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So I have a 15 elantra 1.8 that misfires when starting it in the morning and accelerating to roughly 4-5k. The misfire will keep going until the vehicle is either shut off and sits for a while or its warmed up a bit...letting sit a while and then starting it up again, the misfire will still occur at high rpms. But no sign period of misfire when vehicle is warmed up. Vehicle has 70k miles. So far the vehicle has new plugs, new injectors, new valve cover gasket, new crank sensor and I even swapped coils. I performed a function test on the oil control solenoids for timing and the exhaust one actually failed. Installed a new one of those and problem still occurs. Checked coolant temp sensor and seemed to be working fine via data list of scan tool. Tested compression and static compression is 130 psi for all four cylinders. Checked "running compression" and got roughly 60 psi across the 4 cylinders after 9 cycles give or take. When it was cold, I tried spraying throttle body cleaner around cylinder 4 to see if I could get engine to act sporatic at idle but nothing. Checked fuel quality and quality was good. Next, I then checked engine idle vacuum. Roughly 18 inches of vacuum. Im sort of stuck on what to test for next before I let the dealer take it over. Does anyone have any idea what it could be? Cracked valve spring? Variable intake motor issue? Sticky/carboned valve?
 

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Even if im in the shop when the vehicle is at 65 degrees. I take it out, and get it up to 4k...cylinder 4 goes completely dead..until its warmed up to roughly 90-100 degrees.
 

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Running compression test is done with the engine running. Observe the needle at high rpms and compare to other cylinders.
Don't know what this means.....Checked "running compression" and got roughly 60 psi across the 4 cylinders after 9 cycles give or take.
 

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compression , fuel , spark and air .. this what the engine need to operate normally ,,

if you have a miss-fire means on or more are missing ,,

i suggest you to :
replace spark plug (consumable part and cheap)
try shuffling the coils (i had similar issue because of the coils )
do injection clean (by the way you should do it regularly)
replace air filter and clean throttle body (its regular maintenance )
do compression test ( i case in short millage no need )

if you do you will have better picture about your issue
and tell us what happend with you
 

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If you routinely rev the engine up to 4-5k, and load it heavily before it's fully warmed up it probably has premature wear.
I have a neighbor who would start up his 1990 Accord and immediately take off like a scared rabbit, even in the winter.
After a few years it was leaving a trail of blue smoke when he did that.
Compression at 130psi is very low. Did you do wet and dry compression test?
I'm not sure what you mean by "running compression". Idle engine with one plug out?
In that case manifold vacuum will make the compression reading low.

When I start an engine I let it idle anywhere from 15 seconds to 2 minutes, depending on how cold it is.
Then I drive gently and don't go over 2000 rpm until the temp gauge starts to climb.
 
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