I have noticed less post responses than when I joined decades back. I also notice a lot of people ask for help get that help and never come back to say if it worked. A lot of the information people need is on the web. Your Accord is what Honda's did when I worked at a Honda dealer doing used cars and flushed the anti freeze. It would get an air pocket and then the RPM's would hunt.

 

could it be a crack in the air intake hose?

 

Waw.
No joke eh
Hunting due to a bubble... will definitely look into that.
need to figure out where this blue juice is going. A couple weeks ago the overflow tank was half full. Now its still visible in the throat of the radiator but its receding. Cant imagine that little bubble would interfere with the engine sensors but??? Any idea where the offending bubbles were when this hunting was going on?

Now what the intake leak is about...
I dont quite know what a crack in the rubber intake snorkel would do, as its ahead of all the sensors and such... previously ran it in the yard with it removed without angering the system. There were a couple of cracks that i gopped shut with black silicone.

Speaking of sensors, does this thing have a Mass Air Flow sensor? Cant find it. Also very confused how it continues to run (literally just as good) with the TPS, MAP and air temp?? Disconnected. What is it thats covering for the loss of these? I long thought it could be a sign of a non functional TPS but its not the case as the active plotting showed.

I work weekends. Will mess with it on Tuesday

 

Air will trap at the highest points in the system when the coolant is low and and air drawn into the system. The coolant temperature sensor 1 in the area of the thermostat housing will affect the idle. Air does not hold heat like coolant, so ECT1 will read low temperatures when contacting air and the PCM will think the engine is cold. PCM will raise the idle to warm the engine. Then coolant will touch ECT1 and the PCM thinks the engine is warm and drop the idle.

Regardless of where or how, pressure testing the system will help identify the leak(s), since you are losing coolant.

If your 03 had a MAF, it would be combined with the IAT and be bolted to the air filter housing near the connection for the intake tube. It would have 5 wires. Only the 03 SLEV and LX-P had a MAF. Other 03 models would relay on just the MAP sensor and resort to default values if the MAP was unplugged. That is likely why you don't notice a difference in operation.

Before going down a rabbit hole, address the first known issue and that is the missing coolant. Pressure testing and finding/repairing leaks should be the prioity, then you can move on to the TPS,MAP, etc issues.

 

So this has been fun and its not over

I pressure tested it and found the water pipe into the thermostat housing was pooping out and spewing water. I already replaced this pipe due to being rusted off. Luckily, i didnt have to wait for a new one this time.

I welded a big ugly bracket to the pipe and hung it on the big stud (replaced by a bolt) on the timing case. It might leak.... but it is NOT coming out ever again... lol.

Just got everything put back together including a fresh intake gasket set

Moment of truth came and went. Ran great albeit idling at 1500 til it warmed up then it started with the surging again.

Popped the IAC connection. Did not change. Kept surging. Popped TPS no change. Popped MAP and it almost stalled, leveled out and quit surging.

Put the sensors all back on. Seemed chill. Poked at the gas and it was in a full stumble. Hitching and bucking. Would not rev past 1500.

Shut it off. Restarted and it runs fine but back with the idle surge. Had a pile of codes. Cleared them. They seem to be staying away for the moment despite surging (only with ac off). It did surge briefly with ac on before i cleared codes. This thing really does have a complex little autistic brain doesn't it?


Any ideas how to clear this alleged bubble at the temp sensor?
Does it make sense that it ran like a striped *** ape when i bought it with a rotted off pipe that wouldnt hold more than 1/2 of its coolant? Or that I had zero issues after fixing and refilling, even when the heater core was full of air..... ran great for months with this coolant then suddenly after a long drive (running great) as entering the driveway starts doing this crap and it persists

Does it make sense that this bubble would only cause mayhem with the AC OFF? Currently runs spectacularly with ac on. Idling 1400 ac on. Hunting rapidly 1000 to 1600 ac off.
What is the idle spec anyway?
easy fix... keep the ac on lololz


Lol how does this thing have any idea at all how to run with all the sensors off? Is the O² sensor really that responsive that it could base all functions on it? Er no. It would before. Now if i pop off the MAP all hell breaks loose (stumbling under gas), besides stopping the hunt...

 

Turns out the majority of issues was a bad IAC. Came on a new throttle body that cost 88 total. No wonder when an iac alone is 115....
running decent now but it did throw another CEL. Havent checked yet