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Hello, my name is Bobby. Thank you for the question. Most of the time this is caused by an overly dirty throttle body. I would check and see if it is dirty. If it is then clean it and see how it runs. If it continues then you may need to check the signal from the TPS to see if it is reading correctly. Have these been checked?
The main thing is the throttle plate and bore. If there is even a little build up between then this will occur. The absolute best way to clean it is to remove it and thoroughly clean it with throttle body cleaner and wipe it out with a lint free cloth. If you do not want to remove it you can clean it as good as possible with it still installed on the engine. Just make sure that the key is off and that you open and close the throttle plate slowly as fast motions can damage it.
Really the main thing you want to see is a nice and even increase and decrease in voltage or angle, however your scan tool reads it.
Either way you want a nice and smooth increase and decrease in the signal.
No problem. I will look for your response. Have a good night.
Can you tell me if your scan tool reads live engine data? If it does then please tell me what the fuel trim readings are when the vehicle is acting up.
No problem. What I am looking for is LTFT and STFT.
Sounds good. I will look for the post when you can get to it.
I am away from my PC at the moment so I cannot open them. Once I get back to it I will check them out and let you know what I think.
Be back in a bit.
From those readings it looks as if the engine is running rich when the problem is occurring. From what I can tell the MAP sensor seems like it is not reading correctly when the problem is occurring. I would remove it and make sure it has a good vacuum source. I would also tap on it with the handle of a screwdriver when the engine is running and see if the idle changes at all. If it does then replace it.
Did you tap on it while the engine was running?
Let me know what happens and we can continue if needed.
Do you happen to have a vacuum gauge? If you do can you tell me what the vacuum is at idle and what it is at 2500 rpm and also how stable it is.
Thank you. Have a great weekend.
My last options are that the throttle body itself is failing or you have a programming problem. Will it typically always idle fine again if you rev it a few times?
Yes, the throttle body controls the amount of air entering the engine. From what you are saying it sounds like the throttle plate itself may be hanging up. Does it have a throttle cable on it or is it all electric?
I went back through our discussion to see if we talked about the idle control valve. Have you checked this?
Besides the possibility of a fuel pressure issue, which I think is unlikely, I think that the computer needs to be reflashed. I think that there is a programming issue.