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Loses RPM in transmission drive position

Tiny
MARIOC68
  • MEMBER
  • 1996 TOYOTA COROLLA
  • 1.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
My car loses rpm when placing the automatic transmission in the drive position, sometimes to such an extent that the engine shuts down. By setting it to the neutral position the rpm is normalized.
Tuesday, November 28th, 2017 AT 7:40 AM

10 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Do you still have drive and do you have any other symptoms, does it feel like the transmission is locking up or the engine revs fall away to far in gear?
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Tuesday, November 28th, 2017 AT 2:16 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
The revolutions fall even in the reverse position. When making the transmission changes I do not have problems with blocking. Only that the rpm drops a lot.
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Tuesday, November 28th, 2017 AT 2:29 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
May be look at the idle air control system, as load comes on the engine via transmission load, the IAC should maintain a good idle, look at doing a base idle re set and check the iac valve as well.
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Tuesday, November 28th, 2017 AT 6:37 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
To open the air control valve (ACV) two current signals are needed, one positive (+) and one negative (-). According to my electric diagram of the EFI system, the positive one is delivered to me by the main relay of the fuel injection circuit, it is the same one that feeds the gasoline pump. The other signal, supposedly negative, is given to me by the ECU. How can I tell if the ECU is sending a signal to the ACV? Already verify the removed ACV, connecting it to the battery directly, and it works correctly, that is, it opens the valve.
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Wednesday, November 29th, 2017 AT 1:29 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Back probe the ACV with a multi meter and check for a circuit, maybe do a continuity check from the plug back to the ECU as well you may have a high resistance or an open circuit.
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Wednesday, November 29th, 2017 AT 9:18 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
The ECU was not sending a signal to the ACV (IAC). I had it repaired now it comes signal like pulses, is this form of operation correct? You can also hear that the valve works by clicking with a click.
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Sunday, February 11th, 2018 AT 3:38 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Yes you might be able to hear it work. Does it seem to run okay?
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Monday, February 12th, 2018 AT 12:14 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Yes, I can perceive it at the ear and at the touch. This work, I tried disconnecting and reconnecting the valve, you can see how the revolutions go up and up in each situation. Even before the rpm dropped when placing the lights, now no longer.
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Monday, February 12th, 2018 AT 12:36 PM
Tiny
MHPAUTOS
  • MECHANIC
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This is a stepper motor and from what you describe it is working fine.
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Tuesday, February 13th, 2018 AT 3:49 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Right. Give the problem resolved.
Thank you very much.
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Tuesday, February 13th, 2018 AT 6:30 AM

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