2002 RSK Legacy Sedan - Inconsistent performance

[Guest]

Hi all,

I have an irritation with my Legacy, that I am unable to put my finger on, yet feel as though I can't possibly be the only one, and hope like hell I'm not imagining the problem.

Some days when I drive my car and put my foot down, there seems to be very little turbo lag, the acceleration is great and I really love driving it. Other days it's so laggy it's as if there is virtually no turbo even installed.

In short, my car feels as though it has good days and bad days. I am wondering if this is a common problem and if there are others out there like me?

Common sense would tell me that MOST mechanical issues / deteriorating parts generally get worse as opposed to getting worse, then better then worse again. So I am inclined to think that the engine management is to blame (or information that's feeding it such as sensors).

I.E if the engine management system perceives there to be a problem (not enough oxygen, airflow) then it could throttle back the power and fuel delivery to ensure the fuel to air ratios stay the same so sensors perhaps?

Pure guesses and speculation that comes from 0 years in the auto mechanical industry, just airing my thoughts.

Would love to know if this problem is common and better yet, if there is a common cause that can be fixed?

Subary Legacy Sedan, 2002 RSK, 5 speed manual.

No mechanical mods, only high flow air filter (green panel filter).

[D-Style]

what rpm does this happin? Does it happen during gearshifts between 4-5Krpm?

If yes, then Welcome to the VOD (valley of death) club.

[Guest]

Most noticeable in second and third gear with the first turbo. On good days there is a little lag which is to be expected but on bad days it's as if the first turbo does not exist and you only really feel it start to pull around 5500 rpm when the second turbo kicks in.

[funkytown]

What location..

Get someone thats driven one before to go for a splash in it.. and or check your codes... and or take it to a knowledgable subbie mech

[Guest boostin]

Could be one of many things. You'll need to get it checked over by someone who knows the twin turbo system.

What area are you in??

[Guest]

I find mine feels pretty flat after sitting in traffic/idling for a while which I put down to heatsoak.

Once you've been rolling again for a minute or two it comes back

[suubyduuby]

 SpotMe said:

I find mine feels pretty flat after sitting in traffic/idling for a while which I put down to heatsoak.

Once you've been rolling again for a minute or two it comes back

Yes, was going to mention this. Yeah, following on from SpotMe....

* Heatsoak: Make sure there are no obstructions in the bonnet scoop, stuff which could affect flow to i/c. Check for bent fins - too many, and the top-mount will loose cooling ability. Also remember: On really hot days esp in stop-start, you will get 'heat soak' in your i/c due to lack of flow. And boy, can aluminium hold heat...that's why it makes an ideal heatsink

* Temperatures: As I'm sure you'll know, temps make a big difference to performance as well. Cold air is more dense and so your car will go a lot harder both due to this and less heatsoak in the i/c. But shouldn't make the monumental difference you desribe though...

* Plugs: How many k's have you done since you had a plug change? Make sure you have the right plugs in there as well - correct heat range. Should be NGK PFR 6Gs for yours - reco'd in the service manual.

* AFM: If the car has ever run a pod or aftermarket filter with an oiled filter elements, chances are this could have damaged your AFM. You can get a ball-park idea if its functioning OK by running a test with a multimeter according to the service manual procedure.

I know what you mean about how the car seems to go through moods, and having my 99 GTB for almost a year and RSK's before that, I know what you mean. But I would never decsribe the fluctuation quite as bad as what you have mentioned...

[webup]

Mine does it

[nickmcgill]

Also check what grade fuel your running.

[gtlegacy]

i get a similar thing as well in my rsb and its more of a first turbo boost thing it will do it sometimes mint and then sometimes wont boost at all or takes about 1 or 2 seconds before it starts to boost again (like something opens or closes or switches) and its away

[GravelBen]

 nickmcgill said:

Also check what grade fuel your running.

Wot 'e said ^^

I find a big difference between 98 and 95 in my GTB E-tune, and 95 is also affected much more by temperature. A big enough difference that if I didn't know what was causing it I'd think something was broken.