Worse gas mileage with restrictor plate?

Fixxxr · Sep 28, 2007

I have recently added a restrictor plate to my car - although I love the way the car acts & sounds now, It seems like its using more gas. I'm just judging this based on how many miles I normally get on a tank. Has anyone else noticed this?

the98stang · Sep 28, 2007

Fixxxr said:
I have recently added a restrictor plate to my car - although I love the way the car acts & sounds now, It seems like its using more gas. I'm just judging this based on how many miles I normally get on a tank. Has anyone else noticed this?

What do you mean by restrictor plate?

Many variables can affect gas mileage (weather,gas brand etc). Are you sure what you did to the car is causing the bad gas mileage?

BennyBlown2v · Sep 28, 2007

IAC restrictor plate??? If you put a restrictor plate under the intake plenum I don't know what to call you LOL

Fixxxr · Sep 28, 2007

Uh...yeah, it would be the IAC restrictor plate. I guess I should have specified! lol. I'm not SURE that putting the restrictor plate on caused it, its just kinda strange that after I added it, my mileage seems to be dropping.

04YELLOWGT · Sep 28, 2007

Why would you do that though?

Fixxxr · Sep 28, 2007

04YELLOWGT said:
Why would you do that though?

I did it to correct the irregular RPM's which appears to be a common problem in these cars.

04YELLOWGT · Sep 28, 2007

Are you talking at idle? I think there is a stickey to correct that.

Fixxxr · Sep 28, 2007

Ok, is there anyone out there that has one of these restrictor plates installed that knows what I'm taliking about & has experienced something similar?

2000fordstanggt · Sep 28, 2007

i think hes referring to the hanging idle after the clutch is pushed in. you have to come to a complete stock usually for them to drop. but it doesnt happen to every car

SVT_MAN · Sep 29, 2007

ROFL .. when I read this title I thought the guy installed a restrictor plate on the intake plenum like they do in NASCAR at the superspeedways (And worse gas mileage would be odd since it restricts the RPMs and power ...)

comporange04GT · Sep 29, 2007

Fixxxr said:
Ok, is there anyone out there that has one of these restrictor plates installed that knows what I'm taliking about & has experienced something similar?

I have an IAC restrictor plate on my car and didn't notice a decrease in fuel enconomy. It did fix the hanging idle issue I had. How long have you had it installed? It might take the computer a little time to adjust to it.

SVT_MAN · Sep 29, 2007

comporange04GT said:
I have an IAC restrictor plate on my car and didn't notice a decrease in fuel enconomy. It did fix the hanging idle issue I had. How long have you had it installed? It might take the computer a little time to adjust to it.

When you talk about a hanging idle, are you talking about pressing on the gas in neutral and then the revs take forever to come down? I have that problem on my GT.

joshjwc9 · Sep 29, 2007

I have a hanging RPM's issue, but it doesnt bother me at all. Some people cant stand it while others need it fixed.

I have a buddy with an 02 GT and a restrictor plate and he didnt notice any difference in gas mileage, so I dont know what could have affected your gas mileage.

What was the difference in gas mileage?

comporange04GT · Sep 29, 2007

SVT_MAN said:
When you talk about a hanging idle, are you talking about pressing on the gas in neutral and then the revs take forever to come down? I have that problem on my GT.

Yeah this is the issue. The bore in the idle air circuit is oversized so if you restrict the circuit it will allow the RPMs to drop.

Wolvrin704 · Sep 29, 2007

I think mine may have that idle problem as well but it really doesn't annoy me in the least.

Fixxxr · Sep 29, 2007

I just wasn't sure if poorer gas mileage may have been a common side effect of installing the IAC restrictor....not sure how it really could be, but just thought I'd check! Thanks.

'03GTinFLA · Sep 30, 2007

I didn't notice a drop in gas mileage when I did mine either. I think the best fix for the hanging idle after install of TB/Plenum is to get a blower. That's what really fixed mine for good.

AdRock · Oct 1, 2007

Having the IAC restrictor plate in there should not affect gas mileage in any way. It has to be something else causing your problems.

MyStangGT · Oct 1, 2007

IAC stands for Idle Air Control so restricting it will mean less air is introduced at times and may = richer mixture. I imagine the computer will try yo compensate by opening the valve more to regulate the idle.

Personally I'd just clean or replace the IAC to correct the problem.

thomas91169 · Oct 1, 2007

lol are you qualifying for Nascar?

Worse gas mileage with restrictor plate?

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