Phoenix LSX

Hey guys, I just bought my first 7th gen civic, it's a 2005 EX 5 speed coupe. I bought it for $600 under the impression of a blown head gasket but the more I dig into this, the more I'm thinking it might be something else.

It doesn't have enough power to drive far, barely enough to move it from driveway to driveway.

The idle is quite rough.

I saw what I assumed to be oil in the coolant reservoir after just a quick glance but now I'm thinking it might be a stop leak additive or something, looking like tar.

it's not overheating at all. I left it running at idle for about 10 minutes and the temperature stays normal.

There is no milky substance in the oil.

There is no smoke coming from the exhaust.

I pulled the codes, it was showing o2 sensor, multiple misfires, and misfire on 2 and 4. I reset it, and same thing popped up.

I tested the coils and plugs for spark and all 4 are sparking.

I swapped two of the coils and plugs, checked the codes and now it's not throwing the misfire codes, but still runs the same.

I'm stumped. I've Googled the hell out of this but each post I saw had a different issue, like overheating or smoke.

Can anyone point me in the right direction?

ezone

Compression test

Slumpertcivic

Phoenix LSX

What are normal specs for compression in each cylinder?
Is there a specific condition that I should do the test?

And the car is NOT overheating at all.

ezone

O2 sensor code is what? (post the actual fault code number Pxxxx) That won't cause misfire codes though.
Are cylinders 2 and 4 completely dead, or just weak? Dead cylinder could be as simple as an unplugged injector or as difficult as a burned valve.


The TYPICAL early stages of head gasket failure in that particular engine results in VERY slowly displacing liquid out of the radiator into the reservoir, eventually resulting in a large 'air' pocket in the radiator.
Once the radiator has lost enough liquid to compromise cooling efficiency, people notice it either runs hot, overheats, or has poor heater output.
Refill radiator and all goes back to normal except for the gradual displacement of liquid. Cycle repeats.

If one lets the engine overheat bad enough things go downhill in a hurry.

Black film coating the inside of the reservoir isn't all that uncommon, not necessarily indicative of something serious.


A number spec one would see printed in a service manual is of zero value to me. Many variables. Comparison of all 4 cylinders tells more.

Using my own (known accurate) compression tester and methods I expect to see in the neighborhood of 180 PSI or higher.

Hot engine to start with
Remove all spark plugs, "read" each plug
Prop gas pedal to the floor
Battery charger connected to maintain constant cranking speed throughout the tests (weak battery/slow cranking speed adversely affects test results)
Connect tester to first cylinder
Place it so you can see from the drivers seat (or get a helper to crank it for you)
Watch gauge.
Crank it until the gauge doesn't increase any more, then keep on cranking a few more 'hits' just to make absolutely sure the gauge is maxed out. Write down the reading.
Repeat for each cylinder, in order.

Phoenix LSX

I'll give that a try when my helper gets here. And as far as the O2 code, it's PO135.

Here's another thing. Codes were showing misfire on 2 and 4. I swapped the coils and plugs of 3 and 4, and the code went away. I swapped the coils and plugs of 1 and 2 and codes were showing 1 and 3 lol wtf.

ezone

Logically that would make me suspect 2 bad coils.

Phoenix LSX

Yeah I thought it was odd how the computer will read misfire codes depending on which coils I use in which cylinder. So I guess I'll do the compression test first and if it's good, I'll change the coils.

Phoenix LSX

Waiting for my helper with his compression tester, I decided to check the coils by unplugging two of them at a time and testing how it runs. I've noticed the car is only running on two cylinders, 2 and 3. 1 and 4 are not running. I swapped the coils over and both tries, only 2 and 3 are running, so I'm thinking it's not the coils. Possibly a fuel issue on 1 and 4?

ezone

With coils connected to the harness for cyls 2 and 3, do the coils both throw lightning bolts? (to rule out wiring problems for those two coil positions)

"Read" the spark plugs when you take them out for the compression test

Phoenix LSX

Yes, they're both working.

Phoenix LSX

I did the compression test the exact way you suggested. Results are 180, 165, 180, 185.

ezone

Ok so that makes it LOOK like it should run on the two dead cylinders. I'd probably want to make sure it's not a fuel delivery issue (issues with fuel injectors?) then yank the valve cover off and check valve lash clearances (may find too little clearance on some, especially the exhaust valves....(165 is a bit low compared to the others).

Phoenix LSX

After it was only running on 2 and 3, I suspected a fuel issue on 1 and 4 but I'm unsure on how to check it.

ezone

Stethoscope each injector with it running, do they all click?

Got a spray can of something flammable? (brake parts cleaner, carb/throttle cleaner)
Remove air filter cover and with the engine running, spritz some squirts into the throttle body see if the engine picks up like fuel got to the two dead cylinders

Could lift up the fuel rail with all the injectors still attached and see if they all squirt while cranking (dangerous)

Phoenix LSX

I'll try them out when I'm not working 16 hours lol.

Phoenix LSX

So I decided to buy new spark plugs to make it easier to read them since they're all ****ed up... And believe it or not, the new plugs fixed it. It runs beautifully on a 4 cylinders. CEL is still showing both o2 sensors but it's pretty much fixed. Only thing I need to do now is figure out what the deal is with that tar-like stuff in the coolant.

waxerk5

Not knowing how long it ran like that previously before you bought it, unburned fuel being sent into the catalytic converter from misfires can destroy the cat. Keep an eye on it for overheating (glowing orange) or check for potential plugging by pulling the upstream o2 and install a backpressure tester in it to see what it's doing.