Originally Posted by
mk3-ralf
Cylinder 3 & 4 have a orangey gunk around them and on the spark plug threads. 1 & 2 are clean. This confuses me as 2 & 4 are firing.
Spark plug gaps I have not touched because they are preset. The old spark plugs are causing the same problem which were definately firing correctly before the car went up on stands for a couple of days.
I'm assuming fuel is fine because the plugs are getting covered in carbon buildup in the cylinders that aren't firing.
I will check the resistance on the leads tonight with a voltmeter to definitely rule them out as the culprit!
Unfortunately I don't have access to a lot of these tools including the fuel pressure gauge and cylinder compression tester and I'm only have self taught knowledge of motors.
The gaps are said to be pre set, yet they fit a wide range of cars with different gaps!!, ie they're not necessarily right in your case, so gap them.
In cylinders that DON'T fire, they will just get fuel soaked, NO CARBON can build up as it needs to ignite the fuel to produce that, and they're "not firing", this tells you they ARE firing.
I would clean the plugs, and look at the lambda sensor to see if it is covered in orange stain from tesco dodgy fuel from years back, I did a car late last year a 1.25 zetec that had "passed" so called legit mot's with a duff lambda.
I would for good measure change the fuel filter if not done so as well.
tabetha