Petrol engines Bad idling 2.1
mart 475: Hi any help with this would be greatly appreciated. When I start my bus it idles at 800 ish rpm but after a short distance this becomes 2000 rpm. If I revved it heavily it would drop back down to 1200 rpm but recently the heavy rev tactic hasn't been working and it's sticking at 2000 rpm! It does drop for a split second but the rev counter bounces straight back up to 2000rpm.
My bus is a 1987 club joker 2.1 petrol. I replaced the coil yesterday although this is probably a coincidence but yesterday was the day of the 2000rpm syndrome beginning and it's the same today. Prior to that the bus hadn't moved for a week.
mart 475: Today I checked all connections which appeared sound with the bus idling at 2000 rpm then when i replaced the coil last week - a yellow block, which appeared to come out of the two pin side of the coil, was disconnected. I thought that I must have knocked it so I re-connected it and thought no more. However, with the bus idling fast I disconnected said block and hey presto, immediate reduction in revs to 800rpm. I know this is probably both good and bad! Good 'cos it solved my 1st problem but bad cos it means that summething else is up! Any thoughts and help you good people have would be greatly appreciated.
sonic23:Aha - I too have the same problem at the moment
I believe i've isolated it to being a faulty Idle Stablization Control Unit (ISCU). (Note - I've re-adjused the TrottleValve and made sure the micro switch is functioning as per Bentley)
Unless I'm really mistaken, that little Yellow connector that you joined together is from terminal 1 on the coil to terminal 17 on the ISCU. Here's a little test - remake this connection. (Revs go back up). Now go the ISV itself, and unplug the connector. Do the revs drop again? If they do - it means the ISV is working, but the ISCU is not.
If you unplugged it and the revs didn't drop - it would mean that the ISV is probably stuck open (Carb cleaner time).
Well....that's my pennys worth....i'm sure someone will be along to correct me. :D I'm getting a replacement ISCU from CJ at Syncrospares - so will report back on my findings....
BTW, there's lots of info on this on thesamba.com. A guy called tencentlife seems to be the guru. (Search on ISV and ISCU within the vanagon/eurovan forum):
