9-5 Aero Auto MY 2002 (250) poor performance

[paoloboy64]

Hello all

I have an issue with my MY 2002 9-5 Aero Estate Auto (250) and hope that someone can shed some light on the problem.

Since I bought the car around a year ago, the car has run well enough day to day (8000 miles) but when I put the foot down, it just seams to lack proper go. The real test came the other day when I challenged a bog standard, X plate Ford Focus 1.6L off a roundabout on to some dual carriageway. I was almost into 3 figures before I edged ahead of him. I was also 'blown away' by a MY 2003 9-5 Aero saloon a couple of weeks ago which made me think that all was not well with my own.

Gearbox wise, it's smooth up and down the changes, kicks down on demand and sharpens up nicely when in sport mode.

The car has a full Saab main dealer history, has covered 106k miles (though had a new engine and turbo at 65k miles) and in the last few months I've done the following. Fitted new DI and plugs, cleaned the throttle body, new PCV and also dropped and cleaned the sump. I've owned it for a year now and it's been a great car so far. If I had to guess, I'd say it's currently producing around 150bhp - 170bhp.

It struggles to reach the red line and hesitates between 5500rpm and 6000rpm.

Please, please help me find my missing horses.

[Max Headroom]

Welcome to STT Paulo.

I'm sorry to hear of this problem, but I am sure someone will be along, better qualified than me on helping you diagnose the loss of power.

[sgould]

Welcome!

The first thing to look for is the wastegate operating rod.  It runs horizontally across the front of the engine under the heatshield.  You can just see with removing anything, it if you look closely to the left of the heatshield (left as standing in front of the car looking towards the rear).  If the clip on the end has rusted, this rod will fall down and flop about.  The wastegate will fall open and all the exhaust gas that should be operating the turbo will be bypassing it. Rod is shown in this picture of the turbo.  The clip and retaining pin are parts 35 & 36




If it's not that, it could be a split vacuum pipe, a failed non-return valve in the vent systems,a fault in the brake light system that tells the car the brakes are on (ECU cuts the boost then).  But all these are very vague and you can spend a fair bit of money replacing things unnecessarily, if it's not obvious.

You could block off the fuel tank vent system and see if that does anything.  It's done by sticking a bolt into one of the three pipes running from the boost controller on the front of the engine.  The black plastic bit in this picture (can't remember which pipe though - I'll check!):

[wrighar]

You could block off the fuel tank vent system and see if that does anything.  It's done by sticking a bolt into one of the three pipes running from the boost controller on the front of the engine.  The black plastic bit in this picture (can't remember which pipe though - I'll check!):

The top pipe

[sgould]

Thanks!

[TomPaine]

Just to cover the bases - sorry - you mention it had a new engine at 65k. Was it definitely an Aero engine??

[speedy]

Just to cover the bases - sorry - you mention it had a new engine at 65k. Was it definitely an Aero engine??

[nine-fiver]

When was the last time the car had a proper service? Like a 'C or D' service?

Fuel filter, air filter, plugs ... the lot.

Made a real difference to my Linear Wagon. Just did a 2000km trip last week and got better economy and much more power as well.

Too many caravans on the road these days, but they do look good as they shrink in the rear-view mirror...

Try a decent three tanks of proper fuel too. 98RON, with an added cleaner and octane booster. Your injectors may be clagged up.

Failing that, get it off to a workshop and plug the car in and see what the interrogation brings up. Could be interesting.

[paoloboy64]

A big thanks to all who have replied 

The car was serviced around 4000 miles ago. New plugs, filters, sump drop etc. This was perfomed by myself (using all genuine parts) and it represented the first non Saab service since new, lol. I think a trip to my local indy in Glasgow might be on the cards!

Paolo.

[ScarbSaab]

For the cost, I'd try injector cleaner. A mechanic friend who used to be a trucker recommended I put STP injector cleaner in my Aero, said he did it every year on his truck fleet and it made a difference to economy and performance. Tried it a few weeks ago, and was impressed by the results.

[phoenix]

My favourite to start would be a screw blocking off the R pipe. Dead easy and cheap.

FWIW I just had my injectors cleaned on my Aero (just coming on 140k miles). Didn't need to bother. Negligible difference between flow before and after.

[paoloboy64]

Hi phoenix,

Are you talking about the top pipe on the plastic boost control valve? Or, is the R pipe something else?

Cheers

[sgould]

It's the top pipe of the set of three coming from the black plastic valve in the picture I posted above.

[phoenix]

The 3 pipes connected to the valve are:

C compressor- from the turbo
W wastegate- the wastegate actuator
R return- returns diverted pressure to the intake system

The ECU modulates the pressure fed to the wastegate by varying how much is diverted to the R port instead of being applied directly to the wastegate actuator. The problem is that the R pipe is also connected, via one way valves in the EVAP system, to the intake manifold. If those valves fail, then pressure from the intake manifold gets through to the R port, meaning that full pressure is applied to the actuator. The net effect of this is the car only has base boost.