misterfixit
(Victory Runner)
02/13/15 04:46 PM
Idle Issues? Rebuild your servo module and FIAV.

Hi all,

It's been a long time since I posted any 'work' here. I rediscovered these pictures from about two years ago after a conversation with another Galant guy here. so I'm posting this thread to document the process.

This issue came to me as a colleague had a galant and he told me the car would not idle correctly. He'd been to a shop and they had screwed around with the idle screw and unplugged the throttle stop switch. I checked the ECU which had been capped about 6 months before and it was all fine. The idle screw was wound shut and when I logged the car I found the servo was hard over shut but still the idle was high.

Our cars have 4 methods for air to pass through the throttle body. all work together to make things good.
1/ throttle plate - driver uses this to control the airflow to the motor.
2/ idle screw - this is used to adjust the bypass air to the engine.
3/ servo - ecu uses this to finely adjust the air flow for smooth running
4/ fiav - this is the equivalent of the choke. at low temp it is open and allows air through (more air to go with more fuel for warm up).

The FIAV is under the knockout cover here:


When I took the servo module off the gap was huge so we did some experiments. The FIAV should close at about 90C. So in a pan of hot water it went with a thermometer.


The valve did not close at all. Only option was to reset it all. Here is the valve disassembled:


Now as I had not done this before I was curious how much stroke I needed. so I put the thing in cold water and noted the position of the core poker. then we heated it again and noted the position. Poker is shown here (looking inside the FIAV that has been stripped):


After doing this I set the valve back (with a dab of sealant on the thread to hold it) and adjusted it so I could no longer blow through the servo body. Once I found this position I backed out the valve orifice (round bit with the thread on) approximately the same distance as I'd seen the poker move earlier.

Once this was done I verified the aperture was ok. We then heated the servo again to 90C and verified I could not blow through the FIAV.

After that everything was reassembled and I reconnected the stop screw. We confirmed with the idle screw shut, it would slow, and with it open it was very fast. And also with the logger the servo was controlling open as the screw was closed and closed as the screw was opened.

I set up the logger and adjusted the idle screw so the servo was hovering around the middle of it's stroke after the car had warmed up. And it's been a doll ever since.

Hope this helps

Rich


89Mirageman
(It's no Mirage, man)
02/13/15 08:28 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

Awesome work and info as usual Rich. I messed around with this on my colt a few months ago when rebuilding the TB. How did you remove the threaded part? I used needle nose pliers once the plug was removed. Out of 4 FIAV's every one of them was seized in there and the plastic was very brittle so they broke before loosening up. I finally experimented with a 5th one and ended up cutting the aluminum housing ( I had plenty of spares from old TB's ) to see what was holding them in so tight. All I saw was a white substance that had acted like loc-tite or something. It was caked in the threads. Did you not experience anything like this?

misterfixit
(Victory Runner)
02/14/15 04:14 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

Strange, well it seems like the one I looked at was strange then.

We'd stripped the module off and boiled it at least once, as I wanted to see what happens. It had the white gunky stuff, but it was no issue to pull out on the one I took pics of.
maybe boiling it was a trick?

I have another to do. I guess I''ll find out how brittle it is then

Cheers

Rich


89Mirageman
(It's no Mirage, man)
02/14/15 07:51 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

I bet heating it up did break it loose. Sadly I really didn't think about that at the time. I seem to have a good one on my colt since I have a rock steady idle with no revving up and down but I will definitely do this trick on my next TB build.

tektic
(Senior Member)
02/14/15 08:22 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

it sees coolant temp normally so i doubt it was the 90 degree tap water making the difference. Mine is sliced in half and then JB welded shut. I still idle fine.

Before blocking off a 1g I had, the idle would bounce when she was cold. I had no luck backing out that plastic disk either. It wouldn't budge.

Wheres the rebuild on the servo!? That's the good stuff.


misterfixit
(Victory Runner)
02/21/15 04:44 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

Servo module is the whole lot. The servo is a separate piece. The one off m car here is in pieces.

For reference servo numbers old and new. Mitsubishi's service letter superceding the metal type to the plastic type.




Cheers,

Rich


AllanL
(Heal and Toe)
03/12/15 09:30 AM
Re: Idle Issues? Rebuild your servo module and FIAV.

hey Rich, how much did your poker/plunger stick out after heating?

the one on my experiment was 6mm.

and my valve stopper was metal and not the same as the black one on your exploded view of the valve ass'y.

so approx 6mm from the point when i couldn't blow through is the 'correct' opening right?

i have reassembled it yet...

oh, and the freeze plug is reusable?


misterfixit
(Victory Runner)
03/15/15 08:10 AM
Re: Idle Issues? Rebuild your servo module and FIAV.

I re-use the freeze plug. A quick wipe of sealant around the edge and reinsert.

Cheers,

Rich


holeshotmoe
(subclass marmoreus)
09/20/15 10:42 AM
Re: Idle Issues? Rebuild your servo module and FIAV.

I put it in a vise and sprayed a little liquid wrench on top. Then applied a pool of CRC Brakleen (red). With well fitting needle nose pliers tips, I rocked it back and forth until it started to loosen. The Brakeleen is similar to dry cleaning fluid so that may work as well. The adhesive on the threads looked like contact cement. I've removed two plugs this way...this plastic (bakelite?) version and a metal one from a 90 GGSX. Both had 200K+ miles on them.



AllanL
(Heal and Toe)
09/20/15 06:49 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

were you able to test if it 'helps' on cold starts?

holeshotmoe
(subclass marmoreus)
09/22/15 12:00 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

Did it this summer, so haven't had the cold weather to test yet. But as explained above, I put it in boiling water and the valve never completely closed. Then into ice water I watched it open up fully. This verified the "wax pellet" and rod under the valve were still functional (but out of adjustment, likely due to aging). With the hot & cold measurements, I had to adjust it downward to get to the halfway point. I added another revolution downward, hoping to err on the side of closing a little early (lower temp) rather than late. Also installed new shaft seals during reassembly. Now upon cold startup (70-ish degrees F), idling is 1050-1100 rpm for a few minutes then settles back to 750. And four years of idle surge is gone! BTW, definitely use an impact driver to pull the screws. I fouled the ones on the first fiav and had to use little vice grips to remove them :-O Used the tool on the second one and they came out like a breeze. **Edit to clarify: I used a hand held impact driver LIKE THIS , not a powered one**

fuel
("Just to be pedantic!")
09/24/15 06:52 AM
Re: Idle Issues? Rebuild your servo module and FIAV.

Could someone please explain how to get the knock-out/freeze plug removed? I tried prying it from behind and tapping one side but it didn't seem to want to budge.

AllanL
(Heal and Toe)
09/24/15 07:30 AM
Re: Idle Issues? Rebuild your servo module and FIAV.

pry it slowly in the opening where Rich has his index finger on in this pic:



fuel
("Just to be pedantic!")
09/25/15 09:50 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

Thanks! I did try prying it there but it didn't seem to want to budge. Oh well, I have three spare FIAV's I can try pull apart, and also one from a 6A12 V6 that has the FIAV deleted from factory, only contains the ISC in the housing and a bypass for the coolant.

G
(JDM Unit)
09/25/15 10:41 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

You need JIS bits to remove them easily, not phillips.

AllanL
(Heal and Toe)
09/26/15 06:57 PM
Re: Idle Issues? Rebuild your servo module and FIAV.

got pics of those G?

fuel
("Just to be pedantic!")
10/05/15 03:29 PM
Re: Idle Issues? Rebuild your servo module and FIAV.



Philips on top JIS on the bottom.

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