Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Plug leads

We just used a bit & i drove it for 3hrs yesterday & all is fine. Check the gapping of the plugs from time to time as i found one to have openned a bit after only driving it for 5hrs. .040 inchs

Quick question guys - went over a bump today which somehow managed to disconnect one of the spark plug leads. I ran for about half a mile, with lots of loud bangs from the driver's side exhaust and loss of power, before I could pull over and switch off.

I quickly spotted the problem. But now the (stage 1) exhaust on that side is running almost silent, and there is a strange noise from the engine on full acceleration, almost like a supercharger(!). Or maybe it always made that noise, but the exhaust was drowning it out...

Have I somehow damaged my exhaust by running on one cylinder?

The air cleaner didn't work loose as well over the bump did it?

Second thought - the ECU has tried to compensate - disconnect battery for a while then reconnect, then try engine again.

Thanks Richard
The air cleaner (the Morgan stage 1 one) is still in place

I tried disconnecting the battery for a while but no change. It is also "pinking" (stones in the mudguards noise) at high revs, which I haven't heard since the stage 1 kit was fitted. So I guess there is a fuelling issue linked to the ECU as you suggested.

You could stick with it taking in a few short runs and see if the ECU adapts to correct. It apparently does this in steps waiting to see improvement in between, with fuel to air ratio at least.

If the bump was heavy enough to disconnect a spark plug lead , check the leads to the gas sensors in the exhaust pipes ( I cant remember the posh word for these ! ) are connected and present. They look like spark plugs screwed into each exhaust just forward of the split point.

When mine did that the cat ignited the unburnt fuel and turned the pipe in to a pulse jet . After fixing the plug lead it too ran "lumpy" the cat on that side had turned to dust the removal of the other cat restored harmony

Excuse me smiling but that is a wonderful description of the fault and even better balancing the result out .

If you plug a laptop into your ECU, with S&S Pro Tune II, you can reset the adaptive maps. This is a more positive method than waiting for things to happen, maybe.

So a little update on my situation (its been a long story, I will try to summarise):

1) The initial cause of the HT lead becoming disconnected was that the spark plug end/terminal had become loose with the vibration of the engine. I didn’t know these were removable. Check yours are still tight (they screw on)!

2) The resulting explosion of unburnt fuel in the exhaust caused a small metallic filter which is located in front of the lambda sensor (2012 car with a 2017 sports exhaust) to disintegrate and block the silencer. Thus why it still drove and power was ok, but the noise was strange.

3) The car is currently at the dealer. Since they have no parts and the factory is shut, they will try running the car without the filter tomorrow and see if the Lambda sensor or ECU throws up any faults. The alternative seems to be a replacement exhaust manifold (getting expensive!)

Does anyone recognise the filter in question and do you know what it is for – e.g. protecting the lambda sensor from heat, just noise etc?