Hiya all

Need some help...

Symptom: My car will idle really rough (500-1500rpm range) for a period of 5 minutes intermittently...car can be hot or cold doesn't matter. It has stopped at the traffic lights as a result of the rough idle.

Now I did think this was due to the Link tune (since Link tunes are SOOO much worse than Motec), however when this occured the other night (first time at night) I noticed that my lights dim dramatically at the same time the idle drops below 500.

Now thinking a loose wire (short circuit) or maybe an alternator problem?

Any ideas?

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Back at work.

could be alternator or a loose earth to the coils. Could also be a dying battery.

Check the voltages across the battery terminals when the car is on and off.

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RS Liberty - Because WRX's are only good for parts...

Update:

Since swapping back from Caltex Vortex 98 fuel to Ultimate 98, I've not had this problem again.

Dodgy fuel/water in fuel?

Still, I wouldn't expect poor fuel to cause lights to dim...given the battery is pretty new.

__________________
Back at work.

just stick to ultimate 98, its been fairly well discussed before that vortex98 isnt really up to scratch or consistent

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Long live the WRC

Are you running an Anti-Lag Possumlink ?


Also Possumlink idle tips: (idle is all in the tune and tuner)

For V5/6 (WRX/STi 99/00) PossumLink ECU Users:

Zones 17 and 18 are the ones that are important. Basically try 24 in Zone 17 and between 70 <--> 80 in ZONE 18. Worked for me.



Subaru Impreza WRX/GT ver. 5 6 with stepper motor idle control ZONE 17 (over run vacuum) general notes
This is the point where it registers what a trailing throttle is and it wont try to control idle typically set at 24 (24kpa) Idle is normally around 40kpa So on a training throttle when you back off the vacuum goes below 24kpa, the ECU will ignore the reading hence stopping it from trying to control idle via the idle control motor. This stops the engine from having a fluctuating idle when the situation occurs that you do end up at idle it wont have to massively re open the idle motor to compensate.

Subaru Impreza WRX/GT ver. 5 6 with stepper motor idle control ZONE 18
(default stepper motor figure for off idle position) general notes
These notes are only relevant to later model chips fitted to this ECU Typically a "magical" number of steps, and idle should be approx 60, so as this setting should be then set to 70 - 80. So when you step off the throttle the motor is at 70 - 80 and has not got far to move to a satisfactory idle setting.
The number in the idle screen in select zones, will be in brackets, is the number of steps at idle.

There is five symbols that also appear in this screen
neg (-) means the stepper motor is trying to pull idle down
pos (+) means the stepper motor is trying to pull idle up
V (V) means overrun vacuum condition, actual engine vac has gone below set amount (see notes on Zone 17)
T (T) means the throttle is off idle (and open)
= (=) means the idle has achieved the idle you chose
(IE if idle rpm (zone 8) was set to 800 and the car IS
idling @800 then (=) will appear)
NOTE re zone 8 idle rpm
The number displayed is double divided by 10
IE if idle is 800 the display is 16
IE if the idle is 1000 the display is 20

J

you find that if your car gets to 500rpm everything will struggle to stay alive as it is barely kicking and everything will dim