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Discussion Starter #1
I did a compression test on my genesis which I didnt do it after it warmed up or wide open throttle but I got for cylinder 1 is at 125psi, cylinder 2 is at 125psi, cylinder 3 is at 115psi, and cylinder 4 is at 135psi. Im really sure thats not good at all but id like to know what it could mean.
 

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seems fine to me.
When doing a compression test, what you want to look for are numbers that are obviously not good.
Is there a problem that you are trying to diagnose?
 

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No not really other than it vibrating a decent amount at idle and at certain rpm's but I've looked everywhere for a solution to that but could not find anything. Im honestly just worried about it cuz somtimes the coolant will read a little lower on the fill line and there is not leaks as I can tell but just recently the coolant read to be over full so idk what happend there. And isn't the compression supposed to be like higher than 125psi.
 

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No not really other than it vibrating a decent amount at idle and at certain rpm's but I've looked everywhere for a solution to that but could not find anything. Im honestly just worried about it cuz somtimes the coolant will read a little lower on the fill line and there is not leaks as I can tell but just recently the coolant read to be over full so idk what happend there. And isn't the compression supposed to be like higher than 125psi.
set the climate controls to "fan off"
turn off AC and recirc off
set vent setting to vent to the foot area.

All this is to disable the AC pump, to put less load on the engine. See if it idles smoother.

If it is some sort of misfire...
The following is to identify which cylinder is the problem.
while the engine is idling, disconnect the electrical connection from the #1 fuel injector.
If idle changes and/or it stalls, then it is NOT that cylinder. Plug the connection back in and do the same with the next one.
You'll want to find the cylinder that does NOT change the engine idle when you do this.

When you find the problem cylinder, it could be the following
check spark plugs (likely already did since you took them out to do a comp check)
spark plug coils
fuel injector
or some sort of cylinder failure

to hunt for which one of these is the problem, it's easier to number the coils, then move them around, idle the engine, and then do the injector disconnect, to see if the misfire follows the coil, or if it stays with the cylinder. if it stays, then do the same with the problem cylinder's injector, and swap it with one of the other ones, and see if it follows.
 

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Discussion Starter #5
set the climate controls to "fan off"
turn off AC and recirc
set vent setting to vent to the foot area.

All this is to disable the AC pump, to put less load on the engine. See if it idles smoother.

If it is some sort of misfire...
The following is to identify which cylinder is the problem.
while the engine is idling, disconnect the electrical connection from the #1 fuel injector.
If idle changes and/or it stalls, then it is NOT that cylinder. Plug the connection back in and do the same with the next one.
You'll want to find the cylinder that does NOT change the engine idle when you do this.

When you find the problem cylinder, it could be the following
check spark plugs (likely already did since you took them out to do a comp check)
spark plug coils
fuel injector
or some sort of cylinder failure

to hunt for which one of these is the problem, it's easier to number the coils, then move them around, idle the engine, and then do the injector disconnect, to see if the misfire follows the coil, or if it stays with the cylinder. if it stays, then do the same with the problem cylinder's injector, and swap it with one of the other ones, and see if it follows.
Thank you ill have to try it soon. But what randomly we just found out that the throttle body gasket was broken into pieces and hanging put from where it was supposed to be. So I have one coming. Could that might have helped cause the issue?
 

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Thank you ill have to try it soon. But what randomly we just found out that the throttle body gasket was broken into pieces and hanging put from where it was supposed to be. So I have one coming. Could that might have helped cause the issue?
If the gasket was bad enough to cause a vacuum leak that could cause a rough idle.
 

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Thank you ill have to try it soon. But what randomly we just found out that the throttle body gasket was broken into pieces and hanging put from where it was supposed to be. So I have one coming. Could that might have helped cause the issue?
I think it's enough to freak out the ECU.

there is a MAP sensor before and after the throttle body
 
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