Rep Power: 0

Hi, I have a civic, 1.5l sohc 16v engine, with AT, and it runs really rough.

I replaced the following:
plugs, wires, cap, rotor, 2 exhaust valves, pcv valve, air filter, oil filter, fuel filter

Whats going on:
The engine runs really rough and has limited power. I tried to unplug individual fuel injectors, and nothing happens when I unplug any individual one. Just keeps running crappy. I tried to adjust the timing by turning the distributor a few degrees, and that didn't help. I checked and verified that the timing belt hasn't jumped a tooth. I have yet to try to find a vacuum leak.

The engine will start just fine. It stumbles about every 3-8 seconds. I am thinking vacuum, but also am concerned about fuel pressure/delivery, as when I unplug individual injectors, nothing happens, no matter what one is un-pluged.

 
Rep Power: 518

Compression test?


Instead of pulling wires off the injector to cancel a cylinder, I pull the spark plug wire.

 
Rep Power: 0

yes, I did a compression check. all over 110.

Will try pulling plugs. What do i suspect if a cylinder is dead?

I am also going to try to find a vacuum leak. anything else i should look for?

 
Rep Power: 518

110 would be low to me. I expect to see 180+ PSI when I use my equipment and my methods. Your equipment may not give the same results as mine.

Were all 4 fairly even on compression?


When does it run bad? Does it only run bad at idle? High RPM? No load rev sitting still? Driving only?

Check engine light on?
Does it have any fault codes stored?

Is it lean, does adding fuel (carb spray) make it run better?

Is it equipped with EGR? Is that stuck open?



Hmmm.....you replaced 2 exhaust valves? Are the valves adjusted correctly?
........is the cat or exhaust clogged?

 
Rep Power: 0

ok, did disconnect the spark plugs one at a time. rpm dropped each one, and ran rougher. so each cylinder is firing.

All compressions were within 5 psi of each other.

how do I find out if the cat is clogged? It feels like there is back pressure, and definitely is down on power.

No engine codes. not sure about egr. I unplugged the o2 sensor, and that threw a check engine light of course. Ran different, but not better or worse. It probably is time for a new one though.

I was thinking about putting a strait pipe in place of the cat and try that before i blow the $200 on one. is there any other way to know if it is the cat or not?

 
Rep Power: 0

ps....also checked valve lash, all adjusted properly, no worn lobes on the camshaft.

 
Rep Power: 518

If the cat is underneath the car, simplest way is probably to take apart the pipe at the manifold and take it out for a (loud) drive.

Or just rev it up a couple times --- if it was running really bad and now it revs up good --- you may be on to something.

That's the FREE way to check LOL


If you really wanted to measure stuff, you could screw a pressure gauge in place of the B1S1 O2 sensor and drive it.