Kipper Posted November 30, 2009 Share Posted November 30, 2009 I have a 96' Subaru Impreza Outback. The car randomly started to hesitate when I tried to accelerate. I pulled over at a gas station turned it off and tried to start it again. The car would only maintain an idle for 2 seconds and then the RPMs would slowly lessen the car would stall out. This happend continueously. I eventually had the car towed. My first thoughts were, a bad fuel pump. I didnt think it was a bad spark because the engine would turn over. I before I took the fuel pump apart, I decided to swap out the mass air flow sensor (near the air filter) with my 93 subaru legacy mass air flow sensor (same part number). The car would still not maintain an idle and it had the same symtoms...Then when I was driving my 93 legacy with the other sensor and the same systems were happening. I took the good sensor out of the impreza and put it back into the legacy and the legacy was fine. I think I have a bad sensor, but it doesnt explain why the good sensor did not work in the impreza. Could the impreza have bad wiring harness as well? Maybe the bad wiring harness fried the sensor? Link to comment Share on other sites More sharing options...
Platinum_Racing Posted December 1, 2009 Share Posted December 1, 2009 No check engine lights? If it was by chance the MAF sensor, the problem should follow the part. This doesn't explain why the 93 would run with only the "Good" MAF sensor and not the bad one, or why the 96 would run with neither MAF sensor. Puzzling predicament..... I would check the TPS sensor, just to be on the safe side. Then check for vacuum leaks. Also check the wiring harness to the MAF in the 96. One of the metal tabs on the sensor might have come loose from the plastic plug on the harness. Who knows, one of the metal tabs from the 96 MAF sensor might have broken off and could still be in the plug, which would explain why the 96 won't work with either MAF and the 93 will only work with one. I don't see how the harness could mess up the sensor. The sensor takes voltage and manipulates it into data for the ECU. The harness could short out, causing the sensor to stop working, but it couldn't damage it. The only way you could damage the sensor would be if the internal voltage regulator inside the alternator died, which would probably also mean that the radio, ECU, and every lightbulb that's on would also be fried. Check the little cheap things first, like hoses, plugs, and wires, then if you're completely satisfied that nothing else is wrong start throwing money at it until the problem goes away. That's what I do and it's worked thus far. It hasn't exactly been the cheapest method, but it works. Link to comment Share on other sites More sharing options...
Kipper Posted December 1, 2009 Author Share Posted December 1, 2009 I figured it out. I forgot to reconnect a vacuum line on the Impreza air manifold when I put the "good" MAF sensor on. Miss diagnoses..It was the MAF sensor on the Impreza. Link to comment Share on other sites More sharing options...
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