Subtracting ignition?

[olegblink]

At what point does subtracting ignition from the 0deg cam at idle become dangerous? I've had idle surging problems for weeks now, and ive replaced the IAC, tps is at zero, and idle is set to 850, but my car continues to rev from 1000 to 2000 rpms. Today i tried subtracting 20-25 degrees off the ignition advance and it seemed to help, but how much is too much? is -8 degress too low?.....also i have skunk2 stage2 cams on an 06 type-s, idont know if that changes anything. Some one help pleasee!!! :?

[Hondata]

First test for vacuum leaks by blocking off the idle valve intake port with the engine running (in the throttle body, just in front of the throttle plate). The engine should stall immediately when you do this - if not, you have a vacuum leak.

There should be no reason to retard the ignition to less than about 10 degrees. Check that your cam is staying at 0 degrees. Check that other inputs like AC or PS are not causing the engine to idle up. Otherwise please post your calibration and a datalog.

[kornsined]

I've had the same issue from time to time. I'm planning on replacing my IAC. My engine that I swapped was sitting around for almost 2 years. The power steering pump and alternator have already been replaced due to being pooched.

I'm assuming the IACV is just toast since I have cleaned it and retarded ignition just like you have too. Issue always pops up. It revs very slightly when idling parked once every minute. I even get the revs dipping too low past my set idle (850) when driving above 3000rpm then going into neutral. Other times it hangs for a second at 1800 drops. Sometimes it works fine. So sporadic.

I'm gonna test Hondata's suggestion though.

[Hondata]

Yes, forgot about cleaning the idle valve.

1. Unplug the electrical connector.
2. Remove the water tubes to the IACV. You don't need these to be connected - block off the water passages to prevent the IACV from being heated.
3. Remove the idle valve (two phillips screws underneath).
4. Remove the electrical part (two security screws). I use vice grips and then slot the heads afterwards.
5. Soak the mechanical part in solvent, flush a couple of times.
6. Check the valve rotates freely. If it has any stickly points, chuck it up in a drill and give it 1000 rpm for half a minute or so. Let a little engine oil soak into the bearing before you do this. It should almost be polished afterwards, and rotate very smoothly.
7. Flush the valve with solvent again, and put some engine oil in the bearing.
8. Reassemble.

[kornsined]

Yes, forgot about cleaning the idle valve.

1. Unplug the electrical connector.
2. Remove the water tubes to the IACV. You don't need these to be connected - block off the water passages to prevent the IACV from being heated.
3. Remove the idle valve (two phillips screws underneath).
4. Remove the electrical part (two security screws). I use vice grips and then slot the heads afterwards.
5. Soak the mechanical part in solvent, flush a couple of times.
6. Check the valve rotates freely. If it has any stickly points, chuck it up in a drill and give it 1000 rpm for half a minute or so. Let a little engine oil soak into the bearing before you do this. It should almost be polished afterwards, and rotate very smoothly.
7. Flush the valve with solvent again, and put some engine oil in the bearing.
8. Reassemble.

You mean remove them permenantly? Isn't that risky in colder climates like canadian winters?

[Hondata]

Remove as in remove the rubber hoses that run from the cylinder head outlet and thermostat bypass to the idle valve, and then cap the tubes. In is easily reversable.

There is a pressure drop across the IACV at idle, so it will run colder than ambient, but we have not heard of any reports of the valves freezing in winter.

As far as we can tell the main function of the IACV water is to heat the valve to stop the oil sludge from solidifying. This does not really work that well, and Honda would have been better to put the valve on the side of the intake where oil accumulation is not a problem.