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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 27664
Experience:  GM Grand Master Technician 2007. 11 years experience.
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I just replaced the trottle body on my 07 Tahoe as my TPS sensor

Customer Question

I just replaced the trottle body on my 07 Tahoe as my TPS sensor was giving a Check engine light. Now, when I start the truck, the engine is revving at 3000 RPM. Help. What do I do?
Submitted: 5 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 5 years ago.

Welcome. There is a throttle learn procedure that must be done after a throttle is replaced. Below are the instructions.

Throttle/Idle Learn

Description

The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.

Conditions for Running the Throttle Learn Procedure

DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
The engine speed is between 450-4,000 RPM.
The manifold absolute pressure (MAP) is greater than 5 kPa.
The mass air flow (MAF) is greater than 2 g/s.
The ignition 1 voltage is greater than 10 volts.

Throttle Learn

Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

  1. Start and idle the engine in PARK for 3 minutes.
  2. With a scan tool, monitor desired and actual RPM.
  3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
  4. Ignition OFF for 60 seconds.
  5. Start and idle the engine in PARK for 3 minutes.
  6. After the 3 minute run time the engine should be idling normal.

    Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.

    If the engine idle speed has not been learned the vehicle will need to be driven at speeds above 70 km/h (44 mph) with several decelerations and extended idles.
  7. After the drive cycle, the engine should be idling normally.
    If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds and repeat step 6.
  8. Once the engine speed has returned to normal, clear DTCs.
Customer: replied 5 years ago.
Just tried the idle in PARK. The engine speed is now at 2500 RPM. Idling twice at 3 min with 60 second OFF intervals did not work. Drove the car for 10 KM. Idle seems to set at 680 RMP when stopped with brakes applied with trotte at 5% showing on data reader. As soon as brake is released and the vehicle starts rolling, the throttle opens to 10-12% and RPM goes up to 1000. At the final stop, placed the vehicle in park and the RPM stabilized at 800 (still bit high). When I tapped the accellerator, the engine speed went back up to 2500 rpm. I am doing something wrong>?
Expert:  GM Tech (Cam) replied 5 years ago.
Are there any DTC's set?
Customer: replied 5 years ago.
none appeared during the whole procedure
Expert:  GM Tech (Cam) replied 5 years ago.
What was the system doing that you needed to replace the throttle body in the first place?
Customer: replied 5 years ago.
Throttle position sensor was bad, and since the TPS is a part of the trottle body - the whole TB had to be replaced.
Expert:  GM Tech (Cam) replied 5 years ago.
Ok. Try performing a capacitor discharge (remove battery cables, hold together for 10 seconds) and perform the relearn again. THe App sensor is good them?
Customer: replied 5 years ago.
APP sensor seems to be ok, since the car was working fine before the new TB was put in. I will attempt the discharge. I have read other suggestions, which recommend just simply driving the car for about 30 minutes. Do u think a longer trip may be beneficial, since I've only driven for about 10 minutes.
Expert:  GM Tech (Cam) replied 5 years ago.
It would be worth a try. Honestly, I have not seen one of these fail yet so I am going by what the manual says.
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 27664
Experience: GM Grand Master Technician 2007. 11 years experience.
GM Tech (Cam) and 13 other Chevy Specialists are ready to help you
Customer: replied 5 years ago.
FYI: Discharged the capacitor, started the car and it ran high for 10 seconds and went back to normal. Thanks for your help!
Expert:  GM Tech (Cam) replied 5 years ago.
GREAT!!! Have a great day!!
Customer: replied 5 years ago.
On my 3rd restart, the problem came up again. Here is what happened:

I drove about 60 KM. Everytime time I would stop at a traffic light, the RPM would first settle at ~1000, then slowly go down to ~680. As soon as I let go of the brake pedal, the car slowly starts rolling on idle. As it hits 5 km/h, the RPM jump to 1000 and the car begins to accellarate without my input.

I stopped and took off the positive battery terminal, then plugged it back on. Started the car, the RPM went to 2000, then within 10 seconds came back to normal ~680. As soon as I gently tap the accellerator, the RPM go to 2500-3000 and stay like that. I've had it running like that for about 10 minutes and with no change.

What do you think may be the problem? Faulty TB? I thought that maybe the APP is to blame, but it worked fine before I replaced the TB.
Expert:  GM Tech (Cam) replied 5 years ago.
I agree that the App should not be the issue. Let me do more looking.
Customer: replied 5 years ago.
I failed to mention that I have an aftermarket intake system, but with an OEM MAF sensor. Could the aftermaket intake be causing this problem with increased airflow? The intake is from K&N
Expert:  GM Tech (Cam) replied 5 years ago.
That could do something. Is the filter a dry filter or an oiled filter?
Expert:  GM Tech (Cam) replied 5 years ago.

I found a bulletin that says the ECM may need the throttle reset in the ECM.

  • If a driveability concern is experienced right after throttle body cleaning/replacement and SI diagnosis does not isolate the cause of it, perform step 1a.-1d., re-evaluate the concern after each step, and do not continue to the next step if a step repairs the vehicle:
    a. Perform the Tech 2 "reset idle learn/idle learn reset" procedure to erase/reset the learned throttle angle. Depending on the vehicle, this function is normally found in the ECM menu for Module Set Up or Special Functions/TAC System.
    b. Disconnect the ECM for 15 minutes and reconnect it.
    c. Reprogram the ECM with the latest calibrations by using the "replace and reprogram ECM/PCM" option in TIS2Web (may be the same calibrations in some instances).
    d. If SI diagnosis does not isolate the cause of this concern and it is not resolved after performing the steps above, replace the ECM.
  • If a driveability concern is experienced right after ECM reprogramming/replacement and SI diagnosis does not isolate the cause of it, perform each step below, re-evaluate the concern after each step, and do not continue to the next step if a step repairs the vehicle:
    a. Perform the Throttle/Idle Learn drive cycle described in SI.
    b. If SI does not contain a Throttle/Idle Learn drive cycle for the vehicle you are working on, clean the throttle body and perform the Tech 2 "reset idle learn/idle learn reset" procedure to erase/reset the learned throttle angle. Depending on the vehicle, this function is normally found in the ECM menu for Module Set Up or Special Functions/TAC System.
  • Customer: replied 5 years ago.
    It is an oiled filter from K&N Part 63-3058 on a Cold Air Intake. It has last been cleaned and oiled about a month ago.
    Customer: replied 5 years ago.
    I don't think I can do these mods with my computer. I have a superchips programmer which can give me readouts of various sensors, but I doubt that it would allow me to do these calibrations. Are you familiar with these?
    Expert:  GM Tech (Cam) replied 5 years ago.

    Ok, clean the mass air flow sensor. Often too much oil will cause a false reading and most people over oil the filter.

    No, this is likely a dealer or shop only scan tool procedure.

    Customer: replied 5 years ago.
    I appreciate all your input!
    Expert:  GM Tech (Cam) replied 5 years ago.

    No problem at all, I aim to please!!!

    Customer: replied 5 years ago.
    Once I figure this out, I will send you feedback on the solution!
    Expert:  GM Tech (Cam) replied 5 years ago.
    Ok.

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