Hi. I have a very peculiar problem that has really plagued me for a while now.
This is what it is. I found out very recently that cylinder #3 was not firing (it was a dead cylinder). This problem causes very shaky idle, low idle, and sometimes stalling. I tested it for spark and fuel they both were good, then I was going to test compression, but then I found out that my cylinder was actually still firing, because I tested it again like I did before by taking the spark plug out, and this made the idle bad, meaning that it was working. Pay attention to this part: Whenever I start the car up and let it idle in Park or in Neutral it uses cylinder #3 and idles fine, but whenever I throw it into into any of the gears (D or R) and drive it, it will stop using cylinder #3 altogether!

After this, I found out that my injector resistor box could have gone bad and so I tested it with a multimeter according to the instructions in the Haynes manual. They said to replace it if the proper ohms were not found. The results were that I found no ohms during the test.

So should I go ahead and replace the injector resistor box or are there other causes that I should look into?

Thanks and happy holidays

 

You should still do a compression test, verify that all cylinders are working withing acceptable parameters. Remember, do it when the engine is warm, and the throttle is wide open. Remove the spark plugs from all the cylinders while testing, this reduces the strain on the starter and makes it easier to go from cylinder to cylinder. Disable the ignition and fuel injection.

Being that this only seems to happen when the engine is under a load, its possibly a cylinder with lower compression than the others, but only shows under load. If the engine mounts are worn enough to pull on a wire harness, possibly when under load the harness is being pulled breaking the connection. However, I would find this unlikely as the harness allows for quite a bit of movement without damage to the wiring.

Always test your leads prior to testing anything, if your meter has a ringer/diode tester, then switch to that and see if it beeps. Make sure you really have 0Ω and not just an open circuit, depending on the meter you have it could be reading a 0 but it means open or infinite resistance. Some automotive DVMs need to have the leads changed to a different port on the meter. Make sure you are on the correct setting for the resistance values you are looking for. 0Ω on the 100Ω scale will not read the same on a 10000Ω scale.

 

I just did the noid test and the compression tests. The noid light cam back positive, the electrical connection to the injector was fine...
The bad news is the compression results...

>>> Compression Results<<<

Cylinder #1: 155 psi, 200 with oil.

Cylinder #2: 128 psi, 160 with oil.

Cylinder #3: 26 (!) psi, 40 with oil.

Cylinder #4: 40 (!) psi. 50 with oil.



What is normal psi, 150? Those last cylinders are screwed! What do I do next!?

 

Get another engine.

 

What? Are you serious? Someone else on another Honda forum said it was probably the valves or the head gasket.

 

Do a leakdown test to find out where the compression is being lost. It should be pretty obvious with #s 3 & 4 so low.

 

Yeah, if don't you want to fiddle with pulling the head, having it resurfaced and all that mess, then ya just pull the engine and put another one in.

If the oil makes the psi get up to normal then it could be the valve seals. But obviously that didn't happen. Every one of your cylinders is a mess.

 

And I'm not tryin to be a dick. If you want have it leak down tested to be sure or have someone else do the compression test if you want to be totally sure. I'm just going by the numbers you put up.

 

I know this is a dead thread but guys I now know what was wrong with my engine... I had 2 broken exhaust valves.

Shoulda known that was what caused such extremely low compression in 2 of the cylinders.

Now I am rebuilding the whole bottom end.

 

Thanks for the update. This is where a good leak down test wouldve helped out. You wouldve heard air coming out the exhaust.

 

Yes, I tried a leaky test but my air comp wasn't working properly. Anyeway, I am befuddled that the valves broke and burned like they did, it was a newly rebuilt head with less than 5,000 miles on it when the car started to drive poorly.

Not buying another rebuilt head again. I took mine to a machine shop and the guy there replaced the broken valves and basically rebuilt it again... Don't really know what caused it though, it could have been defective valves is my guess.

I think I know what really happened though. I discovered a crack in my exhaust manifold and this crack is what must have caused excess build up of heat on the exhaust side of the head.

1aauto says this,

"Replacing a burned valve won't fix a compression problem if the underlying cause is a hot spot in the cylinder head. If the hot spot is not eliminated, the new valve will run hot and burn too."



I am pretty sure the crack in the manifold caused a hot-spot.