Engine Problem, Please Help! - Problem Solved Options

[fgvillegas]

Hi Guys,

I have a problem when I have just started the engine specially when the car was not used for an hour or so. And the problem is sure to happen on cold start.

Everything seems normal when I start the engine. But when it starts running, it seems like there is not enough fuel being supplied or maybe the throttle is a little sticky. The reason why I say this is because when I press the gas pedal as I do normally, I experience some hesitations. And when I press the gas pedal a little more the car will suddenly run fast and throw my passengers aback.

What I need to do is to rev the engine to about 3K or so whenever it hesitates. After doing this for maybe 3 to 5 times, the engine will start to work as expected. The longer I drive, the smoother it gets.

What could be wrong? Could it be the following?

• Injectors
• Spark plugs
• PCV valve
• Fuel filter
• Fuel pump
• Sticky throttle

What confuses me is: Why does it only happen at the start? I was thinking that it should always be the same if the problem is any of the above.

Please help!

Thanks

This post has been edited by fgvillegas: May 4, 2010 - 1:37 AM

[808celica]

Auto or manual??

Clean your throttle body, use injector cleaner, change the fuel filter, and check your cap and rotors.

[fgvillegas]

Auto or manual??

Clean your throttle body, use injector cleaner, change the fuel filter, and check your cap and rotors.

Thanks for your immediate reply.

It's a manual 3rd Gen 3SGE.

I just poured an injector cleaner last Friday (i.e., Motor Up's Fuel Treatment). I'm still observing but there seems to be no improvement. Is there anything that you can recommend?

I will have the throttle body cleaned tomorrow. I will also have the others you mentioned done as well.

BTW, how often do we need to change the fuel filter?

[808celica]

idle control valve

every 100k miles

[fgvillegas]

idle control valve

every 100k miles

Thanks again.

What should I do with the idle control valve?

[fgvillegas]

Just an update on this.

I have done the following:
- clean throttle body
- replaced fuel filter
- cleaned fuel pump filter
- replaced fuel pressure regulator
- cleaned some other vacuum related hoses and sensors
- cleaned PCV
- cleaned fuel injectors using in-tank solution

The problem did not go away.

What I did, I adjusted the SAFC to have +23% at 1000rpm and adjusted all the rest and the problem seems solved.

Problem is, the only mods done are the following:
- I-H-E
- MSD
- Exhaust Camgear set to +3deg

Could it be that the injectors are really faulty?
Is setting the exhaust camgear to +deg causing the fuel to lean out?

Please help. I'm a little confused.

Thanks.

[fgvillegas]

I was thinking if the problem could be the MAP sensor or the O2 sensor.

Will the computer use some default settings if I disconnect the O2 sensor? If this is the case, then if the behavior of the car will still be the same, it's not the O2 sensor.

Thanks.

[fgvillegas]

Hi Guys,

I finally figured what the problem is. It's the O2 sensor.

I first reset to ECU before disconnecting the O2 sensor socket then I zeroed out the air correction of my SAFC2. When I started the engine. The problem is gone. Just to check further, I run the car and see if the hesitation is still there. It's gone too.

Just to make sure that the problem is the O2 sensor, I reconnect the socket again and restart the engine. The problem went back.

For now, I just disconnected the socket of the O2 sensor while waiting for my order to come. I know that the default setting A/F setting of a disconnect O2 sensor is not as good as a working O2 sensor. But for now, I can live with that. It's better than having a rich A/F ratio setting using the SAFC2.

Thanks to all who helped and responded.

I hope this will also help anyone who may experience the same problem.