running on 3 cylinders when cold?

my mk1 GTi 1600 has been running rough from cold recently. sounds almost like an inject stuck closed? a few revs and it will eventually run smooth…..is it tappets or injection?

Steve

If it is missing a cylinder check the HT leads first. These can break down in the cold but function at high revs or when the warmed up. Not conclusive just checking for a spark as might be present but not strong enough. Pull the HTs one by one with the engine running (don't hold with bare hand as can hurt). You should be able to identy the misfring cylinder by the change in sound, or lack of change when you pull the misfiring one.

Then swap the HT's to see if the misfire moves onto the cylinder to which you move the suspect HT. If it does then new HT's if not then possible fuel injector/engine issue. When you swap the HTs swap at both distributor and cylinder head end and maintain the firing order 1342 (follow leads back from cylinderhead left to right). Might help to mark no's 1342 on the distributor cap.

Cheers

right well i dont think its temperature dependent. It will go litterally after two revs….thats all it takes. Could it be spark plug gap? i realise the cam wont help at idle….

Could it also be an injector seal? is there a way of testing if an injector works?

cheers for your help

Steve

Have you got a non-standard cam? If the car is actually misfiring (not just running rough), but clears with a blip of the throttle likely to be an injector or spark plug/HT lead. How long does the car continue to run rough if you do not blip the throttle? Do you start the car with the accelerator peddle slightly depressed? Does the problem occur from both hot and cold starts?

Not sure if old seals would cause his problem, you can change the injector seals easily and they only cost a couple of quid for four new ones. Best way to test injectors is to follow Prowlers injector test

Cheers

My money is on leaking or bad injector.  Do Prowler's injector test.

I had problems with mine struggling on acceleration and also with hot starting. I took it to my garage who said that I needed  to take it to a specialist tuning centre. I got a second opinion who told me that it would be the metering unit or the accumulator. I finally went to a VW place in Winson Green who told me to start with the fuel pump. I was sceptical as I could hear the fuel pump kick in when I turned the ignition on. However it stopped starting altogther so I took the path of least resistance and fitted a fuel pump myself. The neighbours must have thought I'd had a lottery win when it started with the moise I made!! It still ran really lumpy and I clicked that it was only running on 3 cylinders. After a ten minute nervous breakdown that the engine was s I checked the spark and it was strong. So I decided to pop the injector and give it an external clean. Going on 4 cylinders within 20 minutes! Unless your fuel pump is very new I would recommend changing it. It takes an hour and the system relies on pressure. If one off your cylinders is not running exclude spark and fuel delivery problems before panicking about pressure. It is now running beautifully and hot starts like a dream. And I reckon I've saved myself £500 on a metering unit and accumulator that I didn't need! Oh and I'd never touched a fuel injection system in my life so thanks to Google, You Tube and the Haynes manual!!!!!

I have a new fuel pump, leads, cap and injectors in my car. It starts ok when cold, although does sound like it's on 3 cylinders to start with and when its hot it starts ok if it hasnt been sitting for long. However leave it for about 20 mins when hot and it can take a bit of turning over before she fires up.