(Cross-posted from another forum)

Imgur cut my video off at one minute but I'll link it anyway since it shows off the noise and behavior I'm talking about: imgur.com/a/DH8FXj3

I finally finished replacing the radiator, thermostat, overflow tank and heater hoses on my 2000 civic EX (non-ABS automatic, 2-door coupe, 260k miles). No leaks!

First, some stuff from before this repair: The car has had a hunting idle issue for the past year at least, but it was never bad enough to make me do anything about it and it never set a code. A month or two ago I noticed a burning plastic or burning electronics smell that was detectable both under the hood and in the cabin, but it went away after a few days. I noticed some noise from the accessories at this time too but it wasn't so bad

I bled the coolant system while it was still jacked up for a bit. While bleeding the coolant system I noticed a rather distinct metal-on-metal squeak coming from the engine near the driver side (in the video). This noise is different than the one I heard before.

After getting it off jack stands after a few weeks of sitting in my garage, I take it on a short set of errands around town and see a check engine light. I take it to shell to use their self-serve scanner thingy and I get back a P0505 (Idle air control system malfunction). Driving home I notice some surging and bucking when applying slight throttle.

I read up on P0505 and I find out that, of course, it can be caused by air in the cooling system. While shopping for a new cap and hoses for the reservoir tank I notice in the parts drawing that there's some kind of seal on the cap. I go down and check and sure enough it's missing. I figure I might as well bleed the cooling system some more anyway since it doesn't cost anything but my time.

With my car now parked facing uphill on my somewhat steep driveway, I start bleeding the cooling system again and only now notice the bucking at partial throttle that you can see/hear in the video I linked. I also notice that if you rev the engine it dips WAY down before coming back up to a sensible idle speed.

I bleed the cooling system for a good half hour but even after that point there are still a few very small bubbles coming up. The overflow cap seal is still missing so I figure I'll wait until I have that in place and try bleeding again.

Now, I'm wondering if I broke something by removing the airbox and moving the intake hose around while working on the cooling system. I did have it bungee corded to the hood for a while. I re-checked and I didn't see any electrical connections or hoses loose.

The other thing I'm wondering: The car's been in my closed garage for a good 2 or 3 weeks and the temperature in the area has been dropping sharply for the past month. Could these problems have showed up because the car got a lot colder than it has been for the past few months?


May or may not be relevant:
* I also changed the transmission fluid at the same time, dunno how that could affect it but figure I should include it anyway.
* I have noticed somewhat worse gas mileage recently but had just chalked it up to using the AC a lot

I drove the car again today and it's actually a bit hard to replicate the rapid oscillation you can see in the video. I could only get it to happen when parking after a 15 minute drive and it only appeared when I turned the AC off. When I got back to my car an hour later it was gone and didn't reappear, even after a much longer drive home.

Also I realized today that it's been at fast idle when warm--sits at 1500 with the AC off.

 

Does anyone happen to know the code-setting criteria for P050 on this ECU?

 

I think the P0505 is electrical fault. The three wire IACV has two coils in it which should be tested with an ohmmeter. Make sure you didn't mix up the plugs for the IACV, TPS and MAP they are all physically the same.

 

I actually never unplugged any of them. I only removed the airbox and bent the intake hose around a bit to access some stuff.

 

https://honda-tech.com/forums/honda-...-here-2127246/

 

Thanks! A few things I'm curious about:

The intake air hose could cause it? But the hose is before the throttle body and the MAP sensor is after, how does that work? Is it just the intake air temp sensor that's at issue there? I guess that makes sense, if it sucks air in from around the engine it'll be a lot hotter than air coming from the proper place.

What voltages should I pick up at the various sensors (i.e. how can I cross-check them against the real values?)

 

Welp https://imgur.com/a/XvXfubf

 

Yeah, people tend to forget about their heater hoses and that loop hose.

 

Seems like you should have replaced all of the hoses

 

Did you not see the fluid leak before hand? Why'd you have a knife down there?

 

To cut the heater hoses off of the heater core, as several people on this very forum recommended

And no, I didn't see it. I don't think it was that bad before. Honestly it could have just been a failing hose that died after replacing the others.

 

heater hose is closer to the firewall, not by the intake manifold.

 

I'm clumsy and yeah I don't remember having the knife anywhere near there but it's all I could think of

 

That hose doesn't look replaced. It also looks bloated af. Hopefully this situation kinda makes you understand why things need to be replaced before **** occurs.

 

I said right off the bat that I didn't replace it. Why the attitude?

 

Not an attitude, just stating something from experience and what some keep doing around here. Nobody has time for downtime these days so why not take care of it before you get stuck somewhere or gets costly. That same line broke on my sisters db7 and she got stuck on the side of the road. There was someone passing by who stopped and knew what to do to get her back on the road. Threw some water in there too.

 

OK so

Already replaced: Upper and lower radiator hoses, all three heater hoses

Ordered: Bypass hose, three hoses that go to the throttle body.

I remember there's one off the water pump, are there any I'm missing?

 

Cruise control vacuum line got disconnected at some point and I missed it when I was checking all the vacuum lines. Arghhhh!!!