I purchased a cheap ST170 from ebay a few weeks ago.

Nothing wrong with it other than the engine management light was on.

Code reader found something along the lines of inlet manifold runner control stuck open - or words of similar meaning.

Turns out the clip on the side of the inlet (DSi clip) had broken off (common fault again) and there was a cable just hanging there. I managed with the help of a friend to repair this as I couldnt source a replacement. We reset the engine management light and upon starting it , it would making this scratching sound from somewhere that lasted about 10 - 15 seconds, followed by the engine management light illuminating again.

Decided to leave the control box at the back of the engine unplugged (DSi control unit) as it drives fine.

A week or two later there was a slight tapping sound that started coming from the inlet manifold and the accelerator pedal would randomnly get stuck but only if you were completely off it and went to press it down, it would go stiff for a minute then go down but as it did the car would lurch. what is tapping inside the inlet manifold and why does the accelerator keep getting stuck?

Im guessing to repair it totally i need to replace that DSi unit, but it did briefly drive fine with it disconnected.

 

Yes the IMRC module bolted to the bulkhead is faulty. Remove it and open it up, sometimes the return spring has come off inside or it just needs a bit of TLC. The scratching sound and ticking is from the plastic gears in the IMRC