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Discussion Starter · #1 ·
just bought a 95 9000 CSE Turbo, ran and drove perfect when i picked it up, drove it 25 miles back home, no problems, now it starts and idles fine but wont rev past 2500, i can drive it but when it hits 2500-3000 rpm it starts bucking wildly, it feels like its hitting a rev limiter, i check under the hood and found a few old vaccume lines dry rotted and the intake tube to the turbo was half off, so i replaced the lines and tube, and the battery(i knew it was bad already) and its still doing it, im not getting any check engine light, or TCS light but i am getting a check radiator light, and i noticed that a plug on the left side or the radiator that has two electrical connection is not hooked up, but i cant find the wires for it, could this be the problem? i believe its a coolant temp sensor, Please HELP
 

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Try a new airfilter and spark plugs (only NGK's). If that doesn't work try another DI.

Could also be overboosting, what is your boost gauge doing? Should not enter far ito the red. In case of overboosting, check hoses around APC valve/wastegate actuator. If those are ok, connect the W directly to the C and plug off the R. Now it runs on base boost only, if it now runs ok but with limited power your apc valve is shot.

95 model does not have sensors in the radiator, looks like your radiator was replaced somehow with a second hand one from an older model.
 

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How do you know the boost pressure is right? Did you measure it accurately?

The symptons you describe are exactly what happens if the ecu detects too much boost: fuelcut, which feels a bit like hitting a brick wall :cheesy:
If you don't have the right equipment to measure the boost pressure, try bypassing the APC valve as I described and see what happens

Afaik the 9000 trionic does not have a limp home mode that will limit rpm to 2500.
 

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Discussion Starter · #6 ·
replaced APC Valve, no luck, let it sit over night it ran great till it got warmed up, the it starts cutting out and bucking, and almost sound like a backfire, i dont know anyone wanna buy it 1500 CASH
 

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If it isn't overboosting there's a good chance the DI is on it's way out. Try to get hold of another DI cartridge from another Saab and bolt that on, is a 1 minute job. If you can't find a red one even a black one from a T7 model will do for testing.

If the car has TCS, it could be the TCS system is faulty. But if I remember well that system was discontinued in '93 so a 95 model should not have it.

Will it do so under full throttle only or also when you press the accelerator just slightly?

Don't ever sell your 9000, you will regret it :cheesy:
 

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Discussion Starter · #8 ·
it does it under full throttel and soft throttle, but it will rev just a little bit higher if i smash it, it will rev between 2500-3000 and sounds like its bounceing off a rev limiter, them it will POP like a back fire, but if i drive it it will only do it under hard acceleration
 

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Is the rev counter dropping when it happens? If so, could still be the TDC sensor, if not almost for sure the DI is dying. Try another one. If that solves the problem, put in four new NGK's and a good DI and be a very happy man ;)
 

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Discussion Starter · #10 ·
Whats a TDC Sensor, and itoday i pulled off the DI and took out the plugs and cleaned them, cleaned the DI to plug connections and it ran better and longer than it has yet, and yes the revs go to about 2500-3000 and drop to about 1500-2000 just like a rev limiter.
 

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If some cylinders aren't firing due to bad DI, then raw fuel is going into the exhaust system and and igniting, hence the backfire. It's a bad ignition cassette imo. Intermittent or weak spark always cause these symptoms. They idle away fairly happily until you open the throttle.
 

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I remember my 9-5 has done similar thing, after DI cassette has died and unburned fuel got dumped into catalytic converter and fried it.
 

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95 CSE with same problem

My 95 CSE turbo runs beautifully when cold. When warmed up, it runs great to 2500 rpm. It then stutters and cuts out. Put in new NGK BCPR 6es plugs, new (used) DI box and new (used) APC solenoid last night. Still does it. Any suggestions??
 

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Digging up an old thread that needs a solution!

I have a Saab 1994 9000 CSE N/A here in the shop with the same problem. Normally I send the Saabs away but the guy was desperate and needed his car right away.

The car would not start at all and I determined the problem to be the DI Module. I put a new DI module and the car started right up. The car left the shop in less than an hour running perfect.

Two days later it came back and the vehicle will not rev over 2500 RPMs. It is EXCATLY as if someone set a rev limiter at 2500. I've seen several posts about this problem but no one seems to have a solution. I installed another DI module and the same thing happens. The vehicle runs PERFECT with no operational problems at all till it hits 2500.

Someone above suggested the TDC Sensor (I assume this to be the crank sensor). I can't imagine how the TDC sensor could cause this. It seems to me that it would not run at all if it was the TDC sensor.

Help! This Diesel Truck Mechanic should not work on Saab. Ugh... What was I thinking.....
 

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My son recently was experiencing a limited RPM issue (I don't recall if it was 2500 or not but that sounds right) but could still start.

Conventional wisdom suggests that a faulty CPS prevents starting altogether but I took a chance and pulled it. Resistance readings on the bench were exactly according to spec.

I was bummed that the CPS was good and would have to look elsewhere. But, since I had already purchased a replacement sensor, I installed it anway.

To my surprise, the problem disappeared with the installation of the new sensor. Been running fine for about 6 months now.

I think the answer lies within the following:




The ECM receives information on the position and speed of the crankshaft from the crankshaft position sensor on pin 41.

A perforated ring with 58 ribs is mounted on the crankshaft. The sensor is of the inductive type and is mounted in the crankcase wall of the engine. The distance between the sensor and the perforated ring is within the range 0.4-1.3 mm and is not adjustable. The sensor acts as a generator and produces a sinusoidal alternating current. By measuring the frequency, the engine control module can determine the speed at which the engine rotates (rpm). After the 58th rib is a gap corresponding to 2 ribs. When rib No. 1 subsequently passes the sensor, the engine control module knows that the crankshaft is 117°before top dead centre (BTDC).

The voltage from the crankshaft position sensor varies with engine speed. During idling the voltage is 7-10 V (AC) and at 2500 rpm it is approx. 15-20 V (AC). However, it is the frequency and not the voltage which is of interest to the ECM.
The ECM chiefly uses engine speed and crankshaft position to calculate ignition timing, fuel injection timing, fuel injection duration and boost pressure as well as for idle speed control.

Fuel injection is cut off when engine speed exceeds 6200 rpm.
As soon as the ECM receives pulses from the crankshaft position sensor, it grounds the main and fuel pump relays.
If the sensor fails to work or if there is a break in the circuit, the engine will not start.
The sensor's resistance is 540±55 ohms .

Engine Speed Signal
The ECM emits an engine speed signal from pin 58.
The signal is a pulse train which varies between 0 and B+. Its frequency is about 30 Hz at idling speed and about 85 Hz at 2,500 rpm. This corresponds to 2 pulses per crankshaft revolution.
The engine speed signal is used by the tachometer.

And by the way, his problem was intermittent just like yours. Several sensors were exchanged and some iffy wiring was renewed. Some repairs did temporarily seem to remedy the issue. But they would only last until the engine was up to temp and being driven slowly (or sitting in traffic). Highway speeds and a cold engine seemed to keep the problem at bay. The CPS was the real repair.
 

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Today I will replace the Crank Sensor and see what happens. I talked to jrs58 over the weekend who was nice enough to message me back right away. He told me he replace either the crank or cam sensor and it fixed the problem (he could not remember which one).

Will post results as soon as I get it done. Thanks you for the explanation chengny. That makes sense.

Thank you, thank you, thank you all!! I hope it fixes the car.
 

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I think SAAB uses the crank position sensor. Other manufacturers have fitted a Hall effect sensor on an intake cam to perform the same function.
 
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