club.liberty.asn.au

Hey guys,

Anyone know why a B4 will limit boost to about 0.5 bar? Valley of death is still there, boost drops to 0.3 and secondary turbo boosts back to about 0.5 bar.

I parked the car, turned it off and its boosting normal again. It seems like the ecu is limiting boost for some reason? But why does an engine restart fix it?

It happened once a month ago and occured again this morning. Other than that, the car drives fine. I havent done anything unusual. Petrol is 98 Ron 1/4 tank atm. All engines fluids are good. No CELs. Car is stock apart from a hurricane? cat back.
Apparently the previous owner replaced the o2 sensor already last year.

Cheers guys.

have you checked the codes? the ecu is probably doing it for a reason.
or the boost controller solenoid is stuck. bud if a reset fixes it id say its more likely ecu related

Check the codes, they will log a code without showing the CEL.

But you should get familiar with the insides of the BBoD, all the vacuum lines, and a can of Upper Engine Cleaner.

Thanks. Definitely getting a can of UEC soon for the 180,000km service. It was last done at 170,000km. Well I hope so.

I'll try checking for codes tomorrow.

Hey guys. No codes. Cel light just flashes rapidly once I connected the black plugs above the clutch pedal.

So what could possibly cause half boost until I turn the engine off and on again?

ECU going into limp mode from it pinging it's head off on the dogsh!t factory tune
or the ECV is stuck open,
Or the secondary BOV won't close porperly
or the ICV is stuck open,
or any of the solenoids are full of junk.

Plug in the other set of plugs (white ones) and then start the car and let it run.
that'll force the ECU to do a full diagnostic check of all the solenoids, valves, etc and report back fault codes

Actually I started my car again after the problem occured. Boost was still limited to 0.5 bar.

However I drove the car after work tonight. Boost was normal again. Hitting almost 1.1 bar in 3rd gear.

The times the boost problems occurred, I wasn't doing any hard driving. Just cruising along the highway, stopping here and there for red lights. I've never had the engine ping since I bought it 5000km ago.. I don't know what pinging sounds like but maybe tapping a glass cup rapidly with a spoon?
It's not like I do hard acceleration for 5 traffic lights non stop.

So the problem is random I've found...

Thanks for the advice. Someone else told me to clean the boost solenoid and have a look around the black box.

Good chance it is the butterfly in the secondary turbo starting to seize,try driving a bit harder as this may get the rust out of the pipe.
Cheers Eddie

Had the same problem for ages, was very frustrating. After replacing the MAF sensor the issue was completely fixed. Turned out the engine was running lean, so ecu was constantly pulling timing and intermittently running in limp mode.

Thanks for the tip guys.

Did an oil change and upper engine clean recently. Ive driven the car hard here and there...it happened again tonight. Last time was a week ago.

I was boosting close to 14 psi and boost suddenly dropped. I wasnt at 4000rpm yet or VoD...

I kept flooring the throttle in 4th gear but every time boost would get to 0.5 on the gauge and stay there. Im sure it'll be fine tomorrow...

The only other thing I did a while ago was clean the maf sensor on the intake. Maybe it made a slight difference in fuel economy but thats it.

Ive never tried to take apart the black box. Any tips?

do it one small piece at a time
remove, clean, re-fit.
then move onto the next bit.

until you get familiar with where all the hoses go

you want to clean the solenoids themselves in both the inlets and outlets as well as the vent caps on top of them.

Also flick it into diagnostic mode with the engine running and it will cycle all the solenoids allowing you to hear/ feel any that aren't opening/ closing.
you should hear the duty solenoids tapping away consistently

Finally got around to recording the boost problem.



http://www.youtube.com/watch?v=JSLUeFjWN2s

can you please put the thing into diagnostic mode as advised before
plug in white diag plugs, start car and let it idle and cycle the fans, solenoiods, etc

Yes. I already plugged the green test connectors, turned ignition to ON and left everything to cycle for up to 5 minutes. To be honest, I don't know when a solenoid is not working or not working as it should. Something or a few things are making tapping/hissing noises from the BBOD.

But I haven't started the engine with the green plugs connected.

The black test connectors were connected, key turned to ON and I get a cel code of 1 long and 5 short.