Jump to content

After replace intercooler AF do i need tune?


Recommended Posts

Hi every one i'm opening another topic wich in it i will explain the all situatuon.

I have FXT 08 old shape,i replaced intercooler to an aftermarket one,than i put a K&N inbox air filter and canceled the noise box.

Changed some vacum lines to silicon and put new 0.8 restrictor pill, (cause the old one i mistakely throw away).

Now my boost is not stable and the mechanic told me after he drove the car that i have knoks abd that's whay the boost is up and down because the ecu lower the boost in order to avoide the knok.

I have to say that when i disconnect the line that goes from the T piece to the BCS the car is very smoothly and fast.when i put a line strate from the boost to the wastgate with out the BCS also the car is ok just the boost is only 6-7 PSI.

Now my quastion is according to what i replaced do i need to tune the car that is why the knoks cause i missing fuel?

I bought new BCS it should arrive soon.

Thanks guys

Sent from my SM-G610F using Tapatalk

Link to comment
Share on other sites

I'm unsure if you can read ecu codes on you model with a Bluetooth OBD connecter and a smart phone but that would be my first point of call (see what codes the ecu is throwing up ).

Are you getting overboost when the boost is unstable ? . Or is it "cutting" the boost ?

What brand / size is the aftermarket intercooler ?

Is it a tmic or fmic ?

Could you try refitting the old tmic to see if it's causing the problem . As it might be a intake air leak or vac line issue .

Link to comment
Share on other sites

I have the obd 2 connector it does not show any code and the cel is off.

I put a tmic intercooler (i will add photos).

The boost is cuting not over boost.it is going down than goes up again ect....leake i dont think so cause i replaced almost all of the vacums line.


Sent from my SM-G610F using Tapatalk

Link to comment
Share on other sites

I'd try refitting the old tmic to see if it's because the aftermarket 1 is causing the problem. Also if it still does it with the old 1 on, then It might be possible that the vac lines weren't put back correctly? .

Otherwise if everything is fitted properly and you haven't got a intake leak (from the y or intake pipework ), I'd say that your mechanic is right and you'll need the bigger tmic mapped in .

Tbh scoobies don't like changes in airflow and can go bang if mods are just "bolted on " and not mapped in.

air fuel ratio is more important on turbocharged cars than it is on a N/A engines due to the amount of air flowing through them .

Link to comment
Share on other sites

After a few days that i have been thinking about all the stuff that i mess with and googling around i start thinking maybe the restrictor pill that i put is not suitable to my car.

I put 0.8mm which this is his part number:22326AA260.

I understood that if i decrease the size of the hole the boost will raise up, so maybe the is to small and the ecu will drop the boost and than it's going up again and the ecu will drop it again.

Some one can tell me what is the size that suit to my car.

It's a 2008 old shape 2.5L XT engine in the license is EJ25 4EAT.


Sent from my SM-G610F using Tapatalk

Link to comment
Share on other sites

A quick call to a subaru main stealer parts department will tell you the right size pill for your model [emoji6]

I tried that for rocker cover gaskets. They flat out refuse to tell you what the part number is or what particular part you need. All about keeping your custom with them [emoji19]

Link to comment
Share on other sites

May be at your country...mine if don't put your car at their garage so they will do the fix they won't let you know nothing , so that's why i try to get the part number and to go just buy from them

Sent from my SM-G610F using Tapatalk

And i ment before 4AT auto trans.[emoji4]

  • Like 1
Link to comment
Share on other sites

Standard restrictor pills are under £5 from subaru main dealers and they will order the correct part when asked over here in the UK .

There's a few opinions on the net as to what the restrictor pill actually does ? .

From what I've learned while fettling my scoobies is that it's to reduce boost spike when the engines under greater loads .

ie uphill in 5th compared to downhill in 1st at the same revs and throttle position , would create different vac line pressure and affect the boost solinoid duty and boost targets met .

Have you tried removing the pill all together ? .

I always get my map "tweeked " after fitting mods but both of my classics ran fine with 3 port solinoids and no pill in situ .

Although before I fitted the avcr, I did used to get a 0.2 bar difference in peak boost between 1 st and 6 th.

Unfortunately I don't know much about the spec of later fozzies ,so all I can suggest is to put a few bits back to standard untill you resolve the issue . Then save up for a remap before bolting on anymore airflow mods.

Although that's only my opinion

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...