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

I have heard that solder can change the resistance in a wire. Since it is measuring resistance they probably consider this the reason for no solid connection.

I read somewhere else that you can't solder Lambda cables as the cables need to breathe, which sounds like total BS to me. Soldering does not change the resistance by much (fractions of an Ohm) especially if you use Mundorf silver/gold/tin solder with a thermostatically controlled iron, like I do. I would also bet that the soldered joint has over time, a far more constant resistance than the screwed together joint that Bosch supply, where the surface of both the connector slugs and the wires will oxidise and in damper, colder climates than where I am using my M3W, corrode

Carroll Smith, whose books I thoroughly recommend to anyone working on or building competition cars (Prepare to Win, Engineer to Win, Tune to Win), said that crimped or screw down terminal block joints were an absolute no-no on race cars as they would inevitably go high resistance or fail. I prepared my various single seat F2 and F3000 engined speed hill climb cars according to his principles and those of the late Ron Tauranac, always using ring-locked, surface-mount aircraft style connectors and as a result, during the 15 years I campaigned those cars, they never had an electrical failure (plenty of other failures - mainly gearboxes, which lead a hard life on hill climb cars).

Wilson

Do the NGK Iridium plugs cause any interference with the ECU, either the MMC ecu, or the Emerald ECU?

No

You cannot solder o2 cables, as the reference (static) oxygen has to flow between the wire core and the insulation around it (and/or between wire strands).

Thank you.

I am afraid I still don't believe the story about sucking oxygen through the tightly insulated wires to the lambda sensor for an external reference oxygen level. There are plenty of posts and videos on the Internet from folks who soldered their lambda wires with no problems. However, I followed the Bosch instructions and used their compression connectors but I would guess that if an M3W were to use these connectors in a damp or salty environment, corrosion problems would occur. Luckily mine is only ever used in the warm and usually dry climate of the south of France in the summer. Sadly I cannot see my M3W getting any use at all this year with France having gone into another lockdown.

Wilson

Planenut do you check the fuel pressure with the ignition on but engine off?

Yes I do. Just run the pump by turning the ignition on and it should show the regulated pressure on a gauge at the test point and hold pressure for a few minutes. It will dissipate over an hour or so. If you have a super "Emil style" fuel system I am told the pressure drops off almost immediately the pump stops but the standard Mahle type filter/regulator should hold pressure for some time.

I was talking to someone recently who has a Ferrari 328GTO, which like the M3W, uses fuel pumps submerged in the fuel tank. He told me that he has found that if he always keeps the fuel tank more than 50% full all the time, the pumps have a far longer life, through presumably being constantly cooled. I always keep the M3W fuel tank near full, not least because my gauge tells porkies. I wonder if this might explain why my original pump has lasted 9 years, which given other folks experience, seems a long life. If I had been able to get to France this year, I had intended to take a Walbro kit with me as insurance, hoping not to need it.

Wilson