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Discussion Starter · #1 ·
Hi all my 2007 3.0 tdi seems to have a hot start issue even if you shut down and try to fire it back up takes about 5 seconds

no fault codes in vagcom

battery only 6 months and is a Bosch 110amp

battery seems to charge well at over14 amps

coolant tempreture matches what it says in vagcom and doesn’t fluctuate

only thing I saw which looked out of the ordinary is the outside amp temp sensor shows 18c when it’s about 2c at the moment
Does this affect fuelling at all

don’t seem to have any major dramas when cold
 

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Monty mate, these kind of issues are often connected to an air leak perhaps on the intake system. And the thing you mention about the incorrect temperature reading seems to back this up. A temp sensor somewhere is reading incorrectly so I think that you need to start looking there, it is probably connected somehow.
 

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Discussion Starter · #5 ·
The alternator isn’t charging came on when I checked the battery with a multimeter it was charging at 14.6 v

Is the alternator system electronic or is it just old school and charges as soon as the cars running

The light went off after 5 seconds which makes it even more strange

I have checked and tweaked the battery connections they all look good and clean and the battery is new like the old owner said


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Discussion Starter · #6 ·
Did a bit more rooting around

- couldnt see any splits or loose clamps got boost pipes

-airbox doesn’t seem to clip in at the bottom properly I have tried to heat this to put it in place it’s fine at the top but not in the bottom corner
Have used some tape for now

-on tickover the cars charging at 14.9 volts. How do the systems work on these? Is this any issue

-The battery showed 12.6 volt this morning before started at 1c so doesn’t seem to be any major drain

Car runs lovely just something minor lol


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The air filter box sounds like the source of your problem, to be honest. The air filter box is totally critical, you mention tape but that is a very bad fix cos it will soon return. Remove the filter and the airbox and start again, if it is damaged then replace it!!!!
 

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Discussion Starter · #8 ·
It’s not damaged at all it just won’t sit in perfect at the bottom I used the tape if it’s fine for a day I’ll grab another airbox.
It’s a good awful design anyway the snorkel on the bottom kept popping off on fitting 😂
 

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Discussion Starter · #9 ·
Nothing I have done seems to have solved it

Taped up airbox at the bottom loads on eBay I’ve look at look the same
Made sure maf sensor cable was on properly
Took cam shaft sensor off to clean it

Started for work this morning wasn’t as instant as it normally is

Did 10 miles then stopped to refuel car then took 5 seconds to start and alternator light came on

Fitted my cigerette lighter that shows voltage to check on the way to work with heaters going was a steady 14.7-14.8 volts

Looked down and the car showed 11.9 volts and wasn’t charging. After about 10 seconds the light went out and the voltage went upto 14.7volts

How is the voltage controller I assumed the alternator just created voltage anyway


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Discussion Starter · #10 ·




Checked the battery was coded as it’s only a few months old

Noticed these fault codes but what’s weird is there not from today. I have recoded the battery again but I’m not holding my breath

The starter and alternator look a pig to change

How likely is the battery management module to be faulty

Starting was terrible 2 hours after getting back from work but battery voltage looks good


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Discussion Starter · #11 ·
Started fine this morning. Stalled it at the lights and when restarted battery wasn’t charging Rev the car in neutral and the car started charging

It charges perfect except this issue mainly when the cars been running and stopped and restarted


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Discussion Starter · #12 ·
I have changed the air temp sensor was a quick job

My display shows way off now shows -9 when it’s probably 0 degrees so will grab another
Only positive is vagcom shows as the same pretty much the same as the display where before showed fine on display but not on vagcom

Idle seems lower too

The alternator looks original and it’s a Bosch. Even when I don’t get the alternator not charging fault the fault still logs on vagcom

Just waiting for a quote from the garage probably grab a new starter while I’m there


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Discussion Starter · #13 ·
Now the weathers a bit warmer I haven’t had this issue for a few weeks

I’ve not had the alternator fault either

I will keep an eye on the voltage and replace both when weather improves ready for next year


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Discussion Starter · #14 ·
I had the alternator not charging fault today

It either sorts itself out after about 20 seconds or if I Rev the car the voltage kicks in

The car charges perfect once this is over with

Could this be the battery cable module and why is it doing this

Surely if the alternator was dodgy it would show some other symptoms


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Did you ever get to the bottom of this out of interest? Think I know the source of my issue but sounds similar to yours, so be great to hear how you overcame it.
 

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Discussion Starter · #16 ·
I changed the air sensor in the front bumper but the temp was even more all over the place. I then replaced it again which helped with fuelling

what did help was pushing the key in and waiting a second or 2 as I normally pushed it in and tried to start it at the same time
 
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