Car starting but not revving

Tiny
VINTAGEFEETUP
  • MEMBER
  • 1997 TOYOTA COROLLA
The engine will idle but when you depress throttle it rev to about 2000 rpm then cuts out. The computer puts up a fault code P0120 which is TPS. I tried a new sensor no change. The spark plug still sparks when engine shuts off so I am thinking fuel starvation. Checked fuel pump it is working. Disconnected MAP sensor no change. Also TPS can be disconnected no change. Is it my ECU? Thanks
Monday, October 4th, 2010 AT 10:15 PM

21 Replies

Tiny
BMRFIXIT
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Check for exhaust restriction and or a bad catalytic converter. This guide can help confirm the issue.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.
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Tuesday, October 5th, 2010 AT 6:19 AM
Tiny
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Checked fuel pressure it was okay. No blocked exhaust, good pressure.
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Tuesday, October 5th, 2010 AT 3:31 PM
Tiny
BMRFIXIT
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Good exhaust pressure ?
What was the reading ?
Do you have a scanner that you can use to read TPS volts and PCM (ECU) data
Does it stalls or slowly fade and stall out
hook a vacuum gauge on a main vacuum source and check vacuum at idle and at 1500rpm

it said you have a spark do you have injector pulse or was it checked

TESTS W/CODES - 1997 Toyota Corolla

DTC P0120: THROTTLE POSITION (TP) SENSOR CIRCUIT MALFUNCTION

CAUTION:If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction.

Circuit Description
The TP sensor is a variable resistor that monitors throttle opening. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when ECM consistently detects less than .1 volt or more than 4.9 volts on VTA circuit. Possible causes are:
à   Open or short in TP sensor circuit.
à   TP sensor.
à   ECM.
NOTE: If DTCs P0105, P0106, P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article.

Diagnosis & Repair
1.Connect scan tool to DLC No. 3 connector. See Fig. 1 . Turn ignition on. Using scan tool, monitor throttle valve opening percentage. Opening percentage should be approximately 10 percent with fully closed throttle.
2.Depress accelerator pedal to floor (WOT). Opening percentage should be approximately 70 percent. If percentages are as specified, check all connections. Problem may be intermittent.
3.If percentages are not as specified, turn ignition off. Disconnect TP sensor connector. Turn ignition on. Using DVOM, measure voltage between ground and terminal No. 4 (Yellow wire) at TP sensor wiring harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 7).
4.Check TP sensor. . Replace sensor as necessary. If sensor is okay, go to next step.
5.Access ECM behind bottom center of instrument panel, in front of console. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 9 (Brown wire) and No. 11 (Light Green wire) at ECM E9 connector. See Fig. 2 . Voltage should be .3-.8 volt with throttle fully closed, and 3.2-4.9 volts with throttle fully open (WOT).
6.If voltage is as specified, replace ECM and retest. If voltage is not as specified, check for an open or short in wiring harness between TP sensor and ECM. Repair wiring as necessary.
7.Access ECM behind bottom center of instrument panel, in front of console. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 1 (Red wire) and No. 9 (Brown wire) at ECM E9 connector. See Fig. 2 . If voltage is 4.5-5.5 volts, check wiring harness for an open in Red wire. If voltage is not 4.5-5.5 volts, replace ECM and retest.


https://www.2carpros.com/forum/automotive_pictures/99387_2_1.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_3_1.jpg

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Tuesday, October 5th, 2010 AT 6:02 PM
Tiny
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Hi, well the car will start as I said as soon as you depress the throttle it shuts off at about 2000 rpm. I tried depressing it slowly it builds up then cuts out like a switch turning off. I also tried releasing the throttle as soon as it cuts out hoping it would continue to run but its out. I put the code reader on in live mode did the throttle test the 10% on closed and 70% on open all correct. I had already changed the TPS for a new on hoping that was the problem but still would not rev. Have not checked injector pulse how do I do that? I feel I am missing something the car drove fine it was going about twenty five mph and just cut out first I could not start it as I kept pushing the throttle it will start if you d not touch the it and it just idles.
Regards,
Simon
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Wednesday, October 6th, 2010 AT 12:44 PM
Tiny
BMRFIXIT
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Place a spark tester on the coil wire.
Place injector pulse tester on one of the injectors.
Start the engine and increase the RPM as you watching the two lights.
Trying to determine which one go out first.
Let me know.
I am going to look up the wiring diagram.
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Wednesday, October 6th, 2010 AT 12:58 PM
Tiny
VINTAGEFEETUP
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Just to add, I am not seeing any fault code now. Turned the engine on and off several times and let it idle for a few minutes still no fault codes. But, it still cuts out when the throttle is pushed.
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Wednesday, October 6th, 2010 AT 1:14 PM
Tiny
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Jack, the injector pulse stops and the spark continues when the engine shuts off.
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Wednesday, October 6th, 2010 AT 4:10 PM
Tiny
BMRFIXIT
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https://www.2carpros.com/forum/automotive_pictures/99387_1_4.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_1_5.jpg


check those two relays.
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Wednesday, October 6th, 2010 AT 6:52 PM
Tiny
VINTAGEFEETUP
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Both relays operate, bench tested.
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Wednesday, October 6th, 2010 AT 8:34 PM
Tiny
BMRFIXIT
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Lets check the relays and if they click when it stalls or cause it to stall.
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Wednesday, October 6th, 2010 AT 9:06 PM
Tiny
BMRFIXIT
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With key on engine off check for battery power at the injector connector.
Do you have power at the yellow/green wire?
Start engine, continue with the power check cause the stalling do you have power or not/
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Wednesday, October 6th, 2010 AT 9:23 PM
Tiny
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Still has power after stall.
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Wednesday, October 6th, 2010 AT 9:45 PM
Tiny
BMRFIXIT
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ECM is not grounding the injectors.
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Wednesday, October 6th, 2010 AT 9:50 PM
Tiny
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How do I correct that?
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Wednesday, October 6th, 2010 AT 9:53 PM
Tiny
BMRFIXIT
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I will look into tomorrow when I go to work. Possible bad ECM.

You did clear the codes and still coming up with the TPS code (correct )?
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Wednesday, October 6th, 2010 AT 9:57 PM
Tiny
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The codes were cleared and they are still clear no TPS fault code.
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Wednesday, October 6th, 2010 AT 10:05 PM
Tiny
BMRFIXIT
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https://www.2carpros.com/forum/automotive_pictures/99387_1_6.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_2_4.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_3_2.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_4_1.jpg

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Thursday, October 7th, 2010 AT 6:34 AM
Tiny
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I do not see a ground for the injectors on this printout. So how do I correct it?
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Thursday, October 7th, 2010 AT 9:28 AM
Tiny
BMRFIXIT
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https://www.2carpros.com/forum/automotive_pictures/99387_4_2.jpg




https://www.2carpros.com/forum/automotive_pictures/99387_1_7.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_2_5.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_3_3.jpg

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Thursday, October 7th, 2010 AT 7:58 PM
Tiny
VINTAGEFEETUP
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I want to let you know the problem was nothing to do with the injectors or a ground on the ECU it was a mechanical problem with translated into a electrical problem. The crankshaft timing gear had a broken tooth on the reluctor part which in turn through off the rpm from the crank sensor and shut the engine down when tried to accelerate. Unfortunately I paid a auto shop to tell me this so there you go for next time.
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Saturday, October 9th, 2010 AT 5:29 PM

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