2006 Scion tC (2AZ-FE) strange start up problem

[Scuderia]

I'm looking for suggestions on what could be wrong with my car. Let me describe the symptoms for you.

• If the car has been sitting in the cold for a while, the car will crank fine, but it fires up slowly. Like it wants stall. This also happens if I disconnect and reconnect the battery.

• 
  If I turn the ignition to "on" and pump the gas pedal a few times it starts up fine. Pumping the gas pedal once doesn't work, I have to pump it like 7-8 times.

• Lastly, I'm getting bad gas milage. On 87 octane it seems to be worse than on 91. And no it's not just in my head, I compared data to back it up. 18 MPG on 87 octane and 20 MPG on 91 octane. The car was designed to run on 87 octane, and my engine is completely stock.

Any ideas?

 

[crinkles]

fuel filter? bad batch of fuel?

 

[javacontour]

Bad throttle position sensor? Your car is drive by wire, so pumping the throttle does nothing but tell the computer you've moved the pedal.

I don't even know if it moves the actual throttle unless the engine is running. So maybe you have a dodgy TPS or throttle actuator?

 

[Scuderia]

When I pump the pedal I can hear the TB valve operating. I didn't know no fuel was being pumped though.

 

[javacontour]

It's not like a carb with accelerator pumps. All the TB is doing is opening and closing the butterfly valve to let more or less air in.

The fuel injectors are fired by the computer.

Could it be that the time you spend pumping the pedal allows the fuel pressure to rise? Maybe you have a leaky injector or some other problem that cause the FP to drop, and the FP takes a bit to build up?

 

[hate2work]

How many miles?

The first thing I'd do is change the fuel filter. If you got a bad tank of fuel it could be permanently impaired. Is the FF in the gas tank on that rig? I know it is on the xa, not sure about the tc.

 

[mechtech2]

So it has a carburetor or fuel injection?
Pumping the pedal won't do jack squat for a fuel injection car.
Holding it down can cause a 'clear flood' mode to help start a flooded engine [many cars].
If the higher octane fuel is helping, you have carbon deposits, stuck EGR, or over advanced ignition timing. Possibly an advance cam.
For 2 MPG more, I'd use the higher octane for sure! That is a huge increase!

 

[94supraonchrome]

any check engine lights? have it scanned with a good OBD2 code reader. Check the MAF. Check anything that has to do with the throttle-it's electronic so it could be a number of things wrong with it or the ECU. good luck and keep us posted on what you come up with.

 

[Cutehumor]

how about testing your battery? do you drive all city miles?

 

[Quest]

Originally Posted By: mechtech2
So it has a carburetor or fuel injection?
Pumping the pedal won't do jack squat for a fuel injection car.
Holding it down can cause a 'clear flood' mode to help start a flooded engine [many cars].
If the higher octane fuel is helping, you have carbon deposits, stuck EGR, or over advanced ignition timing. Possibly an advance cam.
For 2 MPG more, I'd use the higher octane for sure! That is a huge increase!


it's EFI (2AZ-FE family series of cars, include scion and camry LE). These are also drive-by-wire.

If the user has to depress pedal in order to start the car, this is very, very wrong and would require full check to see if the throttle driving motor is receiving signal properly. Also: came across a couple of weird instances of this drive-by-wire pedal piece is bad (mostly past 120~150kkms) and would require replacement to resolve the problem.

All other standard diagnostic steps required on this call (fuel/fuel pressure, air? air temp, thermostat, etc.)

Q.

 

[mechanicx]

Pumping the pedal while cranking as long as you don't floor it (clear flood mode) could increase the fuel supplied (injector duty cycle) and increase airflow. You are increasing the TPS and and increasing MAP pressure. You might have a dirty throttle body and dirty injectors. I would clean the throttle body, run Techron fuel cleaner in the tank, and maybe replace the fuel fliter. It would be a good idea to check fuel pressure.

 

[Scuderia]

Originally Posted By: javacontour
Bad throttle position sensor? Your car is drive by wire, so pumping the throttle does nothing but tell the computer you've moved the pedal.

I don't even know if it moves the actual throttle unless the engine is running. So maybe you have a dodgy TPS or throttle actuator?


I fixed it. Basically I readjusted the TPS (I simply changed it from the position it was at) and reset the ECU. The ECU will adjust itself regardless of the position of the TPS, whenever you reset it. So you would think that simply resetting the ECU would have solved my problem, but it didn't. I wasn't until I moved the TPS manually that the problem was fixed. Hopefully now I get better gas mileage too. Thanks a lot guys.