cause & result..

 

Idle low at Stop

If your car is starting and driving fine, but will idle very low at stops check for vaccum leaks.

Make sure to check all vaccum hoses. Repair or replace any leaks or damages.

Intake System & How it works

The intake system is composed of an air filter, mass air flow sensor, connecting pipes/hoses,

turbo unit and intercooler. The system is connected to the throttle body on the intake manifold.

The air filter, which is located on the right-hand side of the engine bay, removes particles

from the incoming air and also acts as an intake silencer. The mass air flow sensor

provides the engine control module with continuous information on the amount of air consumed

by the engine. The mass air flow sensor signals are processed by the control module,

which monitors the air-fuel mixture of the incoming air.

Low RMP or Power During Acceleration

If you can push the accelerator to the floor and the car barely moves until the RPMs get up

and the turbo kicks in, then check the spark plugs and throttle body.

Turbo Apc Boost Control Valve Failures

APC boost pressure control valve failures make themselves evident by causing the car

to boost excessively which causes bucking in the system by cutting the fuel pump off

when the boost exceeds a pre-determined safe level. Replacement of the valve is the only cure.

 

TURBO BOOST BUCKING PROBLEM

[95, 93 98-03, 93 03-07, 9000, 900 94-98]

 Thanks to Joe Truckenbrod for contributing to this FAQ!

I had a boost problem with my car and had no idea where the problem was coming from.

It would boost then bog down, boost then bog down and so on and so forth. Very hesitant

on hard acceleration. It also would only boost from mid yellow to 3/4 yellow max.

I thought fuel cut off was kicking in because thats all I was able to find on my searches.

Took it to a saab shop and they determined it was my air mass meter. Replaced it and an

wow what a difference. Keep in mind that we have not seen the airmass meter cause

this problem often but we have heard of it happening in some cases. What happens is

that the filament in the meter is failing which indirectly causes readings to the ecm to be

 incorrect.

Another very common problem is the Boost Solenoid (APC Solenoid) failure. When this

component fails the Turbo will overboost causing the fuel the pump to cutout.

Turbo Bucks When Accelerating Into Boost

Bucking on hard acceleration into boost is most often caused by a faulty APC

solenoid/Boost Solenoid. The solenoid is located on the top driver side of the engine

 radiator on most Saabs. When the solenoid fails it will allow excessive boost

pressure which then leads to the over boost circuit being completed shutting

the fuel pump off. The 9000 has a over boost switch which is designed to shut off the

 fuel pump in the event of excessive boost pressure as a safety measure to prevent

the engine from blowing up during boost failures.

Note: In most cases Excessive boost problems come from Turbo hose vacuum leaks

or faulty Wastegates (not common though)

Turbo Bypass Valve Testing for Failures

One can test the bypass valve to see if it is faulty by removing the vacuum hose from

the intake manifold and applying suction to the hose. If the valve is faulty the suction

applied will not hold creating a vacuum leak. A leaking bypass valve will often cause

the car to stall when coming to a stop!

Turbo Drops Pressure While Accelerating

If your turbo is dropping pressure while you are accelerating check the blow off valve

and waste gate. Replace as needed. If both of those are ok or you replaced them and

the problem persists, check the turbo propeller to see if it is worn or loose.

Replace if needed.

Turbo Whistle During Acceleration

Turbocharger whistling is often caused by excessive bearing wear. What generally

happens is that the center section bearings tend to wear allowing the impellers to

rub against the compressor housing of the Turbocharger causing a whistling during

acceleration. This is not to say that all Turbochargers that whistle need to be replaced.

 Some Turbochargers whistle for years without failure. Frequent oil changes will help

prevent Turbocharger failure!

Vacuum Hose

Not all Saabs use small vacuum hoses all over the engine but on the cars that do the

hose diameter is usually 5/32. It is silicone hose that can be purchased at any

autoparts store. The reason we do not sell it on the site is because the hose is

usually sold in 100 ft rolls. Most customers would not want to buy that much hose.

Keep in mind that there are different grade hose and the fuel grade hose is what is

recommended.