| Subject: | Inaccurate Tachometer at High RPM with GM Performance Parts Stage 1 or 2 Kit |
| Models: | 2005-2007 Chevrolet Cobalt SS |
| 2004-2007 Saturn Ion Redline |
| with 2.0L Engine (VIN P - RPO LSJ) |
| and a GM Performance Parts Stage 1/2/3 Kit |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
The tachometer used in the Ion Redline is Class 2 based and the one used in the Cobalt SS is LAN based. As a result, the tachometer display rate is slower than the engine acceleration rate during hard acceleration. This may cause an approximate tachometer
delay of 500-600 RPM in first gear and 250-300 RPM in second gear. As a result, some customers may advise that their engine reaches fuel cut off before the tachometer displays 7,000 RPM even though the actual engine RPM is actually at 7,000 RPM. Once the vehicle
is shifted to third gear, the engine acceleration and tachometer display rates are similar so the tachometer should display actual engine RPM on hard acceleration.
Recommendation/Instructions:
If this concern is encountered, it should be considered a normal operating characteristic of the tachometer when the vehicle is equipped with a GM Performance Parts Stage 1/2/3 Kit. As a result, do not attempt any repairs to try altering this characteristic.
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.
