TPS on 97 impreza outback problems

[gratefuldude]

Hey now,

for the past few weeks my CEL was on. Car idled @ 1400 rpm, so i checked it.

 

threw a p0122, tps circuit low

 

so, i pulled out the old one, cleaned it, and put it back in.

went well for 300 miles, then this happened:

 

while at a steady speed, the throttle DROPS out. takes a couple stabs at the pedal to get throttle speeds again. this is happening alot.

 

so, i bought a new TPS, installed it.

same issue, seems to be worse.

 

Is there a guide to installing the TPS somewhere? all i did was make sure the spring inside the sensor was connected to the throttle body with little tension at idle.

 

any input would be great, as i can no longer drive my car more then a minute or 2.

-steve

[mikec03]

You have to adjust the tps to factory specs. Search for tps and you will probably find the shut off voltage that you need to adjust to. Its a little less then 0.50v.

[gratefuldude]

You have to adjust the tps to factory specs. Search for tps and you will probably find the shut off voltage that you need to adjust to. Its a little less then 0.50v.

 

 

ive been looking around, i found this, the only thing odd to me is the removal of the ECU:

 

 

The manual says:

 

1. Loosen TPS holding screws.

When using a voltage meter.

2. Take out ECM.

3. Turn ignition switch to ON.

4. Adjust TPS to the proper position to allow the voltage signal to ECM to be in spec.

Measure across terminals No. 15 and No. 17 in connector B136. Voltage should read between .45-.55V fully closed.

5. Tighten TPS holding screws. Torque 1.6ft/lb -+ .1 ft/lb.

[gratefuldude]

well, with ecu plugged in, im reading at 5V, everywhere. no matter where i move the sensor.

 

with ECU unplugged, i read 0.00, everywhere.

 

im taking my reading from the red wire and the black wire.

 

what am i missing?!?!?!?!

[idosubaru]

take out ECM may be just so you can have access to the end terminals of the TPS that are the input of the TPS to the ECM(ECU).

 

once i've seen the wiring be bad, it was where the wire went around the bend, about 4 inches (roughly) from the TPS. massaging the wiring between two fingers and working down the length of it the problem would reveal itself by changing how the engine ran - running well it would stall or nearly stalling it would start to run just fine when i pressed in a certain spot. i got a used harness and cut off a foot of wiring and spliced it in to fix.

 

maybe as a test if you continue to have problems, buy a throttle body that has the TPS already mounted and therefore already calibrated. bolt it up as an assembly. TPS failure is so rare that the cost of a new one is completely pointless anyway. and since they never fail, there's zero demand so they're not worth anything. i paid like $20 for an EJ TPS when I broken one with a chain while removing an engine. doesn't matter in this case but in case anyone else ever reads this, maybe it'll be helpful.

 

i haven't done an EJ yet, accept just swapping the entire throttle body, but on the earlier ones you essentially do it by ear - you run the car, have the TPS "open" so to speak and gradually adjust it by hand. keep turning it in littles swathes such that you're causing it to almost shut off (throttle plate just barely closed)...you'll get it to the point where just a hair in one direction makes it stall while idling, back it off a hair from that stall point and that's where you want it. you have to do that on the XT6 as the FSM spec's are actually incorrect. not sure if the EJ is the same though.

[idosubaru]

hmmmm, not sure about your readings. can you take some readings at just the TPS and bypass it being plugged in? like verify continuity at a certain angle? then try and do that the same exact way at the ECU - this might show a bad wire?

[gratefuldude]

well, apprently im not checking the right pins on the ECU plug. i cant find the proper diagram for my plug.

 

i did the adjustments by hand, yeah. i had it sounding pretty darn good, but it loves to crap out when the pedal is bearly being pushed, like at a cruising speed.

 

 

maybe i set it too low to begin with?

[idosubaru]

those instructions i posted are for older stuff....newer OBDII stuff like yours could be completely different.

 

have someone post the FSM info for you? i think i have 97 impreza but i don't have time to post it today.....it's not easy for me with having dial up (no cable, dsl or anything available at my house) at home, posting stuff like that isn't really an option.

[gratefuldude]

well, i figured it out, it was complete idiocy on my part.

 

thanks for the help guys

[cygnus]

How did you fix, or what was the problem that resolved your issue.

[gratefuldude]

How did you fix, or what was the problem that resolved your issue.

 

 

well:

what i did was what the instructions i posted said.

 

realized, that was a waste of time, as they are instructions for a car that isnt like mine.

 

so!

 

there are 2 sweet spots in the tps. if you are installing one, the common thing to do is to line the spring in the tps up with the throttle "pin", then set idle.

well: that is incorrect.

put in tps, leave screws semi loose. turn tps all the way to the left. start to turn clockwise, slowly!, the idle will relax to where you want it.

do not stop there!

keep turning. idle goes up again. then smooths out.

right when the idle is mint for the second time, tighten screws.

 

not much of a tech write up: but i drove 80 miles( i live in the mountains) of interesting conditions...no issues, light went out on its own.

[cygnus]

Ok thanks for the tips, I'm having the same problem will give it a try tonight.

 

(next Day) Tried this and it runs smooth as butter...Thanks for your post..

Edited November 10, 2010 by cygnus