You're basically right.
But I haven't done a comp test....because if the head comes off it all get s too expensive
The mechanic I had the car at for initial diagnoses, said all other cylinders had good compression, but none on number 4.
The car had 'run badly' , at IDLE, for a total of two to three minutes, including roadside assist diagnoses, and not say, at 100kph on the freeway.
And so, when I replaced the #4 intake spring, I also pulled out the pushrod and it had suffered NO damage, so I can assume the lifter is also not externally damaged, although there's no saying if it is fecked internally. The spark plug from number 4 is also fine, not damaged.
So, to summarise:
Car will NOT start, but:
Car has fuel, fuel pump, fuel injection, good spark, good coils, NO fault codes whatsoever, a new CAS, a good battery, no water in oil ( although a little in water, as per normal)
and an engine with dodgey compression on ONE cylinder but it still won't even cough, when I turn it over.
In fact since being to the mechanic, the starter sounds weak or like it's trying too hard to turn the engine over.
Perhaps it's on the way to being seized, or all the main bearings are spun.....?
It could be the DFI, the MAF, the IAC, the Cam Angle Sensor, the Oil Pressure Switch/Sender, the O2 sensors, the this the that.....
I might try a fuel filter, but really, I've already spent nearly $800 of my time and money on a car that still doesn't run and was barely worth $1500 before it broke. I think the writing is on the bin for this VT......