v7 sti boost issue noob

[bams_STI]

As you can tell by the title I\'m a bit of a noob when it comes to turbo cars as this is the first one I\'ve owned and I\'ve had a few issues lately.

Firstly, boost was hitting 1.3bar as far as I knew. Now I have noticed its dropped back to 1bar and will decrease as I rev up. Does anyone know what is happening/may have happened? Is it a boost leak?

Secondly on the weekend I took it for a cruise down country. I was in 4th/5th and when it hit 5000rpm it stopped revving up so I backed off. After this it won\'t boost anymore than 0.5bar until I turn the car off. Then it\'s back to normal.

Does anyone have experience with this? Getting it serviced on Tuesday but was keen to know what to expect. Have looked in other threads but haven\'t found too much. It\'s stock in all aspects as far as I know and is an import. Thanks all

[Kiwi_Fozze]

decreasing boost as you get over about 6k rpm is fairly normal, it\'s a small turbo stock, and runs out of puff at higher rpm, with the stock tune.

1.3 bar is about 18psi, 0.5 bar is 7psi, or wastegate pressure. i\'d imagine your car found an issue with a sensor that dropped it into limp mode. where abouts are you based?

[bams_STI]

Ohh ok interesting. It just seemed strange because it wasn\'t dropping off until a few days ago. Based in howick, east Auckland

[Kiwi_Fozze]

close to me hahaha i could check for fault codes if you like? what fuel do you run on?

[bams_STI]

That\'d be awesome. Im using BP 98 and have been since i got it

[Kiwi_Fozze]

true, true. any mods?

[ben-jamminn]

I used to own a V7 STi with a similar issue - turned out to be airflow meter.

see the thread here http://www.clubsub.org.nz/forum/index.php/topic,32969.90.html

the last few pages are relevant

[bams_STI]

No mods at all. Ok cheers for that

[bams_STI]

I also found out that normally it runs 1.6 bar, not 1.3 - if that makes a difference im not sure

[ADIKT]

 bams_STI said:

I also found out that normally it runs 1.6 bar, not 1.3 - if that makes a difference im not sure

it shouldn\'t be running 1.6bar (23ish psi).

1.3 bar is normal. I would actually expect it to be just under 1.3.

[stiguy]

hey i actually have a similar problem i was hoping someone could help me out with.

so my v8 sti used to boost at 1 bar. now all of a sudden as of about a week ago it wont go past 0.5bar, i dont know what to do anyone can help a brother out here?

ps, im pretty new to all this car stuff

[Rosssub]

;D

 ben-jamminn said:

I used to own a V7 STi with a similar issue - turned out to be airflow meter.

see the thread here http://www.clubsub.org.nz/forum/index.php/topic,32969.90.html

the last few pages are relevant

[boon]

 stiguy said:

hey i actually have a similar problem i was hoping someone could help me out with.

so my v8 sti used to boost at 1 bar. now all of a sudden as of about a week ago it wont go past 0.5bar, i dont know what to do anyone can help a brother out here?

ps, im pretty new to all this car stuff

It\'s in limp mode. Running wastegate pressure. Something will have made the ECU sad so it kicks into this mode - get it checked for stored codes.

Also a v8 STI should be running a bit more than a bar, does it have some sort of aftermarket boost control? Standard on GDBs is about 1.3 bar

[stiguy]

 stiguy said:

It\'s in limp mode. Running wastegate pressure. Something will have made the ECU sad so it kicks into this mode - get it checked for stored codes.

Also a v8 STI should be running a bit more than a bar, does it have some sort of aftermarket boost control? Standard on GDBs is about 1.3 bar

yeah it was running just over a bar, i was just using it as a reference

but hey thanks alot! at least i know what to say when i take into a shop lol

is this quite a common issue? my mates keep giving me a lecture about subis and the afm playing up

no boost controller but i intended on buying one until this problem came up.. anything recommended? i do want to get more power out of my car, just need a helping hand along the way

[Marky]

Don\'t bother

You can get the stock computer re-flashed which also covers the boost you run

[stiguy]

so i took my car for a scan and no faults came up. om gna attempt at cleaning the maf. hopefully that\'ll do it

[Kiwi_Fozze]

Maf can be dead, but still within range so no dtc.

Best option (and safest) is to replace... last thing you want is the car running super lean without the computer realising it.

[ben-jamminn]

 kwi_fozze said:

Maf can be dead, but still within range so no dtc.

Best option (and safest) is to replace... last thing you want is the car running super lean without the computer realising it.

+1

Is there anyone nearby that you can swap AFM\'s with for a test drive before you fork out for a new AFM?

[stiguy]

good news!! i took out the MAF and sprayed it with cleaner. Unplug the batt.

Put it back and drive normally for abit now its back to normal

glad i joined this forum :D:D:D

[bams_STI]

So i got the car back from the mechanics. Unfortunately no fix. They tried a new boost solenoid which apparently didn\'t fix the issue so they didnt replace it. They sealed up some leaks. It runs a little better but have noticed the boost fluctuates. However still boosts to about 1.2 in 1st and 2nd and drops to just below 1bar. 3rd it jumps to 1.5 and then decreases and 5th and 6th it stays solid on 1.5 but doesnt feel like thats what its actually pulling.

Any ideas? I have reset the ECU which didnt have any effect. Thinking I will replace the MAF as that seems to fix alot of other peoples issues. Or just take it to a subaru specialist as it seems to be a bit of a mystery according to the mechanic. However they weren\'t specialised in Subarus or anything.

Cheers, Ben

[Kiwi_Fozze]

Replace maf.

[ben-jamminn]

 kwi_fozze said:

Replace maf.

Replace the MAF

[bams_STI]

The MAF seems to be fine so looks like its an electrical issue

[boon]

 bams_STI said:

The MAF seems to be fine so looks like its an electrical issue

Have you tried another one?

It\'s pretty hard to say a MAF is "fine" just by looking at it.

[stiguy]

at least clean the MAF. i had a similar problem and grabed some cleaner now its running like a breeze