The car is a 94 ex cd5. It's been my tinker thing for a little bit now, and I've finally gotten to the F23a i.m swap. Car has I/H/E, test pipe, t.b, ignition, blah blah, etc etc, and a Blacktrax adapter.

​​​I have a couple f22b1 intake manifolds I've been porting on for a while, swapping them out as I feel one has improved over the other.. I'm not at all unfamiliar with the process.

The parts on the manifold, like the iacv, etc , all go from f22 manifold to f22 manifold, with no issues. Do it all the time..uppers and lowers.
​​It's what I do to relax at home..tinker.

Problem
Stupid *** idle hunt..1,500-,2000 with f23a i.m. Otherwise it drives fine. Hunts with FIA unlugged, plugged, iacv hooked up, unhooked, map plugged in, Unplugged...swap f22b1 manifold back on, runs perfect.

Question(s)
After as much reading as I can find on this subject, and a couple failed attempts, it appears the FIA needs to be drilled and tapped to plug it up, regardless if it's F22b1 or b2. Ok, no problem. Drilled. Tapped. Plugged. 10/32 set screws, lock tighted. Done. Still hunting. Swap b1 mani back on, runs fine. I'm kinda getting frustrated. I've wanted to ask for while, just wanted to make sure I've read everything I can find first. It seems way to freaking easy to be having this many headaches...wtf am I missing here? 0 issues with the b1 mani..only with the f23a.
Thanks in advance.

 

Using the same IACV for both manifolds? I'm assuming the blacktrax adapter you're using is the 3-2 wire IACV adapter? If so make sure both sides are sealed tight. I usually seal the intake manifold side with a little Permatex. Also check to make sure you don't have any vacuum connections left open.

 

Yes sir, ive been using the same iacv. I sealed the adapter to the upper plenum before I bolted it on, I used the black permatex on the plenum side. I've sprayed a grip of brake cleaner all over the manifold, i never get any kind of change unless I spray it directly in the t.b.
​​​​​
It's on the car as we speak, the f23 mani. If I use my thumb to cover the iacv passage in the t.b, the car dies immediately.
Still hunting after it warms up a bit, idles high when it's cold, like 2,300 rpm, then the hunt is on..Tally ho!
If I unplug the iacv the car gives a very fast, low, hunting idle...1,100 rpm-1,300 rpm..fast, rythmic hunting. Very consistant.
It has normal throttle response tho, no bogging, very crisp, it'll do burnouts just fine..no check engine lights. I'm friggin stumped. It's definitely faster with the f23 mani vs the f22b1 mani, that's why I keep trying to make this work. I'm just not sure what I'm missing...

 

Anybody have a clue what might be wrong? I'm more than happy to answer any questions, if I've left anything out that you need to know. I truly appreciate any help I can get. Thank you in advance.

 

An actual question I have.. In relation to the iacv circut, is it possible that I over did it when I matched the opening on the upper plenum to the t.b gasket? Is it possible there is too little restriction, allowing too much air to pass the iacv, making it chase it's own tail? I think it has something to do with the iacv, since I can use my thumb to make the car idle perfect. Would it be detrimental to make a "plug" that fills most of the iacv circut in the upper plenum? Is there something else that may be contributing to the situation, that I am not seeing?

 

What happens if you unplug the IAC valve? I know you said the car dies when you cover the port. Just wondering if you can set base idle with the IAC unplugged and go from there.

 

With the car warmed up and the iacv unplugged, the car idles very rough between 1,100 rpm and 1,300 rpm.

I took a piece of rubber hose, stuck a tight fitting bolt in one side, and shoved it in the iacv opening on the t.b. The hose darn near blocks the hole completly, and the car will now idle perfect. I have no idea what this means.

Thank you Ghost

 

Is the throttle cable tight or is there some slack in the cable? If the cable is over tightened it can act like a vacuum leak. There should be 10-12mm (1/4" - 1/2") deflection in the throttle cable between the throttle bracket and the throttle body linkage. If the cable is good to go then you can check the idle setting.

With the engine up to temperature, IAC unplugged and no load on the engine (radio, lights HVAC off) the engine should idle @ 550 ±50 RPM. If you are seeing 1100-1300 RPM there is unmetered air getting passed the throttle plate.

With the engine up to temperature, shut it down and unplug the IAC. Ensure that all electrical systems are turned off. Start the engine back up and try adjusting the idle set screw on the top of the throttle body. Adjust it so that the idle RPM is down to 600ish if you can. Then shut her down, plug the IAC back in and see what happens.

 

reset base idle with f23a mani on, like Ghost said

 

Do you know if you or anyone else has previously adjusted the throttle linkage stop screw? If it has been adjusted to stop the throttle plate early that will cause idle issues as well. This screw is set from the factory and the ECU maps are tuned for that. Any adjustments to the throttle stop screw will result in an unknown air flow and the ECU will continue to make IAC adjustments as per factory.

 

The throttle cable is good to go. I tried to reset the idle speed, as instructed, to no avail.

The throttle blade is untouched from skunk2.

When the iacv passage is "plugged" with the hose/bolt combo, and iacv unplugged, the idle is 500rpm.

I'm wondering if the iacv passage on the t.b side is exposed on the inside of the manifold, I'll be taking the upper plenum off tonight to see what I can see.

 

Top left..thats the iacv passage. Is this potentially the problem? Might this be fillable, with an epoxy of some kind, if it is the problem? The t.b is a skunk2 70mm alpha..

 

The hose/bolt..

 

Ah.... I didn't see that you where using an aftermarket throttle body. When it is running good with the B1 intake. Is it with this same throttle body?

Looking at those pictures. It looks as though the throttle body is slightly larger than the upper intake manifold. It looks as though there may be some ports that are open.

 

Yes sir, it is with the same t.b.

The B1 manifold is opened like the f23a manifold. I'll get some more pics tomorrow after work.

​​​​​​Thank you Ghost, your help is very appreciated.

 

OK, the areas that look suspect to me I have circled in red. They look like they may be open into the upper intake manifold/IACV ports.


by GhostAccord, on Flickr

 

Filled the iacv passage with hightemp jb weld steel stick, used a 19/64 drill bit to re-drill the passage over to the left, and now the car idles perfect. I filled the exposed part of the vaccume ports as well.

Thank you Ghost for helping me out. I went from stumped and frustrated, to all smiles and victorious.