02 bug STi - rough idle after a hard drive? and after filling up only?
 

hi guys

ive noticed with my car that when i fill up, the first start up after filling up is always kinda rough and it sounds like its not running right, i just drive off and it sorts its self out by the time i hit the next set of lights.

having taken it on some hard drives over the last few days ive also noticed it does it sometimes after a hard drive when stationary. revs dont move at all, just the gear leaver and engine shakes really bad..

no fault codes or engine management lights.. what could it be?

i did post a thread up before about it and put it down to nf race formula/the lambda sensor pre turbo

lambda sensor pre turbo has now been changed with one off a blob sti.. and ive stopped using nf for the last 3 tank fulls.

its nowhere as bad as it was before i changed the sensor and i have notived an increase in fuel economy. so that must be working.

any other ideas of what it could be?

cheers

it just worries me sometimes as i dont know why it does it out of the blue.. could it be maf?

bump

Hello mate,

Has the car had a plug change,fuel filter change of late. Do you let the Fuel Pump prime etc?

Steve

hi steve

plugs were changed 6k miles ago

and fuel filter at the same time

how do you mean let the fuel filter prime?

i normally start the car after ive heard the fuel pump switch off.. normally 2 or 3 secs after it goes on second click if you get me..

When you fill it the ecu monitors the fuel quality via the sensors as a safety back-up.

Once "happy" normal service is restored.

IMHO.

dunx

dunx so what your saying is the instant rough idle is normal? by the time i hit the first set of lights it has stopped..

however it sometimes does it after a hard drive, actually only does it after a hard drive on a hot day, never does it on a cool day..

The ecu knows you've thrashed it, and tries to psyche you out....

LOL

dunx

lol u joker, it hasnt done it at all today and ive driven 200 miles.. must be just in hot weather and after fill up..

Is it not partially due to heat soak when shutdown for short periods?

Just keep it gentle for a few miles to allow things to cool down. I run a gems ecu and that can be a real sod at times.

The DENSO ECU looks at the intake temps and when they get above 34 degrees (I think thats the temp) starts to get a bit peeved !!

easy to get when stopped for a couple of minutes.

Either that or your ICVS is playing up and get ready to be raped by Subaru for a replacement LOL

Shaun

lol sounds like it

where is this idle control valve? i'll see if it makes a difference if i clean it up

The other day, after having just been running in hot weather for a while, then when I restarted the car soon after shutting the engine off (engine still warm), it took a while to fire and it felt like it wanted to die when idling. After a minute or two, it cleared up though.

I have a JGM/Zen mapped PFC which otherwise runs/starts perfectly, etc.

Hot weather can be a bummer when restarting an already warm/hot engine... :(

just a bump up for this again, as its still doing it, and i plan to up the power so dont want this causing a problem.

it only does it on first start up after putting fuel in.. idles rough, gear lever shaking, as soon as i leave petrol station and get to the lights its gone..

any ideas what it could be? it does it with no fail at every fill up for the first 30 secs then never again..