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IAC Control Restrictor Plate + EGR Restrictor plate

10K views 25 replies 9 participants last post by  rc5liter 
#1 ·
Hey guys,
After reading online on how to make my exhaust pop more (lol random google search) I stumbled upon a thread on another forum and this came up

Ford Mustang Cobra Mach 1 Saleen Bullitt GT 4 6L IAC Restrictor Plate | eBay



It's a IAC restriction plate. It's meant for the hanging rpms between shifts on a 5-speed but a side effect is a much more crackling exhaust note upon deaccel.

I figured for $10, why not? I do have the hanging rpms like all of us do so I figured I'd try it out. Anyone else have these? It's a pretty popular seller so I was curious.

The same person also sells a restrictor plate for the EGR that prevents so much hot gasses getting back into the plenum. Has anyone tried this as well?

Thoughts?
 
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#2 ·
I tried an ebay iac restrictor plate and it didnt do squat. It seems like theyre hit or miss. As for the egr restrictor plate, whats the point? The egr is there for emissions and improved fuel economy. I dont see how restricting it would affect anything except running rich because the amount of air the ecu expects isnt making its way into the motor.
 
#3 ·
The ONLY good reason to delete the EGR is to clean up the underhood area.

It's one of the rare emissions devices that don't really have a downside. It absolutely increases fuel economy, and is one of the things in the tune that you actually increase if you want better economy.

That being said, if you want to delete it, it's not going to negatively affect the tune or driveability. Since EGR is already burned and inert, it doesn't affect the air/fuel ratio.
 
#5 ·
I made my own IAC restrictor using a soda can. I traced the outlines using an IAC gasket and cut it to shape with a pair of scissors. Easy peasy. Definitely got rid of the hanging idle and the car gurgles and pops on deceleration. It's awesome!

I'm in CA so I'm not messing with the EGR.
 
#7 ·
I've made my own two different ways. I tried the gasket approach and I've tried putting a obstruction in the hose with a smaller hole. They mostly got rid of the hanging rpms but I'm willing to try something else just for grins. Let us know if it works.
 
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#9 ·
I made my IAC restrictor plate. I used 2 felpro gaskets #71216 and a piece of aluminum from a soda can that I cut to fit like macuser27 did. My restrictor holes were drilled to about 5/16". That thin of aluminum isn't easy to drill through and end up with a clean looking hole so if anyone uses this method take your time and make sure the plate is held down good. I stepped on it with both feet while it was on a block of wood. I also used rtv on the sides of the gaskets facing the aluminum plate.

The drop in RPM's with the plate installed is very noticable. When I let off the gas while revving the motor the RPM's drop pretty darn quick. Like I said before its not a slight change. I could notice right away after startup the RPM's dive down very quick. I didn't think this mod would make that much of a difference. I only drove to the the local gas station and back to test drive it. In the future I may make a better plate out of better material than soda can aluminum but am going to leave it alone for now.

For $3.40 I would say its money well spent and took maybe 20 minutes. I'm pretty happy with the results. Try it out if you are thinking about it. You will probably be glad you did.
 
#10 ·
Thanks for the replies all! My plate that I bought hasn't come in yet so no results yet but everyone's input in fantastic! Can't believe I had this car so long and just now found this .
 
#11 · (Edited)
Just got it installed. Working on editing the video now. The pros and cons of this thing (Mods that would affect exhaust sound is C&L Plenum, BBK TB, Pacesetter offroad H pipe, Flowmaster Super 44 mufflers, all mandrel bent 2.5" piping to the rear)

PROS:
-Def more muscle car sounding. It sounds more... raw now. On deacell it sounds more nasty then just a slight lowering hum it did before. Even at idle it sounds more bum bum bum rather then just typical Flowmaster exhaust at idle.
-The RPMs drop so much faster. It's going to take a bit to get used to but I really like it. It feels more like a sports car now.

CONS:
-Holy exhaust fumes. I can smell it a lot more and you'll see in the video but I was standing behind the car capturing footage of the exhaust at idle and my eyes started to burn. I can def tell if was an emissions thing. Also doesn't help I am catless.

Video coming up soon. I am editing it so only the parts show where the exhaust is different. I don't think anyone wants to see 7 minutes of me driving.

Here is the second video I made. It shows the exhaust at idle. It's more of a bum bum bum sound versus your standard Flowmaster sound. Adds more of a bumping sound similar to a cam. At 23 seconds in you can see me back off because of the exhaust fumes



OK the video I shot while driving SUCKS but yes - it does make the exhaust pop. I got Flowmasters to pop when I got the rpms high enough and let off the gas. Never thought I could do that. This mod would make an exhaust with an X pipe and flow thru mufflers like Stingers or M80's pop a lot.

I like it with my current set up - it adds a more raw sound to the exhaust. Less tame sounding. For 10$ (or even cheaper if you do it yourself) I'd say why not.

Here it is installed:



As it came in the mail - I swear I could have made this with some gasket material from an auto parts store and a coke can and drill bits. That's how thick the metal is.


My car
 
#12 ·
+1 on the exhaust fumes, sports car feel, modded V8 sounding idle, and getting used to the new driving manors. My drive to work today was a lot more fun than usual:) Sitting at stop lights I couldn't help myself from revving the engine although I tried not to be too much of a tool. It just sounds nastier but in a good, don't eff with me, way.

I like it ! A gem of a find I'd say.

Rep^
 
#13 ·
Thanks and I can't take credit for this. It's been around for a while and wildly popular. Im just shocked I just now found it after having my car for 5 years.

What exhaust do you have? Is your car a foxbody like in your avatar?

Just got back from a night cruise as it's beautiful out. I can smell the exhaust fumes on my clothes and hands. Not sure if I'd keep this if it was a DD lol
 
#17 ·
you got a gasket metal gasket then another gasket?
i just used the metal gasket lol
but ya everything you said is true fumes suck especially in traffic on a warm day
 
#18 ·
Yes sir - that's the way the kit came. It works fine - idle's great at 800rpms and all. No loss of power noticed. I don't drive it enough to honestly comment on the MPG but from what I read it isn't effected.

Yes the fumes are something else - I didn't see any other threads mentioning this or I just didn't notice. That'd be the biggest downside to this that I've noticed.
 
#23 ·
That's properly why you don't have the fumes. I have an Off-Road H pipe with no cats. It was pretty bad before, now it's eye bleeding. I can smell fuel on me when I get out. I left the computer disconnected for 30 minutes while I did the mod and when I was done let it sit to let it fully reboot. I then drove it for about 30 minutes to let it relearn. Still the smell.

Idle, power, everything is the same. I can see why hanging idle is an emissions thing.

---------- Post added at 09:13 AM ---------- Previous post was at 09:11 AM ----------

I thought after maybe 50 miles or so the computer would adjust itself. I'll reset it and see if it helps now that you mention it.
Keep in mind the hanging RPMs and large diameter hole of the IAC is for emissions. The engine kept higher in RPM's (hanging RPMs while shifting) to keep air flowing so the engine can burn off fuel between shifts. Now that the engine doesn't do this, the fuel goes out the tail pipes.
 
#26 ·
I did notice exhaust fumes at first. I reset my comp like macuser27 said and it seemed to change that issue. Ive been driving with my IAC restrictor for about a month now and I rarely notice an exhaust smell and have never had my clothes smell like fumes. I am running cats on my mid pipe, I dont know if that has anything to do with it or not. Im still pretty happy with the mod.
 
#25 · (Edited)
I bet my mustang has this! The rpms hang for all loooong time but my exhaust pops like crazy. Always thought it was abnormal how long it takes for the rpms to drop, but the exhaust pops quite a but on downshifts.
 
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