Dec 122016
 

1994 Toyota Corolla idlingI have a problem with my car’s idling. Every morning the idling goes down instead of going up. What could be the cause of it?


RESPONSE

Under normal circumstances the engine idle would go up when first started with a cold engine. This happens because the engine has an ECT (Engine Coolant Temperature) Sensor that lets the engines computer know the engine is cold. When the ECT reads cold it will increase the amount of fuel. As the engines temperature increases the it may reduce the amount of fuel. So what does this mean? If the ECT is stuck or giving a false reading the engines computer may think it is already warm.

 

Dec 122016
 

2012 Toyota PriusI have a 2012 Toyota Prius V. As I am traveling along my engine accelerates or engine revs. The only way for me to stop this is to step on the gas pedal.


RESPONSE

I consider this as a severe safety issue. Sounds like your accelerator is sticking. This may be from a faulty accelerator pedal sensor. Testing will require a capable scan tool. You may need to take this to a Toyota dealer because not every local shop will have one for a Prius.

Accelerator Pedal Sensor On-Vehicle Inspection

1. INSPECT ACCELERATOR PEDAL ASSEMBLY

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Hybrid Control / Data List / Accel Pedal Pos #1, Accel Pedal Pos #2.

(e) Read the Data List.

Result:

Tester Display

Accelerator Pedal Condition

Specified Condition

Accel Pedal Pos #1

Not depressed

(8 to 28%) 0.4 to 1.4 V

Fully depressed

(62 to 92%) 3.1 to 4.6 V

Not depressed → Fully depressed → Not depressed (Accelerator pedal should be operated slowly)

Value changes progressively as shown in the illustration

Accel Pedal Pos #2

Not depressed

(20 to 44%) 1.0 to 2.2 V

Fully depressed

(78 to 100%) 3.9 to 5.0 V

Not depressed → Fully depressed → Not depressed (Accelerator pedal should be operated slowly)

Value changes progressively as shown in the illustration

Remove Accelerator Pedal Assembly

accelerator pedal sensor
(a) Disconnect the accelerator pedal assembly connector.
(b) Remove the 2 bolts and accelerator pedal assembly.

Nov 252016
 

2004 Toyota Corollaon a 2004 Toyota Corolla with 182,00 miles…when i took the car to the shop about 2 months ago and the car had code p0133, p0420 and p0171..the mechanic tells me if i install a new oxygen sensor the codes will probably clear. so i had a new o2 sensor installed..3 days later i get just the p0420.. since its expensive to install a new catalytic converter I Drive the car like that for a month , try to save money..about 5 days ago i notice now i have the p0133 and the p0420 again, I Take it back to the shop since the oxygen sensor is under warranty. The mechanic tells me its best to install a catalytic converter. that the codes might clear, but i always thought u have to clear the p0133 b4 installing the sensor..is he giving me the run-around?


RESPONSE

The codes do not have to be cleared before installing a sensor. Generally the codes are cleared after the sensor or parts are installed and tested. You stated above that the code p0133 had gone 3 days after the O2 Sensor was replaced. So the code was gone(cleared). The Code P0420 usually means you need to replace the catalytic converter. The converter does absolutely nothing for the drivability of the vehicle. This is for Government mandated emissions only. You do not have to replace the converter but the check engine light will remain on for the code p0420 until you do.

When the P0171 is combined with the P0174 code, it’s very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the Mass Air Flow Sensor. If the problem persist the front oxygen (O2) sensor may need to be replaced. Also replacing the converter will not fix the code p0133. The mechanic said it MIGHT which leaves you open for IT MIGHT NOT. Therefore I would say NO to the converter until the P0133 code is taking care of unless you want to of course.

I think your mechanic is trying to help you clear the codes but I also think your mechanic may be overlooking a possible intake air leak. Or there may be something more involved. There may be a damaged wire in the O2 Sensor circuit itself. And it is possible the o2 sensor is bad, but it can be checked with a scan tool. I would assume the o2 Sensor operation was checked since you took it back in for warranty purposes.

Code Information

The P0420 code means that the vehicle’s control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

Toyota Code P0133 – HO2S11 Circuit Slow Response

Possible causes
– Faulty Front Heated Oxygen Sensor Bank 1
– Front Heated Oxygen Sensor Bank 1 harness is open or shorted
– Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
– Inappropriate fuel pressure
– Faulty fuel injectors
– Intake air leaks may be faulty
– Exhaust gas leaks
Toyota Code P0133 Description

The front heated oxygen sensor (or O2 sensor 1) is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. A heated oxygen sensor 1 signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.

Toyota Code P0171- Air/Fuel Mixture System Lean Bank 1

Possible causes
– Intake air leaks
– Faulty front heated oxygen sensor
– Ignition misfiring
– Faulty fuel injectors
– Exhaust gas leaks
– Incorrect fuel pressure
– Lack of fuel
– Faulty Mass Air Flow (MAF) sensor
– Incorrect Positive Crankcase Ventilation (PCV) hose connection

Toyota Code P0420 – Catalyst System Efficiency Below Threshold Bank 1

Possible causes
– Three way catalyst converter Bank 1
– Exhaust tube
– Intake air leaks
– Fuel injectors may be faulty
– Fuel injector leaks
– Spark plugs may be faulty
– Improper ignition timing
– Engine Control Module (ECM)
Nov 222016
 

1998 Toyota AvalonNo Starter engagement. Using wiring diagram from Toyota, I can jump over ST relay sending current from terminal 3 to 5 will crank. I suspect Neutral/Safety Sw, wiring diagram shows 2 terminals, but actually have 8 terminals on Sw. Willing to pay for quick response. HArold


RESPONSE

The Neutral switch may have eight wires but only the two wires shown on the starting system diagram have to do with it starting. The Black/White wire and the Black/Red wire. However there are several fuses to check as well as the starter relay. The starter relay is the most common failure component. You can rule out the theft deterrent system as it shuts off the fuel system, not the starter.

You should see battery voltage at PIN#5 on the starter relay at all times. If not check the Main 40 amp fuse, the AM2 30 amp fuse, the ALT 120 amp fuse and the main fusible link.

You should see battery negative on PIN#2 of the starter relay at all times. Also should see battery voltage at PIN#1 (Black/Red wire coming from neutral switch) only when the ignition key is held in the “START” position.

You should see battery voltage leaving the relay on PIN#3 only when the relay is activated by battery voltage being applied at PIN#1. This will cause starter engagement. If this does not occur and all voltages check out. Replace the relay.

Starting System Wiring Diagram 1998 Toyota Avalon

1998-toyota-avalon-starting-charging-starting-circuit-1-of-1
Nov 192016
 

2010 Toyota Tacomaknocking/pinging/dieseling noise:
Toyota dealer couldn’t figure it out after trying tune up, fuel injector service. They sent a recording of the noise with a scan tool to a Toyota engineer and their response was that is normal. I have been using premium gas, tried carbon cleaner in my gas and nothing helps. I’m not an over sensitive driver, the knocking gets REALLY bad when the car is going up a slight hill or getting on the highway via on ramp.


RESPONSE

I would suggest using a premium grade fuel from a different fueling station and even go as far as to add some Octane Boost to the gas tank. This would be a good test to determine if it is a pre-detonation issue occurring. It is common for fuel to become contaminated, this is why I suggest changing fueling stations.

Engine Knock Sensor – Pinging Deterrent

The Toyota is equipped with a knock sensor. The Sensor will try to correct the ignition timing if this occurs but is not always as efficient as the human ear. If by chance you think the knock sensor is faulty it can be tested. Using a multi-meter check the Ohms between the two terminal ends on the sensor. Therefore you should see 120 – 280 ohms at room temperature(68-72 degrees). If out of range, replace the sensor.

Nov 062016
 

2009 Toyota CamrySometimes, when I’m sitting/idling, say, at a traffic light, my car shakes/vibrates; I can really feel it in my steering wheel but it seems to be the whole car. Turning the a/c off seems to make it better. If I put it in Neutral while at the light, the vibrating stops or lessens so that’s what I’ve been doing when it happens. Otherwise, the car is in good shape; I do regular maintenance and I’m pretty easy on cars, in general. Any help will be much appreciated.


RESPONSE

Sounds like you may be experiencing an engine misfire. Is the check engine light on? Have the engine trouble codes pulled and post them below in the comments. This can be done for free at just about any local auto parts store. If the check engine light isn’t on you may need to continue driving it for a while until the like does come on. This allows the engines on board computer time to pinpoint the effected area.

What can be done now?

You could start by replacing the spark plugs  and air filters which wouldn’t hurt anything and may be time to do so anyway. Another cause may be fuel related. If this has just started happening since your last fill up, you may want to switch to a different gas station and try a higher octane for a few fill ups. Your last fill up may have some bad gas and the higher octane should help bring up the octane level of any fuel that is left in your tank.