Hodgeee
Member
- Joined
- Sep 5, 2023
- Posts
- 59
- Reaction score
- 58
Figured this could be very useful if someone else has this problem. Had a rpm drop of 200rpms when coming to a complete stop, and idle surging also, which would cause the vehicle to lurch forward, almost hitting curbs and cars at lights.
Had at two different dealerships, and no one after every possible other check could not fix or find the problem. Was suggested to replace the throttle body, and even the ECM. Put a new Hitachi throttle body on the vehicle, and it fixed the issue for two days, then slowely problem returned. Did the idle relearn procedure countless times to no avail.
Finally had a diagnostician come to the house, and with a Snap On diagnostic tool found that the throttle body open position, was off by 80% of the desired position, along with a hidden lean code on both banks. The vehicle when i bought it had a Dorman TB on it, and it had the problem since I got the truck. He said that these values need to match or be within 10%, except at idle. He then adjusted the numbers with the tool. When at light throttle the vehicle indicated 15 degrees, but the desired position was at 30%. This cleared the lean codes, as it was giving fuel for much smaller than the air coming into the vehicle. The vehicle has now picked up significant power, and the gas mileage has increased, but mostly the rpm dip and idle surge have been irradicated.
Finally he explained that the idle reset only helps set the idle, but also can cause huge rpm related items. He stated that the idle relearn only helps when you clean the throttle body, but when you put in a new unit, it has to be relearned and sometimes adjusted to work correctly. Even sometimes the idle relearn, or reset does not work without a high end scan tool to adjust this, so he recommends to not clean a really dirty TB, cause it causes problems like mine, unless its original and recieves regular cleanings. He states that this applies to all 2000 to current Tahoes or Yukons, and Denali.
Ive been trying to fix this for months, and like stated, had two dealerships that couldn't figure it out. And he did it right after I explained the problem. Hopefully this will help others that have related problems.
p.s. He stated that a ECM reset does not erase the memory, or a disconnect of power as some people have discribed. The ECM has an internal storage that holds running data, that can only be erased with a proper scan tool only. The reset can fix some issues. I have found that many electic items when replaced must be Flashed to your ECM, like the stereo, or the fuel pump control module, or the THROTTLE BODY!
Had at two different dealerships, and no one after every possible other check could not fix or find the problem. Was suggested to replace the throttle body, and even the ECM. Put a new Hitachi throttle body on the vehicle, and it fixed the issue for two days, then slowely problem returned. Did the idle relearn procedure countless times to no avail.
Finally had a diagnostician come to the house, and with a Snap On diagnostic tool found that the throttle body open position, was off by 80% of the desired position, along with a hidden lean code on both banks. The vehicle when i bought it had a Dorman TB on it, and it had the problem since I got the truck. He said that these values need to match or be within 10%, except at idle. He then adjusted the numbers with the tool. When at light throttle the vehicle indicated 15 degrees, but the desired position was at 30%. This cleared the lean codes, as it was giving fuel for much smaller than the air coming into the vehicle. The vehicle has now picked up significant power, and the gas mileage has increased, but mostly the rpm dip and idle surge have been irradicated.
Finally he explained that the idle reset only helps set the idle, but also can cause huge rpm related items. He stated that the idle relearn only helps when you clean the throttle body, but when you put in a new unit, it has to be relearned and sometimes adjusted to work correctly. Even sometimes the idle relearn, or reset does not work without a high end scan tool to adjust this, so he recommends to not clean a really dirty TB, cause it causes problems like mine, unless its original and recieves regular cleanings. He states that this applies to all 2000 to current Tahoes or Yukons, and Denali.
Ive been trying to fix this for months, and like stated, had two dealerships that couldn't figure it out. And he did it right after I explained the problem. Hopefully this will help others that have related problems.
p.s. He stated that a ECM reset does not erase the memory, or a disconnect of power as some people have discribed. The ECM has an internal storage that holds running data, that can only be erased with a proper scan tool only. The reset can fix some issues. I have found that many electic items when replaced must be Flashed to your ECM, like the stereo, or the fuel pump control module, or the THROTTLE BODY!
