Golf TDI MK4 hot starting problem

[scotty15]

Hi Guys
I could do with your help to help my golf mk4 GT TDI 110 1998.When she has warmed up even after a 2 or 3 mile run and stopped ,then when you try and restart it it takes 10 or 15 seconds to start.I have had the vag com software on and there are no faults and the pump timing is spot on I have changed the 109 relay the temp sender was changed 6 months since,that was changed to try and cure the over heat warning light coming on when the car has being parked up over night and the air temp is below 5c but the new sensor did't cure that but back to the issue ,I have put new o rings in the fuel filter T ,It has had new fuel return pipe from injectors to the pump.There is some random air bubbles in the fuel pipe but that is there when is starts from cold and there is no problem then.The battery is in a1 condition only 18 months old.So after all that I am at a loss to what to do next so it is over to you guys to try and shed some light on what I could do next.

Scotty

[Crasher]

I have had this due to a faulty starter motor. The rather odd diagnostic procedure is to recode the ECU for an automatic box and see if the problem goes away. If it does, replace the starter.

[scotty15]

Thanks I will plug the old girl onto the laptop and try it thanks.It does sound odd but anything is worth a try.

I will keep you posted

Scotty

[25annigolf]

check earth cable from battery to gearbox make sure it is clean & secure it was a known fault on 20v turbos with hot start problems

[greg123]

Have you checked out the usual suspect, the sticking anti-shudder valve? It's the 'throttle' on the manifold, when you turn the engin off observe it operate. When stopped, it shoudl then spring back to the 'open' position. Make sure you work it and check it's 'open' before starting the car, see if this fixes. If so a clean and service of your manifold likley to fix it. It's also possible to remove the egr and the anti shudder thouch each has consequences and more involved than just unbolting the bits - read past posts.

[scotty15]

I have now checked and cleaned the earth strap so I will see how it goes 2morrow and the anti shudder valve you can hear when you turn the engine off every time, but I will check it when it has a run 2morrow I have also replaced the duel temp sender again because when you disconnect the plug when it won't start it starts straight away so it is a total mind boggler.

Thanks scotty

[scotty15]

It is still no better where will I find the setting within vagcom to alter the setting from manual to auto as to check the starter motor fault.

Thanks Scotty

[Crasher]

You recode in Engine 01, coding 07 changing the value from 00002 (manual) to 00001 (automatic), exit coding, exit engine 01. Turn off the ignition and back on and you will see the coding in the ID section has changed to 00001. Now try starting the car and see if it is better. If it is, change the starter motor. The ECU will log a fault code saying the auto box isn't communicating but just delete that when you have changed back to manual coding. As to what effect this recoding has on driving, I don't know as I have never driven one like it, I just static test.

[scotty15]

Thanks crasher I will try it 2morrow now as it now being pout to bed in the garage and it is blocked in with my Disco and I will see what it drives like in the auto setting and let you know for reference.

Thanks Scotty

[greg123]

What goes wrong with the starter motor? If it's swinging the engine over, how can it be faulty? Is there some kind of electronics in there - I thought it was the standard 'passive' single feed wire from battery and the solonoid activation wire, which if it swings the engine over, means it's okay?

[scotty15]

It must be that the starter is drawing to much power and that it might not be turning the engine over fasting enough.That is my only sugestion about the prob I have found some info on a ecu repair company and that says about the hot start problem http://www.bba-reman.com/content.aspx?content=hints_and_tips_volkswagon.

Scotty

[Stevef.]

It is something to do with the starter motor speed, when the car is warm it will not inject fuel until the engine reaches a certain rpm, I think its 250rpm when cold it injects straight away, this is what i have read elsewhere switching the ecu to auto will allow it to inject straight away even if its hot.

[Crasher]

As I said Greg, I don't know why this works.

[scotty15]

Quick update I altered the ecu to think it is a auto and it starts fisrst time everytime and I have being using it in the auto setting and there does'nt seem to any driverablity issues it just put a fault code in the ecu saying there is no TCU input signal.Thanks for the info lads I will be stripping the starter us to see if there is any probs that can be fixed if not then a new starter it is.

Scotty15

[Alex Himself]

Hi,

Got the same problem with my car and starting when warm. How do you change it from manual to auto? Is there any problems when changing over to auto?

Cheers

Alex

[Crasher]

You need a fully working copy of VAG-COM to recode the ECU. I can't recommend driving the car like this, I am sure it must do long term harm, it is purely as a diagnostic aid and if people end up using it as a bodge, I will regret revealing it.

[scotty15]

Quick update I have removed the starter and stripped it down and cleaned it up got all the cr*p out of it and it is back on the car now and it starts just like it used to first time everytime.

Thanks for the help and advice

Scotty15

[Crasher]

Was it full of black dust?

[scotty15]

yes it was but it is'nt now.

Scotty

[Crasher]

That is an indication of dual mass flywheel failure. A lot of remanufactures now refuse warranty on recon starters that fail if they are full of this dust.

[scotty15]

no sorry the starter gear side was as clean as it was when it was new the dirt was in the brushers bit.

Scotty