Air Idle Control Valve EJ25 SOHC

[Pepperami]

Disconnect the battery, over night if possible.

[stubbie]

OK the problem has been fixed, at least I hope so......
The cause was the Neutral Position Switch being earthed. My donor engine was from an automatic and the NPS was found to be earthed. For some strange reason this led the ECU to perform all sorts of strange and irregular things such as 1) occasional rough idling (sounded like it was running on 3 cylinders) 2) irregular over- revving during gear (sometimes it would be ok and sometimes it would over rev, this problem tended to appear once the van exceed 70 mph) 3) VSS fault code - (nothing wrong with VSS).

So there you have it. A big thank you to Richard (RJES) for bearing with me and finally getting to what I believe was the problem. The van has been running fine for the past 3 weeks and confidence is high that the problem has finally been nailed down

So guys if you have any of the above symptoms, you might just fix them by disconnecting your NPS from earth (if of course it's been earthed) If it's not been earthed you might find that earthing instead will also clear the problems.

For info and to save reading through entire thread, engine was a 1999 EJ 2.5 AT SOHC this now pushes along a 4 speed manual syncro.

[silverbullet]

Nice one stubbie!
I'm definitely going to check the various "dead" wire tails on the ecu and see if any of them are NPS - I don't know if my engine/ecu were auto or manual sourced. I was going to try the "reverse polarity" wiring trick on the MAF in desperation, as it's had a code 49 since the day I acquired it and the previous owner (not the convertor) was clueless.