PD150-ARL Engine problem

[med roberts]

Hi ,
My golf 150 (53reg) on ocassion on start up, the engine will not rev-up.At the same time, I have noticed lots of smoke coming from the exhaust(unburnt fuel possibly?) By switching the engine off/on several times the engine fault seems to clear along with the smoke, and then it will drive perfectly. No error/message is being created by this intermitant fault.The car has 62,000 miles on the clock.Has anybody experienced the above fault? Is there some testing which I can carry out ?
The above fault has occured 3 times in the last month to give you an idea of this strange occurance.Please help!!!!!!
MED ROBERTS.

[veedub76]

Could be your coolant sensor,or the MAF at fault.My PD150 ARL has been a pain recently a new MAF cured a flat spot.Have you had any camshaft problems,does it make any tapping noises from the top half of the engine on start up???

[med roberts]

Hi,
My golf does not suffer with noises from the top end of the engine, and I don't suspect camshaft wear, as I have changed the oil @ 3,000 mile service intervals with the correct grade of engine oil ! since when I purchased the car with 36,000 miles on the clock (60,000 miles@present)
Is the mass air flow meter likely to give my sympthoms ? Why is there no errors/messages created if it is this? Is there any way of testing it , bearing in mind that the fault is so inttermitant ?
Also you suggest the coolant sensor, could you enlighten me as to why that could be ? How can I test this ?

Many Thanks,
MED ROBERTS

[carcus]

Hi, I have just had the same problem with my 150 ARL engine, bought new MAF and MAP sensors and didn`t cure it, it turned out to be a butterfly in the inlet pipe at the back of the engine bay where the plastic intake pipe joins onto the metal casting. There is some sort of a actuaor that works the butterfly and when the butterfly sticks with old oily deposits and carbon then you will have difficulty starting and no revs and clouds of smoke from the exhaust. just remove plastic pipe to gain access to butterfly inside casting and clean thoroughly with carb cleaner until it moves freely and doesn`t stick. when you turn off the engine watch the actuator and after 3-4 seconds you should hear a click and see the arm move. if not it is sticking and you will have the symptoms you have described.
Hope this helps and saves you some money.
Carcus.

[med roberts]

I have removed the EGR valve and cleaned it, as it was heavily choked with oily carbon deposits. And could well have been causing the "butterfly" flap to stick. Time will now tell, as they say !!! as to whether the engine fault I posted is cured. Many thanks to Carcus for this valuable tip.