Change a ECU paramater !!!!

[cbrpaul]

I dont think this is possiblle but if it is , and a vagcom expert knows how , please let me know :D

Some may know that the ECU ( on 1999 110 tdi,s anyway) , demands 250 rpm from the engine before injecting diesel, ONLY WHEN THE ENGINE IS HOT ,, and thus starting, if you dont hit the 250 rpm it wont start for a while , a weak starter motor has been blamed for this ,

Anyway there is a way to test if you have weak motor by doing the following using vagcom


Recode the ecu for auto Gbox.

connect to the engine block, go to recode, and change the value from 2 to 1,
so basically we tell the ECU we have an auto gearbox fitted so it disables the 250rpm demand when hot and starts within a second!!!

So does anyone know where this peice of code resides , is it possible to just alter disable this demand of 250rpm using vagcom and not changing the whole software coding to a auto gear box ,

If not and i keep the auto gear box code , will there be any ill effects of having the ECU think its an auto gear box fitted , :confused::confused:

i have enquired about a new motor , but they all seem to be re-con starters , so worried I will still have the same problem ?


all advice appreciated ;)

:beerchug:

[cbrpaul]

thought this might be abit of a difficult one ,


i just got a reply from ross-tec and they dont know either lol

I think only way is via a total remap !!!

:beerchug:

[ini]

You can not disable the min rpm function directly with vagcom, only set it to 'manual' or 'auto' box.

Throttle response will be jerky if you leave your box set to 'auto'.

If the starting problem vanishes when you disconnect your temp sensor, you could try using a simple relayed circuit to disconnect the sensor whilst the starter operates.

A remap would also make the symptoms go away.

If the starting revs are not obviously low, the problem is most likely fuel pump related, not starter/battery/alternator.

[cbrpaul]

hi ini

Thx for taking time to reply m8 ,;)


I did change to auto and she starts under 1 second everytime hot or cold , perfectly ,


Im pretty sure its the way VW programmed the " 99 " tdi AFN engines to work this way , for some unknown reason !!!! :confused:

This is why a remap solves the problem ,

Pulling the coolant temp sensor also makes it start imediately, due to the ECU using the cold start mapping in its absence, but i dont want to hack the wiring up to make a switch/relay setup though



I would buy a new starter, but they are all re-con starters apparently , so run the risk of still have the same problem after spending £100!!!!

Also im just worried one day , the mrs will pull out at a junction , and stall it half way across , and by the time shes re-started have an accident !!!! with kids in the car too , :(

So i think i will leave it in auto mode and live with the jerkiness, although it didnt seem to bad when i tested it out a few weeks ago , and it appears leaving it in auto mode will not do any harm to the engine as such !! :D

thx again
:beerchug: