Go Back   EcoModder Forum > EcoModding > DIY / How-to
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-31-2010, 03:52 AM   #21 (permalink)
Junkyard Engineer
 
Jim-Bob's Avatar
 
Join Date: Dec 2010
Location: New Port Richey, Florida
Posts: 167

Super-Metro! - '92 Geo Metro Base

$250 Pizza Delivery Car - '91 Geo Metro Base
Team Metro
90 day: 43.75 mpg (US)

Fronty the wonder truck - '98 Nissan Frontier XE
Thanks: 7
Thanked 19 Times in 12 Posts
Normally you test a car with all three plugs out, throttle wide open, coil wire pulled, and with a fully charged battery. I also like to put jumper cables on the battery and attach them to a running car so that there is sufficient charge to maintain RPM across all 3 cylinders. I would also check the compression tester on a known running car to be sure that it is not faulty. Honestly, 0 PSI is pretty hard to achieve unless all three pistons have giant holes in them which is again unlikely.

__________________
No green technology will ever make a substantive environmental impact until it is economically viable for most people to use it. This must be from a reduction in net cost of the new technology, not an increase in the cost of the old technology through taxation



(Note: the car sees 100% city driving and is EPA rated at 37 mpg city)
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 01-01-2011, 02:26 AM   #22 (permalink)
EcoModding Apprentice
 
Join Date: Oct 2010
Location: New Zealand
Posts: 119

Laura the Lancer - '81 Mitsibishi lancer LX
Thanks: 0
Thanked 27 Times in 8 Posts
Quote:
Originally Posted by Jim-Bob View Post
Normally you test a car with all three plugs out, throttle wide open, coil wire pulled, and with a fully charged battery. I also like to put jumper cables on the battery and attach them to a running car so that there is sufficient charge to maintain RPM across all 3 cylinders.
all you do for a compression test is take the spark plug out of the cylender you are testing .

chuck the compression tester in

crank it about 4 times then look at the results for that cylinder.

repeat for each cylinder and dont forget to put the plugs back in

dont know what your on about jim-bob. but thats the most interesting way ive heard someone do it (no offence intended just my 2c)
  Reply With Quote
Old 01-01-2011, 03:11 AM   #23 (permalink)
Master EcoModder
 
Ryland's Avatar
 
Join Date: Jan 2008
Location: Western Wisconsin
Posts: 3,904

honda cb125 - '74 Honda CB 125 S1
90 day: 79.71 mpg (US)

green wedge - '81 Commuter Vehicles Inc. Commuti-Car

Blue VX - '93 Honda Civic VX
Thanks: 867
Thanked 433 Times in 353 Posts
I've tested a motorcycle that had a pencil sized hole in it and still had a reading of 10psi, so if you doubt your compression tester then check the same cylinder twice.
pulling all the plugs, wires and coil wire is a good idea to prevent damage but most people don't bother, nor do they see negative results that are strong enough to tell them that they are doing it wrong, but it's still a good idea, jumper cables to a 2nd battery seems a bit much, just make sure your battery is fully charged and you should be fine fore 10 minutes or more of cranking.
  Reply With Quote
Old 01-02-2011, 03:08 AM   #24 (permalink)
Junkyard Engineer
 
Jim-Bob's Avatar
 
Join Date: Dec 2010
Location: New Port Richey, Florida
Posts: 167

Super-Metro! - '92 Geo Metro Base

$250 Pizza Delivery Car - '91 Geo Metro Base
Team Metro
90 day: 43.75 mpg (US)

Fronty the wonder truck - '98 Nissan Frontier XE
Thanks: 7
Thanked 19 Times in 12 Posts
Quote:
Originally Posted by pounsfos View Post
all you do for a compression test is take the spark plug out of the cylender you are testing .

chuck the compression tester in

crank it about 4 times then look at the results for that cylinder.

repeat for each cylinder and dont forget to put the plugs back in

dont know what your on about jim-bob. but thats the most interesting way ive heard someone do it (no offence intended just my 2c)
The method I described comes from both the factory GM service manual for my 1992 Metro and the factory Nissan service manual for my 1998 Frontier. I will trust the wisdom of engineers working for two of the world's largest automakers over that of others who are not as well versed in the proper methods of servicing an automobile and may or may not be capable of proper spelling.
__________________
No green technology will ever make a substantive environmental impact until it is economically viable for most people to use it. This must be from a reduction in net cost of the new technology, not an increase in the cost of the old technology through taxation



(Note: the car sees 100% city driving and is EPA rated at 37 mpg city)
  Reply With Quote
Old 01-02-2011, 02:01 PM   #25 (permalink)
EcoModding Apprentice
 
Join Date: Mar 2010
Location: Los Angeles
Posts: 110
Thanks: 0
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by pounsfos View Post
all you do for a compression test is take the spark plug out of the cylender you are testing .



repeat for each cylinder and dont forget to put the plugs back in

dont know what your on about jim-bob. but thats the most interesting way ive heard someone do it (no offence intended just my 2c)
You disconnect the ign. wire,remove ALL the spark plugs,then check compression on each one.Leaving spark plugs in will just add resistance to the engine spinning.
  Reply With Quote
Old 01-03-2011, 12:38 AM   #26 (permalink)
EcoModding Lurker
 
Join Date: Nov 2009
Location: california
Posts: 4

unknamed - '97 hyundai elantra wagon
90 day: 30.72 mpg (US)
Thanks: 4
Thanked 0 Times in 0 Posts
boken timing belt?

Jim-Bob is correct "Normally you test a car with all three plugs out, throttle wide open, coil wire pulled, and with a fully charged battery."

Did you notice "throttle wide open" That is the step most forget.

"0 lbs" all three cylinders my bet is a bad gauge or possibly a broken timing belt.
tom
  Reply With Quote
Old 01-03-2011, 04:10 AM   #27 (permalink)
Junkyard Engineer
 
Jim-Bob's Avatar
 
Join Date: Dec 2010
Location: New Port Richey, Florida
Posts: 167

Super-Metro! - '92 Geo Metro Base

$250 Pizza Delivery Car - '91 Geo Metro Base
Team Metro
90 day: 43.75 mpg (US)

Fronty the wonder truck - '98 Nissan Frontier XE
Thanks: 7
Thanked 19 Times in 12 Posts
The other reason you do it with the throttle at WOT is that it puts the ECU in "clear flood" mode. In other words, it shuts down the injector and you can skip the step of pulling the fuel pump relay or fuse to disable it. Failure to disable fuel will potentially fuel wash the cylinders and give a false low reading, not to mention potentially pollute the oil with unburnt fuel.
__________________
No green technology will ever make a substantive environmental impact until it is economically viable for most people to use it. This must be from a reduction in net cost of the new technology, not an increase in the cost of the old technology through taxation



(Note: the car sees 100% city driving and is EPA rated at 37 mpg city)
  Reply With Quote
Old 01-03-2011, 11:35 PM   #28 (permalink)
EcoModding Apprentice
 
Join Date: Oct 2010
Location: New Zealand
Posts: 119

Laura the Lancer - '81 Mitsibishi lancer LX
Thanks: 0
Thanked 27 Times in 8 Posts
Quote:
Originally Posted by Jim-Bob View Post
The method I described comes from both the factory GM service manual for my 1992 Metro and the factory Nissan service manual for my 1998 Frontier. I will trust the wisdom of engineers working for two of the world's largest automakers over that of others who are not as well versed in the proper methods of servicing an automobile and may or may not be capable of proper spelling.
fair enough mate, you got me their
haha my car manual doesn't say that but that's justa 28 year old car manual
for ya.
sorry for the bad spelling, i chopped the top of my finger off a wee while ago so its a bit stumpy.....

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to properly test modifications (AKA: don't believe every MPG claim you read) MetroMPG EcoModding Central 119 11-20-2020 07:28 AM
My first coast-down test: results, analysis, your input daqcivic Aerodynamics 14 02-19-2010 10:46 PM
Alternatorless Test in a Neon (still disappointing, but now w/slightly better results TOOSTUBBORN2FAIL EcoModding Central 10 12-07-2009 12:44 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com