96 Saab 900 2.0 turbo 5 speed blow head gasket car died I repeat head gasket now it wont start. It cranks over then back fires one time it sounds like a pop

SOURCE: saab 9000 cse turbo

Hi Steve,
I had a similar problem on a full pressure SAAB 9000. With me it only happened under hard acceleration, and it was caused by the Waste Gate Controller being sticky and over-boosting the engine to the point where the overpressure switch came into play - this cuts out the engine till the pressure drops to a safe level again - hence the sudden loss of power. On the full pressure turbo's you get a boost gauge so you can see it happening, but I don't think the LPT's have one fitted - so its probably a garage job - otherwise Saab9000.com will show you how to test it yourself.

Regards

Hugh

SOURCE: SAAB 900 '96.

It may not be the wipers. If a manual, the reverse light switch is on the same circuit. These switches can fail and create a dead short to ground. To test, put in a new fuse with the car off and in neutral. Start the car and turn on the wipers. If they work, shift into reverse and see if the wipers stop. If they do, you need to replace the switch which is very accessibly located on the top of the transmission bell housing beneath the main fuse box. The fuse box can be moved aside by removing the nut between it and the fender, and prying the clip up that is on the drip rail lip beneath the weather stripping that runs under the back edge of the hood. Once you have moved the fuse box out of the way, you can see the little switch sitting on top of the tran bell housing. Unplug the connector and use a 13mm (if I remember correctly) open wrench to remove it and replace with a new one.

SOURCE: APC Solenoid Valve Knocking

The APC valve regulates boost pressure (via the wastegate) to avoid over-pressurising the engine. It ensures that a safe boost pressure isn't exceeded. Don't run with it disconnected or you risk blowing the engine!

Problem areas can include: knock sensor on the engine block (also poor quality fuel, dirty engine causing knock); engine ECU.

You need to provide more information about when this happens:

hard accelerating? (likely poor quality fuel, dirty plugs/engine causing knock) and general driving similar.

idling? possibly a knock sensor or ECU related problem

What rpm? what boost gauge pressure?

as an outside chance, maybe a sticky wastegate

Saabreur

SOURCE: rough idle on 1990 saab 900 convertible, 16V

Because the car has adaptive technology, it may take a while to reset and adjust to the new, cleaner and better conditions than those to which it had previously adapted.

Did you change the cap and rotor? if the plugs needed replacement, likely they do too

Possible other causes include:

loose or corroded connections to any electrical component you disturbed (make a checklist and tick them all off as you check them);

mis-reinstallation of any F.I. part disturbed(checklist again)

obstructed water flow through the AIC valve;

improper voltage output from the AIC valve (for LH 2.4 systems, should output 8 volt at idle, dropping as load increases; for LH 2.4.2 system output 7 volt at idle etc; testing between terminals)33 and 17 at disconnected LH connector;

possible problem with MAF.

Hope this helps

Saabreur

SOURCE: 1995 saab 900 turbo

Two most common problems for this are the DIC and the fuel pump. Can also be the CPS. First check the code. You can try this first before going to a code reader: 1.With the car already off, switch on the ignition without starting the engine. 2. After approx. 6 seconds, the 'Check Engine' light goes out for an instant before lighting up again for 3 seconds. This 3 second flash is a warning that the actual flashing code is about to start. 3. The flashing code consists of a number of short flashes lasting 0.4 seconds. The 'Check Engine' light goes out for 2 seconds between each new flashing code (if there is more than one fault). 4. After the last flashing code, the 'Check Engine' light goes out for 3 seconds before lighting up again for 3 seconds, after which the flashing codes are repeated. Readout continues in this way as many times as you wish. Number of flashes / Function 2 / Manifold absolute pressure sensor 3 / Temperature sensor, manifold 4 / Temperature sensor, coolant 5 / Throttle position sensor 6 / Oxygen sensor 7 / Adaptation 8 / Purge valve (EVAP valve) 9 / ECM, internal fault If no flashing codes display, the problem is something else (other than those nine listed above) and must be determined using a generic code reader that supports OBD 1, or using the GM/Saab Tech II code reader and programmer. My money is on the DIC as it is a very common failure component and fuel pump failures rarely throw a code. The DICs are good generally to 100,000 to 150,000 miles, but this varies wildly, especially if the car is run with overgapped plugs for any length of time. The plug gap should be 1 mm and no more. Cars that are scrupulously maintained vis-a-vis the plug gapping can see DICs last over 200,000 miles.