TOPIC: 2003 Ford Focus ZX3 2.0L plastic TB w/ IAC port restriction

Here is a '03 Ford Focus 2.0 ZX3 TB, in plastic. It got a large Groove, and I filled the huge IAC bypass port w/ JB Weld. Then I drilled a 1/4" dia. hole thru the JB filler to provide air to the IAC. This engine has the Idle Air Control valve downstream on the intake man. across the big IAC duct.

The TB was cleaned, then I used a small file to scratch the plastic surfaces in the IAC port, to give better adhesion to the JB. I cut some card stock from the JB package, covered it in clear box tape then taped the card over the top entrance of the port. I mixed several batches of JB Weld and carefully placed it in the port working from the downstream side. After a 24 hour cure, I removed the card, and smoothed down the JB filler, to give a close match to the contour of the TB entrance walls.

Ford put this huge IAC bypass port and a big radius tapered reduction in the TB bore leading to the throttle entrance/ plate. By filling, smoothing and drilling the 1/4" hole in the filler epoxy, I'm giving a better entry transition to the throttle bore. There should be much less turbulence in the total airflow, and possibly more CFM total potential. This TB has the biggest IAC port I've seen yet- and it's massive in proportion to the throttle bore size. I still wonder why the OEM's put such big IAC bypass ports in so many TB's, maybe they want to ensure the thing can idle even if the TB is completely grunged-up? Anyway based on experience and Ron's whiteboard explanations, I believe this 1/4" dia hole can give enough air to allow a good idle, even for fast idle at cold start. I also smoothed the top edge of the TB entrance and did a slight radius to the edge of the taper leading to the actual throttle bore w/ sandpaper.

This Groove isn't the prettiest, it got sorta rough towards the right side. I back filled the bore outer wall w/ epoxy, expecting break-thru. It did break through, and in 2 spots I had to add more epoxy to cover tiny holes. And the IAC port was another area needing back-fill, necessitating filling in that yawning port! I'm happy I got full depth w/ the large bit, and the flat Groove floor is pretty good. Obviously Grooving in plastic is far different than aluminum, it goes fast, I turned down Dremel speed a lot.

This TB goes out to our friend Filipp S. in Seattle tomorrow. Filipp has done some homework w/ the Groove, he has already re-gapped the plugs w/ good results. Any results he sends to me I will post in this thread!

Tracy G

I hope your client reports back with before/after numbers...Is there a way to make that a condition for certified gadgetmen with their clients?
remind him to re-address plug gap and reset the IAC valve's operation in the computer.

I just spoke w/ Filipp, I'm going to mail his TB back to him after I post this. Filipp did a huge increase in the plug gap from 1.3 to 2.0 Millimeters, on stock Motorcraft plugs. He says it runs smoother like this. The ECU gets reset to factory baseline via the re-learn process at TB reinstall.

Well, you can tell customers that it's Mandatory to do before/after testing- but it's up to them of course! I just explained the idea of the Orange Test to Filipp, he says he will give results when he has some. Also invited him into the Forum, so we will give Filipp a warm welcome when he comes here!

Filipp when you read this- you are Welcome here, we are friendly like-minded folks!

Tracy G

yeah, my ford engine liked big gaps too, especially with finewire iridium plugs...to a point.

And yes, Please, Filipp, join the convo now that you're part of the family!

bump!

Tracy G

Hi guys.
Here is some very quick feedback. (Followed the directions on computer reprogramming carefully. Did all the progressive accelerations etc etc.)

-More power. Accelerates easier - simply there is more power, more juice.
-MPG seems to be the same, around 29-30mpg. (I was really hoping for more increase but hey no big deal)

And since I did not smell the exhaust pipe before the mode, I can not really comment on if it smells cleaner after.

That's it in the nutshell.

F.

Wow, hi Filipp, long time! So- if there IS more power, there ought to be more potential for increase in MPG too. It can also be a paradox, to have extra power and try not to use it! Everyone likes more power, I sure do, power is like chocolate! Have you done any of the other stuff in the instructions besides increase the plug gap? There is a definite trend when more of those "tricks" are used, then higher MPG potential. Of course driving conditions, traffic, weather, and driving style are big factors too. My own experience on my Subie has been that higher tire pressure reduces rolling resistance, along with having tires with a sidewall pressure rating of 51 lbs. Heysoundude swears by the RVS friction treatments.

Glad you gave this long-term Groove feedback, thanks! I'd say, if you want more MPG, then read the instructions I sent along, or just start digging in here in the forum Index. IF the Focus is still in good condition, I'd say high 30's MPG is achievable with more attention.

Happy New Year, Filipp!

Tracy G

The "more power, faster acceleration, same mileage" statements here add (if only in my mind) credence to my theory that the groove's resultant waveform simply mixes the fuel and air together better for more even combustion. I'd bet that now the spark plugs could be re-gapped again for some gains...but what about o2 sensors? Are they reading accurately, sending correct fuel trim compensation info to the computer? Might they need replacement? These types of details help making suggestions...proper fuel pressure at the rail? MAF and TPS functioning correctly?

Yeah, the RVS is very good stuff ...reducing friction by restoring original tolerances. Which will reduce blow-by, so that the expanding combustion gasses move the piston rather than sneaking past it.
Tracy's high 30s guesstimate is probably conservative. Those are good little engines.

Just a general comment on a Grooving technique. I've done the JB Weld fill-in of the IAC inlet port-on this and 2 or 3 other TB's I've Grooved. I'm speaking of TB's that have these big IAC inlet ducts, as cutouts in the inlet side bore wall. Idea is to reduce inlet air turbulence, and direct air to the
Groove's upstream edge. Also to restrict IAC inlet air. I'm guessing that this might even increase WOT CFM flow volume from matching the bore wall's shape w/the fill.

The fill-and-drill technique has contributed to power increases every time I've used it. I think this can now be a recommended technique.

Tracy G

I replaced O2 sensor with a new factory one at the same time. Nor am I driving it more aggressively because it has more power. Just seems to produce the same MPG....

I need to tap into the gasoline additive Tracy recommended. Are you guys using it? What % gain did it do for you?

Thanks
F.

MPG remedy is the additive; the recipe (and discussions about it) can be found in a couple of threads on here. In my case it gives a small gain, but a gain nonetheless.

Have you made the associated modification, the PCV re-route, in addition to installing your grooved TB? Have you hunted and killed vacuum leaks? Have you reprogrammed your ECU? Increased tire pressure?
Go down the checklist and you'll find your gains in mileage. There will be one thing that will have the greatest impact.