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ST220 UIM IAC problem

S

SJon85

Veteran CEG'er
Joined
Sep 11, 2009
Messages
906
Ok back to the drawing board. I just finished putting the ST220 on, everything seems to be fine besides the IAC overspeed code, and the weird idling that goes like this: Say I am in gear at any RPM and I push the clutch in, the rpm's will go to 2500ish and hang there until the car completely stops, and then it will come down to 1100ish rpm and idle there. I swapped the IAC directly from the stock manifold I took off to the ST220, so I know for sure the IAC is fine. Here are pics of the hose I have going from the IAC port on the manifold to the intake pipe between the MAF and TB.

iac2.jpg


iac1.jpg



As soon as this happened I put a 2.5L IAC on and thats when one of my spark plug wires decided to pop off and not seat onto the spark plug, I think something is broken inside of it, they are old and crappy anyways so new magnecores are on the way. So anyways I didn't get a chance to drive it around at all to test the 2.5 IAC but it does idle where it should now. Since my ST220 didn't come with the IAC or the gasket I would like to know what others are running on their ST220?
 
Well here is a Mondeo installation...

dsc02610l.jpg


So your hose looks fine. One thing I was thinking... maybe try installing a pipe end in the hose and drilling a small diameter hole. Much like the moosing fix. See if that changes your RPM hang.
 
can you get better shots of the hose? it looks like it comes off the intake tubing pointing towards the front and then has to go to the back and bend around again to face the front. if its kinked really bad it could prevent enough air from flowing through it and so the PCM opens the IAC further to try to compensate.
 
That second picture is actually of the hose for the front valve cover, the IAC port is identical but hard to take a pic of because its on that same intake pipe but on the bottom side. In the pic mike posted the IAC looks more like a 2.5L IAC, and here is a pic of a stock 2.5 IAC on the right and the stock 3L IAC on left. I also had to grind down a small part of the 3L IAC to get it to fit, you can sort of see this in the picture.

IACs.jpg
 
You might also want to check your tps voltage. I had the tps pig tail go bad, and also more recently a tps get sticky... both instances also had issues similar to this.
 
Well I took a picture of my Mondeo IAC, but go figure its not loading as an attachment on CEG (even after I shrunk it), imageshack is not working, and I can't log on to photobucket. Trying this 'TinyPic' website and it's stuck loading. So I don't know. It's not ment to be. However that said the Mondeo one looks similar to your 3L one, but the openings follow the edges of the mounting flange. If I ever get a pic up you'll see what I mean.
 
Well apparently restarting my computer corrected the issues... so that said here is a pic of the Mondeo IAC.

mondeoiac.jpg
 
I think I may have figured out the issue. If you look at both the ST220 UIM and the stock 3L UIM you will notice that the air coming into the IAC is coming from the port closest to the TB. Heres the difference, the IAC has to be turned around in order to fit on the ST220, so now the two ports on the IAC have been switched around. I looked at the stock 2.5 IAC setup and the IAC is setup the same way as the st220, so a 2.5 IAC should work just fine, besides the fact the the ports are much smaller. I wish my damn plug wires would get here so I can figure this out!! Heres some visuals:

st220iac2-1.jpg


st220iac1-1.jpg



st220iac4.jpg


st220iac3.jpg
 
CSVT#49 said:
That would do it :laugh:

Didn't even think of that. Nice find.
Click to expand...

Yea can't believe I didn't think of that like 10 years ago. Feels like I am the very first one to put this manifold on! So now that everyone knows the stock 3L IAC can only be used on the 3L intake.
 
On the st220 you can only put the IAC on one way, with the sensor part going towards the TB like in my picture.
 
Still having problems with this manifold, starting to wonder if its even worth all the trouble because the car runs perfect with the stock manifold on. I got my coil wires in the mail finally. With the 2.5L IAC it still runs like crap, surges when idling, dies sometimes, feels like it still has the stock tune, and just overall runs like crap, but no CEL and the rpms idle and come down correctly. From looking at pics of the MPV engine, I found out that the IAC on the mpv is set up the same way as the ST220. So I went and picked up an MPV IAC today and it still runs like crap, dies sometimes, surges when idling, feels like its not tuned correctly, and has the annoying throttle hang around 2k rpm, but has no CEL. Heres pics of the MPV IAC I got from autozone:

http://www.autozone.com/autozone/pa...&fromString=search&itemIdentifier=779374_0_0_
 
you can't turn around the iac and expect it to work. you need an iac from a 2001-2003 taurus UIM (plug faces the TB)

the one you are trying to use is likely from a 2004-2005 which the plug faces the intake manifold. so what is happening, is when you let off the gas and the car sees vaccum, the IAC plunger is being sucked in therefore opening the IAC causing your high rpm idle.

i have the correct IAC sitting here because i had the same issue with this on my mazda6 intake.


also, if your car was tuned for a smaller volume UIM, you will have low rpm problems with the st220 uim (large volume)

it doesn't know what to do with all that air at idle :) your tuner can dial it in no problem
 
Yea with the 04-05 taurus IAC on it throws an overspeed code and runs like it is right now. Thats when I realized the taurus IAC system is opposite from the ST220. If you look in Pblack's MPV 3L build thread he has pics of the engine and the IAC points toward the TB just like the ST220, so why is the MPV IAC still running like crap on my st220 right now. Maybe I should try an 01-03 taurus IAC? and get my $75 back for the MPV one I just bought.
 
Just picked up an 02 taurus IAC valve, which did have a different part number and has some slight differences from the MPV IAC. Got it installed and it seems to run a little bit better, the idle after being on the gas comes down perfect and idles right where it should. Sometimes it still surges when idling, but doesn't seem as bad. The only problem now is steady throttle position is horrible when driving, and acceleration in low rpm sucks, like the air/fuel is waaay off. The tune is from Joey, and I haven't hooked up my wideband yet so we haven't got the air/fuel dialed in perfect. I am thinking that now it just needs a final tune.
 
SJon85 said:
Yea with the 04-05 taurus IAC on it throws an overspeed code and runs like it is right now. Thats when I realized the taurus IAC system is opposite from the ST220. If you look in Pblack's MPV 3L build thread he has pics of the engine and the IAC points toward the TB just like the ST220, so why is the MPV IAC still running like crap on my st220 right now. Maybe I should try an 01-03 taurus IAC? and get my $75 back for the MPV one I just bought.
Click to expand...

I guess i gotta follow more 3L threads. i'll let you know what issues i have when i get the MPV motor dropped in also do u have more pics of your vac lines and how / where you routed them to? just curious. since our UIM's are similar. and btw your ST UIM is worth it because you have that clean ST V6 engine cover .. it really makes the engine bay look nice :) Im jealous .. just a lil bit ..
 
Pblack003 said:
I guess i gotta follow more 3L threads. i'll let you know what issues i have when i get the MPV motor dropped in also do u have more pics of your vac lines and how / where you routed them to? just curious. since our UIM's are similar. and btw your ST UIM is worth it because you have that clean ST V6 engine cover .. it really makes the engine bay look nice :) Im jealous .. just a lil bit ..
Click to expand...


I don't have the ST220 engine cover, I believe #49 is who your thinking about. Theres a few threads floating around with pics of where the vac lines go on the st220. Doesn't the mpv uim not clear the hood?
 
SJon85 said:
I don't have the ST220 engine cover, I believe #49 is who your thinking about. Theres a few threads floating around with pics of where the vac lines go on the st220. Doesn't the mpv uim not clear the hood?
Click to expand...


About the st cover u can get one off eBay uk but as for the mpv uim not clearing the hood, Idk I haven't gotten that far.. when I get there ill let you know if It doesn't ill space the hood and modify the hood ribs to reduce the amount of space needed. I may end up getting a hood or another uim preferably the st220 uim but I'm going to try and make it work.. its all about being different.
 
Just wanted to update this with one small thing Joey found when I datalogged for him. We still haven't done a new tune, but he finds it weird that bank 2 is pulling 15% more fuel than bank 1 when idling. Any ideas?
 
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