I have scanned the various threads regarding hard starting issues and I would speculate that this is a very common and frustrating problem for many TDI owners. My 2000 Beetle has the average issues which I remedied with a VagCom change for the glow plug duration. I verified compression, timing, no air in fuel, fuel shutoff solenoid, egr valve, etc. The engine runs fine with no issues once started.
If I didn't have the VagCom option, it appears that the VW dealers offer no solution to this problem, other than replacing good parts with a shotgun troubleshooting approach. I've never read that the dealer will perform a GP duration adjustment.
It makes me wonder why VW decided to disable the glowplugs above 9C/48F. A new engine seems to start fine with this arrangement, but experience indicates that this is a dicey situation which can be degraded by many factors, resulting in hard start issues. It is unfortunate that VW did not foresee this issue and provide a system with a manual GP button that could assist in starting. Or design the ECU with an automatic 2 Second GP cycle regardless of temp.
Perhaps they were trying to promote the TDI in a difficult US market and wanted to portray the diesel as similar to a gas engine. Just jump in and start with no GP needed!
My TDI is still difficult in certain situations. It starts fine when warm or when it has been sitting long enough for the ECT to drop for the GP to come on. I'm in Anchorage and have found that at around 0F, the ECT remains around 25C after 2 hours sitting outside after shutdown. This disables the GP circuit, because the ECU thinks the engien is warm, but will not start with the 0F air. It does no good to cycle the ignition and GP cycle because the GP's get no juice at all in this configuration. If I wait another hour, the ECT drops, the GP's come on, and it starts immediately. Otherwise, it's crank and wait, crank and wait, cross your fingers, and as the battery eventually begins to wear down, the engine will kick over. I hate walking out the Beetle while studying my wristwatch. Will it start this time ? Whats the wind chill factor? How long has it sat? Is it pointed to magnetic North??
I am tempted to install my own GP activation circuit with a set of relays and a momentary button. Then I can give it a couple seconds of heat when needed, regardless of what the ECU thinks.
The other option appears to be putting a momentary switch into the ECT sensor circuit, fooling the ECU into thinking it's cold. There are several threads dealing with this approach. This also activates some injection timing advance which also helps with a hot start problem that some have.
I kind of like the brute force external relay method. It avoids the possible fault codes from the ECU. And I control the GP cycle directly.
If I didn't have the VagCom option, it appears that the VW dealers offer no solution to this problem, other than replacing good parts with a shotgun troubleshooting approach. I've never read that the dealer will perform a GP duration adjustment.
It makes me wonder why VW decided to disable the glowplugs above 9C/48F. A new engine seems to start fine with this arrangement, but experience indicates that this is a dicey situation which can be degraded by many factors, resulting in hard start issues. It is unfortunate that VW did not foresee this issue and provide a system with a manual GP button that could assist in starting. Or design the ECU with an automatic 2 Second GP cycle regardless of temp.
Perhaps they were trying to promote the TDI in a difficult US market and wanted to portray the diesel as similar to a gas engine. Just jump in and start with no GP needed!
My TDI is still difficult in certain situations. It starts fine when warm or when it has been sitting long enough for the ECT to drop for the GP to come on. I'm in Anchorage and have found that at around 0F, the ECT remains around 25C after 2 hours sitting outside after shutdown. This disables the GP circuit, because the ECU thinks the engien is warm, but will not start with the 0F air. It does no good to cycle the ignition and GP cycle because the GP's get no juice at all in this configuration. If I wait another hour, the ECT drops, the GP's come on, and it starts immediately. Otherwise, it's crank and wait, crank and wait, cross your fingers, and as the battery eventually begins to wear down, the engine will kick over. I hate walking out the Beetle while studying my wristwatch. Will it start this time ? Whats the wind chill factor? How long has it sat? Is it pointed to magnetic North??
I am tempted to install my own GP activation circuit with a set of relays and a momentary button. Then I can give it a couple seconds of heat when needed, regardless of what the ECU thinks.
The other option appears to be putting a momentary switch into the ECT sensor circuit, fooling the ECU into thinking it's cold. There are several threads dealing with this approach. This also activates some injection timing advance which also helps with a hot start problem that some have.
I kind of like the brute force external relay method. It avoids the possible fault codes from the ECU. And I control the GP cycle directly.
