MK2 KR 16V GTI RUNS ROUGH ONLY WHEN STARTING TO GET WARM.

[KRdubber]

Hi everyone, been having a few issues with my 16V KR motor recently. Continuous Injection System (no knock control) and Fully Electronic Ignition System with no vacuum advance mechanism.

The vehicle starts, runs and drives beautifully when cold but as soon as the engine temperature reaches approx. 50-60 degrees so the idling starts to get rough and gets worse the hotter it gets but would never cut out, however, when driving its pretty much fine except the odd misfire here and there but nothing constant once up to 50-60 degrees. I carried out basic checks and replaced plugs leads cap and rotor just to rule them out then checked the ignition timing and found that the timing was being adjusted by the hall sender/ distributor very erratically whilst idling, carried out tests on the hall sender, coil and Ignition control unit including the temperature sensors on the passenger side of the cylinder head which I have recently replaced. All tests came back good except for my hall sender signal so I replaced the complete distributor with hall sender, Now the engine still starts, runs and drives perfectly when cold, then when the engine starts to get to around 50-60 degrees the engine still runs badly on idle and gets worse with temperature increase so checked timing again and now timing is spot on and not fluctuating BUT engine still runs rough on idle and once up to complete operating temperature actually cuts out on idle which it never did and still doesn't do with the old distributor fitted so part of me thinks I have a separate issue but another says how come the engine cuts out with new distributor and not the old so is it that the new distributor/ hall sender is more sensitive to engine running signals or is it a related fault?


The thing to keep in mind is that it seems temperature related, the warmer she gets the worse she runs.
Engine does not overheat nor does the cooling system over pressurise.
I have also tested the idle stabilisation and the overrun cut-off system which seems to be operating correctly along with the electrical side of the warm up regulator.
Need to carry out fuel pressure tests later on but if theres any KR experts out there then your help would be highly appreciated.
Thankyou all in advance.

[Gambit]

Where did you buy the dizzy from? Only use a bosch dizzy in them, might cost a bit more but will last for years. Also, i presume you are checking the timing with the red wire at coil disconnected? Also, check co% and set 2%

does the idle hunt or is it static at 950-1000rpm

[jakethesnake180]

I recently had cut out problems with my KR.
Once the car was warm the rev counter would dance about and engine would die.
Turned out it was the hall effect as you have mentioned.
replaced dizzy with a Bosch unit from VW and issue went away.

However I also replaced the coil at the same time.
Could this be your issue? Rare that coils fail in such a way but it could be affected by the heat.
They are only £20 so could be worth a shot.