Right where do I begin.. When I got the car I noticed that it would constantly rev at 1,250 rpm even after the engine warmed up so I did a little investigating. I found a bolt stuck in the pipe that runs from the IVAC (so air was free to enter the throttle body (pipe was tucked away). I took the bolt out and connected the pipe back but after starting the car whenever I pressed the accelerator the revs would rise to 2,500 rpm and stick.
Blipping throttle did nothing. So I got someone who also has a Rover 200 (exactly the same year but a 16v version) and tried their IVAC, throttle body which definately worked in their car to no avail.
Messing around with the pipes I found that if you discconected one of the rocker cover breather pipes and blocked it (and re-connect the IVAC pipe) the car would idle fine. However more often than not the revs still stick especially after driving on a motorway doing 70 for a little while (i.e. engine is hot).
I have checked all the pipes (including MAP sensor pipe) and they are unblocked so I have come to the conclusion the MAP sensor or ECU might be goosed. Oh and fuel economy is quite bad too compared to the MPG my mate gets in their 16v.
Firstly thank you to David of MobileTuning in Spennymoor (Tyne & Wear). If anyone has ECU, alarm fob or alarm box probs I can't recommend anyone better. He definitely knew his stuff. His contact details are [email protected].
He matched my new ECU to the alarm and did a full diagnostic on the engine for 25 quid. I drove down as he was only 30 ins away and he did it there and then.
Right engine diagnostic said engine was fine running as it should be so ECU wasn’t faulty. He had a look at the blocked pipe and said that there should be some form of restrictor either in the pipe or in the rocker cover valve. He said sometimes they disintegrate over time or fall our. The pipe might not have been the original one also.
This meant that air was free to enter the plenum instead of the restrictor forcing the air out of the other rocker cover breather and into the throttle body where the butterfly can open and close to rev the engine. The gases where free to go into the engine and it had no way of controlling it.
Problem solved but he also thought my throttle body had a problem as it sticks when the engine is warm (blipping throttle does solve this problem) which didn't help try and diagnose the problem.
So i though I would let people know in case they have similar problems.