Rep Power: 0

I know it probably has something to do with my IACV, which I cleaned, and it was fine for a few weeks, well its back, with the same loopy idle, I'm thinking I might actually have to replace it, cleaning it isn't working, but anyway, when I let it idle, once the engine gets warm, like the beginning of the temp gauge, it starts that crazy idle sweeping from 2k-1k constantly in a rhythmic timing, but also EVERY light on the car dims and brightens, like a small strobe effect, in rhythm with the idle sweeps up and down, kind of like the car's battery is drained almost then instantly re-charged, and there is a small chirp/whistle noise coming from the belt drive every time the idle hits 1k then goes back to 2k, and now my speedometer gauge does not work either, and it jumps around sporadically when I am driving too..

Please help me..

 
Rep Power: 285

Is the alternator belt too loose?

 
Rep Power: 0

I have no clue, I will check in the morning, but there is a definite noise coming from down there.. maybe try to see if some belt dressing will help?

 
Rep Power: 285

Scratch the alternator belt, I had a theory, but I don't think the ECU would compensate quicky enough. nm that suggestion.

I thought about it and I think it's probably your Fast Idle thermo Valve, clean that out and see what results you get. Also, check all the hose connections on your IACV.

 
Rep Power: 189

Describe the noise to us or get a sound clip of it so we can hear it. Intake manifold leaks can cause some weird stuff as well, might want to check that with some throttlebody cleaner sprayed all along the gasket. Also when you put the idle air control back on did you use a new gasket or reuse the old one? Sometimes when you reuse the old one it can roll a but allowing air in, I would check that before you go throwing parts at it. As a side note the dimming of the lights at idle is common on civics, they have a charge system that is different from a lot of cars. They use a electric load sensing device or an "eld circuit" that kind of gives the alternator a break when there is low loads. Check all battery terminals make sure they are clean and tight, in the engine bay fuse panel there are 2 philips head screws that hold down the 2 main wires for the battery + terminal make sure those are tight. Then check engine grounding straps there should be 2, make sure those are clean and tight, simple test for these is to throw a set of jumper cables from the engine to the neg terminal of the battery if the lights suddenly go bright then replace the ground wires. (the oem ones are kinda junk) I will be changing mine out for better ones soon here. On top of that check what mindbomber told you.

 
Rep Power: 0

Well after a lot of investigating, I found that it was the 7.5A fuse for the alternator sp. i switched it out for another, it ran great for about 2miles, then blew that fuse, jumped up to a 20A fuse where the 7.5 should be, and it still blew, I checked the grounds, they all seem fine and clean..

Also i heard that the o2 sensors are on the same fuse as the alt, and my front o2 sensor was sitting on the heat shield for some time, noticed it when i bought it, and i can see the green and white wires inside, the white casing is melted but the wires inside are fine, i took it off the heat shield the day I bought it, could that be the issue?

 
Rep Power: 189

Yes it could be easy enough to check out and see just remove it from the heat sheild and I would be checking the wires out melted casings can mean melted wires inside the loom best to check it out thoroughly. fyi never stick a 20 amp fuse in a 7.5 amp slot if it blew the 7.5 then it will blow the 20, you could cause much more damage by allowing that kind of current to run through a 7.5amp circuit.

 
Rep Power: 0

They all appear fine, no melting or combination of wires at all, and it would probably throw a CEL if that was out..

 
Rep Power: 189

well keep the wiring off the manifold and see what happens.

 
Rep Power: 0

I am starting to think its the engine harness rubbing on the manifold exposing the wires over time, and now grounding it out.. but the only way to get to that specific part of the harness is under the car which is hard to do when you have no garage, no cement, and no car lift in the middle of winter ..

http://chowcman.com/krispycreme2010/...r%20Wiring.pdf

Problem found, i was correct on the engine harness grounding out on the intake manifold, but the wire was in a different spot than the one in the diagram, but thanks for the input guys!