Not boosting right..... AGAIN!!!

[Scruff]

Heres my pickle, bear with me:

Every now and then (say once every five or six weeks) my car decides not to boost properly. Rather than peaking at 12ish, it goes up to about 8.5 to 9. When this has happened in the past its been a case of taking off the air filter and Maf and giving it a little clean with some carb cleaner and a cotton bud, then also doing having the pipes off the boost solenoid and cleaning that out too. Reconnect all hoses, put back filter and maf. Since then i have found that just cleaning out the solenoid seems to do the trick. In the past this has always fixed it and its been ok for a few more weeks.

Yesterday however, i was driving to work and the boost didn't reach the norm so at lunch i did the usual and cleaned the bits out. On the drive home it still wasn't boosting properly so had it all apart and did the same again when i got home and left the car til this morning.

Started on my way to work today, waited for it all to warm up, floored it, lo and behold... not boosting Stopped off on my way to work just to have a look for any little air leaks/horrible noises etc. Didn't find anything. Seeing that i was getting fairly irritated by this stage i floored it out of the services and rather (unexpectedly) it boosted really well.... but i hadn't touched anything!!! Apart from the throttle assembly which i'd poked at and don't really understand, why are there two separate little levers? Is one for the throttle then the other for the turbo?

Anyway, i need some things that i can try next time it happens. Being that i thought it was the solenoid causing the problems i'm getting another in the week (not costing me much) so i'll be able to rule that out of the equation.

Thoughts please


*Oh yeh, for info, its a 96 WRX

[Scott.T]

MAF is on it's way out.
if it starts to read lean the ECU puts it into limp mode without giving any dash light warnings.

due to a dirty or part failed MAF this will cuase it to run about 7-8psi.

cleaning the maf may fix it but if it keeps dropping in and out then theres a good chance it needs replacing.

[Scruff]

Ok, quick update. Changed the solenoid and all was ok for a few days as the car was behaving at the time anyway. Then yesterday on my way home i was only achieving 8psi. Have borrowed a maf from Partmaster (cheers Dave) but still no difference. However, on my way to work this evening, making my way down the 23. Tried putting my foot down a couple of times and no change. Tried it once more a few minutes later and the boost gradually crept up to full power. Then got to work, put my MAF back in and took a quick blast up the road and its still behaving itself so i guess the maf isn't the issue???

This makes me think that either a pipe is clogging up then gradually blowing through, or something is sticking open/shut and after a bit of persuasion (my right foot on the happy pedal) it lets go and does what its meant to.

Please, ideas anyone? Was thinking maybe actuator related... any way i can test this? Or is there any diagnostic tool that can be plugged into the car? I'll give anything a go once

[Scott.T]

pull the bottom hose off the boost control solenoid (the one that retuns to the air intake with the restrictor in it) and see what that does
http://www.polarperformance.co.uk/boostsolenoid.html

[majorscooby]

mmmmm actuator? worth a try to get hold of a second hand one, which i would expect not to be to easy though fella! my actuator arm mysteriously jumped of from the turbo over night (and i aint joking) giving me no boost the next morn. scott found the problem, poxy E clip had come off.

[Scruff]

Originally Posted by SilverSurfer

pull the bottom hose off the boost control solenoid (the one that retuns to the air intake with the restrictor in it) and see what that does
http://www.polarperformance.co.uk/boostsolenoid.html

I'd best tie myself in so i don't end up putting my face through the windscreen. The problem is that its not making enough boost though, not too much but i'll give it a go. I have a spare set of hoses for that so maybe i can swap them all over anyway. One might be gunked up? Problem is that the cars behaving itself at the moment so i really need to wait until it goes wrong again.

I'll have a look for an actuator too. Could that be a cause? I don't know exactly what the actuator does but as i understand, it pulls a little arm and makes boost get bigger. Could the little arm be seized?

[majorscooby]

Originally Posted by Scruff

I'd best tie myself in so i don't end up putting my face through the windscreen. The problem is that its not making enough boost though, not too much but i'll give it a go. I have a spare set of hoses for that so maybe i can swap them all over anyway. One might be gunked up? Problem is that the cars behaving itself at the moment so i really need to wait until it goes wrong again.

I'll have a look for an actuator too. Could that be a cause? I don't know exactly what the actuator does but as i understand, it pulls a little arm and makes boost get bigger. Could the little arm be seized?

I know as much about the actuator as you fella but i think your pretty much right, could just be sticking some how but i dont know whats in side them to stick or clog up but they do get bloody hot!!