3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.
Sponsored by:

compression test

Thread Tools
 
Search this Thread
 
Old Feb 8, 2004 | 03:01 PM
  #1  
mr g lord focker's Avatar
Thread Starter
Full Member
Tenured Member 05 Years
 
Joined: Oct 2003
Posts: 238
Likes: 0
From: Orange County
compression test

Ok, I have the intercooler piping/elbow out. I removed the top two sprak pulg wires. Then I reached in and felt the plugs and wondered...what tool do I use to take these off? Any help appreciated

I am doing a compression test....
I am figuring i remove the top 2 plugs and then stick in the compression tester to where the plugs went and crank over engine...is this how it goes?

I cant start my engine but it is still getting air/fuel/spark...so is it still possible to test compression on just having it turn over as much as it can?

Do I need to remove any fuses while turning th engine over?

Thanks for the help guys...always appreciated! =)
Hope results come out good
Reply
Old Feb 8, 2004 | 11:49 PM
  #2  
ooEfiniRx7oo's Avatar
Banned. I got OWNED!!!
 
Joined: Sep 2003
Posts: 261
Likes: 0
From: CA
if you want to know your motor condition without going through all that, you can just check your boost guage.

During idle, your vacuum should be hitting above 450mm/cm^2. If below, most very likely you will be needing motor rebuilt due to low compression.
Reply
Old Feb 9, 2004 | 12:32 AM
  #3  
Sesshoumaru's Avatar
Tenseiga
iTrader: (1)
 
Joined: Apr 2003
Posts: 2,252
Likes: 0
From: Iowa
there is a bunch of procedures to do. There should be a few threads about this.

off the top of my head......

unplug ONE spark plug at a time and use the top one.
take fuel/spark fuse out
press pedal all the way down
take check valve out of compression guage

watch for 3 even bounces

when cold the readings are inaccurate
Reply
Old Feb 9, 2004 | 06:54 AM
  #4  
moehler's Avatar
Rotary Freak
Tenured Member: 20 Years
Liked
iTrader: (12)
 
Joined: Mar 2003
Posts: 2,319
Likes: 32
From: South Jersey
Originally posted by ooEfiniRx7oo
During idle, your vacuum should be hitting above 450mm/cm^2. If below, most very likely you will be needing motor rebuilt due to low compression.
WTF is 450 mm/cm^2 ??? those are some crazy units, man . If your vacuum is less than 450 mmHg that doesn't mean that you'll need a rebuild soon... My compression is 7.2 for both rotors for all faces and my vacuum on a great day 430 mmHg (usually 410 or 420). It's a stock motor with over 60k on it, so it's a little tired, but it runs hard and will not need to be rebuilt soon. My point is, you can't tell that you need a rebuild from a vacuum reading. As far as your compression check... take it to the dealer or someone who has the appropriatre electronic equipment to read it accurately.
Reply
Old Feb 9, 2004 | 11:11 AM
  #5  
Sesshoumaru's Avatar
Tenseiga
iTrader: (1)
 
Joined: Apr 2003
Posts: 2,252
Likes: 0
From: Iowa
With a street port idle vac will go down.

I think there are too many variables to just check vac at idle.

compression checks are not that hard. I don't think it's worth 70 bucks or whatever to have the dealer tell me my car is fine.
Reply
Old Feb 9, 2004 | 11:30 AM
  #6  
SPOautos's Avatar
Hey, where did my $$$ go?
Tenured Member 10 Years
 
Joined: Feb 2001
Posts: 4,413
Likes: 0
From: Bimingham, AL
As long as its running dont worry about it. You can pull one leading plug out and a time and pull the main efi fuse then just turn the engine over. Listed for all even bounces.

STEPHEN
Reply
Old Feb 9, 2004 | 06:51 PM
  #7  
mr g lord focker's Avatar
Thread Starter
Full Member
Tenured Member 05 Years
 
Joined: Oct 2003
Posts: 238
Likes: 0
From: Orange County
compression is 5.2 kg/cm^2 on rear rotor and 12.5 kg/cm^2 on front rotor. Also equals 70 PSI on rear rotor and 185 PSI on front rotor. Looks like i am getting a rebuild.
Reply
Old Feb 9, 2004 | 07:06 PM
  #8  
rynberg's Avatar
Lives on the Forum
Tenured Member: 20 Years
 
Joined: Dec 2001
Posts: 14,716
Likes: 10
From: San Lorenzo, California
Originally posted by mr g lord focker
compression is 5.2 kg/cm^2 on rear rotor and 12.5 kg/cm^2 on front rotor. Also equals 70 PSI on rear rotor and 185 PSI on front rotor. Looks like i am getting a rebuild.
Your numbers are not possible, at least on the front rotor. Maximum psi is about 125 psi for a new motor. The difference between rotors looks bad though.
Reply
Old Feb 9, 2004 | 07:12 PM
  #9  
Beast From The East's Avatar
Racing is Life.....
Tenured Member 05 Years
 
Joined: Nov 2001
Posts: 576
Likes: 0
From: Northern California
Using the right tool?

Rotaries require a special compression gauge. If you're using a piston gauge, it might explain the numbers you are getting.

Beast
Reply
Old Feb 9, 2004 | 07:16 PM
  #10  
mr g lord focker's Avatar
Thread Starter
Full Member
Tenured Member 05 Years
 
Joined: Oct 2003
Posts: 238
Likes: 0
From: Orange County
probably..but it atleast showed me what I needed to know. All for plugs were pulled and both readings on front rotor and back rotor were the same. But the rear rotor had only about 1/2 the reading of the front rotor BOTH times so I know I need rebuild....but thanks for letting me know about the #'s
Reply
Old Feb 9, 2004 | 07:40 PM
  #11  
Sesshoumaru's Avatar
Tenseiga
iTrader: (1)
 
Joined: Apr 2003
Posts: 2,252
Likes: 0
From: Iowa
a piston guage will work fine.

you just have to take the check valve out.

Lots of ppl use them.
Reply
Old Feb 9, 2004 | 07:41 PM
  #12  
Snook's Avatar
Tony Stewart Killer.
Tenured Member 20 Years
iTrader: (12)
 
Joined: Mar 2002
Posts: 5,156
Likes: 4
From: London
when you have a suspicion that your motor is blown you dont need a guage to tell you anything. Just pull the fuel pump relay take out 1 of either plugs on each housing out and listen. Do one plug at a time then replace it and go on to the next housing. youll hear a pattern of the motor spinning over it needs to sound the same on all 3 beats or there is a problem

now to do a relative compression test to see what the condition of an old motor is a guage is needed

sorry about your motor
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
ZacMan
Build Threads
4
Sep 19, 2015 09:20 PM
BLK 93
3rd Generation Specific (1993-2002)
11
Sep 9, 2015 10:56 AM
SCinfidel
3rd Generation Specific (1993-2002)
4
Sep 8, 2015 05:36 PM
ZaqAtaq
New Member RX-7 Technical
2
Sep 5, 2015 08:57 PM




All times are GMT -5. The time now is 05:33 AM.