I have own my new to me 2003 Lexus SC 430 for 6 years. I drive the car a few time a week. My engine misfires quite a bit when I first start driving. I only use premium fuel and I have had the timing belt replace, fuel injectors cleaned, and tune up. The car has 102000 mile. No mechanic can tell me what’s wrong with the car. There are no engine codes. Has anyone ever experience this problem.

 

Did you use TechStream . Problem like this would generate DTC with TechStream.

 

Raven01750 found cracked coil packs on his car.

perhaps you have a coil failing, there is one per plug.

Is the check engine light on?
like Gman said, need to check for codes.
another common problem is the vacuum lines fall apart…
https://www.clublexus.com/forums/sc4...gs-2002-a.html

 

Check engine light does not come on and there are no codes in the system.

 

That is weird there are no codes. If that is the case, we have to go back to the basics.

When you say my engine misfires when it is cold, what do you mean? How often does it happen? Does it matter what the outside temperature is? Is it just in the morning?

 

When I start the car and start driving, the car has stalling feeling to it as if the engine is not getting fuel. This happens most after I have stopped and start driving. Once the car gets to the speed limit and continues it does not misfires again until I stop and start driving again. After about 30 minutes of driving the misfire goes away even if I stop and start driving. I have taken the car to a Lexus mechanic and they can't tell me what is causing this problem. Again there are no codes in the computer.

 

So does the car ever make any mis fire noise, or does it just seem "laggy" like it isn't running on all cylinders?

I just had a similar problem with a pickup truck at work. It would drive fine and then start to lag like it was about to die, then drive fine again. It turns out it was the fuel pump control module. This probably won't help you, because it was a Ford truck and not a toyota.

Still, if there are no codes, it makes me wonder how efficient your fuel pump is. (since air and spark is monitored)

Anyone know if Techstream will give you live data on Fuel Pressure?

 

try this…SC430 Accelerator Reset

1. Get in your car and insert key. (It doesn't matter if you close the door or not.)

2. Turn the key to the on (not start) position.

3. Press the gas pedal to the floor.

4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position

(don't remove the key), then release the gas pedal.

5. Wait 2 minutes.

6. Remove key.

 

I think ii’s something to do with the fuel pump or related to.

 

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