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Compression numbers - HELP

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Old Jul 13, 2017 | 09:41 AM
  #1  
Scouttster's Avatar
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From: Ft myers FL
Compression numbers - HELP

2011 hhr with 108k

1) 220
2) 225
3) 220
4) 210
Numbers are high?
Tested, WOT on a 198° F. vvt engine..
Old Jul 13, 2017 | 10:27 AM
  #2  
firemangeorge's Avatar
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Posts: 11,718
From: Alabama
Most likely the wrong testing procedure or faulty test gauge.

Maybe an explanation of why you're doing a comp test. Would help us to better understand what you're looking for.
Old Jul 13, 2017 | 10:44 AM
  #3  
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From: California
Those numbers do seem high. It's recommended to do the test cold or slightly warm, but only because removing the spark plugs on a hot, aluminum engine is risky(thread damage, stuck plug). Did you pull the fuel pump fuse and run it out of fuel prior to testing? That may have a slight effect, but I wouldn't expect much change in your results.

Different test equipment can give different results also. If you have access to a different tester, you could retest. I would expect numbers in the 140 - 180 range. High compression like you are seeing may be the result of carbon buildup on the piston.

My search here showed 1 other with similar results, but the thread was a dead end.
https://www.chevyhhr.net/forums/prob...ell-fix-40393/
Old Jul 13, 2017 | 01:30 PM
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Just guessing; if it is "hot" vs "warm" perhaps the VVT has not adjusted itself to cold, thus giving very short durations?
Old Jul 13, 2017 | 01:51 PM
  #5  
Scouttster's Avatar
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Negative on the pulling of fuses.
Tester is hardly used, but old.. It could be broken.......
High numbers, albeit all in the 20% range of each other.. Im in S Florida.. Hot hot hot!
Old Jul 13, 2017 | 02:59 PM
  #6  
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From: Welland,Ont Canada
A thread in tester? Or push to plug hole and hold ?
I'd pull the fuel pump fuse and redo the test.
Old Jul 13, 2017 | 04:35 PM
  #7  
Scouttster's Avatar
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From: Ft myers FL
Yes, its your regular plain old HF thread in or screw type tester..
Old Jul 13, 2017 | 04:43 PM
  #8  
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From: Welland,Ont Canada
Try a new tester , the old one could be toast
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