving it to air in the sun for an hour after getting the engine warm. Use a hair dryer if no sun available. There may be slight traces of moisture condensing inside the distributor cap. Polish the cap inside and out with a soft cotton cloth.

Thanks @Beeutey! I'll give it a try after work today. I'll let you know how it goes! Otherwise I'll go for the amplifier module... I was thinking about doing your Bosch conversion a few years ago actually. Maybe this is the opportunity I've been waiting for.

Does this mean that oxygen & LPG is harder to ignite than oxygen & petrol vapour and consequently needs a cleaner spark? If my problem is failing ignition...

My Rangie left me on the side of the road the other week for the first time. Not a biggy only took a couple of minutes to sort out. It was a bit of water on the ignition module plug. But I don't like people to see a Range Rover on the side of the road with the bonnet up . No good for any of us.

So prior to that I was having some issues with ruff idle and a miss every now and again that was probably fowled plugs.

So I didn't want that happening again so I fitted a MSD Street Fire ignition with the Tach adaptor to my RRC and it has sorted the little issues I was having and runns sweet as now. I've still got it on std 0 dec ignition timing but I'll be winding up the advance soon. You know advance till she pings and back off a smidge .

I don't mind sticking in MSD ignitions on older cars as they work great and it was the best modification I ever did to my sigma years ago.

Cost $220 for the ignition and $80 for the tach adaptor and took half an hour to fit. All the original stuff is still there so if it does happen to crap itself its a 2 min job to plug in the old ignition.


I was going to do a write up on it when I get some miles and a couple of tanks of gas through it and give some stats on the conversion.

Here it is fitted just next to the coil behind the left side headlight.

IMG_0003.jpg

and a youtube video on MSDs

MSD Ignition Controls - Playing with Fire - YouTube

Originally Posted by gussy

Does this mean that oxygen & LPG is harder to ignite than oxygen & petrol vapour and consequently needs a cleaner spark? If my problem is failing ignition...

Pretty much. A mixture of LPG and air takes a higher voltage gradient across the plug gap to ionise the mixture and initiate a spark compared to petrol/air. Momentary lean mixtures on LPG can be a real hazard to forwards motion due to less ionisation available. And retarded timing means a higher cylinder pressure at the point of ignition so 10 degrees BTDC at idle assists low to medium speed power.

Reduced plug gaps (0.7 to 0.8mm) helps a bit. The type of plug lead can cause odd running problems with LPG too due to resonances in the high voltage section.

I knew a guy once who swore by MSD systems, gave me one to try in the wife's old P76. Worked well until it left her stranded by the side of a country road miles from home. It got a Bosch module soon after that and that never let her down. No doubt the newer MSD's would be reliable but the Bosch one works well as well under 1/2 the price.

Originally Posted by FisherX

My Rangie left me on the side of the road the other week for the first time. Not a biggy only took a couple of minutes to sort out. It was a bit of water on the ignition module plug. But I don't like people to see a Range Rover on the side of the road with the bonnet up . No good for any of us.

So prior to that I was having some issues with ruff idle and a miss every now and again that was probably fowled plugs.

So I didn't want that happening again so I fitted a MSD Street Fire ignition with the Tach adaptor to my RRC and it has sorted the little issues I was having and runns sweet as now. I've still got it on std 0 dec ignition timing but I'll be winding up the advance soon. You know advance till she pings and back off a smidge .

I don't mind sticking in MSD ignitions on older cars as they work great and it was the best modification I ever did to my sigma years ago.

Cost $220 for the ignition and $80 for the tach adaptor and took half an hour to fit. All the original stuff is still there so if it does happen to crap itself its a 2 min job to plug in the old ignition.


I was going to do a write up on it when I get some miles and a couple of tanks of gas through it and give some stats on the conversion.

Here it is fitted just next to the coil behind the left side headlight.

IMG_0003.jpg

Originally Posted by FisherX

My Rangie left me on the side of the road the other week for the first time. Not a biggy only took a couple of minutes to sort out. It was a bit of water on the ignition module plug. But I don't like people to see a Range Rover on the side of the road with the bonnet up . No good for any of us.

So prior to that I was having some issues with ruff idle and a miss every now and again that was probably fowled plugs.

So I didn't want that happening again so I fitted a MSD Street Fire ignition with the Tach adaptor to my RRC and it has sorted the little issues I was having and runns sweet as now. I've still got it on std 0 dec ignition timing but I'll be winding up the advance soon. You know advance till she pings and back off a smidge .

I don't mind sticking in MSD ignitions on older cars as they work great and it was the best modification I ever did to my sigma years ago.

Cost $220 for the ignition and $80 for the tach adaptor and took half an hour to fit. All the original stuff is still there so if it does happen to crap itself its a 2 min job to plug in the old ignition.


I was going to do a write up on it when I get some miles and a couple of tanks of gas through it and give some stats on the conversion.

Here it is fitted just next to the coil behind the left side headlight.

IMG_0003.jpg

and a youtube video on MSDs

MSD Ignition Controls - Playing with Fire - YouTube

those MSD ignition controllers look great. The difference in spark gap is huge. For now I will stick with a Bosch/Lucas replacement though! If I ever decide to restore the sports rover, that will go in! Thanks for the idea Fisher X