Do these compression numbers look ok?

[cammed3800]

cylinder 1- 150
cylinder 2-130
cylinder 3 130
cylinder 4 135
cylinder 5 130
cylinder 6 130

This was with the car cold, not warmed up and the throttle was closed the whole way. I am also getting a p0300 code which could be from the cam but im also getting a p0102 code cylinder 2 misfire and i changed all plugs wires coil packs etc. If the code was due to the cam it wouldnt be cylinder specific, any suggestions?

[malice10985]

Based on your screen name, I am assuming you have a 3.8 with a large cam.

The last time I did a compression check, I had about 210 psi in each cylinder on a stock cam.

Having the throttle open or closed never made more than a 5 psi difference with my engine.

Hopefully, your large cam is the reason your compression is so low. If not, you need a new engine. 130psi is pretty bad.

[Wicked 3800 V6]

Put it on a dyno when you get the misfire taken care of -- if you have 200 hp, you're ok, but if you have 125, new engine time.
-Rob

[cammed3800]

Better not need a new engine i just spent 1800.00 having this one rebuilt by a machine shop

[cammed3800]

I cant get the misfire taken car of because i put new plugs, wires, coil packs on i cant think of anything else

[3.4 slow to go]

it should still be all good as long as all the numbers are within 10~15% from highest to lowest. do leakdown check to test for ring failure.

[cammed3800]

I have a compression tester from advance auto, how do i do a leak down test? Those numbers were also achieved with the engine cold and the throttle closed.

[cammed3800]

I have a compression tester from advance auto, how do i do a leak down test? Those numbers were also achieved with the engine cold and the throttle closed.

[awesomeame]

<blockquote>quote:</font><hr>Originally posted by cammed3800:
I cant get the misfire taken car of because i put new plugs, wires, coil packs on i cant think of anything else<hr></blockquote>

<blockquote>quote:</font><hr>Originally posted by cammed3800:
Better not need a new engine i just spent 1800.00 having this one rebuilt by a machine shop<hr></blockquote>

you can't get rid of a misfire & your engine was just rebuilt, and you have low compression. i'd check your timing before you do anything. pull your front cover off & see if the marks line up...i bet they won't...maybe your valves are opening up early/late, causing your low compression & misfire.

--matt

[Mikael]

<blockquote>quote:</font><hr>Originally posted by Wicked 3800 V6:
Put it on a dyno when you get the misfire taken care of -- if you have 200 hp, you're ok, but if you have 125, new engine time.
-Rob<hr></blockquote>

Terrible, terrible advice.

[jc Kyle]

misfire could be due to an injector....
What's the specs on ur cam?

[cammed3800]

My timing in my pcm was advanced by dave buckshaw when he did the programming, I also tried changing the number two injector. I dont think the programming made the code come up p0302 cylinder 2 misfire and p0300 engine misfire detected, I also understand that with my bigger cam i would most likely get the p0300 code but if the misfire code was due to just the cam im sure it would be cylinder specific by staying in the number two cylinder, my car doesnt sound like its misfireing wouldnt i hear it if it had a misfire in teh cylinder 2? What would cause the valves to open up early or late?, The rings not seating? How do i fix that or find that out for sure besides adding oil in the plug holes and checking cr?

[awesomeame]

<blockquote>quote:</font><hr>Originally posted by cammed3800:
What would cause the valves to open up early or late?<hr></blockquote>

improper timing between the crank & the cam.

there's a timing chain that connects the two, and two marks, one on the crank & one on the cam sprocket must line up. if they don't, your valves are going to be opening earlier/later. that would definitly cause lower compression.

--matt

[cammed3800]

Please tell me how i can fix this problem and would my pcm tuning have messed this up? i had the timing advanced, please help i appreciate it
to check if the marks line up is there some sort of steps i have to take? doe sthe engine have to be tdc? please help

[ December 03, 2003: Message edited by: cammed3800 ]</p>

[awesomeame]

buy a haynes manual first.

basically you have to remove the harmonic balancer & front cover. it's easy. then turn your crank until the dot is at 12 oclock. then the dot on the cam sprtocket should be at 6 oclock. they should be exactly at 12 & at 6 oclock...if you can't get them to be at 12 & 6, then your cam to crank timing is incorrect.

fyi...your cam sprocket has twice the circumference of your crank sprocket, so you could get the crank sprocket at 12 oclock & also have the cam sprocket at 12 oclock. just turn your crank until you get near the 12 & 6 postion.

--matt