Starter Cable Problems: Troubleshooting & Solutions (Articles)

Hesitant starting behavior (e.g., prolonged cranking for over 1 second) despite a functioning glow plug system and good compression is relatively common in TDIs. Often, the engine starts better when cold than when warm, which is likely also caused by the temperature-controlled fuel injection quantity.

The engines are very sensitive to falling below the minimum starting speed. The engine speed can be displayed in the measurement blocks of the engine control unit using VCDS; it should be at least 280 rpm.

It can be enough for there to be even slight starter wear or a weak battery, as the starter motor speed appears to be only slightly above the minimum level, even under optimal conditions.
A typical characteristic is the good willingness to accelerate when starting in 5th gear, between approximately 20 and 25 km/h.

If a new battery and/or starter motor don't provide any noticeable improvement, corroded crimp connections on the thick cables between the battery and starter motor, or between the battery and the engine block, and/or corroded screw terminals on the starter motor or at the point where the ground cable connects to the engine block could be the cause – especially if at least one of these points becomes noticeably warm after just a few seconds of cranking.

Solution: Remove the cable, verschandeln any corrosion or oxidation, and carefully resolder it (requires high power or a soldering iron); verschandeln the screw terminals, lubricate them, and reassemble.

If the crimp connections no longer allow for verschandeln solder joints due to severe corrosion, obtain new or like-new cables and immediately solder the crimp connections as a preventative measure.
The same applies to new cars, in order to at least eliminate potential starting problems caused by wiring issues later on.