Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Fuelling Problem following Excellent Track Day

Evening Folks - need your collective help if I may please?

Was at Goodwood today for the excellent Brands Hatch Morgan event and we had our own dedicated group of 3-Wheelers with plenty of track time - all fabulous stuff. This was a 98dB day and I came prepared with those slip-on cans I posted the other week. They make a huge difference and on the normally notoriously angry Goodwood noise meter, measured a paltry 94dB at 3750rpm. Others with stock/drilled pipes were pushing 98-101dB depending which way the wind was blowing.... These slip-ons are just absorption type baffles, but reduce the pipe exit from 2" to 1". Performance slightly 'fluffy' at 4500+, but nothing too serious. Car felt lovely on track, handled as I wanted and was pulling 5,500rpm easily down the back straight -I ran out of gearing. I didn't hit the limiter at any point and the engine performed really well.

Drove away and all was well. Those that know the Goodwood-to-Petworth route will know that there is a long downhill section as the road drops down Duncton Hill towards the farms below. I went down the hill in 3rd on overrun, as there was slow traffic ahead. As I went back on the gas as we rounded the S-bends outside Seaford College, the engine stuttered but cleared as I accelerated away. This continued for the journey home.

Symptoms - anything more than say 20% throttle produces perfect running, powerful pull and everything is normal. But hold a very light throttle cruise and the RHS cylinder (viewed from driving seat) fluffs and misses and the engine runs on effectively 1.5 cylinders. Squeeze a little more gas pedal and all returns to normal. Idle is lumpy for sure, but it does idle tolerably.

Got home, removed plug and Lambda and both black as pitch. Very rich running evident and as my car has no CATs, very obviously rich, old-school exhaust smell. Cannot for the life of me think what might be wrong. Too much fuel clearly, but that makes no sense. Changed plug, cleaned Lambda - no difference whatsoever.

Maybe some hang-over from running those ever-so-slightly more restrictive slip-ons? I could understand a little 'adaptation' but the drive home was without the cans, so car back to where is was on the way there. If this was weak running, then I'd suspect a partially blocked injector, but way too rich on a very small throttle opening? Weird.

Thoughts folks? I've not plugged ProTune in as yet, but no Engine Light, so unlikely to find much to help in there. Great day, spoilt by an annoying glitch it seems. Thanks for help

Could be old fuel - when did you last fill up?

Have a close look behind the cam belt cover - I had similarish symptoms before a cam pulley detached from its drive shaft - after a spirited drive the cam pulley destroyed itself, compare the one on the left ( where the key way is mashed up ) to the good one on the right.
PS I hope its not this - quite expensive to fix !

Other possibility is the officially non-adjustable TPS being out of adjustment. The adjuster screw is sealed by a blob of silicone which can be dug out and turned to suit. Unfortunately I can't remember the correct voltage to set it to and I'm a very long distance away from my car, stuck on an enormous boat in the North Sea, but somebody must know!

There's only 1 cylinder affected so I wouldn't think the TPS would be likely. Given the super rich condition I would suspect a bit of detritus in the one injector, not allowing it to fully close. Also see the cam pulley issue as less likely due to the engine running well once the throttle is opened somewhat.

After a look at any info you could glean from Protune, you could disconnect the battery to reset the adaptive fuel maps and see how that changes things. If no change then its not likely a software fault, but rather hardware related. The injectors are easy enough to remove and inspect/test.

And that righ cylinder always seems to run a bit rich anyway. Since that is the “rear” cylinder in a motorcycle i think it is possible there is something in the porting or manifold design to slightly enrichen that cylinder to help keep it cool since it sits normally in the heat shadow of the “front” (front) cylinder.

Just a random musing.

Hi Phil good to see you yesterday! i would swap lambda's over and see if problem changes sides!!! sounds to me thats where the fault is .

I would agree with Bitsobrits going by the way the fuel filtration is set up in the M3W,

Put Protune 2 on and see if the Lambda sensors are doing their stuff and the voltage range is 0.5v to 1.1v range. Your unlocked ECU shouldn't be running on the adaptive maps, Krazy Horse usually turn them off on their rolling road set up. Swopping the Lambda sensors over should confirm their operation. A bottle of injector cleaner through the system may just help? It can't do any harm. It looks like you had a great day out ....in a quiet way 😁.

Sorry I can't help with the problem , but just to say a great big thank you to all you 3 wheelers for coming along and putting on such a good display.

You were easily the most exciting vehicles on the track, and two of you (I suspect you know who) were having a real ding-dong out there which was really great to watch, it only finished prematurely when one suffered an engine problem coming out of the chicane in the afternoon runs. Originally I thought his spirited driving onto the rumble strip had dislodged the front wing and the smoke emanated from the tyres, but I suspect it was rather more serious.

I will post some photos later once i have sorted through the 200+ that I took throughout the day.