Many codes from ECU, hesitates under load

[91leg]

My '91' turbo legacy (180k mi) runs ok until I ask it for some acceleration. When I push on the pedal, it coughs, makes a chirping sound, cuts out, then pulls hard and cuts out some more. All thru a wide rpm range.

 

I checked ECU codes and found:

 

13=Cam position sensor

21=coolant temp sensor or circiut

22=knock sensor

23=air flow meter or circuit

24=air control valve or circuit

 

I tried clearing the codes since there are so many, they won't clear. And when I connect the "self diagnostic" as well as the "read memory" connectors, the cooling fan on the radiator runs (oscillating between two speeds), several relays click and check engine light indicates 60 (when engine is running).

 

I thought maybe the cam position sensor is going bad and possibly generated the 21 thru 24 codes. I went to the parts house and learned that they want $310 for the sensor!

 

That made it worth investigating further.

 

I found that the crank position sensor has ~1800 ohms, the cam sensor has~1200 ohms . . . Does anyone know how much resistance it should have?

 

Is resistance measurement even a valid test for a sensor like that?

 

Does anyone have any touble shooting tips other than flipping out cash for new sensors?

 

Thanks for assistance . . .

[Legacy777]

Checking the resistance is not a valid test. What you need to do is put your multimeter on AC volts. Have someone crank the engine with the starter. Measure the AC voltage across the two pins coming from the cam sensor. The voltage should be at least 0.1 V

 

Try pulling the EGI/TCU fuse (fuse 14) for about 30 minutes, and see if that clears the codes.

 

The coolant temp sensor is pretty cheap $20 or so. I'd recommend replacing it, especially if it's original. Knock sensor isn't too expensive....around $60. You may want to replace that one too. They've updated the knock sensor design because the old one cracks and shorts out.

 

www.subarugenuineparts.com is a good place to get parts, much cheaper then local suby dealers.

[Log1call]

those are strange symtoms and not really interconnected by anything except perhaps a bad connection on a main power or earth wire. Try wriggling all the wires you can find on the motor while it's idling.

[Skip]

I to own a 91 SS with 189k on the clock.

 

She has a list of 6 error codes that will not clear

even after 12 hours of battery disconnect.

 

Many of the same codes you have seen.

 

the difference and why I am typing this is.....

she runs like a jewel, pulls very well thank you

no sputtering or coughing

 

She just passed PA emissions with typical Subaru flying colors.

 

Your problem could be as simple as the basics.

I would start with the fuel filter

Maybe the coil pack/wires.

 

 

I present C-dan

[Chef]

Your problem could be as simple as the basics.

I would start with the fuel filter

Maybe the coil pack/wires.

I present C-dan

 

I second this notion. Plugged fuel filter are a very common cause of this kind of problem.

[color-blind]

You really need to find a way to get the codes to clear. I normally use my oe scanner, try disconnecting the battery for a time. Cam and crank sensors of your vintage Subaru rarely fail. Knock sensors, coolant sensors, and air mass meters are common though. You also may have a problem with the main relay. Yet I need to know what codes come back. You also could try dis-connecting the ecu; that also may help clear the codes. Chances are you have both a failing temp sensor and a failing knock sensor. The air mass meter is the expensive one. Good luck. If you get the codes to clear, be sure to post which codes come back.