S2000 Under The Hood S2000 Technical and Mechanical discussions.

Odd Compression Test Results

Thread Tools
 
Old 09-20-2018, 05:59 PM
  #1  

Thread Starter
 
treimche's Avatar
 
Join Date: Apr 2006
Location: Fort Myers, FL
Posts: 550
Received 24 Likes on 23 Posts
Default Odd Compression Test Results

Performed a compression test today since I'm starting to compile a list of parts for a turbo project. Car is a 2005 with 150,200 miles. I've only had it for 2 years and 5,000 - 6,000 miles.
Engine was warm, all 4 spark plugs removed, fuel pump fuse removed, throttle held open while cranking.

Results:
Cylinder 1 - 190
Cylinder 2 - 218
Cylinder 3 - 220
Cylinder 4 - 265

Obviously cylinder 1 is low and 4 is high. Cylinders 2 and 3 seem to be normal. Why would cylinder 4 read so high? Cylinder 1 being low makes me think maybe exhaust valves? But from what I've read here on the forums, 06-09 are usually the ones with tight exhaust valves. I'll rent a leak down tester and see where its leaking from. Any ideas on these numbers?
Old 09-20-2018, 07:51 PM
  #2  

 
Car Analogy's Avatar
 
Join Date: Aug 2012
Posts: 7,846
Likes: 0
Received 1,311 Likes on 991 Posts
Default

Any chance your battery was running low by the time you tested #1? (Was #1 tested last?)
Old 09-20-2018, 07:55 PM
  #3  

Thread Starter
 
treimche's Avatar
 
Join Date: Apr 2006
Location: Fort Myers, FL
Posts: 550
Received 24 Likes on 23 Posts
Default

#1 was tested first, and then tested a second time at the end. Same results. Battery was fine.
Old 09-20-2018, 08:52 PM
  #4  

 
noodels's Avatar
 
Join Date: Nov 2013
Location: Norfolk UK
Posts: 5,315
Received 344 Likes on 321 Posts
Default

Carbon build up ?
Old 09-21-2018, 11:56 AM
  #5  
Registered User

 
VashTheStampede's Avatar
 
Join Date: Jul 2017
Posts: 127
Received 18 Likes on 16 Posts
Default

Try a wet test and see if there's a difference. Check and adjust all valves. Re-test.
Old 10-07-2018, 08:04 AM
  #6  

Thread Starter
 
treimche's Avatar
 
Join Date: Apr 2006
Location: Fort Myers, FL
Posts: 550
Received 24 Likes on 23 Posts
Default Valve adjustment findings

Went ahead and performed a valve adjustment last night. Check out the before and after, some of these are really odd. Some exhaust valves were tighter than my smallest feeler gauge, which is .005". This poor car has probably never had a valve adjustment. Most of the intake valves were in spec. I set all intake clearances to .009" and all exhaust clearances to .011". I'm crossing my fingers that the next compression test comes out better than what I posted before. I'll find time to do that this week and record my findings.


Old 10-07-2018, 09:35 AM
  #7  

 
liybzd's Avatar
 
Join Date: Jun 2013
Posts: 129
Received 2 Likes on 2 Posts
Default

I did mine last week, my figure was uniform 220 across all four. I did it cold, worried about removing plugs from a warm engine.
The 2nd round I accidentally cranked a few seconds more at cylinder 4 and get 245, did you crank it evenly?
Old 10-07-2018, 10:30 AM
  #8  

Thread Starter
 
treimche's Avatar
 
Join Date: Apr 2006
Location: Fort Myers, FL
Posts: 550
Received 24 Likes on 23 Posts
Default

Engine should be warm. I crank until the gauge stops increasing.
Old 10-07-2018, 11:14 AM
  #9  

 
rpg51's Avatar
 
Join Date: Jun 2016
Location: Vermont
Posts: 3,295
Received 256 Likes on 219 Posts
Default

It will be interesting to see the next compression test results. I'll be surprised if the tight valves explain the compression test results. We shall see.
What did the plugs look like?
What kind of oil consumption do you see with the engine?

Last edited by rpg51; 10-07-2018 at 11:27 AM.
Old 10-07-2018, 12:42 PM
  #10  

Thread Starter
 
treimche's Avatar
 
Join Date: Apr 2006
Location: Fort Myers, FL
Posts: 550
Received 24 Likes on 23 Posts
Default

Originally Posted by rpg51
It will be interesting to see the next compression test results. I'll be surprised if the tight valves explain the compression test results. We shall see.
What did the plugs look like?
What kind of oil consumption do you see with the engine?
Plugs look fine, light brown in color. For oil consumption, it does use a little, but I haven't really kept track. I only get maybe 3,000 miles on the car each summer with a couple track days in there. It's always ran great for me. Crossing my fingers for more even compression numbers after this.


Quick Reply: Odd Compression Test Results



All times are GMT -8. The time now is 09:13 PM.