How can u tell if u r maf or boost solenoid is faulty
 

Hi, how can you tell if:

1. your maf sensor is faulty.

2. your boost solenoid is faulty.

wrx sti type uk ppp 2002.

The reason i ask is that the car drives fine and pulls really well in tha lower gears but when i get to the top end of the rev range bout 6k plus in 4th 5th & 6th, it seems to judder & miss a bit sort of holdin back as well,, any ideas would be appriciated.

thanks
shaun..

Are you sure it's not boost cutting? A MAF will show up a fault code on the CEL, I'm not sure about the solenoid. You can clean boost solenoids though :)

soz i forgot to put i have a boost gauge and it reads bout 16-19 psi def doesnt go over 20psi...

Do you know what the fuel cut/boost cut limit is on a ppp?

MAF wont show on your CEL unless its completely fried.

To check if the maf is dying, you need to disconnect it when the car is running - if the car stalls then the maf is fine, if it continues running then its likely to be dying or dead.

However your simpsoms point more to something like a fuel pump/fuel filter. Could be spark plugs too.

if i unplug the maf when its running will it also log it as a fault & alter the cars ecu & dash warning light, or is it ok & wont record n e thing,,,,

il change the fuel filter this week & c if it makes a diff....

the spark plugs were changed bout 5k miles ago...

how do i clean the maf & boost solenoid????

i havnt got a clue wot a ppp sti max boost should be.....


thanks

shaun...

Have you done any mods.

well about 2yrs ago i , put in a k&n panel filter, bov, decat 2nd , but kept the 1st sports cat & replaced the prodive backbox with a larger one.

thanks

shaun.

If you unplug the maf when the car is running it will log it as a fault.
However all you need to do is disconnect the battery for a 5 minutes and put it back on and it will clear your codes.

So
1) start the car and disconnect the maf to see if the car is running or not without it.
2) connect the maf back and start the car ( if it stalled when you disconnected the maf). If it didnt stall then turn the car off, plug the maf back in and start the car.
3) Turn the car off and disconnect the battery for 5 minutes
4) start the car again, all codes should be cleared.

Dont disconnect the maf! You could try cleaning the maf and boost solenoid with carb cleaner and a few cotton buds, just give the element in the maf a gentle clean to remove any contamination. When cleaning the solenoid make sure the pipes are reconnected back to the correct ports. My bet is on the fuel filter needing to be changed but you should also give your air filter a clean or replace it with a less oily make.

P.s- disconnecting the battery does not work on a newage;)

cheers guys,,,i have just bought a new fuel filter & will change it 2nite, & i will also clean the maf & boost solenoid,, fingers crossed....

thanks again

shaun

you can check the maf by using a multi meter to get an idea if its ok. ground the meter and i think its pin 4 on the maf plug cant remeber just find the signal wire. you should get about 1v when the engines running and the voltage rises when you rev the car you will soon so if its a bad one.
adam

rite i fitted a brand new fuel filter, cleaned the maf, cleaned the boost solenoid, blew throu the boost pipes while they were off, just to make sure they werent blockd.....and as i woz checkn for any splits, pipes loose etc,,,i noticed tha the bung for the bov wasnt seated correctly, it lookd as thou it had come out at an angle and im sure i could see a 1-2 mill gap.....so i brought tha car to wrk with me & will b takin it for a run after....

fingers crossed.


shaun

Well i still have the problem,,took the car out 2day for a few hours & it struggled to rev past 6k in tha higher gears.....the boost acording to the gauge is there, but its still sort of, missing,judderin/holding back.....

so just to re-cap,,,,new fuel filter,,,maf cleaned,,,,boost sol cleaned...

any ideas guys????


thanks

change the maf :)

It might not be the maf,as they dont take the engine to be at 6k rpm to start to show a problem ,a faulty maf can show itself at 3 - 4 k rpm.
I had exactly the same symptoms on my old impreza,car ran fine till you got to 6000 rpm,turned out to be the fuel pump,which was a little surprising as i had just fitted a brand new walbro 255 lph and car was not pumping enough fuel at the top end of the rev range.

Yes it does.

Thanx guys,,,,but im still no further to sorting the problem out,,,,,my car starts first time,,,,idles with no misfire,,,when u rev it thru the lower gears it pulls well,,,,

becoz its a sti uk prodrive & its on the log book & i have a ppp cert as well surely it will have had an uprated fuel pump fitted,,,,if it is the pump,,,wot r tha symptons??


thanks

shaun...

Even if it has an uprated fuel pump, it has been pumping fuel to your engine for the last 8 years,and like everything electrical can be prone to failure. The pump I fitted was brand new, fitted correctly, and still failed to deliver at higher rpm
A fuel pump can fail by simply not working,but most people who upgrade there fuel pumps do it not because there existing one has failed, but merely as a precaution as the std pump can get weak over a period of time and simply not deliver the same amount of fuel when increasing the power.

Well its fixed now, could be down to 1 of 3 things i did on the wkend:

1. New ngk sparkplugs.
2. removed the manual boost controller, that was always in the shut position.
3. Cleaned the aftermarket BOV VTA.

Took the car for a run after doin all this on tha wkend, & its back to normal...pheww.......

i have a boost gauge in psi & boost was around 15psi, is that normal for a 2002 wrx sti uk prodrive with ppp????

thanks to all that helpd me with your valuable input..

regards

shaun

Hi, this is a really interesting post as my 04 WRX is showing the same symptoms and is really frustrating me.

Couple of things:

You mentioned you cleaned the aftermarket BOV VTA. What are these exactly??

I have my local specialist looking at it but only once I have the money together for some more mods will get it all done at once when the mapper is present.

Wonder if I can try any of these things before then.

Cheers,

Blow Of Valve - Vent To Atmosphere :)

Glad it got sorted in the end :thumb:

Thanks Spanair, actually only just sorted it today. As I mentioned my cars symptoms were Identical to those you described on yours. You mentioned you changed three things but you dont know which cured it; I can say for sure that it was the plugs for me that cured it if anyone else out there has the same frustrating problem quite a simple fix.

Back to full performance laaaaaavley!!

Thanks again mate - useful thread :thumb: