Contour Enthusiasts Group Archives Forums Modifications Duratec Performance TH Fix advisory!

And BTW Brad, the moose isn't killed by the IAC alone.. You have to install the special hose along with it.. I have installed that hose.. Which I took off of a 00' Cougar.. and I noticed no difference.. But I never had the moose since I've owned it... 57,000 miles later and still no moose. I don't think I'm that lucky.. So it must be the maintenance that I do to the engine that keeps it away. (Always clean the throttle body once a year!!!!!) A big must.. this will cause the moose.. I have cured a couple of cars with the moose by doing this..

Lincolns have the same moose problem in the 4.6L.. They install what they cal "bagpipes" and a new IAC to correct the problem.. I've seen that a hundred times so far.. But really it's coming from the fact theat the EGR passages get clogged up and the throttle bodies get coated with sludge.. (Hey FORDTECH!!! would you agree??) anyhow.. This is just something I put up here as an advisory.. Everyone can do what they please... I'm ASE Certified and also Factory Certified... But you won't find me ever in one of my posts bragging about it.. And I'm not going to now. This is just personal experience stuff and things I've seen in the field that I talk about.

Dom

I have done it 2 ways. The quick and dirty approach is to remove the IAC tube and spray some tuneup cleaner (I use Ford) into the IAC intake hole while its running. You may need to rev it a bit to keep it running. Then let the revs drop and let it stall. I let it sit for a few minutes then reconnect the tube.

The second better approach isn't too much harder. I remove the IAC to clean it. There are 2 bolts. The top one is easy but the bottom one is a bit harder. I removed the brake booster vacuum line to make access easier. Watch out that you do not loose the gasket. When its out just spray in some tuneup cleaner and let it sit. I repeated this several times until the fluid was coming out clean. Then reinstall. Generally this lasts me for 4-6 months before I start to notice a slow return to idle. If this doesn't help you should probably just get the IAC valve replaced.

// Chris Root
// '99 SVT

After reading some of the comments regarding this thread the past few days, I decided to take my (13/64th) THF cap off last night. My observations since:

PROs:
-Perhaps a little more pep in the mid-ranges. I can't say for sure yet, though. More "research" beyond 4000rpm definitely needed!
-Cleaner emissions. My main catalytic converter was, umm....STOLEN a few weeks ago (wink, wink!), and ever since there has been a noticeable stink coming from below/behind. But since removing the THF cap yesterday, it seems to burn and smell better today. Weird....

CONs:
-A DEFINITE decrease in shift quality due to the hanging revs, obviously. I'd forgotten how bad it was!
-Much worse gas mileage. I left home this morning with just under a half-tank, but that dropped to below a quarter-tank on my 30-mile commute to work (20+ miles of which is 70-80mph Interstate). Not good.


I'm gonna leave the cap off through the weekend and see how things go, but my initial impressions are to keep my THF. The "pros" of not having the fix are very slight, but the "cons" are glaring and annoying.

Just my 27 cents worth...

It's a trade off for me. I, too noticed a little less umph in the low range, and a big kick when the IIRC opens. But, like my post a couple of weeks ago (general mods) said, I've been spoiled by dropping revs. If I ever take it to the track or something, maybe I'll take it out.

I've had the TH plug in mine for so long I've forgotten how big the hole is! IIRC I erred on the large size of the spectrum. Is it possible that this fix affects the EEC4 & 5 differently? I've had the throttle body off recently and it was hardly carboned up at all. I believe this is a consequence of the EGR restrictor plate I installed. Also, Chris Root advises cleaning the IAC-the Ford manual states that it cannot be cleaned, throw it away and buy a new one. Very interesting.

Funny, I have had the IAC valve start sticking 3 times now, at about 6 month intervals. Cleaning has worked every time. It was the Ford dealer shop manager that suggested I try cleaning it!

The design is a little plastic disk that slides on a shaft. I think the shaft (which sits in the airflow) gets gunked up and it stops sliding smoothly and the spring isn't strong enough to force it closed.

// Chris Root
// '99 SVT

Tim935... I hope that you were exagerating that a bit.. Because my fuel mileage has not decreased whatsoever.. I'm at 180 miles on my tank now and I just passed the halfway point... And it's following its usual marks.. So I think you have other problems my friend. I definatly don't miss the hesistation when accelerating in the midrange.. Makes it so annoying and as the test showed.. Makes it run slower also. The pro's are definatley outweighing the cons... The only con is the throttle hang.. and I really don't care about it.. it's only annoying when shifting slow.. When racing it doesn't matter and actually helps you keep your power into the next gear.. Try it!

Dom

On my 95 the TH fix was one of the first, MUST do things as the "hang" was very noticable, and made it hard to drive the car smoothly on the winding rally type roads that I frequent. It seems that later model year cars have different results that the early cars do. I would gladly trade a little HP for the quicker RPM drop.

What I cant understand is that people want the rpms to drop fast, why? Ok, I drive with a lead foot and I get like 20-22mpg, but what I can't understand is the TH. Under normal conditions (regular driving) how does this (the hang) effect your driving habits? Maybe my car doesnt suffer from it (It does take time to rev down from 5-7k) Maybe I am all wrong on my thoughts, but I just dont see it.

Well I've driven without it for a bit and I like it better. It seems that either the computer hasn't fully adjusted back yet or the hang is a fraction of what it used to be. Perhaps I had a dirty IAC and the gunk got knocked loose? I don't even know where to look for this valve to check. I definately have better acceleration through the full spectrum. The gas mileage seems to be down but the with the heat here and all the A/C at full blast it's hard to say. I'm not throwing the cap away, just enjoying the way it's running right now.