Chevy Trailblazer SS Forum banner

1 - 7 of 7 Posts

·
Registered
TrailblazerSS
Joined
·
130 Posts
Discussion Starter #1
I was bored at work on saturday so I figured I'd clean my throttle body out. Ever since it seems as if the truck will not idle down or like its sticking open. Im guessing this is because the IAC is set for the dirty throttle body. So I tried to reprogram the ECM and that did not change it. Tried to disconnect the battery for 30 mins. That didnt change it. Anybody heard of this before? Im gonna try to load in the factory GM tune tomorrow and see if that fixes it, then load in my HP tuners tune.
 

·
Premium Member
'08 TrailblazerSS
Joined
·
4,146 Posts
Be patient and just drive it. The ECM needs to relearn the new idle airflow rate thru the now cleaned throttle body. Leave the tune alone. Your truck does not have an IAC motor / system that is for cable driven throttle bodies, it is all done thru the drive by wire and throttle blade angle adjustments on your drive by wire.
 

·
Registered
TrailblazerSS
Joined
·
130 Posts
Discussion Starter #3
Good point! I didnt think about these things not having IAC's. It has gotten better the past few drive cycles. I wonder if there is an idle relearn that you can do with the tech 2?
 

·
Premium Member
'08 TrailblazerSS
Joined
·
4,146 Posts
Good point! I didnt think about these things not having IAC's. It has gotten better the past few drive cycles. I wonder if there is an idle relearn that you can do with the tech 2?
Yes there is actually but from what I understand the idle relearn with the Tech2 just clears the learned data to clear the way for idle relearn through drive cycles.

Throttle/Idle Learn
Description
The engine control module (ECM) learns the airflow through the throttle body to ensure the correct idle. The learned airflow values are stored within the ECM. These values are learned to adjust for production variation and will continuously learn during the life of the vehicle to compensate for reduced airflow due to throttle body coking. Anytime the throttle body airflow rate changes, for example due to cleaning or replacing, the values must be relearned.

An engine that had a heavily coked throttle body that has been cleaned or replaced may take several drive cycles to learn out the coking. To accelerate the process, the scan tool has the ability to reset all learned values back to zero. A new ECM will also have values set to zero.

The idle may be unstable or a DTC may set if the learned values do not match the actual airflow.

Conditions for Running the Throttle Learn Procedure
Reset Procedure
• DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0351, P0352, P0353, P0496, P0601, P0604, P0606, P060D, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 are not set.

• Ignition ON, engine OFF.

• The vehicle speed sensor (VSS) is 0 km/h (0 mph).

Learn Procedure
• DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0351, P0352, P0353, P0496, P0601, P0604, P0606, P060D, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 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 voltage is greater than 10 volts.

Throttle Learn
Reset Procedure (Performed after the throttle body is cleaned or replaced)
Ignition ON, engine OFF, perform the Idle Learn Reset in Module Setup with a scan tool.
Start the engine and monitor the TB Idle Airflow Compensation parameter. The TB Idle Airflow Compensation value should equal 0 percent and the engine should be idling at a normal idle speed.
Clear the DTCs and return to the diagnostic that referred you here.
Learn Procedure (Performed after the ECM is flashed or replaced)
Note: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

Start and idle the engine for 3 minutes.
With a scan tool, monitor the Desired Idle Speed and the actual Engine Speed.
The ECM will start to learn the new idle cells and Desired Idle Speed should start to decrease.
Ignition OFF for 60 seconds.
Start and idle the engine for 3 minutes.
After the 3 minute run time the engine should be idling normal.
Note: 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.

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.

Once the engine speed has returned to normal, clear DTCs and return to the diagnostic that referred you here.
 

·
Registered
TrailblazerSS
Joined
·
130 Posts
Discussion Starter #5
Well after driving it today it seems to be back to normal. You wouldnt belive how goofy it was acting after I first cleaned it. Even the downshifts were crazy. Thanks very much for the info!
 

·
Dirty Mexican
'08 9-7x Aero AWD
Joined
·
1,051 Posts
Well after driving it today it seems to be back to normal. You wouldnt belive how goofy it was acting after I first cleaned it. Even the downshifts were crazy. Thanks very much for the info!
So what did you do to fix it? I just installed a brand new throttle body that I had ported and polished on my Saab but its also idling higher than before after driving it. Once you get to a full stop, the idle comes back down to normal after a few seconds of idling high.
 

·
Premium Member
2008 Imperial Blue
Joined
·
4,473 Posts
Same thing here. I'm awaiting the self re-learn.
 
1 - 7 of 7 Posts
Top