Did one because I had misfire codes for all 4 cylindars, so I did this first before anything else, plugs look good, stock ign system and retarded to about 13-14deg

Came up with these numbers:

#1 165
#2 165
#3 165
#4 175

Cranked enough till it stopped moving, engine hadn't been on for 1/2 hour but it was kinda warm, mabye not fully warmed up.... What do you think?

Block is completely stock... Anyone know LS spec range b18b as far as compression goes?

PS: Just remembered I don't think my engine was really that warm because I started it after doing the test and it was revving 1000+ like it does before it warms up.... think this could be why I have a lower reading? I'm gonna beat on her a bit and then try it again.... wish me luck


[Modified by shadowdawn, 11:06 PM 9/24/2002]

 

I got 185 all the way across on my B18B. My engine was warm

 

Did you keep the throttle floored while cranking?
Did you pull the ecu fuse?

At least they are all the same......

 

Ouch. Instead of 1 bad cyliner, guess who has 4?

Seriously though, they do look a little low; but at least they are consistant so you might be doing something wrong across the board.

jB

 

Details of first test, semi-warm engine ONLY took out fuel injectors clips, nothing else, and did not floor it while doing it, but cranked it to highest number a good 5-7 seconds on each cyl and did 3 tests on each cyl...

ok ok I drove around for 5-10 mins to get engine warm and did it again. THIS time I pulled ECU and BACKUP fuse plus removing injector clips, cyl 1-3 could NOT get above 100psi..... this scared the **** outta me so I plugged back in the fuses and left injector clips un-hooked and got these numbers (engine cooled down during the time I did it again, not as much as before though)

#1 170
#2 175
#3 185 (but put oil in it because this is before I figured out the ecu fuse was causing my problem) but did it twice after putting in oil and number here was the same
#4 175

Again this time I didn't go WOT either, just cranking, btw my car is obd2 if that has anything to do with anything.

 

::

 

Sounds fine to me. Putting oil in the cylinder will cause it to raise a little bit. I believe honda says a variance of up to 28psi is accecptable. However, most good motors will be within 10psi.

 

what EXACTLY is the best way to do a compression test anyway? ive heard a few different ways and seen people do it differently.

 

1. Take out ECU/Backup fuse so that it wont start
2. Remove spark plug wires and spark plugs
3. Screw in compression tester in to cyliner of choice
4. Get in car and let crank usually 6-7 times. This is usually how long it takes for the compression # to even out; and about as high as you will get.
5. If it's low, you can try adding oil to a certain cylinder to see what's going on; and may help boost it a little bit.
6. Repeat.

jB

 

make sure you are at wot too ( petal to the metal). when i first did the test i got 115 across, i was like WTF!@!!!. then the next day i warmed up the car and did it at wot and got 200 psi across!!

 

When I took out ecu and backup I couldn't get above 100psi.... put em back in and got the numbers above....

 

because your were dumping fuel when u plugged the fuse back in, raising cylinder volume. Hate to say it but time for a rebuild. Not hitting 100 psi in 3 cylinders indicates worn or cracked ringlands

 

Nah, I don't think so. A little bit a fuel isn't going to do much. Once the fuel is compressed with the air it's going to shoot out the exhaust as soon as the vavle opens. Besides, we held the throttle open and it got 200 across the baord.

I would be interested to find out why the fuse made such a big difference. The only way to do it would be to compare the #s with the throttle WO.