Surge Or Bump Feeling At Stops - keywords 6.0L 6spd 6L90 brake cal calibration clunk idle L90 LY6 MYD prop propshaft sag shift shaft stop stumble yolk
| Subject: | Surge or Bump Feeling at Stops |
| Models: | 2007 Chevrolet Silverado |
| 2007 GMC Sierra |
| Equipped with the 6.0L engine (RPO code LY6) and the 6 speed 6L90 transmission (RPO code MYD). |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A customer may describe a surge or bump feeling when the vehicle is at idle, in gear, and brake applied. The surge/bump feeling can be intermittent.
The surge or bump felt at idle may be induced by a catalyst monitoring diagnostic event. During the event the system calibration will drive the fuel system lean then rich. The test is done to monitor catalyst efficiency. This test can cause a noticeable bump or surge when the vehicle comes to a stop (at idle), transmission in gear, and the brake applied.
Recommendation/Instructions:
There is a new ECM calibration for the surge/bump feeling. The calibration is included in the latest TIS2000 calibration. If the customer concern is an idle surge/bump at stops (as described in this PI), install the latest calibration and evaluate the customer concern.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
