Matt P

First post on SN and I'd rather it was under happier circumstances!

Run out of ideas now. I've lost boost pressure, no error codes, cleaned out boost solenoids (both ones on the OS front wing), ECU reset, no change. It was on full throttle at 5k rpm when it shut the boost off, had just been on the mway so not a heat soak problem. Engine will still rev but no boost at all. Thought I heard a crackle of det when I joined the mway but never heard any at any other time. No idle hunting or any other strange symptoms.

Car is my99, completely standard. Any ideas?

Delboy2

Do you have a boost gauge fitted, if so is there any swing from negative(vacuum) to postive pressure between 3-4000 rpm?

Cheers

Bob Rawle

ECU has probably shut the boost down due to prolonged knock retard above the preset level, do an ecu reset and it should come back, what fuel was in it ?

bob

Matt P

Delboy, no boost gauge fitted but feeling is that just when the turbo should start to boost the engine performance drops off.

Bob, Have tried the ecu reset using the under-dash connectors but made no difference. Do I try the battery disconnect method? Is a MAF failure the most likely cause of prolonged det (even though I haven't noticed any?) Last time car came back from dealers I noticed that the oil level was slightly higher than normal (to full on the dipstick, usually done 1/2 way), so poss oil contamination?

Matt P

Oh and has run on Optimax since the stuff went on sale. SUL previous to that I believe.

Turbo_Steve

Could just be a blown intercooler hose, or a wastegate could be stuck open. Can you hear the turbo trying to spin?

You really should stick a boost gauge on before you go any further with this.

Bob Rawle

Try disconnecting the battery for about 20 mins, if its still the same then its possible you have a bad connection to the boost contrl solenoid, oil contamination gums them up, this could be a problem but it wouldn't happen overnight. The first thing that normally happens if you do have contamination is overboost not the reverse.

Checking the intercooler to turbo pipe is a good idea as they are prone to falure, also check any other pipework connected to the inlet manifold.

Bob

[Edited by Bob Rawle - 4/20/2003 3:36:53 PM]

silver:scooby

Mat p i had the same with my MY 99 scooby, boost would drop off to 0.5 bar turn off engine go out for a another run and wolud be fine for a while then would drop off, then slowly over time it got worse i had to do ecu reset every 2-3days to get back full boost . While all this was going on subaru had the car for a full day and change loads of sensor and boost solenoid but no joy. so had a look my self and fitted a dawes afr and found that on wot it would not even light up the red led so fitted a new maf sensor and bingo full boost and blue led on wot. It turned out the maf was under reading on boost detting so the ecu was going in limp home mode 0.5 bar to save the engine.

hope this helps


[Edited by silver:scooby - 4/20/2003 3:52:15 PM]

Delboy2

You said that you thought you heard a slight crackle at about 5k. As the car began to boost between 3-4k did the car seem to feel more powerful than normal before crackling? If so this could have been overboost which could have damaged the MAP sensor as it would have taken it out of range. You do need to fit a boost gauge to see what's now occurring.

Cheers

[Edited by Delboy2 - 4/21/2003 12:03:43 AM]

Matt P

Thanks guys

I can't hear the turbo spooling up at all and leaky pipes in the engine bay tend to make quite a racket in my experience (not on the Scooby tho!)

Will fit a boost gauge and try another ECU reset tomorrow and see what gives. The MAF under-read and limp home mode theory sounds most likely to me. Am I correct in thinking that if the MAF sensor was covered in oil (from the sump being overfilled for example) it would underread or not read at all?

Thanks again

dhorwich

Is the car totally standard..??? have you fitted a different air filter..!!??

Dont know if engine oil would be able to reach the MAF sensor, its usually oil from foam air filters that damages it..!

Dan



[Edited by dhorwich - 4/20/2003 7:29:32 PM]