Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Violent misfiring on full throttle at 3-4000 RPM

That is exactly what I did.

I had the same problem with my M3W. Couldnt figure it out. if I was gentile with the throtle input around that RPM it wasnt too bad. Seemed worse sometimes, not as bad others. I used Protune to look at the Lamda senors, O2 sensor if your North American like myself. I Found that one of the sensors was not producing a stable reading. It was then telling to sofware to add fuel and had a mountain in the middle of the fuel map. New O2 Lamda sensor fixed the problem 3000 miles later, not a single issue. You will not find the same sensor no matter how hard you look if your in North america. Just go to you local auto parts store and get one that matches the screw in part exactly and the plug end is universal. 5 minutes with simple tools you will have your old plug cut off and installed on the univeral. I changed the other sensor after discovering that the problem was fixed. New sensor also had very stable readings on protune. The none problem sensor wasnt as stable and jumped around more then the new one. So I changed it. You will need to completely disonnect both battery terminals after you install the new sensors to clear the memory the computer was getting from the bad sensor. Not sure if you can clear fuel logs in Portune on an locked ECU. I am lucky and got an UNLOCKED ecu that the PO installed.
Good luck.

Good tip Scott.

Forgot one more thing. Buy Bosch O2 sensors. Dont go cheap. I think part of the problem is that they are getting shaken so hard. They are automotive sensors. Probably never designed to get shaken like they do. So get brand name. They are inexpensive. I paid about $75us/ per if memory serves me correctly. Its a morgan. It deserves the best. LOL

The lambda sensors makes sense, as I know they go suddenly. It is running better with the old Champion plugs with a 40 thou plug gap and they might cope better with over fuelling than the rather tatty looking Iridiums. I have added a pair of Lambda sensors to my Brands Hatch Morgan order. So if I have replaced coil pack, leads, plugs and lambda sensors, hopefully that will keep me going for another few years or at least until the fuel pump dies. I just hope that Bozo the Clown's quarantine clamp down for France does not wreck the post/courier services even worse than they are at present. I have already been caught on this, when I bought a rare Leica historic lens from New Zealand, only for it to get stuck as quarantine set in and all flights were cancelled. It sat for two months at Auckland Airport then vanished. It turned out the sender had not insured it properly either, but only by weight, which was about a third of its value.

Wilson

Perhaps if you had ordered a pair of Bosch 0258986615 (LS615) lambda sensors, that I would guess are readily available locally, you wouldn't be concerned about any "clown" quarantine measures. That would have involved looking here though. https://www.mtwc.co.uk/wp-content/uploads/2020/07/Updated-list-16-14-July-2020.pdf. As the fuel pump is a known problem, I see no reason why anyone would wait for it to fail at the most inconvenient time before replacing it with a more reliable item.

Sadly I was using an older alternative parts list, which did not list the Bosch Lambda sensors. I have already ordered and paid for them from Brands Hatch Morgan. I am thinking of bringing out the whole pump kit from Glencoe next year.

Wilson

What an exceedingly helpful company Brands Hatch Morgan is. When I explained that I did not know until this morning that I should be using different Lambda Sensors (Bosch 0258986615-LS615, which I can source locally at a big spares place the other side of Marseille and they have stock), it seems as if it is no problem not pack the Morgan Lambdas with my order, refund me and just send me the rest of the order; coil pack, leads and 2 Iridium plugs. I see that the Bosch sensors come with a connection kit for various types of socket. I just hope it is not like the last Lambda sensors I changed on a friend's Diablo, where I had to swap the plugs over from the originals. Both the old and new Magnetti Marelli sensors, very helpfully had 4 unmarked white wires coming out of them. It took a bit of puzzling with my Avometer to work out which was which. Looking at the tiny image of the Bosch on Méca-Trouve's website, I fear the Bosch may be the same.

Many thanks to Planenut for the heads up on the Bosch Lambdas. I have replaced the old alternative parts list in my computer with the updated one.

Wilson

Total success. Misfire completely gone and running better than it has done for some time. I don't know which of the changes, coil pack, plug wires, plugs or lambda sensors did the trick but I suspect it was the lambda sensors. Fitting the universal Bosch lambdas is a bit of a fiddle with the weird connecter block they supply to re-use the original loom plugs, which you cut off the old lambda connector wires but at €55 each as against £158 each for the OEM lambdas, I can live with a bit of fiddling about. They specifically say not to solder the wires, which would have been my first thought, then to cover with glue filled heat shrink sleeves. There is so much more torque in second gear, that it means I need to tweak the drive belt. Now where did I, ever so safely, put away the envelope containing a supply of new big split pins for the rear axle spindle?

BTW on another thread, there was some discussion on the correct gap for the NGK Iridium plugs. On the box for the latest set, there is a picture of the plug being gapped with a feeler gauge, crossed out. I assume this means that these plugs should not be re-gapped from the pre-set gap. Given how well my M3W is now running, I can't argue with this.

Wilson

Thanks for the positive feedback about the Bosch Lambda Sensors Wilson. It's always good to get some confirmation that the alternative parts found by other owners actually does work. Better availability and a handy saving as well.