An major bugbear with this car was the stubborn refusal to idle below 1800rpm, preventing it from getting an MOT. This issue was what caused the previous owner to give up and sell the car to me in the first place and I have been working very diligently on finding the root cause of the issue.

To date I have replaced the inlet manifold gasket, throttle body gaskets, ICV gaskets, Entire throttle body twice (with 2nd hand parts), MAF sensor, spark plugs and O2 sensor in the pre-cat position. Happily, I can now say that the idle speed issue is no more and my 'to do' list is now very short indeed. Today my 5-lobed torx bits arrived from ebay, I needed these because the stepper motor for the idle control valve is held onto the ICV housing with 2 torx screws, but to stop people with a LEGITIMATE INTEREST in fixing the wretched things from getting inside the inner workings, they use 5-lobed screws. Getting hold of male versions of these is surprisingly difficult...

I had all the throttle bodies off the car at this point, I grabbed the original one that was fitted by the previous owner and carefully undid the 4x phillips screws that hold the ICV onto the throttle body itself

with that removed, I could then carefully undo the black stepper motor from the valve spindle

Its magnetic and just popped off the end of the spindle. This was where victory was obtained. The spindle was seized solid, meaning the poor little stepper motor couldn't adjust the position of the valve to close off the airflow though the throttle body butterfly bypass. I gripped the end of the spindle betwixt my mighty thumb and index finger and twisted back and forth gently. suddenly there was a click, and it started moving. w00p w00p. I squirted some plugsgas onto the valve bit and repeated and could feel the roughness as I spun the valve 360 degrees in the ICV body, a few more rotations had it spinning cleanly, so I refitted the stepper motor to the end of the spindle, did the 5-lobed screws up again and refitted the 'troll face' gasket between ICV housing and throttle body.

With this done, I refitted the throttle body to the car, plumbed in all the hoses, bolted the air filter duct back on and started the car up. It began to idle at 1200rpm, lower than before, but still a bit high. I let it idle for a few mins then poked the accelerator pedal with my foot, the revs jumped up, then it settled back down to 1200rpm again. Previously, doing this would send it up to 1500-1600rpm so we were making progress.

I let it get up to temperature without touching the accelerator, then gave it a poke and was rewarded for my tenacity with this beautiful sight

A 900rpm idle! It sat at 900rpm perfectly, ticking away perfectly. I let it idle away for a few more minutes and tried again with the same result, revs up then settles back to 900rpm. I'm so pleased that I've managed to sort this out! When the third (!) throttle body produced identical results to my existing two, I really did start to question whether I was chasing some terrible ECU fault or something hideous, but no, it was just plain bad luck. Three separate throttle bodies, all with identical issues - the ICV was sticking and the stepper motor couldn't produce enough torque to free the spindle.

This is a closeup (a bad one) of the actual valve

The air flows in the top port, and there is a spindle with a blanking plate section that opens and closes the gap to let air through to the bottom port and into the inlet manifold. as the valve couldn't move, the idle speed was stuck because the flow of air couldn't be regulated. I'm surprised this didn't trigger an EML or something, but anyway. Its now fixed, the idle is spot on where it needs to be and I have two spare throttle bodies and will soon receive a new ICV from Aliexpress.....

...leading me to phase 2. With a new ICV, I decided to give one of the spare throttle bodies a polish up. Before:

A bit grotty, wouldn't you say?

After a seeing to with autosol and an old t-shirt

It needs more work, I plan to buy myself a dremel and give it a really thorough polishing to make it as smooth as possible and see what difference (if any) it makes. Shiny things can only help, right?

This leaves just two things. Welding and tyres. With the idle issue sorted I will probably buy a set of 4 new tyres for it as I know the welding - while awkward - is possible and then we can get it down to the MOT station and back on the road, hopefully by the summer.

I am literally elated!