Compression test done on my friends 04 black cobra

[04cobracop]

Hey guys,

A friend of mine and I just completed a compression test on his 04 black cobra. The cobra is sitting on 40k miles and has a STEG stage III with the basic bolt-ons. We ran the car until normal running temp, then started the test. We started with 5,6,7,8, then went 1,2,3,4,

5-175
6-175
7-175
8-175
1-170
2-175
3-150
4-165

We noticed that the engine was really low on temp, when we reached cylinder 1,2,3,4. I noticed that 3 was really low, so I went back and checked cylinder 5 and it still read 175. So, what does everyone think about his motor and is 150 that low????. He is getting ready to install a KB 2.8H this week and just wanted to conduct a compression test, before having it tuned. Thanks for everyone's imput!!!!. :thumbsup:

 

[TrickStang37]

im not sure how you numbered it. you should put the results based on the firing order.

 

[03cobramanIII]

Hey guys,

A friend of mine and I just completed a compression test on his 04 black cobra. The cobra is sitting on 40k miles and has a STEG stage III with the basic bolt-ons. We ran the car until normal running temp, then started the test. We started with 5,6,7,8, then went 1,2,3,4,

5-175
6-175
7-175
8-175
1-170
2-175
3-150
4-160

We noticed that the engine was really low on temp, when we reached cylinder 1,2,3,4. I noticed that 3 was really low, so I went back and checked cylinder 5 and it still read 175. So, what does everyone think about his motor and is 150 that low????. He is getting ready to install a KB 2.8H this week and just wanted to conduct a compression test, before having it tuned. Thanks for everyone's imput!!!!. :thumbsup:

3 and 4 are different, im wonder is that 7 and 8? the one that needs the cooling mod? 7and 8 are on the drivers side.

 

[04cobracop]

We started on the driver side closes to the firewall working our way down to the front bumper. Then went on the passenger side starting at the front bumper working our way to the firewall.

 

[brad65ford]

:read:

 

[IronTerp]

I believe that cylinder #8 is driver's side, closest to firewall. But, as long as you know what cylinders are which, this is inconsequential.

Certainly, your #3 is a tad low at 150, as is #4 at 160. May want to look further into that #3 reading with a leak down test.

Here are my results from 10/31/2005 and I've driven another 15,000 miles and 30+ track passes since then.....

Cylinder #1 = 192
Cylinder #2 = 193
Cylinder #3 = 189
Cylinder #4 = 169*

Cylinder #5 = 174
Cylinder #6 = 175
Cylinder #7 = 170
Cylinder #8 = 182

 

[LT1Porsche]

Did u disconnect the fuel pump relay or fuse when doing the test? If so it is possible that when doing the other 6 cylinders you may have lost some compression due to fuel in the cylinder. I would start the compression test over again and start on the driver side rear firs

 

[03cobramanIII]

just rap that deal in the trunk, that shuts your fuel pump off if in a wreck, thats what i was told? then reset it after.

 

[04cobracop]

Did u disconnect the fuel pump relay or fuse when doing the test? If so it is possible that when doing the other 6 cylinders you may have lost some compression due to fuel in the cylinder. I would start the compression test over again and start on the driver side rear firs

I did start with cylinder 8 first and worked our way down to five. Then started with cylinder 1 and worked our way to four. Thanks, Jason.

 

[Mystic03]

where can we get the compression tests done at and also where can i get it for most accuracy

 

[image]

you can do it yourself with a 9 dollar compression tester.

 

[IronTerp]

Sears sells a real nice kit for about $45 that is multi functional for many different makes of cars. JRS BLOWN SNAKE has one and did mine way back when.

 

[TriPodRacing]

When you did your compression test did you have all the spark plugs out?
Also did you hold the throttle wide open when cranking engine over ?

 

[04cobracop]

When you did your compression test did you have all the spark plugs out?
Also did you hold the throttle wide open when cranking engine over ?

YES!!!!

 

[TriPodRacing]

Ok was just asking.

Like others said perform it again and then perform a leakdown test.

Good luck.

 

[03yllwguy]

Out of curiousity, I had the dealership do a Leak down test on my car when they messed up some cooling maintenence. They did it with me in the car, they hooked a lap top up to the OBDII and then ran the test. Every cylinder said Ok, but there were no numbers read out. Is this test valid for anything?

 

[Mystic03]

noob question but what exactly are the steps to do a compression test myself?