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Old 01-21-2014, 07:53 PM   #1
freewave
 
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Question Help! The weirdest thing started happening today...

I have a 2007 Yaris. Base model, auto, 2 door, only owner. The last three years not a lot of maintenance has been done. Oil changes and fluids only, sorta thing. Has a small exhaust leak, but it hasn't been there long.

This morning I started her up, and it sounded normal. Then it stalled when I brought the gearshift down past neutral into drive. I started it again, and again everything sounded fine. I feathered the gas as I brought the gearshift down and it went into drive. Drove to work normal. When I got to work I tested it to see if I could replicate it, and I could.

I searched on here all day at work, but couldn't find anything really relevant. A coworker suggested it could be the spark plugs, so I changed those myself as well as the air filter. Both were overdue.

When I started it back up, the engine sounded fairly "off." Like it wasn't firing right. It immediately stalled when shifting into drive.

What could cause this?

Thanks in advance!
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Old 01-21-2014, 08:23 PM   #2
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A bad torque converter could cause the stall when shifting into drive, but in park or neutral the engine would run perfectly fine. If it is running rough, I would double check that the plugs are the correct ones and are gapped correctly.
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Old 01-22-2014, 12:20 AM   #3
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I did double check the plugs, and they came pre-gapped to the correct distance. I double checked the gap as well before putting them in.

What I didn't do, but have seen suggested now that I'm doing my panic research, is unplug the battery for a minute to "refresh" the firing rate after changing the plugs. For some reason it wasn't in any walk through I found but it was in the troubleshooting guide. :P

Any idea how to check the torque converter? Or is it a straight replacement and hope that's the issue?

Thanks!
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Old 01-22-2014, 04:41 AM   #4
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Quote:
Originally Posted by freewave View Post
I did double check the plugs, and they came pre-gapped to the correct distance. I double checked the gap as well before putting them in.

What I didn't do, but have seen suggested now that I'm doing my panic research, is unplug the battery for a minute to "refresh" the firing rate after changing the plugs. For some reason it wasn't in any walk through I found but it was in the troubleshooting guide. :P

Any idea how to check the torque converter? Or is it a straight replacement and hope that's the issue?

Thanks!
Typically resetting the ECM is not necessary with plug replacement, but you can try doing so by disconnecting the battery for a minute. You can also try cleaning the throttle body and MAF sensor.

For testing the torque converter, the thing that would fail with it causing stalling on start is the one-way-clutch within it. Testing that requires pulling the torque converter out of the tranny.
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Old 01-22-2014, 10:12 AM   #5
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Typically resetting the ECM is not necessary with plug replacement, but you can try doing so by disconnecting the battery for a minute. You can also try cleaning the throttle body and MAF sensor.

For testing the torque converter, the thing that would fail with it causing stalling on start is the one-way-clutch within it. Testing that requires pulling the torque converter out of the tranny.
I will check into cleaning the throttle body and MAF sensor today. I'm not sure about the torque converter though - its not stalling on start, its stalling when I pass through neutral into drive (unless I feather the gas when shifting) or back through neutral into reverse or park.

I showed it to a former mechanic coworker and he thinks it sounds electronic. There are no sounds to indicate an issue, the motor just dies. Like it does't know how high to idle in neutral so it shuts off.
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Old 01-22-2014, 10:22 AM   #6
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Originally Posted by freewave View Post
I will check into cleaning the throttle body and MAF sensor today. I'm not sure about the torque converter though - its not stalling on start, its stalling when I pass through neutral into drive (unless I feather the gas when shifting) or back through neutral into reverse or park.

I showed it to a former mechanic coworker and he thinks it sounds electronic. There are no sounds to indicate an issue, the motor just dies. Like it does't know how high to idle in neutral so it shuts off.
So, once you get past neutral in either direction it is fine?
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Old 01-22-2014, 11:28 AM   #7
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So, once you get past neutral in either direction it is fine?
Exactly. I can feather the gas to get past neutral without stalling. That works in both directions (reverse to drive, and drive to reverse) however its awkward to do when going from drive to reverse. I am currently just letting it stall when I park.
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Old 01-22-2014, 11:34 AM   #8
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Exactly. I can feather the gas to get past neutral without stalling. That works in both directions (reverse to drive, and drive to reverse) however its awkward to do when going from drive to reverse. I am currently just letting it stall when I park.
OK. For that behavior the service manual points to the ECM, shift lock ECU (lives inside of the shifter) or the Park/Neutral switch (the switch that the shifter cable moves on the tranny) being the culprit. Diagnosis would best be done with the Toyota TechStream tool, as the data that it shows would allow one to narrow the problem down to one of those three devices.
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Old 01-22-2014, 01:41 PM   #9
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OK. For that behavior the service manual points to the ECM, shift lock ECU (lives inside of the shifter) or the Park/Neutral switch (the switch that the shifter cable moves on the tranny) being the culprit. Diagnosis would best be done with the Toyota TechStream tool, as the data that it shows would allow one to narrow the problem down to one of those three devices.
I'm going to test the Park/Neutral safety switch myself in about an hour. From what I read, you can test by starting the vehicle, then unplugging the switch. From there I would see if the car stalls in neutral. If it doesn't, then I clean or replace the switch. Otherwise I move on to the next part.
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Old 01-22-2014, 02:37 PM   #10
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I'm going to test the Park/Neutral safety switch myself in about an hour. From what I read, you can test by starting the vehicle, then unplugging the switch. From there I would see if the car stalls in neutral. If it doesn't, then I clean or replace the switch. Otherwise I move on to the next part.
That will work for testing the park/neutral switch. There's a voltage test that can be done for the shift lock ECU as well.
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Old 01-23-2014, 10:57 AM   #11
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That will work for testing the park/neutral switch. There's a voltage test that can be done for the shift lock ECU as well.
It turns out it was the neutral safety switch! I pulled it out and opened it up (its fastened together with rivets, not exactly meant to be serviceable). It was full of nasty oil and water. I cleaned it out, took a small file to the contacts to make sure they were flat again, stretched the springs out so the contacts fit in place better, resealed the unit and closed her up. I had to drill and tap holes for fasteners to replace the rivets.

But overall, it was about 3 hours work start to finish and it saved me the $200 part plus install at a shop!

Thanks for your help!
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Old 01-23-2014, 11:13 AM   #12
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Quote:
Originally Posted by freewave View Post
It turns out it was the neutral safety switch! I pulled it out and opened it up (its fastened together with rivets, not exactly meant to be serviceable). It was full of nasty oil and water. I cleaned it out, took a small file to the contacts to make sure they were flat again, stretched the springs out so the contacts fit in place better, resealed the unit and closed her up. I had to drill and tap holes for fasteners to replace the rivets.

But overall, it was about 3 hours work start to finish and it saved me the $200 part plus install at a shop!

Thanks for your help!
Nice!
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