Accufab add on idle problems

[SROBERTLAW2003]

I have a 1997 mustang GT, just bought a 75mm plenum from accufab and bolted it on and car ran fine. it was new in box. bought a used with 800 miles on it 75mm accufab TB guy said it was cleaned and ran fine when he pulled it off. with the accufab plenum and stock TB car ran good just had a compression sound in motor when i turned it off. when I added the accufab TB it 's idle was 1300 or so RPMs until I gave it gas and it was jump up to 2300-3k RPMs and want idle back down. Im also using a stock mass air meter and a BBk cold air kit with fender K&N filter. when I emailed the guy he said his tech guy told him it was getting to much fuel for the computer to compensate for it and causing it to idle high, and that I just needed a tune up. the accufab TB came with a throttle position censor already on it looks new. anyway does anyone have any idea's I was trying to get it running good for a carshow in my area by sat. any help would be appreciated.

 

[Jbauer]

Is your car an automatic?

If not- you may need to fiddle with the idle screw.

 

[SROBERTLAW2003]

ya its a 5spd car.

 

[SROBERTLAW2003]

Is your car an automatic?

If not- you may need to fiddle with the idle screw.

if thats the screw in top left corner of the TB, I screwed it to where it nearly came out with no change to the idle.

 

[Jbauer]

I could be wrong, but i think that New edge mustangs came with a diffrent TPS, is that TPS also from a new edge? I do know the new edges have TPS that don't requre calibration.

I'd try disconnecting the battery for half an hour, then reconect it, and turn the car on and let it idle for 5 minutes without touching the throttle and drive it for 3 or 4 days to see if it fixes itself.

 

[myponyrocks]

Another vote for checking the TPS voltage AND resetting the computer.

You should not need a tune even with ALL bolt ons (except LT's) for the car to run decent.

 

[propellerhead]

If it's anything like mine, there's a screw on the throttle that hits when the throttle is closed. If I read it right, the screw keeps the blade from closing fully and has something to do with the idle. The Accufab instructions says do not ***** with this screw. Ever. Maybe the previous owner did. The side effect of messing with it is that the blade will close too much, which will make the IAC try to compensate and provide more air, hence jacking up the idle. The vacuum also makes opening the throttle a bit harder. It tends to stick. Once you apply enough pedal pressure, it opens up really wide and the RPMs shoot up.

I don't know if any of this applies but I remember reading this on another forum. You might dig into it some more.

 

[SROBERTLAW2003]

If it's anything like mine, there's a screw on the throttle that hits when the throttle is closed. If I read it right, the screw keeps the blade from closing fully and has something to do with the idle. The Accufab instructions says do not ***** with this screw. Ever. Maybe the previous owner did. The side effect of messing with it is that the blade will close too much, which will make the IAC try to compensate and provide more air, hence jacking up the idle. The vacuum also makes opening the throttle a bit harder. It tends to stick. Once you apply enough pedal pressure, it opens up really wide and the RPMs shoot up.

I don't know if any of this applies but I remember reading this on another forum. You might dig into it some more.

ya the throttle adjustment screw was all jammed up when I recieved it from a ebay purchase. I had a freind of mine come over and adjust the voltage to the TBS and it idle down but ever time throttle is applied it stays at what ever RPMs I rev it at and want go down at all. unless I grab the throttle my self and pull real hard trying to close butterflies and then it idles down. the throttle screw was back nearly all the way out and the throttle cant even touch it that far back. there is also a round whole in butterly fly of throttle body and I thought there was suppose to be a screw in it not shure though. ive also done the disconnect battery and wait 5 mins and then reconnect and crank car wait 5mins or so then apply throttle and still sticks. Im at a loss to what to do.

 

[Will Smith]

sounds to me like a bad iac or possibly a vacuum leak. take the iac off and clean the inside.see if it helps and search for maybe a loose vacuum hose or one with a hole in it...

 

[nyuk98gt]

ya the throttle adjustment screw was all jammed up when I recieved it from a ebay purchase. I had a freind of mine come over and adjust the voltage to the TBS and it idle down but ever time throttle is applied it stays at what ever RPMs I rev it at and want go down at all. unless I grab the throttle my self and pull real hard trying to close butterflies and then it idles down. the throttle screw was back nearly all the way out and the throttle cant even touch it that far back. there is also a round whole in butterly fly of throttle body and I thought there was suppose to be a screw in it not shure though. ive also done the disconnect battery and wait 5 mins and then reconnect and crank car wait 5mins or so then apply throttle and still sticks. Im at a loss to what to do.

SROBERTLAW2003:

The blade does not come with a hole in it from Accufab. It is letting in more air than is required for idle. The spring should be pulling the blade back with some decent force. Maybe the previous owner installed a lighter spring? The throttle blade stop (the L-shaped metal tab that contacts the set screw) should be square or 90-degree shape. It may be bent too far so it does not contact the set screw.

My advice: take it off and send it to Accufab and ask them to reset it. They will charge you a fee but the t/b will be set up correctly.

HTH,

Chris

 

[joshheat25]

my car used to surge with my accufab upper plentum and TB before I got a tune!

 

[SROBERTLAW2003]

sounds to me like a bad iac or possibly a vacuum leak. take the iac off and clean the inside.see if it helps and search for maybe a loose vacuum hose or one with a hole in it...

I put my old 65mm back on it and it idles fine, a freind of mine was nice anuff to let me use his BBK TB and it worked fine. guess I might have to send it back to accufab for a rebuild. there saying 75.00 out the door.

 

[SROBERTLAW2003]

I just wonna say thanks for all the input, and I decided after speaking to the guy I bought it from he agreed to pay the cost for the rebuild and shipping. so I dont think ill do better than that. so atleast when I get it back I know if it doesnt work this time its something else other than TB its self. Ive installed these on countless mustangs luckly with no problems, guess I was bound to miss one day. Ill post some of my pics of it for people to bash me on later. basically its a 1997 mustang cobra clone. with all BBK suspension and lowering kit with true from ford 17" cobra R's h-pipe flows, 373's,cold air kit and short stroke shifter,accufab plenum. complete cobra kit bumpers,badges,hood ect.ect.