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2004 kia rio
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32 Posts
Discussion Starter #1
The car has a misfire around idle I have been chasing and trying to fix.I did a vacuum test and compression test to see if the engine is ok.

heres the vid of the vacuum test
https://www.youtube.com/watch?v=SY34...ature=youtu.be

So with a/c off it seems good,we see 22in of vaccum BUT when the a/c kicks on we start seeing 15in of vacuum?when the a/c is on is when the car shaking seems worst.I do see very slight fluxuation of the needle but its so slight I dont see it as a problem.

the compression test results
dry
1# 150
2# 149
3 143
4 #150
wet
1# 182
2# 175
3 170
4 180

with this said can I rule out the engine low compression being the cause of misfire?
 

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2014 Hyundai Veloster Turbo / 2001 Kia Rio
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279 Posts
those numbers are fine. they are within 15% which most would consider fair.

piston rings a little worn though. i remember you did the bearings in the bottom end did you do the rings?
 

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2004 kia rio
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32 Posts
Discussion Starter #3
those numbers are fine. they are within 15% which most would consider fair.

piston rings a little worn though. i remember you did the bearings in the bottom end did you do the rings?
Good memory and yes the cylinder walls were deglazed and rehoned along with new rings that were gapped to spec.I have a theory on the slight low numbers being because I did the compression test on a cooled down engine this may have lowered the number slightly.

I just wish I had a scan tool that had cylinder misfire counter because now Im unsure if its misfire at idle or just vibration from somthing else.

Thanks for your post it was very much appreciated and it was very much good news to hear.
 

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2014 Hyundai Veloster Turbo / 2001 Kia Rio
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279 Posts
It’s possible but I always did checks cold (so I didn’t get burned lol)
 
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