GW2000

I'm currently having a possible overboost problem when I change from 2nd to 3rd at high revs (5000+). The car seems to engine brake for a brief moment and then carries on as normal, this is obviously slowing the car down. However more importantly I'm also wondering if I am doing any damage to the engine itself.

After reading some of the threads however, overboosting appears to happen when you are increasing your revs in one gear rather than changing up to a higher gear.

I'm wondering if it's even my poor clutch control and whether I should be feathering in the clutch or just drop it straight in. I rarely have the revs up that high but it has been doing this for some time. This is my first Turbo (previous sport owner), but I have had previous plays in Turbos with no problems like this...

MY00 Turbo 13K miles

Advice would be most appreciative or even driving lessons

Ian

NM

Hi Ian

From your description it doesnt sound like overboost. I suffered from loads of overboost soon after I purchased a MY98 5 months ago. It generally happened when accelerating between 3500 to 4500 revs 'IN' most gears (not changing). The cause was excessive oil in the engine, after draining some out and cleaning the relevent pipes it hasnt missed a beat.

As yours is a MY00 I should take it back to the dealer as it should be within the Subaru 3yr warranty.

Cheers

Neal

DaveMcC

Ian

I also get this sympton on MY00 - I also thought it was my driving at first - but drove another MY00 and it was fine. The engine appears to cut momentarily after the clutch is released in 3rd gear. Mine only does it if you hold 2nd gear past 6000 revs. Even then I can avoid it by pressing the throttle more slowly after releasing clutch - ie not instantly flooring it again. However, it clearly shouldn't do it.

Dealer was asked to look at it, but they couldn't repeat the fault, so I'm going to take the service manager out and show him what it's doing when I get time.

Would be grateful for any suggestions as to what's causing this.

Oh, the other MY00 I drove had the PPP fitted (which is why I drove it). Boy - what a difference!


Dave

GW2000

Richard,

Not sure about that. I will see if I can get it looked at in the next service.

Ian

DaveMcC

Apparently my "purge valve" was cleaned at the intermediate service to try to cure this - is a purge valve the same as the boost control solenoid??

Also, which is the boost control solenoid - I can see 2 things on the o/s inner wing both connected to the inlet manifold by rubber tubing. What should I use to clean out the excess oil.

How much overfilled does oil need to be to cause this problem - mine is ~5mm above the max mark on dipstick after last service.

Cheers

Dave

dowser

If it's oil gunking up the boost control solenoid and associated pipework, it *is* overboost

Common problem when there's slightly too much oil in the car.

Take off the solenoid and pipes, clean and refit. A good trick for cleaning the solenoid is to remove pipes, turn upside down (with a rag underneath) and join just the green under-dash connectors. This sends all the under-bonnet electrics into mad-cow mode, with each cycling in turn. Squirt your cleaner into ther solenoid while it's pulsing - job done.

Oh, keep your hands away from the fans

Richard

GW2000

Thanks for the quick response.

Neal: I think you are right about it not being an overboost issue, after reading more of the threads I'm convinced it's not that. I had the pipes cleaned out during an intermediate service I had at 10K, it turned out that the garage I bought it from overfilled the oil during the 6 months service. However this problem was still there.

Dave, Sorry to here that you are having similar issues, but I'm also glad it's not me. However I'd be interested to here what the service manager has to say after you show him the problem. I need to take mine back at some point for its 15K service, so I will get them to look at it them.

Would not say no for a drive of a PPP myself

Ian

dowser

Unless the solenoid was cleaned/replaced at the same time as the pipes were cleaned at service, it's still likely to be the issue....imho

Richard

dowser

The boost control solenoid bleeds away air from the wastegate, allowing boost above the limp home 7psi you'll get if the solenoid doesn't function - depending on car it'll be two port or three port. my99/00 Euro cars are two port.

If you follow the tubing from the wastegate you'll come to a T piece - one junction leads to the solenoid.

As mentioned above, if you just join the green under dash connectors together and turn on ignition you'll be in test mode. This nicely operates the solenoid for you - just squirt in some carb cleaner and let it flush through. Clean all the pipework too.

As for how much oil - don't really know. 5mm over sounds way too much though - check you're reading the level correctly and then remove some oil before cleaning everything.

Richard

DaveMcC

Ian

Took the service manager out in the car today - it played up beautifully! Said it was definitely an overboost and may be caused by a faulty purge valve, so they're ordering a replacement which they'll fit (under warranty). If that doesn't work, they're going to change the size of the restrictor - apparently this doesn't affect the ultimate boost level, just smoothes out the initial spike which is what may be triggering the overboost.

Hope this is helpful - I'll let you know what the final outcome is.

Dave

GW2000

Appologies for not replying sooner as I've just spent a hectic 2 days trying to get out of Israel. Now back in the UK only to discover that my car was being an ar$e to start this morning - getting cheesed off .

Dave, good to hear they have recognised the problem. I would really like to know what the outcome is. Personally I just need to know what is under the bonnet - purge valves, solenoids etc.

Thanks again for everyones responses

Ian

cdg

Try to do the test connecting the jackets under the direction wheel!