What is involved in a compression test for a NSX? How is it done?
compression test
- Thread starter VegasSpeed
- Start date
you do it like any other car, you take a compression test gauge. you then warm the engine up so the piston rings will expand to its normal size for a good seal. You then disconnect the fuel pump fuse so the engine won't flood when you are cranking.
After you run the engine with the fuel pump fuse disccnnected the should stall out in a few seconds. You when than remove the spark plug from the cylinder you want to test. The compression test gauge is basically a spark plug threaded tube with a gauge attached to it. You would now put the gas down all the way ( Wide open throttle ) and crank for around 3-5 seconds. You would look at what the needle reads in PSI and compare it to the manufacturers specs. You now repeat the steps 5 more times on each cylinder. You have to look if its at the minimum end of the factory tolerance and how much variance there is from cylinder to cylinder.
But the engine has to be in operating temp and the throttle has to be wide open when you test.
After you run the engine with the fuel pump fuse disccnnected the should stall out in a few seconds. You when than remove the spark plug from the cylinder you want to test. The compression test gauge is basically a spark plug threaded tube with a gauge attached to it. You would now put the gas down all the way ( Wide open throttle ) and crank for around 3-5 seconds. You would look at what the needle reads in PSI and compare it to the manufacturers specs. You now repeat the steps 5 more times on each cylinder. You have to look if its at the minimum end of the factory tolerance and how much variance there is from cylinder to cylinder.
But the engine has to be in operating temp and the throttle has to be wide open when you test.
Also be sure to ground your ignition coil, if not it will cause damage to it.
How is that done? I just unplugged mine.
BTW: If you don't know or you're lazy, the compression should be in the range of 140 - 200 with ... something like 10 or 20 variance. Good compression is considered 180+. I personally would be scared it if was in the 140 range...
195+ on good engines is not uncommon.
