MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: mclarengineer on December 02, 2019, 01:36:19 pm

Title: Engine Starting Problem When It's Hot
Post by: mclarengineer on December 02, 2019, 01:36:19 pm
Hello All,

I have a vw golf, diesel 1,9 TDI match, 2007. my car has a problem which my service couldn't find the root cause of it. when I start my car in the morning, there is no issues, it starts perfectly. However, if I drive it for a while, like 20-30 minutes and stop and start it again, it struggles to start the engine and it takes 3-4 seconds to start properly. I firstly thought that it's a battery problem and changed it, it has got a bit better however didn't fix the problem completely. my service said that it can be eirther a temperature sensor problem or an injector problem which might cost quite a lot.

Did any of you guys observe the same problem on your car? Your help is appreciated.

Thank you..
Title: Re: Engine Starting Problem When It's Hot
Post by: Llew on December 05, 2019, 09:53:41 am
if i remember its might be a software issue try searching hot start - i think it can be sorted through mapping
Title: Re: Engine Starting Problem When It's Hot
Post by: Dan_FR on December 05, 2019, 10:26:21 am
Its an issue with the software delaying fuel injection until the engine reaches a minimum cranking speed - emissions nonsense

Fine when new, but older cars with ageing Starters and batteries often fail to achieve this minimum speed, and there is a delay until a secondary/back-up map is used that will inject fuel at any RPM

Cheapest solution is finding somebody to patch the map, often done as part of a basic remap

Otherwise time to fire the parts cannon at it - starter, battery and all associated cabling could be the culprit
Title: Re: Engine Starting Problem When It's Hot
Post by: mclarengineer on December 16, 2019, 11:35:17 am
Its an issue with the software delaying fuel injection until the engine reaches a minimum cranking speed - emissions nonsense

Fine when new, but older cars with ageing Starters and batteries often fail to achieve this minimum speed, and there is a delay until a secondary/back-up map is used that will inject fuel at any RPM

Cheapest solution is finding somebody to patch the map, often done as part of a basic remap

Otherwise time to fire the parts cannon at it - starter, battery and all associated cabling could be the culprit

Thanks a lot for your answer. I have been told that changing the temperature sensor might help. What do you think? It’s also a cheap solution.