wierd boost problem 9000 aero

[marky]

Hi all,

I have got the following wierd boost problem:

When I fit new spark plugs, the car goes like dream, but after a while (not even 1000km) it will reduce boost back to base boost after 3k rpm

Peak boost is around 1.05 bar, it will then settle down to 0.9-1.0 bar and will then reduce and reduce untill it's at base boost around 3k.

I have made a little video of the gauge in 5th gear:

http://users.pandora.be/saabtuning1/ima ... %20025.avi

Base boost is set at 0.45 bar, wastegate actuater has not fallen off and I already tried three different DI cassettes combined with new spark plugs. Right now, I have no idea anymore

All I know for sure is that when i fit new spark plugs, the car will go like a dream again, but only for a couple of 100km...

[lutte]

my english is not good but i hope that you will understand something atleast. the brakecontact on you'r brakepedal (black lite thing) want's to get tha car on boost base if it sense that you are braking.
and try to test with another magneticvalve(the blake thing to the right on the radiator) but to me it sound like you got a problem with your ignition. what spark plugs do ypu buy? becuse you need some high tech plugs with DI. how di the sparkplugs look after the car go as like a "bag of nuts"

[DrBoost]

Hej !

First of all, do you fit NGK BCPR7-ES-11 ? (gap should be 1.10 mm)
Do you burn fuel of good quality ?
Any signs of deposits on the tip when you remove "the old plugs ?"
When the boost drops down, does the engine still runs smooth on all four cylinders ?
Airfilter OK ?
Exhaust system / catalytic converter = OK ?
Using any fuel additives ?

As session with the Tech2 can tell you if the engine is indicating knock.

Checked fuelpressure over the complete rpm/load range ?

[danielk]

Do you fit the car with good Sparkplugs? To me it seems that the sparkplugs is the problem here?

[marky]

Hi, Thank you for the answers so far.

Some more information:

Spark plugs: NGK BCPR7-ES gapped at 1.0 ( Is there much difference between 1.0 and 1.1?, the book says between 0-9 and 1.1)



Brakecontact: working.

Fuel: 98 unleaded, no fuel additives. Fuel pressure hasn't been checked yet.

When the boost returns to base boost, the engine keeps on running smooth, no fault codes are being triggered.

airfilter: new since 1k

Exhaust system: not leaking, but not sure if the cat is clogged up or not. I have a new JT system which will be installed later this week.

Will try to hook up tech2 later this week, I assume ISAT can be used too to see if it senses knock or not?

Can something internal cause this type of fault? At 230mil it is still on the original chains and I can hear them a bit when the engine is cold.[/img]

[Mackan]

It's a little bit unsharp but is the tip and base of the sparkplug bown/rusty?

[Fredrik.j]

Cheeck the engins cooling system and the oil so it isn´t the water who is the problem.

[marky]

Sorry for the bad picture, it was quite late yesterday and I wanted to go to bed.

Here is a better one:



As for the cooling system, I already flushed it twice and it seems to get black real easely. (no oil) The oil is looking good, no signs of any water.

[DrBoost]

Hej !

Try new plugs and another fuel brand.
Fuel additives may be the root cause.