I and SMC slough have had a real job finiding a replacement throttle body for my 97 +4.
I tracked one down for them.

But this is the second throttle body to fail in 2 years due to the stepper motor.

It could be bad luck but I am suspicious there is a hidden cause. Anyone got any ideas?

Heat fatigue, Water ingress or voltage stabalisation (spikes).


My favourite would be Heat Fatigue especially as it takes so long to fail.... Any idea what your under bonnet temps are?

No idea but the fan comes on as it should & it doesn't overheat.

It's not the temperature of the running engine, but radiated heat or inducted heat....

OK point taken.
Lets hope this one survives.

hhmmm. the plot thickens!

Indeed lets hope

I don' t know the issue but could you get some heat shied wrap around the suspect item?

The plot does indeed thicken. Having now got a new throttle body SMC discovered the problem was still there. They are now testing the ECU.

Hell may freeze over before I get my car back at this rate!

When my Lumenition ignition module produced an intermittent fail on an MGB, it shut down when the fans cut in, so the current spike caused the problem. It was a long time before this was solved, as it presented more like a heat related failure. That's one reason why I've gone to town on the Roadster insulation, because over the years I've had electronics pack up, and heat is usually in the sketch.

At last I have my P&J back complete with replacement ECU.
I picked her up from Slough on the way back from LHR after 2 weeks in France.SMC fixed her the day after I left.

It pissed it down & the hood was up but the smile was large.