Compression check and spark plugs
01-20-2006, 03:02 PM
#1
Banned
Thread Starter
Join Date: Mar 2005
Location: Santa Clara, California
Posts: 2,976
Likes: 0
Received 0 Likes
on
0 Posts
Compression check and spark plugs
I did a compression check on my car today... I noticed that spark plug tips were a little white, does that mean the car is running too lean or rich??? (I have a vafc so I think I way be running it too lean)
As for my test results I had 210 across the bord which I was happy with. But I was hoping for higher and I know I need a valve job badly. If I get a valve job will the numbers go up??? Thanks
As for my test results I had 210 across the bord which I was happy with. But I was hoping for higher and I know I need a valve job badly. If I get a valve job will the numbers go up??? Thanks
01-20-2006, 03:18 PM
#3
Banned
Thread Starter
Join Date: Mar 2005
Location: Santa Clara, California
Posts: 2,976
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Twiztid,Jan 20 2006, 04:14 PM
Did you do it cold and with the throttle wide open ? Throttle has to be wide open to do a compression check .
Got a pic of you plug ?
Got a pic of you plug ?
01-20-2006, 05:45 PM
#6
Banned
Thread Starter
Join Date: Mar 2005
Location: Santa Clara, California
Posts: 2,976
Likes: 0
Received 0 Likes
on
0 Posts
took pics of the spark plugs... but they came out terrible, they are just a little white and pasty looking but nothing too much... And I rechecked the compression and got 225 across the board!!! Thanks for the help 
I'm still not sure about the plugs though, is white mean too lean?
I'm still not sure about the plugs though, is white mean too lean?
01-20-2006, 07:37 PM
#7
Registered User
White normally means lean, but a street driven car will exhibit this characteristic. When you are driving around at partial throttle, the ECU will try to maintain a stoimetric mixture (14.7:1). Yanking the spark plugs to read the tea leaves is a fairly inaccurate method. The real way to determine your fuel mixture would to strap the car onto a dyno and shove a wideband 02 sensor into the exhaust path.
You are only modifying fuel trim with the VAFC for WOT right?
You are only modifying fuel trim with the VAFC for WOT right?
Trending Topics
01-20-2006, 08:05 PM
#8
Registered User
Join Date: Oct 2001
Location: Driving around idiots in TX
Posts: 3,451
Likes: 0
Received 0 Likes
on
0 Posts
Test should be done WARM for accurate results.
If you do it cold, your pistons have not expanded and you will get abnormally low readings. If you get 210 psi compression readings when cold, your car will have too high of compression when warm and will not run on 91 octane.
If you do it cold, your pistons have not expanded and you will get abnormally low readings. If you get 210 psi compression readings when cold, your car will have too high of compression when warm and will not run on 91 octane.
01-21-2006, 12:03 AM
#9
Banned
Thread Starter
Join Date: Mar 2005
Location: Santa Clara, California
Posts: 2,976
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by RWD_RCKT,Jan 20 2006, 09:05 PM
Test should be done WARM for accurate results.
If you do it cold, your pistons have not expanded and you will get abnormally low readings. If you get 210 psi compression readings when cold, your car will have too high of compression when warm and will not run on 91 octane.
If you do it cold, your pistons have not expanded and you will get abnormally low readings. If you get 210 psi compression readings when cold, your car will have too high of compression when warm and will not run on 91 octane.
01-21-2006, 05:13 AM
#10
Registered User
Join Date: Dec 2001
Location: Manchvegas, NH
Posts: 8,058
Likes: 0
Received 0 Likes
on
0 Posts
Sorry you guys are right , It should be warm .
I dont remember what i was trying to write , I was trying to leave the shop and people were talking to me while I was posting . I think I was going to write charged in the second post . I know I asked if you did it cold meaning you would net low #s . Who knows what I was thinking , all I know is I went home and passed out till this morning
I dont remember what i was trying to write , I was trying to leave the shop and people were talking to me while I was posting . I think I was going to write charged in the second post . I know I asked if you did it cold meaning you would net low #s . Who knows what I was thinking , all I know is I went home and passed out till this morning