Experiencing a sudden shudder in your car can be concerning, especially after modifications. Like many car enthusiasts, I’ve encountered this issue firsthand. My BMW, with a performance tune for about 15,000 miles without prior problems, recently started shuddering after a short drive and brief park. Initially, the start-up was rough, escalating to a very rough idle, almost mimicking a poorly running boxer engine. Restarting the car didn’t resolve it, nor did reverting the tune settings. The service engine light illuminated, but no half-engine warning appeared. My onboard computer indicated “Car is OK,” which was clearly not the case.
Using my Bav Scan Tool, I pulled a Cylinder 6 misfire code, a recurring issue previously solved by a simple restart. However, this time, the misfire persisted. Interestingly, no fuel pump codes were detected by the scan tool, despite fuel pump issues being a past concern.
My immediate plan is to remove the aftermarket tune to see if that resolves the shuddering. If the problem persists, I’m unsure of the next steps before considering dealership assistance. While I don’t expect the dealer to address tune-related problems, I’m not convinced the tune is the root cause.
Many in the car community suggest frequent spark plug changes. Could plugs be the culprit? If so, what replacement interval and plug type is recommended – OEM or aftermarket? The common replacement sequence seems to be plugs, coils, and then injectors. Is this order standard practice? Does coil replacement necessitate dealer reprogramming? Crucially, can a scan tool like my Bav Scan Tool handle coil reprogramming, or is dealer intervention unavoidable?
Seeking advice from experienced individuals who have tackled similar shuddering issues, especially those related to misfires and diagnostic tools, would be greatly appreciated. Understanding the engine’s common weak points and effective troubleshooting steps using a scan tool is my priority.
