Troubleshooting EACV

[peanut]

How does an EACV work?

I understand it bypasses air from the throttle body to the dashpot so as to maintain proper idle speed. For example when the air-conditioner is on, the eacv solenoid powers up to pull a valve shaft so as to maintain the idle speed when the vehicle is stationary or when throttle is at 'closed' position.

Why are there two coolant hoses connected to the eacv as well?

 

[pills_PMD]

so the valve doesn't freeze

it's never actually at a closed position from what i've experienced datalogging with hondata.. it always has a duty cycle

 

[peanut]

That's what I suspected but I live in the tropics so it doesn't really matter. However, I found something strange. When I start up the car cold and during warming up and moving off, pressing and depressing the throttle, the rpm climbs then goes down very low i.e. below 400rpms, at some stages stalling my engine. It only happens with my air-conditioner on. Other than that, it was fine.

However, I found that when my coolant temp climbs and stabilises, pressing & depressing the throttle, the rpm climbs and drops stabilising around 750rpms. When the engine is warmed up, in some instances like every one out of eight times at a stop when I want to move off, I depress the clutch and at the same time press the throttle gently, there is this huge time lag and hesistation before the engine reacts. I always need to engage the throttle first then depress clutch in order to move off without this time lag and hesistation. This problem also happens when my air-conditioner is on.

I believe the a/c clutch relay and a/c switch should be no problem.

Anyone have the same problem? Can it be due to a stuck valve in the eacv? I have no error codes except for 13 (pa sensor).

 

[radnulb]

what year ECU are you running again?

Try setting your idle with the IACV unplugged using the idle adjust screw. Get it vaguely close to the target RPM (750RPM) and then turn the car off, plug in IACV, and go. The idle dipping with AC engaged may be because of hte IACV not being able to bypass enough air. You may also want to follow the more detailed troubleshooting guide in the helms instead of my quick+dirty method.

 

[peanut]

Thanks for the replies.

I managed to pick up an eacv (carb cleaner required) and a tps sensor (unscratched and far from broken) from a jdm si intake manifold for free, courtesy of my friend Joe who runs a workshop 4 miles from my home. I tested the eacv on my car and the one I just got, and the resistivity is about the same. The voltage at the terminals was battery voltage and there was no continuity to ground with either terminals. The valve clearance is also about the same. I wasn't 100% sure the eacv was the culprit but it might also be a contributing factor. I also figured that at the stops, I opened up the throttle for more air to bypass the 'faulty' eacv and the response was still very shitty but after a while it normalises when speed picks up or when I pushed the throttle lightly to make up for the missing power. At times the acceleration was jerky at a certain rpm band even when a/c was off. I decided to swap the tps sensor instead. I do not have a test harness so there is no way I can guess the optimal voltage setting at idle, so I used the 'force' ehh twice and got it right I think. Chk eng light didn't come on for tps. Took it out for a spin with a/c on. There was no problem and acceleration was good, the engine sounded healthy without the 'hollow' I used to hear at times. However, the drive was too short a duration to tell. I may have to drive it with the a/c on during longer trips to see whether this is the only problem. My old tps was chipped at many places very slightly and there was a small fine hairline crack, which was very difficult to spot. I could have spotted the problem earlier with a test harness to catch the voltage 'spikes' when I gradually open throttle. I also cleaned out my current eacv with so much wd40 that it almost sparkles inside, even the mesh shiny. I still have chk eng light on for missing pa sensor but I am not in limp mode as I can still go past 5000rpms.

Any thoughts about the above?