Since replacing my head gaskets I've had an issue with misfiring (causing a heatshield fire), revs sticking and a high idle.
The misfire cleared itself up - I never found what was causing it as when I came back to the car to take a look it was running fine.
The sticking revs was really bad straight after the rebuild. Initially they would stick/hold at whatever RPM I revved up to, occasionally continuing to rise slowly on their own. I'd have to turn the engine off to correct this.
After a little while the engine would rev up and the revs would drop on their own - only to get stuck at around 2K RPM. Again, the only way I found to stop this was to turn the engine off. Sometimes the RPM would drop quickly from whatever I revved up to down to 2K where it would "snag" and then drop more slowly.
When I was finally able to drive it I found that it was holding revs well enough on it's own to chug along at 30mph without needing the accelerator pedal. Not slowing down on it's own and not speeding up. Using the brakes would slow the car down and the engine revs seemed fine once I came to a stop.
Now, after having it on the road for a few days the rev holding seems to have settled down and it's not sticking at any RPM but I have noticed that my idle RPM seems high. It seems to vary between 1,100RPM and 800RPM. It's not bouncing between these values, it's just sitting smoothly at different points in this range at any given time I look at it. It never gets as low as the 660RPM that RAVE says it should be.
I've had a brief chat with Sloth about it as the symptoms seemed to match an old thread of his that I found online. He said he fixed his by moving the throttle cable routing. My cable seems to be routed well and as far as I can see the cable is moving freely. The throttle body seems to be closing fully when the throttle pedal is released - the cables are returning to rest against the stop properly. I tried to check the throttle body by removing the intake pipe with the engine running but the engine immediately died. I guess the sudden change in airflow was just too much for it cope with. I think my symptoms are now a bit different to his.
Given that I lack a Nanocom to investigate with, can anyone suggest things for me to try to diagnose this issue?
I've seen a few threads online (mostly Disco 2 related, in America) saying that they've reset the adaptive values and that's sorted high idle issues. Is this only possible with a Nanocom?