toasterblt Posted September 7, 2011 Share Posted September 7, 2011 Hey everyone, new to posting on this board, but have been a reader for a while. So heres the deal: I have a 95 impreza outback 1.8 liter automatic. My car started throwing a tcu code referencing a TPS sensor. This made sense as the car was exhibiting symptoms of a bad TPS that I have read on numerous board posts. Well to make a long story short, I got 2 TPS sensors from a junk yard (bench tested working), and installed one. I put it within spec voltage wise, reading from the ecu. The car drove fine for the first day, exhibiting none of the former problems. But after the first day, it kept having symptoms of a bad TPS. I installed the other one, again putting it in spec, and same thing happened. Drove GREAT for the first day, then after that, its like i didnt change out the TPS at all. Other info: ATF fluid, oil, and air filter have been changed. MAF has been cleaned. Also, when I pull the "current" code from the tcu, it comes up with nothing. Its only when I pull the "past" codes that it shows TPS sensor malfunction. Also, before I replaced the first TPS, I pulled the past codes and along with the TPS code, it came up with "engine revolution sensor". What is this? Is this the Crank sensor? Is this my problem now? Any info is greatly appreciated. Thanks Link to comment Share on other sites More sharing options...
toasterblt Posted September 10, 2011 Author Share Posted September 10, 2011 BUMP Anyone have an answer? Am i posting in the wrong forum or something? Any help is appreciated Thanks Link to comment Share on other sites More sharing options...
92_rugby_subie Posted September 10, 2011 Share Posted September 10, 2011 Youre in the right forum, some of our experts just may not have seen it... Link to comment Share on other sites More sharing options...
lewisd Posted September 10, 2011 Share Posted September 10, 2011 Engine revolution sensor is the crank sensor. I thought if that didn't work right the engine would barely run, could be wrong. I'm not an expert by any means but is the code consistently the same? I chased codes saying TPS, knock sensor, o2 sensors.... and I don't have a MAF with my 99 legacy. I did seafoam treatment and replaced lots of old rubber emissions hoses, pcv valve and it helped run smoother. I think I had pin hole puncture in aged rubber that raised havoc with the engines computer. I was experiencing the mystery throttle stumble...like engine would cut out and then wake up and kick back on... I had around 225,000 miles at the time. now at 254,000. Link to comment Share on other sites More sharing options...
toasterblt Posted September 11, 2011 Author Share Posted September 11, 2011 Thanks lewisd and 92 rugby subie for the replies. Put a new battery and terminals on the car last night and it seemed to drive much much smoother. I also dumped some fuel injector cleaner in the car, that may have helped as well. I plan on replacing all the vacuum hoses. Mine are really old looking. When I get time Im gonna probably take the throttle body off and inspect it. maybe its gunked up in there? Link to comment Share on other sites More sharing options...
Fairtax4me Posted September 11, 2011 Share Posted September 11, 2011 I don't get it. You're reading TCU Transmission Control Unit codes or ECU Engine Control Unit codes? What are the numbers for the codes you are pulling? Is the check engine light on? Link to comment Share on other sites More sharing options...
toasterblt Posted September 12, 2011 Author Share Posted September 12, 2011 Reading the Transmission control codes. The check engine light is NOT on. My 95 has the "Power" light and when i start the car it blinks. When I pull the code, it is code 31, which indicates a throttle position sensor. When installing a new TPS, the part needs to be put in spec voltage wise and I take these readings from the ECU with my multimeter. Link to comment Share on other sites More sharing options...
Fairtax4me Posted September 12, 2011 Share Posted September 12, 2011 Since the code keeps returning I would check wiring connections. Somehow the signal gets from the ECU to the TCU. Check the wiring at the TCU connector, be sure all the pins are clean and make sure none of the wires are knicked. Have you done a full range sweep of the TPS to make sure there are not "flat" spots in the signal? Link to comment Share on other sites More sharing options...
toasterblt Posted September 13, 2011 Author Share Posted September 13, 2011 Did the full range sweep, didnt really notice any flat spots. Havent really found any info regarding the TCU. Whereabouts is the TCU on the car? What would I have to look for electrical wise? Can I read the same voltage readings at the TCU? Link to comment Share on other sites More sharing options...
eulogious Posted September 13, 2011 Share Posted September 13, 2011 Engine revolution sensor has nothing to do with the engine if you are talking about the tcu. It's talking about the rpm signal coming from the ecu, not about anything with the engine. If the tps was bad, you would have a cel as well I would think. The tps signal is "shared" by the ecu and the tcu from my understanding, so if you are not getting a cel for the tps, then most likely the tps is fine, so I would check the connections for corrosion and the wires for shorts. Have you tried another tcu? I would swap it out for another one before I really tried too much else. These old computers do tend to fail in strange ways... Oh, and just chill out about wanting help... One thing about USMB is that it is not known for it's speed, but for it's answers. Be patient and help will come TONS of smart people on here, just not everyday. Link to comment Share on other sites More sharing options...
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