After replacing my throttle body when starting the engine it idles high and when braking vehicle lurches forward slightly

EMILY.FITZ7

MEMBER
2010 CHEVROLET EQUINOX
4 CYL
4WD
AUTOMATIC
150,000 MILES

Today I replaced my throttle body in my car. The shop I went to was able to do it within a few hours and they told me it was all good to go and passed the test drive. When I started the car, it immediately accelerated to over 2,000 RPMs and then settles down to normal idle. While I am braking it will accelerate slightly until it finally settles. Is this normal? Like will this eventually go away? Or did they not do something right?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

That sounds odd. I'm questioning if they did the relearn procedure after the install. Normally, a scan tool is used to do it. However, I found directions that can be done without a scanner. Try this and let me know if it helps.

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Without Scan Tool - Learn Procedure

Note: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.

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

Note:
* During the drive cycle the malfunction indicator lamp (MIL) may illuminate and idle speed DTCs set. If idle speed DTCs set, clear the DTCs so the ECM can continue to learn.
* If the vehicle is driven for more than 10 km (6 mi) a BARO update is necessary so the ECM can continue to learn. To update the BARO, accelerate to wide open throttle (WOT) and then release the throttle.

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 the DTCs with a scan tool.

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Note that where it says you need a scan tool to do something, those are things that will not affect the relearn procedure.

Let me know if this helps or if you have other questions.

Take care and God Bless,

Joe