Mechanical timing is o.k. too. Spark plugs look like this now: i39.tinypic.com/2vxlqu0.jpg i40.tinypic.com/2evqeex.jpg I guess cylinder 2 runs lean. But why? I can't find any leaks..

 

So, scantool results:

At idle (750rpm):

STFT: from -5.47 to 1.56 (fluctuates all the time)
LTFT: 0 to 0.78 (remains almost constant)
O2 sensor before catalyst: from 0.1 to 0.9 (fluctuates all the time)
O2 sensor past catalyst: 0.1 (remains almost constant)

At 1500rpm:

STFT: from -9.38 to 10.16 (fluctuates all the time)
LTFT: -0.78 to 0 (remains almost constant)
O2 sensor before catalyst: from 0.1 to 0.9 (fluctuates all the time)
O2 sensor past catalyst: 0.1 (remains almost constant)

At 2500rpm:

STFT: from -13.28 to -5.47 (fluctuates all the time)
LTFT: -0.78 to 0 (remains almost constant)
O2 sensor before catalyst: from 0.1 to 0.9 (fluctuates all the time)
O2 sensor past catalyst: 0.1 (remains almost constant)

At 3500rpm:

STFT: from -10.16 to 2.34 (fluctuates all the time)
LTFT: -1.56 to -2.34 (remains almost constant)
O2 sensor before catalyst: from 0.1 to 0.9 (fluctuates all the time)
O2 sensor past catalyst: 0.1 (remains almost constant)

Any ideas?

 

So, maybe somebody with experience can comment that data?

 

Can this be because of clogged intake manifold? EGR passages and holes into IM were blocked with carbon, i cleaned that, but maybe there's much more to clean inside IM runners and this causes problems? Is that common on hondas? It's not so simple to take entire IM off and clean it, but maybe it's worth to give it a try?

 

Bought myself a new compression tester, and did compression test once again. Results:

DRY:

Cyl. no.1 first try - 200PSI, second try - 200PSI
Cyl. no.2 first try - 190PSI, second try - 195PSI
Cyl. no.3 first try - 190PSI, second try - 195PSI
Cyl. no.4 first try - 200PSI, second try - 200PSI

WET:

Cyl. no.1 - 220PSI
Cyl. no.2 - 210PSI
Cyl. no.3 - 210PSI
Cyl. no.4 - 220PSI

Any comments?

 

Those look pretty good.

 

Did two videos on cylinder 2 compression test. Take a look, as I understand sometimes on the first crank it does not build up 100PSI, as it normally does. Other 3 cylinders always make ~100PSI on the first crank

Normally it goes like this:


But sometimes it goes like that:


I did not notice this happen on other 3 cylinders. What could be the cause?

 

You have very likely eliminated spark, timing, compression as possibilities. This leaves fuel.

First, I would measure fuel pressure to make sure it's in spec.

Also check fuel pressure regulator diaphragm for rupture by pulling vacuum reference line and sniffing. Any gasoline smell would indicate a ruptured fuel pressure regulator diaphragm. This would allow raw fuel to enter intake through vacuum line. High fuel consumption would be likely.

Another possibility. Slight tendency for negative STFT suggests perhaps excess fuel from one fuel injector. This combined w/ a lean tendency from another fuel injector might cause a miss under heavy load; too little fuel to lean injector. Absence of any miss codes or lean/rich codes makes this theory a stretch, but if missing is only occuring under heavy acceleration it might not be enough to set a miss code.

See following link for explanation of fuel injector balance testing. Not easy to do as requires special tool and fuel pressure measurement rig. It might be as cheap to install a rebuilt set of injectors.


good luck

 

Well, fuel pressure is in spec. Fuel pressure regulator vacuum hose does not have any smell of fuel. Tried other set of injectors - and nothing changed. But I've noticed one more thing. When performing a power balance test (by removing spark plug wires one by one at idle) when cylinder no.2 spark plug wire is removed - engine dies almost instantly. When spark plug wires are removed from cylinders 1, 3 and 4 - engine just starts to shake more, but continues to run. Tried a few times, result is always the same. Maybe this says something? Maybe intake valves on this cylinder are possibly leaking? Or exaust is somehow restricted on this particular cylinder?

 

Rereading your original post, the only possible thing I can think of is that your knock sensor is bad. This assumes you have one and I seen you mention a "ks" so I assume that's a knock sensor. I had issues that were knock sensor related when I did my swap originally. I used a regular wire instead of a shielded wire and radio interference was causing the same exact issues you were seeing. When I pushed the throttle it hesitated. It took me about a year and I went through many things before I realized it was that I didn't use a shielded wire for my knock sensor I had to wire in.

However, in your case it's not a wiring issue but I suppose it could just be your knock sensor is bad. This is just a guess and you can't really test a knock sensor and just because it's not throwing a code doesn't mean it's working properly.

If it was me, I would test the sensors that don't require the car being warmed up so the MAP and TPS sensors. I would manually test them to be sure they are working properly. The TPS sensor could have a really dead spot on it which causes it to jerk when you open up the throttle, the MAP sensor could be bad or if the MAP sensor on your car is off the engine and has a vacuum hose going to it, the hose could have a crack in it. Also, I hope your spark plugs are gapped properly. Improperly spark plug gaps could cause your issue too.

I'm just throwing out ideas here.