CEL is always coming on for a while then goes off for a good few hours or so then back on.

99si with stock b16a2

I got a compression test done and results came up as 150, 150, 155, 98

Cylinder 4 is obviously the poorest and I was told I had a burnt valve or so. Is it necessary that I tear down my head and inspect and rebuild? I mean I got cams and a new valvetrain minus valves waiting to be put in, but I really dont wanna put them in yet cuz im not ready.

I was thinking could the distributor play a part in it? The dizzy has 104k miles on it. Also my vtec gives a hissing noise as it engages. U can hear the vtec kick in loud as hell, but its like my car doesnt wanna "kick" while in vtec, just hisses all the way up through vtec.

Please help me. Im strugglin hard to pass emissions with the constant CEL on. It's throwing random missfires and cylinder 3/4 misfires.

TIA

 

Do a leakdown test to make sure.

 

I thought that was the leakdown test =\

 

compression test and leak down are different...you might have to find some one who has the leak down test and watch...basicly a leak down test uses air Pressure... and compresstion is using craking compression...

 

your dizzy has nothing to do with your low compression. You can easily check to verify if it's your valves or your rings that is causing you cylinder to loose compression. Put @ an oz of oil in the cylinder thru the spark plug hole and then check the compression. If compression jumps it is the rings, if no difference it's the valves. If it were me i'd repair asap. It's not good for an engine to run with a cyl more than 25% less compression than the highest compression piston.

 

I had the same trouble but not as low as ur numbers (180, 175, 180, 150). And someone said to just put a lil oil directly into the cylinder. I did that then did a another compre. test a week later and the last cylinder came back up to 180.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shorty C &raquo;</TD></TR><TR><TD CLASS="quote">
99si with stock b16a2

I got a compression test done and results came up as 150, 150, 155, 98
TIA</TD></TR></TABLE>

All those numbers look low... did you remember to disable the fuel system when you were doing the test? if not the gas washing down the cylinders would certainly lower all those numbers. That last number is concerning and would indicate engine damage of some sort.

 

How do you disable your fuel systems? I just removed my ECU fuse and unhooked all my spark plug wires, then ran the compression test. Then I started the car with the petal floored and let it turn over 7 or 8 times. I don't think I did it right and my numbers were fucked up!

Can some one descibe how to do this right?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00Red_SiR &raquo;</TD></TR><TR><TD CLASS="quote">

All those numbers look low... did you remember to disable the fuel system when you were doing the test? if not the gas washing down the cylinders would certainly lower all those numbers. That last number is concerning and would indicate engine damage of some sort.</TD></TR></TABLE>

Doesn't matter if all the numbers look low.. the variation is what matters. If he were to do this test and all cylinders were low but even, it's 99% likely he has a bad compression gauge. Trust me I've been doing it for 5 years.

A leak down test is where you make the real diagnosis. This puts WAY more pressure into the cylinders than a compression test.

The most tried and true way to make sure you aren't spraying fuel is to unplug each injector clip.

Also, make sure the engine is warmed up when doing compression testing.

People DO NOT put oil into the cylinder on a compression test, if you do, you're going to get bad test results. Only on leak down should you do this... and it's still not necessary.

On compression testing crank the engine 6 times on each cylinder.

shortyc, I'd do the test once or two more times to verify that problem. If it's still there go get a leak down test to discern between a ring or valve seal problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nameless RB26 &raquo;</TD></TR><TR><TD CLASS="quote">

Doesn't matter if all the numbers look low.. the variation is what matters. If he were to do this test and all cylinders were low but even, it's 99% likely he has a bad compression gauge. </TD></TR></TABLE>

Variation is key yes, but low numbers across the board could also mean a bad motor just as much as a bad guage. Leak down test is always the best way to go.

 

Well a compression test is usualy done at operating temp, so run the car till it gets warm and try it again,

Dont forget to disable the distributor and unclip the injectors, and the only reason why you would put oil is to check to see if your piston rings are worn.


If you can, do a running compression, you put in everything but disconnect one injector and then take out the spark plug for that cylinder and then install the compression gauge, make sure you ground the spark plug wire by either using the spark plug to ground or a bolt. do this for every cylinder and post the results for idle and at 2000K RPM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00Red_SiR &raquo;</TD></TR><TR><TD CLASS="quote">Variation is key yes, but low numbers across the board could also mean a bad motor just as much as a bad guage. Leak down test is always the best way to go.</TD></TR></TABLE>
not true really, ive seen some engines with huge cams that have large overlap give around 100 psi per cylinder and thats completley normal. this is why a leakdown is so much better. compression will only give you a reliable number on variation of cylinders not a real accurate PSI. too many variables.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kamin &raquo;</TD></TR><TR><TD CLASS="quote">
not true really, ive seen some engines with huge cams that have large overlap give around 100 psi per cylinder and thats completley normal. this is why a leakdown is so much better. compression will only give you a reliable number on variation of cylinders not a real accurate PSI. too many variables. </TD></TR></TABLE>

I agree, however if you built a motor to have low compression for boost etc, or you're running big cams with large overlap, then you'll expect to see the low comp #'s. A stock engine was what I was talking about.