4v_mach1

I ordered a pre made one from ebay and it came with 3. Am I supposed to install all 3? Came with 2 soft bendable ones and 1 metal sheet metal type of material.

Bmitchell373

Yes, the aluminum is the actual restrictor plate, and the 2 gaskets are for each side.

Romer

Hey Cliffyk would the 40% duty cycle log as .4 ? whats the range? mine stays around .590 when datalogging the iac valve duty cycle.

cliffyk

.4 and 40% are the same value...

It will vary depending on how much air is bleeding past the throttle plate (this is set with the throttle stop screw). If the plate is more closed at idle the IAC duty cycle will be higher to pass more air, if it is more open the IAC d/c will be lower as it does not need to pass as much air.

IAC restrictors affect this as well, gasket or "pipe-cap" it doesn't matter, as they get more restrictive the PCM will increase the IAC duty cycle to pass enough air to maintain idle speed.

59% is a bit high, unless you have an aggressively sized restrictor, As the throttle stop screw wears of the years, or you have replaced the TB, or someone mucked about with the throttle stop screw, you might want to following the procedure for the initial setting...

Or if the engine idles OK and holds idle speed properly when the AC and other loads are applied, then don't worry about it...

4v_mach1

Car is idling at almost 1,000 rpm and the car sounds like it's misfiring at idle. Strange, but the RPM do drop quicker.. And the car sounds a bit different.

cliffyk

Did you disconnect the battery for 5-7 minutes while installing the restrictor plate? That will reset the KAM (Keep Alive Memory) and force the PCM to re-learn the idle air trims...

BigGary

just did the copper cap method with a 3/16" hole, took about 15 mins including the trip to Canadian Tire and a cruise around the block, its like driving a different car in concern of shifting, much smoother now, tranny even seems to go into gear alot smoother, not sure how or why, love it!

Grey-03-GT

another advantage to this mod is you wont be wearing on your clutch because the revs wont be floating...they will drop right away faster when you shift...not a big deal but still a plus....Has anyone failed state inspection with this mod in place? I usually change it back to stock on inspection day then replace it after...just curious...thx

smitty2919

When I did this to my old 04 GT, I noticed that you have to "keep up" on the shifting. If you feel like crusing around very relaxed and take longer in between the shifts, the rpms will fall quick and not make the transition between gears as smooth.

You constantly have to shift on the quicker side that's all. Sometimes I take my sweet time shifting because I'm just in that mood.

cliffyk

It could depend on the inspection process. When the restriction is placed in the IAC feed tube there is obviously less air flow available to the IAC--this is what makes the revs drop faster between shifts, and if the restriction is too great (the hole too small) there will be insufficient flow to support a proper idle.

However as this is all metered air (it "comes" from after the MAF) the PCM will within reason continue to properly adjust the AFR--so unless the tester is very sophisticated (it would have to know the proper deceleration rates/etc. for the vehicle being tested) it should not be bothered by the restriction mod.