EM1Guru

Is it possible to have a good cylinder compression reading, with a bad leak down test reading? The leak is coming from the exhaust valves, since I can hear air coming out of the exhaust manifold. The test was done correctly and new equipment was used.

Here's whats wrong with the car:

-car mysteriously died and wouldn't turn on.
-once the head was refurb. the car idled, but wouldnt accelerate past 3000 rpms in neutral. it sounds like its being choked. I couldnt even get the car to move out of my driveway without it dying
-the spark plugs are completely black from just idling the car from the first start up.
-CEL came on bc one of the o2 sensors is broken

no corners were cut when the head was installed. new head gasket, valved were adjusted before and after the first start up, belt tension was readjusted, timing was dead on, etc.

Former User

Maybe the mechanical timing is off by a tooth.

Post the compression and leak down numbers.

racebum

totally agree on being off a tooth. a lot of black on plugs means the spark is happening too late in the combustion cycle. if you drove the car it would be REALLY down on power. either ignition timing is beyond off or cam timing is off a tooth and it totally sounds like cam timing

this also can effect leakdown and compression. your compression numbers will increase when you fix the cam timing

EM1Guru

the numbers were 180-170-170-175 and 60%(moderate)-90%(good)-90%(good)-90%(good).

If the mechanical timing was off, it would most likely be on the exhaust cam since the air was leaking out of exhaust manifold? Wouldnt that make all the other cylinders have a bad leak down reading too?

And I couldnt drive the car, I couldnt even back it out of my driveway.

Former User

60% reading may have been caused by the engine not being perfectly at TDC for that cylinder. I say this because the result is inconsistent with the compression reading.

Post clear pictures of the cam and crank when the engine is at TDC1.

EM1Guru

Here ya go!

Former User

Does cylinder 1 have the bad leak down result? If so, what I meant was that cylinder 1 may not have been set perfectly at TDC1 when the leak down test was done. Is this possible?

EM1Guru

Yeah cylinder 1 is the only one with a bad leak down result. But I'm 100% positive that it was set perfectly at TDC while the test was performed. I've rechecked the same cylinder a few times while trying to find out where the air hiss was coming from.

Should I bother skipping a tooth on the exhaust cam just to see if it reads differently?

Former User

What car and engine do you have?

motegicivic

Strange I have low compression in one of my cyl, I am pretty sure it is a burnt exhaust valve, but still runs rough but does not stall.

Have you ruled out ignition issues?

EM1Guru

It's a 2000 Civic DX with a B16A2 off of my EM1

This was the original problem I had with the car:

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/combustion-chamber-diagnosis-3055487/

What I'm dealing with now is after the refurbished head.

Former User

Not sure whether it means anything, but your cam marks seem just slightly misaligned.
But I think the crank pulley mark is also just askew of the pointer.

EM1Guru

I've swapped out plugs, wires, and the distributor. Would there be anything else I'm missing?

EM1Guru

I'll skip a tooth and see how the leak down test reads. Are the cam marks suppose to point slightly more upward?

motegicivic

You said rebuilt head? Did a reputable shop do it? Maybe check the valve adjustment esp on the exhaust side.

gsrjdmej2

If you drive it not being timed could bend a valve

Former User

Unless you see that the timing marks are off, I don't see any benefit from doing this.

Is the engine having any performance problems?

EM1Guru

Yeah it's having some performance problems lol. It's not revving past 3000 rpms in neutral. I can't even move the car a foot out of my driveway without it shutting off.

motegicivic

You didn't answer my post 15.

Former User

Have you checked for swapped sensor connectors?

EJ8_Man

Maybe the head is cracked? What assurance did the shop give you when they handed the head to you? Did they pressure test the head or perform any kind of magnetic particle inspection before handing it off to you?

EM1Guru

Yeah he vacumm tests all the heads before he gives them back. I've dealt with him before on numerous occasions and is very reputable.

I did a valve adjustment before I turned the car on. I also did it afterwards thinking that the adjustment came loose. And I also adjusted the valves during the leak down test. When I did it with air going into the cylinder, the air hiss got louder when I tightened them, which I though was weird.

EM1Guru

I've looked, but nothing really looks out of place. Wouldn't the CEL come on if that was the case? Which are the most commonly mistakenly swapped sensor connectors?

Former User

Swapping sensor connectors does not always throw CEL codes. What you need to do is verify that wire colors in connectors match to the sensors.

Check the IACV, TPS, MAP, EVAP, IAT, etc.

jjenkins

Make sure you didn't swap your map and tps.