club.liberty.asn.au

Hi All,

I have an intermittent rough idle issue. It's happened twice now at random times but cant replicate it. I pulled up at the lights and the car started shaking and idling really low, eventually stalling. The first time it started happening i drove it straight to the mechanic. It came good after while. They spent 5 hours and found nothing. plugs, coil packs, hose leaks all fine and nothing showing on the computer. They did run a injector cleaning kit. A week later it did it again but came good after a few minutes. Its just an idle issue, once the car gets going it runs fine. Took it to Subaru and they found noting on the computer and suggested they should do the following;

replace AFM
replace in tank fuel filter
reset ECU and base idle
remove and clean injectors

Total cost is about $2000

This was just something to try and they reckon it will probably fix the problem. No way i'm going to waste $2k on a guess.

Past 2 mornings i've noticed my car runs crap going up my hill. I can hear the engine misfiring but once i get up the hill and and revs get up a bit it runs fine again. Thinking back the 2 times I had idle issues was about 5 mins or less from a cold start.

I'm outta idea's. I've read all the rough idle threads here and most seem to be injector issues. Should i get them ultra sonic cleaned?

thanks

Aaron

If it hasn't been done start with the fuel filter. If you add some throttle when its rough what happens?

Dropz wrote:If it hasn't been done start with the fuel filter. If you add some throttle when its rough what happens?

if i add some thottle its fine.

Could be related to iacv. Maybe get a Subaru upper engine cleaner can and spray it through the throttle body.

I'm far from an expert, but this is most likely the O2 sensor at the top of the dump pipe isn't it? Several members here have gone through more than one.

You could always try to clean the AFM sensor with some electrical contact cleaner/MAF cleaner as well.

Barring an injector overhaul, you could get an O2 sensor and AFM from Phat for under $450, install them yourself and see if that fixes the problem? And I assume all they do to reset the ECU is unplug the battery??? How much will your local mechanic charge to clean the injectors (as a last resort)?

There are lots of thread about this if you do some searching using the search function. Cleaning the injectors would be the last option and some options are free, cleaning the MAF sensor. Where are you based?

Dropz wrote:Could be related to iacv. Maybe get a Subaru upper engine cleaner can and spray it through the throttle body.

thanks but i actually just had that cleaned

teflon wrote:I'm far from an expert, but this is most likely the O2 sensor at the top of the dump pipe isn't it? Several members here have gone through more than one.

You could always try to clean the AFM sensor with some electrical contact cleaner/MAF cleaner as well.

Barring an injector overhaul, you could get an O2 sensor and AFM from Phat for under $450, install them yourself and see if that fixes the problem? And I assume all they do to reset the ECU is unplug the battery??? How much will your local mechanic charge to clean the injectors (as a last resort)?

Thanks mate, Just spoke with the subaru guy at Capalaba brisbane (forgot his name) and he said he doubts its the O2 censor as it would show computer errors. He said he can loan me an AFM to see if that helps.

I'll talk to my normal mechanic today find out about and proper injector clean

Ben wrote:There are lots of thread about this if you do some searching using the search function. Cleaning the injectors would be the last option and some options are free, cleaning the MAF sensor. Where are you based?

im in brisbane. the AFM sensor is clean

snaza wrote:Thanks mate, Just spoke with the subaru guy at Capalaba brisbane (forgot his name) and he said he doubts its the O2 censor as it would show computer errors. He said he can loan me an AFM to see if that helps.

I'll talk to my normal mechanic today find out about and proper injector clean

There are several examples of members not having a fault code but the fault being the O2 sensor so I wouldn't write it off. Russell at Subievolution is pretty good (brendale way though). But if you're willing to drive try Michael at Toowoomba (OPMSport) as well. A mate of mine, same model car as you, same problem (+ fuel economy gone to crap) had the front O2 sensor replaced after he brought the car to Michael with that problem and it fixed it. Several workshops (including Mercury) couldn't work out what was going on. Have you noticed any problems with fuel economoy prior to the rough idle issue?

teflon wrote:

snaza wrote:Thanks mate, Just spoke with the subaru guy at Capalaba brisbane (forgot his name) and he said he doubts its the O2 censor as it would show computer errors. He said he can loan me an AFM to see if that helps.

I'll talk to my normal mechanic today find out about and proper injector clean

There are several examples of members not having a fault code but the fault being the O2 sensor so I wouldn't write it off. Russell at Subievolution is pretty good (brendale way though). But if you're willing to drive try Michael at Toowoomba (OPMSport) as well. A mate of mine, same model car as you, same problem (+ fuel economy gone to crap) had the front O2 sensor replaced after he brought the car to Michael with that problem and it fixed it. Several workshops (including Mercury) couldn't work out what was going on. Have you noticed any problems with fuel economoy prior to the rough idle issue?

Thanks again. Fuel ecconomy hasn't been any worse than before (about 450/tank around town) and up to 700km highway. I'll talk to them about the 02 sensor

Youngy69 mentioned it can be o2 with no code.

Give it a shot

O2 sensor on the dump. Happened in mine, didn't show any fault codes at first they only came up when it basically failed. Phat has these at the moment for a very cheap price for what they normally go for. Fixed my issue right up and has been good ever since

Dropz wrote:Could be related to iacv. Maybe get a Subaru upper engine cleaner can and spray it through the throttle body.

DBW has no IACV

but cleaning the Throttle body isn;t a bad option anyway
-Remove the plugs, inspect and replace them anyway,
-inspect all the boots and connections on the coilpacks

The car has both o2 Narrow-band (near Cat) and AF wide(er)-band sensors (top of dump) either may have an intermittent fault

does it happen when cold, hot or intermittently both?

check for intake/ exhaust/ vacuum leaks
leaky BOV,

Robbks wrote:

Dropz wrote:Could be related to iacv. Maybe get a Subaru upper engine cleaner can and spray it through the throttle body.

DBW has no IACV

but cleaning the Throttle body isn;t a bad option anyway
-Remove the plugs, inspect and replace them anyway,
-inspect all the boots and connections on the coilpacks

The car has both o2 Narrow-band (near Cat) and AF wide(er)-band sensors (top of dump) either may have an intermittent fault

does it happen when cold, hot or intermittently both?

check for intake/ exhaust/ vacuum leaks
leaky BOV,

Hi mate,

the 2 times it happend was less than 5 mins of driving. I noticed that when its cold and driving up my hill first thing in the morning it cuts out / pings and runs like crap if the revs are less than 2500rpm. once it warms up its seems ok

they mechanic checked plugs and coil packs