hey guys,
today on the way home from uni i had a quite confusing problem, the drive in this morning was fine ... upon start up in the afternoon my car idled wierd, as in it was jumping from 900 - 1300 Rpm. it continued to just bounce up and down, when i started to move out of the carpark this continued to happen and under acceleration it was also bouncing instead of the revs increasing smoothly. pooing myself i pulled over. turned off and started again, only to experience the same thing. then after the car warmed up completely it got a little better but continued to happen.

About 15 minutes into the trip i pulled up at a set of lights, and everything went back to normal... Anyone have any ideas as to what might have happened ? :nuts:

thanks, Dylan

Odd one. Hunting for idle but not dropping below 800-900rpm?

What was it doing while driving? Surging 1000rpm then dropping again?

it was driving normal, just a bouncy increase in revs, not a smooth curve like it normally is ...

hmmm. How cold was it when it played up?

I have 2 theories - with my motorbike i have a similar problem with it going onto auto choke on really cold days and it hunts for an idle. Perhaps there is an error on the ECU? and this doesn't happen everytime. But could be relating to the choke function? Maybe - the other theory - you have an issue with your ISC idle speed controller and when it's on choke its not reading correctly.

When you are under heavy load and it's warm and not playing up is it all good? Like never has cut out?

maybe try talking to http://www.aussiemagna.com/forums/member.php?u=18 as he has a shop in Bayswater South and i'm sure he would have a look for you! he is very smart with this sort of stuff too being a mits spec

Just for shyts and giggles, try dis-con your battery for a while, and then re-connect, on some cars, it helps to refresh the computer, then it will auto diagnose, and perhaps not have the same problem.
Presti, if it was cold weather, could that effect a poor condition MAF sensor? perhaps cleaning that may be a good thing to try????

thanks for the input guys, umm yeah its never happened before, :s yeah i was thinking potentially isc ... car was cold today when it happened ... Never cut out.

Yeah mal was my next option if no one had any idea here, he's already done a few things for me and he always does a great job

A car with an auto gearbox behaves exactly like that when it has an intermittent misfire. Could be a plug lead not seated correctly, or a plug lead damaged and arcing over to metal. Could also be leaking plug tube seal(s) leaking oil onto plug(s).

thanks for the input guys, umm yeah its never happened before, :s yeah i was thinking potentially isc ... car was cold today when it happened ... Never cut out.

Yeah mal was my next option if no one had any idea here, he's already done a few things for me and he always does a great job

sorry about the multiple posts, my phone loves spam :P

okay so yesterday i disconnected the battery and then started my car after reconnecting, and everything appeared to go back to normal ? could this mean an ecu fault ?

okay so yesterday i disconnected the battery and then started my car after reconnecting, and everything appeared to go back to normal ? could this mean an ecu fault ?

If it is, and it comes back, it would show up on a diagnostic code check. The ECU retains any error codes that can be read out. (but it disappears when you disconnect the battery.)