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Discussion Starter #1
Hi guys

every time i get into a stop sign or a traffic light my car dies on me :( , sometimes i can start the engine and some times it real hard.
change the battery check the alternator, anything else to do ?
 

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What are your RPM's doing when you come to a stop? Any codes thrown? Does it want to die again after you restart it or will it idle from then on?
 

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What are your RPM's doing when you come to a stop? Any codes thrown? Does it want to die again after you restart it or will it idle from then on?
the rpms stay on 1 before it dies and yes it dies again not in every stop light but it can occur 2 or 3 times a trip while getting into a stop sign
 

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Try cleaning your throttle body too.
 

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Dying at stop is more common with aftermarket ECU/piggyback because of deficiency in the tune - but with a stock ECU I would suspect the Idle Air Control Valve. If it is not responding correctly then the engine can be choked of air. The fuel mixture in a stock ECU is not adjustable unless you monkey with your intake/MAF or your injectors - like "the" MAF mod - or if you have bad O2 sensors.
 

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Discussion Starter #12
Dying at stop is more common with aftermarket ECU/piggyback because of deficiency in the tune - but with a stock ECU I would suspect the Idle Air Control Valve. If it is not responding correctly then the engine can be choked of air. The fuel mixture in a stock ECU is not adjustable unless you monkey with your intake/MAF or your injectors - like "the" MAF mod - or if you have bad O2 sensors.
I really appriceate the help man the idlle air valve was replaced with the throttle body and cleaned.
How can I test the oc2?
And does the stock have only 2?
 

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I really appriceate the help man the idlle air valve was replaced with the throttle body and cleaned.
How can I test the oc2?
And does the stock have only 2?
The stock US car has three O2 sensors. Two primary upstream - Bank 1 Sensor 1 and Bank2 Sensor 1 - that the ECU uses for regulating the fuel mix and one downstream Bank 1 Sensor 2 post-cat that does very little or nothing for the fuel mixture, it is mainly for monitoring the operation of the catalytic converter. The two upstream sensors are identical. Normally they oscillate between 0 and 1v (more like 0.1 and 0.9v) but if either one gets stuck at one end of the range because of some defect or malfunction it can cause the ECU to fuel incorrectly. Usually this would set off a CEL. But if the sensor is not yet to the point of triggering a CEL then use a OBD2 scantool to check the fuel trims on both banks. The ECU responds to the feedback of the O2 sensors by compensating the short term fuel trim (STFT) and this leads to a change in the stored value of the long term fuel (LTFT). If your scan tool tells you that the STFT and LTFT on either bank 1 or bank 2 are consistently high (positive, lean) or low (negative, rich) this means there is a possible issue in the O2 sensor or in the fuel injectors for that bank or possibly a vacuum leak affecting that bank. You can also check the voltage on each O2 sensor directly on the scantool and it's possible you can see a pattern of malfunction looking at the voltages. Testing the resistance value of the O2 sensors with a multimeter is an option but it is useful only if the O2 sensor is broken outright and in this case you get confirmation of what the ECU tells you with a CEL.

Dying at stop can also be a symptom of insufficient fuel pressure due to faulty fuel pump or even faulty alternator and battery together not providing enough voltage so there are a lot of possibilities to go through here.

Does the engine die if you race it then let off the throttle in neutral at a stop.

Your MAF sensor should be reading about 2g/s at idle on the scantool, so check that to verify that it is functioning correctly.
 

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Discussion Starter #15
The stock US car has three O2 sensors. Two primary upstream - Bank 1 Sensor 1 and Bank2 Sensor 1 - that the ECU uses for regulating the fuel mix and one downstream Bank 1 Sensor 2 post-cat that does very little or nothing for the fuel mixture, it is mainly for monitoring the operation of the catalytic converter. The two upstream sensors are identical. Normally they oscillate between 0 and 1v (more like 0.1 and 0.9v) but if either one gets stuck at one end of the range because of some defect or malfunction it can cause the ECU to fuel incorrectly. Usually this would set off a CEL. But if the sensor is not yet to the point of triggering a CEL then use a OBD2 scantool to check the fuel trims on both banks. The ECU responds to the feedback of the O2 sensors by compensating the short term fuel trim (STFT) and this leads to a change in the stored value of the long term fuel (LTFT). If your scan tool tells you that the STFT and LTFT on either bank 1 or bank 2 are consistently high (positive, lean) or low (negative, rich) this means there is a possible issue in the O2 sensor or in the fuel injectors for that bank or possibly a vacuum leak affecting that bank. You can also check the voltage on each O2 sensor directly on the scantool and it's possible you can see a pattern of malfunction looking at the voltages. Testing the resistance value of the O2 sensors with a multimeter is an option but it is useful only if the O2 sensor is broken outright and in this case you get confirmation of what the ECU tells you with a CEL.

Dying at stop can also be a symptom of insufficient fuel pressure due to faulty fuel pump or even faulty alternator and battery together not providing enough voltage so there are a lot of possibilities to go through here.

Does the engine die if you race it then let off the throttle in neutral at a stop.

Your MAF sensor should be reading about 2g/s at idle on the scantool, so check that to verify that it is functioning correctly.
Does the engine die if you race it then let off the throttle in neutral at a stop.| YES
I don't think it's the battery or the alternator cause I change the battery and the alternator is working good, and becuse of the rich fuel. Will check the O2, what i don't understand that if the O2 why its working good when the car is cold and only when the car is warm and let go of the gas it happen
 

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Did you check your air filter? Is it free of obstruction or debris? What kind of IAC valve did you use for replacement? Is it known good? Is it a OEM Toyota IAC or aftermarket? Aftermarket IAC's are unreliable and to be avoided.
 

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Discussion Starter #17
Run a compression test. Any codes for misfires?
The compression is great no codes
the IAC i got for a OEM car , regarding the air filter i change it to K&N 33-2041-1 for Toyota Corolla VI washable reusable drop in panel air filter.

i am thinking on the o2 but am not sure way it will make the car stall at stop signs
 

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I always suspect vacuum leaks when cars don’t idle well or when coming off a high RPM into neutral. I would connect a vacuum gauge. That said a vacuum gauge did not reveal a very minor leak in my intake manifold gasket that occurred only under specific conditions. Thought 2 - Throttle body smooth operation - is it possible there is friction? Particularly the alignment of the ’butterfly’ (can’t recall term).
 
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