[urq] //S4cylinder (#4 cylinder misfire)

[AUDIJIM at aol.com]

Today I finally performed a cylinder leak down test. My leak down tester 
reads in percentages and the percentages are further categorized as LOW. MODERATE 
and HIGH leakage. SET pressure is 0 (zero) of course. 10-40% is LOW, 40-70% is 
MODERATE, and 70-100% is HIGH. I did the test twice because a couple 
cylinders would not let me get a good seal when I screwed the hose tester into the 
spark plug hole. I cured this by spraying some WD-40 on the threads of the tester 
and it then screwed in just fine. Cylinder #1 was the best on both tests, 
testing at LOW/35%. Cylinder #2 was at the low side of MODERATE/45%. Cylinder #3 
was at the low side of MODERATE/40%. Cylinder #4 (the problem cylinder) was at 
the low side of MODERATE/42%. Cylinder #5 was at the low side of 
MODERATE/43%. All lost pressure was through the dip stick indicating some blow by with the 
piston rings. I squirted some oil down each cylinder and performed the test 
again and every cylinder was then reading LOW. So I ended up doing the test 
three times. There was no noise from the tail pipe and no bubbles or noise 
through the coolant expansion tank. I removed the hose to the throttle and had no 
noise coming from the intake side of the head. I'm very happy with the results 
because now I know that I do not have a mechanical engine problem with cylinder 
#4. I can also say that I can rule out fuel, because I can use a mechanic's 
stethoscope and hear #4 fuel injector click while it's misfiring. So I have 
compression, and I have fuel. The only thing I have left to check is the wiring 
from the ECU to the POS. Since all the POS's are new and the #4 coil is new, I 
have eliminated them as a fault. I might have some wire degradation between 
the ECU and the POS. I may run completely new wires from the ECU to the POS and 
see what happens. I ran out of sun light today, so I will test tomorrow, 
weather permitting.

Angry Jim
///S4cylinder