Mechanics

ENGINE DOES NOT REV ONLY IDLES

1997 Toyota Corolla

Engine Performance problem
1997 Toyota Corolla 4 cyl Two Wheel Drive 115000 miles

The motor 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 working disconnected MAP sensor no change also TPS can be disconnected no change. Is it my ECUThanks
Avatar
Vintagefeetup
October 4, 2010.




Check fuel pressure
pressure should be 37 to 44 PSI
CHECK FOR EXHAUST RESTRICTION AND OR A BAD CATALYTIC CONVECTOR

BMRFIXIT
Oct 5, 2010.
Checked fuel pressure OK no blocked exhaust good pressure.

Tiny
Vintagefeetup
Oct 5, 2010.
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:
Open or short in TP sensor circuit.
TP sensor.
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.


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BMRFIXIT
Oct 5, 2010.
Hi Well the car will start as I said as soon as you depress the throttle it dies 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 dead. 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 problenm 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 25 mph and just cut out first I coukldn't start it as I kept pushing the throttle it will start if you don't touch the it and it just idles.
Regards
Simon

Tiny
Vintagefeetup
Oct 6, 2010.
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 1st
let me know
iam going to look up the wiring diagram

BMRFIXIT
Oct 6, 2010.
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

Tiny
Vintagefeetup
Oct 6, 2010.
Jack The injector pulse dies and the spark contiues when the engine dies.

Tiny
Vintagefeetup
Oct 6, 2010.


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check them two relays
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BMRFIXIT
Oct 6, 2010.
Both relays operate bench tested

Tiny
Vintagefeetup
Oct 6, 2010.
Lets check the relays and if they click when its stall or cause it to stall

BMRFIXIT
Oct 6, 2010.

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