Intemittent rough idle MY04 GT - FIXED

[Robbks]

Possible there's an intake/ vacuum leak (small leak that closes up when warm) have seen this previously on a subie with intake manifold gaskets leaking when cold
spraying some UEC or carbie cleaner at any joins/ gaskets along the intake tract will result in a change in idle speed, or a "cough" if it gets sucked into the engine at the point of a leak

Less likely to be the Rear o2 Sensor given it's cold, could still be the front one though

Quite possible the Coolant Temp Sensor may be faulty so the car is not getting the required extra fuel it needs when it's cold
or the TPS/ throttle body butterfly is sticking slightly when it's cold (contracted) if the TB is a little dirty
has it had a new air cleaner recently?, if not, that's a place to start
fuel filter?/ bad fuel (use 98RON only)

[snaza]

Possible there's an intake/ vacuum leak (small leak that closes up when warm) have seen this previously on a subie with intake manifold gaskets leaking when cold
spraying some UEC or carbie cleaner at any joins/ gaskets along the intake tract will result in a change in idle speed, or a "cough" if it gets sucked into the engine at the point of a leak

Less likely to be the Rear o2 Sensor given it's cold, could still be the front one though

Quite possible the Coolant Temp Sensor may be faulty so the car is not getting the required extra fuel it needs when it's cold
or the TPS/ throttle body butterfly is sticking slightly when it's cold (contracted) if the TB is a little dirty
has it had a new air cleaner recently?, if not, that's a place to start
fuel filter?/ bad fuel (use 98RON only)

Hi again,

When my normal mechanic had is for about 5 hours they said they check everything for leaks, but like you said, it could close up when it warms.

I use 98 fuel and have tried different servo's.

Air filter was replaced about 20-30,000km ago.

Spoke with Michael as scorpion subaru today and he reckons in is probably the air flow meter or cam lifter sticking (something like that). I'll try and get it to him next week.
Would the Coolant temp sensor show errors on the computer?

thanks for your time

[youngy69]

Hey Aaron,How long have you had the car,if you are not the original owner what sort of km`s did you but it at,do you know the history of the car?So how often does this happen,does the fuel level play a part in the issue,have the injectors been cleaned properly ie removed and bench cleaned,if they have were the rails flushed properly as they are returnless so crap builds up in there?Has anyone had a scan tool on there when it was playing up so the AVCS cam pulley`s can be monitored so you can watch the cam sprocket timing as well as the OCV settings ie %/current draw,has anyone measured the A/F correction ratio at the same time as this will prove if there is a air leak,injector leak,weak pump,air leak in the fuel pump assy?Has the car ever had the mod (not recall) for the code P0031 which include a PAK file as well as a wiring mod.If a coolant sensor plays up it will run rich providing a signal of -40c to the ECM for safety sake.Food for thought.
Cheers Eddie

[snaza]

Hey Aaron,How long have you had the car,if you are not the original owner what sort of km`s did you but it at,do you know the history of the car?So how often does this happen,does the fuel level play a part in the issue,have the injectors been cleaned properly ie removed and bench cleaned,if they have were the rails flushed properly as they are returnless so crap builds up in there?Has anyone had a scan tool on there when it was playing up so the AVCS cam pulley`s can be monitored so you can watch the cam sprocket timing as well as the OCV settings ie %/current draw,has anyone measured the A/F correction ratio at the same time as this will prove if there is a air leak,injector leak,weak pump,air leak in the fuel pump assy?Has the car ever had the mod (not recall) for the code P0031 which include a PAK file as well as a wiring mod.If a coolant sensor plays up it will run rich providing a signal of -40c to the ECM for safety sake.Food for thought.
Cheers Eddie

Thanks for the detailed reply Eddie

Ive had the car 3 years. got it with 60k and now done 120k. i am the second owner and got it from bill buckle subaru in syd.

its only happend twice where it idles really rough before stalling, then comes good a few minutes later. doesnt seem to be fuel level.

havent done the injectors yet (just bottle of injector cleaning stuff)

I can't get it to replicate it for the mechanics but subaru in brisbane and my normal mechanic have looked it at. no fault codes on the computer.

The only problem i can now replicate everyday is 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

thanks for your time.

[Dropz]

I love reading youngy's posts

[snaza]

Got an update in the symptoms

Hasn't done the hunting for 2 weeks now.

One thing I managed to replicated 5 mornings in a row is the engine ping / cough when driving up hills. It goes away after the car warms up. Does that help diagnose anything? Does it sound like any particular sensor is stuffed. I'm going to take it to Michael at Scorpion or subi evolution next week, I hope.

If it was something like injectors/ 02 sensor or Airflow meter would the problem go away when the car warms up?

thanks

[Dropz]

If were o2 it would stay asthe car doesn't use the readings from the o2 until the sensor is at operating temp. Sounds like afm.

[youngy69]

I love reading youngy's posts

Be nice!This may be a dumb question but have you been using SA459?I would say since you have mentioned pinging etc I think you need to soak the motor due to carbon build up.Get a couple of tins,get the car nice and hot,soak it for a while and then repeat the process.You must change the engine oil after due to dilution as I dont think you want a bearing issue.After you have done this let me know how it goes,I had a RS Lib back in 93 that had a similar issue.
Cheers Eddie

[snaza]

Hi Eddie,

No i've not been using it or heard of it. I just did some research and it looks good. I'm not comfortable doing it myself but i'll talk to Subievolution about it when i drop my car in

cheers

[mincedmeat]

sorry if its been fixed. but i couldnt be bothered reading the rest of the posts. i put $10 on the O2 sensor.
its on the way out and not showing a code YET.
i replaced mine for the uk. sparkplugs.co.uk, or sparkpulgs.com
Dealer wanted $500, aftermarket local was $360. got them for $130 (70pound + shipping but got a few plugs at same time)

[MixGT]

Hi All, first post and I hope this will help:

Aaron, I also have an 04 GT, last year mine was idling rough, misfiring (had to nurse the throttle at the lights to keep the engine running), stalling, sulphur smell, pinging, etc worse when cold but pretty constant, I thought bad fuel at 1st. Seemed fine under throttle but not 100%. Took it to my mechanic, he had it for almost 2 weeks, plugs replaced, weird compression test results, O2 sensors, AFM and he even replaced the timing belt. He spent hours diagnosing but was getting nowhere, thank god he only charged me about $1k for the timing belt and a few hours labor.

I ended up doing him and me a favor and eventually took it Subaru Docklands, 2 hours and $275 later it was running like new again 1 of the solenoids for the variable cam timing had seized with carbon and only half the engine was running with variable timing!!! The guy there told me it isn't a common problem but they have seen it a few times, they clean em out and away you go.

Hope it helps and maybe saves you some time and a crap load of $$$$.

Mick

[snaza]

Hi All, first post and I hope this will help:

Aaron, I also have an 04 GT, last year mine was idling rough, misfiring (had to nurse the throttle at the lights to keep the engine running), stalling, sulphur smell, pinging, etc worse when cold but pretty constant, I thought bad fuel at 1st. Seemed fine under throttle but not 100%. Took it to my mechanic, he had it for almost 2 weeks, plugs replaced, weird compression test results, O2 sensors, AFM and he even replaced the timing belt. He spent hours diagnosing but was getting nowhere, thank god he only charged me about $1k for the timing belt and a few hours labor.

I ended up doing him and me a favor and eventually took it Subaru Docklands, 2 hours and $275 later it was running like new again 1 of the solenoids for the variable cam timing had seized with carbon and only half the engine was running with variable timing!!! The guy there told me it isn't a common problem but they have seen it a few times, they clean em out and away you go.

Hope it helps and maybe saves you some time and a crap load of $$$$.

Mick

Hi mate,

Just read this but had the problem fixed yesterday.

It was exactly what you said. Banjo bolt filters had broken down and stuff was stuck in the solenoids. Computer showed one cam stuck at 52% and the other was 0%. problem was diagnosed by SERGE in 10 seconds and running as new in less than an hour. I'm so happy i called him as my local mechanic would have never found this. I did leave it with subaru for the day (a few weeks ago) and they couldn't find anything.

Thanks everyone for the help and advice

[teflon]

Just read this but had the problem fixed yesterday.

It was exactly what you said. Banjo bolt filters had broken down and stuff was stuck in the solenoids. Computer showed one cam stuck at 52% and the other was 0%. problem was diagnosed by SERGE in 10 seconds and running as new in less than an hour. I'm so happy i called him as my local mechanic would have never found this. I did leave it with subaru for the day (a few weeks ago) and they couldn't find anything.

Thanks everyone for the help and advice

That's awesome mate. Was that Serge who used to work with Russell out at Subievolution? If so, they're great blokes!

[Robbks]

Good to see it's sorted mate.

I did leave it with subaru for the day (a few weeks ago) and they couldn't find anything.

surely if they plugged in the scanner they would have seen the cam timing issue
fkn retards

[snaza]

Just read this but had the problem fixed yesterday.

It was exactly what you said. Banjo bolt filters had broken down and stuff was stuck in the solenoids. Computer showed one cam stuck at 52% and the other was 0%. problem was diagnosed by SERGE in 10 seconds and running as new in less than an hour. I'm so happy i called him as my local mechanic would have never found this. I did leave it with subaru for the day (a few weeks ago) and they couldn't find anything.

Thanks everyone for the help and advice

That's awesome mate. Was that Serge who used to work with Russell out at Subievolution? If so, they're great blokes!

Yeah he still does work out with russell (only to use his workshop) and contacting