Very nice videos, I studied autotronics a few years back and based on that experience I can tell your videos are among the best. Very informativel, thanks!!!
this is a good video. I've had air, fuel, spark and static compression testing check out good. running compression test can tell you if valves are sticking. i can't agree on your method on using the straight jumper wire to ground. a spark plug and spark tester have a 6000 ohm resistor in the center electrode of the plug. a jumper wire has no resistor in it and would blow a fuse if it were connected in series.
since you still have the valve installed in the hose shouldn't you release the pressure after cranking and let it go up when the engine is already idling since cranking pressure would be higher than idle?
jay matias how would cranking have more compression then idle??? slowly rotating while starting vs. running at 800-1,000 rpm idle. idling Obviously builds more compression. you have been mislead.
kent kirkpatrick the engine when cranking at 200 rpm would have more time to suck in air than at 800 rpm. if you have an oscilloscope and pressure transducer you would actually see the pressure going down when the engine starts to idle. I'm sorry bro but it was you who was mislead.
Fuel injection does not have anything to do with compression testing. It's physics, if you try to draw in air from a small opening into a container it would take a considerable amount of time to fill it, increasing the speed would increase the vacuum but not the mass of air entering the container.
So you should test each cylinder for proper amount of compression when you wanna buy a car? shouldn't only would be enough? And what is the proper reading for chevy prizm because I want to buy one. Thank you,
Good video on how to perform the test, but no info on why. Know what your static compression is. Idle compression should be about half of that and snap throttle should be about 80% of static. A lower than normal reading on throttle snap indicates a restriction of intake air (clogged air filter or stuck runner flaps, carbon build up on intake valves, Etc.). A higher reading, a restriction in the exhaust (clogged cat or muffler, etc.).
Hi there , are you not supposed to REMOVE ALL THE COILS AND SPARKS ? Then you have to disconnect the FUEL PUMP FUSE , this is the right way i guess .... and by the way because CRANKING the car would discharge the battery FAST , you got to connect the battery to a BATTERY CHARGER all the time during the cranking ..... isn't is this the perfect method ?!
How come your car works fine on 3 cylinders only My car stalls every time when I try to do the same process it works only with the 4 cylinders I have 2001 Corolla, What I did wrong
You have a coil for each cylinder. The coil also has a circuit called ignition fault (IGF). When the engine computer commands the coil to fire it tells the igniter inside each coil to turn on and off. When it turns the igniter off the coil fires. The circuitry inside the coil sends a signal, IGF, to the engine computer to let it know the coil fired. I believe if the PCM doesn't see that signal because you unplugged a coil's electrical connector, the PCM won't fire the injectors. On your design you have to do what he did in the video by shorting the coil secondary to ground. Another reason is if you have another cylinder not firing and you disable a working cylinder, two cylinders working isn't enough to keep the engine running especially if they are companions.
Basically, a running compression test allows you to check the breathing ability of each cylinder. A vacuum gauge can do that also, but you are checking all cylinders at that same time instead of just one at a time using the running compression check method. In the video he didn't describe the reason it is used or what different readings mean. That is important to determine what is a good reading, what is a bad reading, and what they mean. It is too bad it wasn't covered here because how to perform and set up the test was done really well in this video.
I'm going to school for auto mechanic and this is actually the exact same way I was taught to do it . Great video and very informative . Thanks
Very nice videos, I studied autotronics a few years back and based on that experience I can tell your videos are among the best. Very informativel, thanks!!!
this is a good video. I've had air, fuel, spark and static compression testing check out good. running compression test can tell you if valves are sticking. i can't agree on your method on using the straight jumper wire to ground. a spark plug and spark tester have a 6000 ohm resistor in the center electrode of the plug. a jumper wire has no resistor in it and would blow a fuse if it were connected in series.
Hu? There is very little current on the coil secondary side. Jumping the coil secondary output to ground will not blow fuses or damage the coil.
not sure how FUEL is stopped in an individual cylinder with a (spider, inside the intake manifold)
Spider? Fellow 4.3 owner I assume?
snapping sound is the ignition? good info!
You mentioned to use a spark tester or jumper wire , couldn't the coil connector just be taken off during test?
since you still have the valve installed in the hose shouldn't you release the pressure after cranking and let it go up when the engine is already idling since cranking pressure would be higher than idle?
+jay matias That is correct. As per what I was told in school.
jay matias how would cranking have more compression then idle??? slowly rotating while starting vs. running at 800-1,000 rpm idle. idling Obviously builds more compression. you have been mislead.
kent kirkpatrick the engine when cranking at 200 rpm would have more time to suck in air than at 800 rpm. if you have an oscilloscope and pressure transducer you would actually see the pressure going down when the engine starts to idle. I'm sorry bro but it was you who was mislead.
maybe on fuel injection. I've never heard this before tho.
Fuel injection does not have anything to do with compression testing. It's physics, if you try to draw in air from a small opening into a container it would take a considerable amount of time to fill it, increasing the speed would increase the vacuum but not the mass of air entering the container.
So you should test each cylinder for proper amount of compression when you wanna buy a car? shouldn't only would be enough? And what is the proper reading for chevy prizm because I want to buy one. Thank you,
Good video on how to perform the test, but no info on why. Know what your static compression is. Idle compression should be about half of that and snap throttle should be about 80% of static. A lower than normal reading on throttle snap indicates a restriction of intake air (clogged air filter or stuck runner flaps, carbon build up on intake valves, Etc.). A higher reading, a restriction in the exhaust (clogged cat or muffler, etc.).
Hi there , are you not supposed to REMOVE ALL THE COILS AND SPARKS ? Then you have to disconnect the
FUEL PUMP FUSE , this is the right way i guess .... and by the way because CRANKING the car would
discharge the battery FAST , you got to connect the battery to a BATTERY CHARGER all the time during the
cranking ..... isn't is this the perfect method ?!
not for a running compression test
How come your car works fine on 3 cylinders only
My car stalls every time when I try to do the same process it works only with the 4 cylinders
I have 2001 Corolla,
What I did wrong
You have a coil for each cylinder. The coil also has a circuit called ignition fault (IGF). When the engine computer commands the coil to fire it tells the igniter inside each coil to turn on and off. When it turns the igniter off the coil fires. The circuitry inside the coil sends a signal, IGF, to the engine computer to let it know the coil fired. I believe if the PCM doesn't see that signal because you unplugged a coil's electrical connector, the PCM won't fire the injectors. On your design you have to do what he did in the video by shorting the coil secondary to ground.
Another reason is if you have another cylinder not firing and you disable a working cylinder, two cylinders working isn't enough to keep the engine running especially if they are companions.
what does a running compression test do or look for when you do that test
Basically, a running compression test allows you to check the breathing ability of each cylinder. A vacuum gauge can do that also, but you are checking all cylinders at that same time instead of just one at a time using the running compression check method. In the video he didn't describe the reason it is used or what different readings mean. That is important to determine what is a good reading, what is a bad reading, and what they mean. It is too bad it wasn't covered here because how to perform and set up the test was done really well in this video.