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

I've been doing some research on the infamous "Throttle hang fix"... I installed one on my SVT just to see what the difference was.. I drilled a 7/64" hole.. and the results I got over the last three months have been dissappointing.

True, it does bring the revs down.. But there are more side effects to this then I think everyone notices.

1. When pulling at low RPM.. engine will bog to 4K.. then pull real hard to redline.. Never as bad as to the extent of what it has been with the cap in.
2. Idle quality worsened.. When the engine was allowed to sit and idle for more than a couple of minutes the O2 sensors would go rich and the idle would start to hunt and break up.. Then the engine would pick up speed and smooth out.
3. Took it to a local track.. Running two times with and without the "fix" I lost .8 of acceleration time with the cap installed. Now the car is back to the sub-7 second mark like before instead of 8's that it's been running.
4. Most of that god-awful tinny moosing sound with the KKM is gone... Doesn't sound like air trying to be sucked through a straw anymore in the intake.

Some people mentioned that a slight power loss was reported on newer 2000 SVT's with this mod.. Well.. Mine's a 98 SVT and it lost power also. Unfortunatly it is a sound idea.. But has some negative impact on the airflow through the IAC that the computer is counting on... And when this is interrupted it runs slower..

Just try it.. Run for a while one day with the cap in.. Full acceleration to redline, then un-install the cap... And repeat the procedure.. You'll notice a big difference in the performance and the responsiveness of the secondaries. The cap seemed to magnify the lag before the secondaries opened and the lurch afterwards.. Not a real good feeling..

So.. unfortunatly I'm not recommending the TH Fix to anyone anymore.. My G-Tech has shown me the facts and the seat of my pants has also.. Plus the engine idles better and it pulls much smoother to redline.

Dom

I've been running with it for a couple of months now. I'll pull it tonight and let you know later.

I never installed it, why let the engine rev down faster anyway? When at the track you want to stay in your power band. I just never saw the point in it.

Ditto KnuKonceptz... I have thought about trying this since so many have mentioned the enhanced drivability of the car but never did it. The engine not dropping the revs instantly has never really bothered me.

I have the SCA CAI and my idle already occasionally searches (but never stalls like others have had with ths setup) so if what you are saying is true Cardoc, this is definately not for me....

Well the secondaries definately were smoother. It seemed to pull better at lower RPMs. Dam you Dom. I was getting such good gas mileage with it in.

Did your computer have time to learn without the THF? Or was it still running with the "idea" that it was still installed?

I fixed the THF idle problem by just opening the hole a little more. Before that I was having a stalling problem, but now it seems to be fixed.

Well sure if you have your hole to small it will "hunt" the engine and possibly stall it out! Your blocking the air coming in for the engine to breath! Don't make the hole so small and your fine.

But I will deffinatly try out your theory Doc about pulling hard to redline etc. Not sure about supposed to get better mpg with it in, mine sucks anyway so it hasn't helped me out at all (to much heavy footed!!..lol)

My cap has been in the trunk for the last couple of weeks and I feel there is an improvement in mid-range pull. I had THF installed for about 6-8 months and discovered the extra pull by accident when I forgot to tighten the clamp and the hose fell off. One morning my idle got very rough and was hunting-stalling, but the car was pulling like crazy when I stepped on it. When I got to work I popped the hood and noticed the hose had come loose. With an ATX this wasn't that useful anyway. I just let it warm up for an extra 10-15 sec. now.

I opened the hole a little bigger a few times... Only because my cold start idle was about 1500 RPM and it would surge a little bit. The theory that made me think that the cap was making problems was that under full throttle acceleration you could still here it sucking through the cap and for some reason the Ford PCM opens the IAC to full 100% duty cycle under full acceleration... Hence the throttle hang.. But it does rely on the air it recieves in that passage for acceleration.. Restricting that little passage effects it like you restricted the main throttle housing. It definatly pulls harder... and it doesn't seem stressed/straining to do it.. That was a big thing I noticed when I listened to the engine.. ( after removing the cap)...

Ok... who in here has a bigger hole than 7/64" drilled in theres? Mines approximatly half the circumference of the cap itself.. Drilling it any bigger would be pointless anyway. So I took it out.. Like the way it performs better without it.

Dom