Fwiw gas to the floor while cranking disables injectors

 

Well guys this might turn into bad news...

I got a compression tester today.

And i only had time to check cyl 1 and 2. I spent the rest of the day installing 2" lowering springs on a customers cobalt (looks sick btw lol)

Anywho, cyl 1 was 178 psi and cyl 2 was 151... i know these gotta be right because the car held the start cycle for a bunch of cranks each time and the gauge held the pressure afterward so it wasnt leaking or some ****.

Thats a pretty big difference. I cant find my 5/8" socket for the life of me right now or id have the other 2 cylinders.

 

How did u get the first 2 plugs out?

 

5/8" socket? Lol

 

Only you would test two cylinders and then take a break lol

 

Yeah hopefully ill get to the other two tonight

 

That's super depressing news man, hope it's not catastrophic

 

Yep. Lol. Well see.

 

Try it wet also. Should beat it's ***** off the start

 

With oil in the piston?

Well i did cyl 3 tonight...

5psi.


Jk. 154ish psi.. after the 2nd try, 1st try was 130.

My test results are inconclusive. The battery is really low so ive been doing this of my truck battery and jumper cables. So im gonna charge my battery and do it all over again.

 

Well since your starting again the first reading wasnt accurate i would go more with the second reading. You scared me for a bit there

 

Lol you need to do all 4 at the same time with a solid battery.

If you end up still having an imbalance, you have 2 options.
1: tear it down for a fresh hone and rings.
2: check it again in 10k. If it hasn't gotten any worse, it's just bad seal from a poor break in. You can either live with it, or revisit option 1.

 

What's your process for checking compression rice? One at a time with the rest of the plugs out and the fuel relay out?

 

All 4 at the same time?? Why, so that theres the same number of cranks?

 

Nope fuel relay was in, good idea to take that out actually
One at a time, rest of the plugs in.

 

You cant comp test with the fuel pump not disabled....

 

Smh all you gotta do is put the gas to the floor while cranking. This cuts the injectors and holds the throttle open.
Take all the plugs out before you start.

 

Important part right there.

 

Sorry guys I'm definately learning this as i go lol.

So what, i need 4 compression testers or can i do this with all the plugs out and the tester in one cylinder at a time? Ive never heard of having to do them all at once.

 

By "all at once" I simply meant not taking a 3 day break in the middle..

 

This^

 

Gotcha. You guys are confusing me haha.

So let me confirm:

Fully charge battery.
Take all plugs out.
Go from cyl 1 to 4, try to crank the same # of cranks each time.

 

Hold the pedal to the floor as well.

 

And realize your engine is cold so the numbers maybe a little low. Normally you want to have a warm engine, so if the numbers across the board are close don't freak out if they seem low. Also do what MrB told you too and make sure your tb is working

 

Yeah im not too concerned about what the numbers are as i am consistancy, with the compression this motor makes anything in the 150-180 range is fine especially for 85000 miles id say

Oh also i did test the TB and it is working.

Also the PCM has gotta be good if im getting spark, fuel and codes