MMMGIRL

My b20b has been running rough ever since I put it in, I thought it was the fuel injectors, changed them. Then plugs and wires, changed them. Then I pretty much assumed i had warped valves due to my timing belt being loose. Well, I did a compression check earlier and got these numbers.

4- 190
3- 185
2- 195
1- 195

Is this normal? My oxygen sensor isnt pluged up but that would cause it run run almost as if its not firing on 2 cylinders would it?.

el crapitan

why is the o2 not plugged in? and is that the secondary? or primary o2? a disconnected primary o2 will cause it to run rich, maybe even rough.
have you checked your codes?
those numbers look pretty damned good

LDForget

compression for a b20 is good ranging from 135-220 believe it or not. the biggest factor is the different in compression between the cylinders. As long as their all within 10 % you are fine, and your numbers are good. My b20 has 150 145 150 150 and it runs great.

emicha1

the car cant' start.
with starting fluid starts and die immidiately
Fuel pressure is 45 psi.
New battery, new cam and crank positioning sensors,
The timing is perfect.
compression is :
Dry 220 220 140 220
with oil 260 260 170 260
Is it the Head Gasket?

Thanks

el crapitan

since it runs off the starter fluid, that indicates a lack of fuel.
since you say you have 45psi, assuming at the rail, i'd check for injector pulse

emicha1

The injectors are fine. What bothers me is the compression at Cyl#3

VINCERE

Time to step it up and get a REAL engine...Just my 2 cents.

LDForget

Your compression is fine. the fact that it starts with starting fluid means its not getting any fuel. You say the fuel injectors are shooting, but how do you know? Fuel pressure on b20b's with the stock fuel rail is determined at the fuel filter with an adapter (im sure you know this as you know what yours is at, but this is for other people). Connect the fuel pressure gauge and try to start the vehicle. If the gauge fluctuates up and down then you know the fuel injectors are indeed working. My guess is that their not. My other guess is maybe your fuel is really old and lost all of its volatility.

emicha1

copmression at cyl. #3 is 40% lower then the rest. This is Not Fine.
I tested the injectors out of the rail individually. they are fine

el crapitan

just because you tested the injectors separately doesn't mean the system is working. check injector pulse. use a 194 marker bulb. it's super easy.

your compression isn't perfect. but that's not where your no start is stemming. you could be running with 1 completely dead cylinder and it would still start

LDForget

40% lower would be 117. Just because the rails are firing doesn't matter its happening at the right time. If youd like ill go take a video of mine running with 1 spark plug removed.


::Edit::

sorry i was going off the numbers in the first post. the difference between 260 and 170 still isnt 40% though. Listen for where the oil is squirting out of when doing the compression check and you'll find your culpret. If it bubbles out the side of the head, its clearly a head gasket, if you can hear it in the intake, its a valve. Either way, this isnt stopping the engine from running. It'll run bad, dont get me wrong.

el crapitan

why did the numbers vary so much from the first test?

regardless, the compression isn't why it's not starting

emicha1

I have the head gasket, in a few days I'll let you know if that was the reason

c0alition

Are these not 2 seperate people posting about compression? Am I the only person reading that?

First person said car was running rough, this person posting car won't start.

MMMGIRL

Even though the compression test came back good I ended up having warped intake valves which I found through a leakdown test. I replaced the head with a PR4-5 LS head, new head gasket, and intake and exhaust gasket last night. Set valve lash and everything. Car runs much better now but I noticed that my idle fluctuates to where it almost cuts off and when I give it gas the rpms drop for a few secons then it catches and goes. It doesnt do it all the time either, any suggestions?

el crapitan

ohhh. thought they were for the same vehicle with 2 different accounts. now it makes sense why the 2 tests varied so much.

el crapitan

check the codes first before anything

MMMGIRL

It turned out my oxygen sensor was wired wrong, whoever made the extension plug for it let wires touch and thats what the problem was.