Thread: Inconsistent Compression Numbers?

It has a new starter but the battery is 4 years old (says aug 2006) I guess that could possibly be something but I just re-grounded my battery.

Muhahaha! I just looked it up and my mom's car (99 mazda protege, LX) uses the SAME battery!!!!!!!!! Her axle seal or transmission or something just went out so now I get to use it to test.... Be back in like a hour to give the results if it's the battery or not lol

Edit: Back... That battery died after cranking like 10 times LOL It was all greasy so I whiped it off and I guess it's over 5 years old..................

All you have to do to keep the injectors or spark from firing is unplug the distributor. Simple as that. No pulling fuses or disconnecting all injectors. If it has no signal from the distributor they wont fire.

Easy as that. Cranking speed has an affect on compression numbers as well.

I ended up running another 4 gauge wire from the starter to the battery and it made a little little bit of a difference but then I tried another battery and still the same slow cranking. What else could it be?

What I've done is:
-Different battery
-New battery grounds
-New battery to starter wire (4gauge)

Bump, I need to figure this out ASAP so I can know what I'm going to be fixing, my engine or getting another transmission and axle / other misc parts

if you're positive everything is 100% good that you listed, pull the starter and get it tested. You need to solve this cranking issue before you know anything more.

Ehh I was scared of that... Haha I'm the only one with a car at my house so I couldn't have it tested unless I pulled it in the parts store parking lot :X if it's going bad already I'm going to be pissed, things brand new, looks like it's right out of the box haha

it doesnt really matter what the numbers are as much as that they are all close together on each cylinder. You should really pull the fuel pump fuse and run the fuel out before testing.

I do do that.. The thing about the numbers is sometimes it will crank harder than other times. I have about 150 across the board with a weak crank but sometimes I can get 1 or 2 cylinders up to 175ish

I think you are only supposed to crank enough times for the suck squish bang blow to happen in all cylinders... someone correct me if i'm wrong.


My numbers have been around 140 across the board for years as have other sr20 owners I know