idle surge

[Pr377yRicky]

alright my idle is surging 1.5k to 2k rpms after warm up. I have taken off the EICV and the Fast Idle Valve and hit them with Carb cleaner. The surging stop for about 10mins after the engine warms up; then starts surging again. Need ideas of what to do.
also should I hit with carb cleaner multiple times, if so how many?
P.S. I have also bled the coolant to make sure there wasn't any air in it.
P.P.S. I warmed the engine, then unplugged the EICV, there was no change in the surge. So, I'm thinking that I should remove it, then carb clean it a few more times before buying another one.

[Biscuit]

Did you reset the ECU?
If not, reset the ECU, top off the coolant, and drive the car.

Nathan

[Pr377yRicky]

yes I did that, every time I did anything to the car.

[Biscuit]

Remove the Throttle Body and inspect the gasket for leaks. Also check the vacuum hoses attached to the TB for cracks/leaks and all of the vacuum hoses attached to the Intake Manifold. The Hoses on the charcoal canister should also be inspected.

Nathan

[d16a3teg]

did you remove the fast idle valve internals? If yes did you then reseat the threaded part back to the bottom of its range ie twist it till it was all the way down? Found that this was needed to be done on a couple of the cars I've had to get the fast idle to reset to factory - the wax thingy had rotated up out of place a little bit.

[Pr377yRicky]

I didn't find any vacuum leaks in the hoses.
next I'll check the gasket next.
any opinions on the Fast idle valve,twisting the wax stopper? the SFM says not to touch it but hey i'd like more info on this, so i'm know what i'm doing before I fluff up my only car.

[Biscuit]

That fast idle valve is another vacuum leak source. Turn it in 180* and see what happens.

[d16a3teg]

The one on a B16a that i'm currently playing with took about 4 complete 360 to get to seat again and the surge problem has gone; I also removed this wax stopper on my neighbours car (94 Prelude) and cleaned out the fast idle valve body and then reseated to the bottom of the range - problem of inconsistent surging was gone. Also seemed to help with the cold warm up rpm which had moved up to about 2500 rpm now its back down around 1600 rpm.

[Pr377yRicky]

alright i'll try it today, will be back with an update

[EhBrah]

A tricky one to find but another cause of this is the diaphragm on top of the charcoal canister.
Locate the vacuum line that runs to it.
Warm up the car and get it to start surging.
Disconnect the vacuum line from the end connected to the solenoid on the firewall.
Plug the port/nipple on the solenoid (you should feel/hear a vacuum) with your finger.

If the surging stops then you probably have a blown diaphragm on the canister.

I have the same problem, just haven't gotten around to fixing it since I stored it 12 years ago.

[MinkelR]

^+1
The top of the diaphragm just pops off.
Mine was torn in two spots a few years ago:


You can replace it with one from a Legend. They're the same diameter and thicker.

[Pr377yRicky]

alright I will try this.
update I screwed the wax thing on the FICV up and down a few times didn't make a difference.

[EhBrah]

^+1
The top of the diaphragm just pops off.
Mine was torn in two spots a few years ago:


You can replace it with one from a Legend. They're the same diameter and thicker.

if this isn't in the FAQ section it should be and also include which gen/model Legend you sourced the diaphragm from or part number would be good too. Nice to include the picture and image from the manual.

[Pr377yRicky]

been uber busy at work, still looking into the diaphragm thing when I get time

[Pr377yRicky]

FOUND THE PROBLEM...( O.0)
Intake manifold gasket is blown....
never saw the problem till today, next time I look at it better instead of glossing over it. /wrist!!!!!!!!!!
anyways back to it...
to change that gasket do I need to remove the head and intake manifold together??? cuz it does seem possible to reach the nuts underneath or the manifold bracket.

[d16a3teg]

You can remove the inlet manifold without removing the head. There is a manifold bracket which supports it underneath and has two 12mm bolts that hold on to the inlet manifold. Then there are the upper and lower nuts - it is sometimes easier to remove the fuel rail to give better clearance from the top. From underneath the support bracket might need to be removed to give enough room to pull those ones off.

[EhBrah]

First thing that should have been done was to spray around possible leak areas with carb cleaner or my preference is starting fluid. You would have seen an immediate change in rpm as soon as the spray hit the vacuum leak. Oh well, lesson learned. Yes just remove the manifold, no head removal needed. Good luck.