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  • SN95 4.6L Mustang Tech

Fix your Slow dropping/hanging RPMs

  • Thread starter Thread starter magnum347
  • Start date Start date May 1, 2005
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02GTRX

I told an admin to shut up...now I live with the S
20+ Year Stangneter
Sep 27, 2004
213
8
19
Jan 10, 2006
#121
  • Jan 10, 2006
  • #121
This mod actually helped my motor. Before in the mornings when I would take off it would hesitate kinda like a misfire until it would warm up, and now it takes off nice and smoothe. The ride also isnt as jerky as it was before when I would shift, now everytime I shift its very smoothe like an automatic. Do it and dont look back
 

billfisher

Active Member
Jul 17, 2005
1,296
4
38
huntsville, AL
Jan 10, 2006
#122
  • Jan 10, 2006
  • #122
the problem is idle mixture.

i had this problem until yesterday with the 5.4.

i added a little fuel pressure and the idle mixture was richer to the point it idled down and smooth. to check it remove a small vacuum port and if the idle gets worse look to idle mixture as the problem. how you are going to fix it for 99+, maybe look to a vacuum source to eliminate. but idle mixture was my hanging idle fix.

i suspect it is the problem with aftermarket elbows also.
 

stangGT97

New Member
Dec 22, 2004
1,299
1
0
Boston area, MA
Jan 15, 2006
#123
  • Jan 15, 2006
  • #123
got one from Ebay for $7 shipped, made out of Mr. Gasket gasket material. Works like a charm, I'm very pleased
 

USMstang

Member
Oct 30, 2004
114
2
19
Mississippi Gulf Coast
Jan 16, 2006
#124
  • Jan 16, 2006
  • #124
Done! That took all of 30 mins start to finish. I used some aluminum flashing. My GT only utilizes one hole in there (on the IAC), the other is dead space. Nice roll-off in rpm's, just like the carburetor days.
 

98blackstallion

Member
Mar 30, 2005
602
0
17
mtn home arkansas
Jan 23, 2006
#125
  • Jan 23, 2006
  • #125
hey guys i tried contacting the guy that makes these and he says that he cant make anymore can someone give me a link to how i can make my own or where i can buy one of them. Thank you
 

trailblazr81

Member
May 17, 2003
571
0
16
Hollister, Cali
Jan 23, 2006
#126
  • Jan 23, 2006
  • #126
Theres a couple people selling them on Ebay. http://cgi.ebay.com/ebaymotors/03-0...33553QQitemZ8032305936QQrdZ1QQsspagenameZWDVW
Or do the copper cap mod. Get a 1/2 inch copper cap, drill a hole in it and put it in the rubber hose.
 

hotrodnut

Member
Jul 12, 2004
672
0
17
North Florida
Jan 23, 2006
#127
  • Jan 23, 2006
  • #127
98blackstallion said:
hey guys i tried contacting the guy that makes these and he says that he cant make anymore can someone give me a link to how i can make my own or where i can buy one of them. Thank you
Click to expand...
Contact Stangnet Member 34ford, he makes them.
http://forums.stangnet.com/showthread.php?t=470711&highlight=34ford
 

98blackstallion

Member
Mar 30, 2005
602
0
17
mtn home arkansas
Jan 24, 2006
#128
  • Jan 24, 2006
  • #128
Well i did the copper cap mod and drilled a 3/16" hole in it first and put it in. Well then it didnt want to idle or anything so I enlarged it some more and I had to keep doing this for another 4 sizes up and then it started to work better. Maybe its because my car needs a tune? I have a full bolt on (minus plenum and TB) and stage 1 VT cams and still have the stockish tune. SO that might be my problem i will try it again after my dyno run next month.
 
W

wht03GT

New Member
Nov 2, 2005
41
0
0
Pittsburgh, PA
Jan 27, 2006
#129
  • Jan 27, 2006
  • #129
Bringin it back....

Does anyone have a hiss after installing this when pressing the gas, or at idle?
 

hotrodnut

Member
Jul 12, 2004
672
0
17
North Florida
Jan 30, 2006
#130
  • Jan 30, 2006
  • #130
wht03GT said:
Bringin it back....

Does anyone have a hiss after installing this when pressing the gas, or at idle?
Click to expand...
Nope . . . no noise, no stalling, works as intended.
 

sgarlic

Founding Member
Apr 21, 2001
3,085
1
56
Apr 2, 2006
#131
  • Apr 2, 2006
  • #131
Another bump for an old thread for new guys..

I just made one of these puppies up today, and installed it. Both were a breeze.

I borrowed a piece of brass stock from work, and removed the IAC. One wire harness, one hose, 2 5/16" bolts.

Removed the gasket and the IAC assembly. Laid the gasket down on to the brass stock, and traced the outside and the 2 big holes with a magic marker. Used a scribe to trace the bolt holes.

Used tin snips to cut the shape. Used different sized drill bits until I find one that was the right size for the bolts to fit through. Used a dremel with a metal spiral shaped bit to cut out one of the middle holes. I kept matching it up with the IAC to make sure the hole I cut was bigger than the IAC hole.

Last fabricating step was drilling a 9/32 hole in the center of the other marked hole, and using a wire brush attachment on my dremel to clean up all the burrs. I threw it all back on, from front of car to back is IAC->plate->gasket->TB. I think perhaps I'll pick up another IAC gasket and put it between the IAC and the plate just to be sure.

Impressions:

Fired it up to be sure it worked. Ran fine. Turned blower to max, then switched to MAX A/C. Slight dip in idle as usual, but no stalling. Turned blower off. Switched to defrost and used max blower. Same dip in idle, no stalling. Rev'd to around 3k and let off. WOW. What a difference. Idle drops faster, but not annoyingly fast. Took it for a quick drive down the street, and noticed idle drops a lot nicer between shifts (not surprised since that was the whole point.) That "popping" when you let off I would call "cackling" instead. I noticed the delay from when you let off the throttle to when engine braking occurs is much less.. used to take 3 or 4 full seconds before I got full engine braking.. now it's easily less than 1/2 second.

I'm still not sure about using brass, but now that I know how to do it, I may find some aluminum and use that instead.

Great mod, took less than 30 minutes from start to finish, and cost me nothing.

Thank goodness for whoever thought of this.
 
W

WillDuhhBeast

New Member
Jun 25, 2005
339
0
0
Jacksonville Florida
Apr 2, 2006
#132
  • Apr 2, 2006
  • #132
I recently took mine out because it started to bug me. The rpm's would drop too fast from time to time then it would make it harder to shift smoothly. The rpms would drop down to 1500 and i'd have to ease out the clutch really slowly to not bounce it a little. It started to get really annoying. Having the rpm's "hang" for just a second allows a much smoother transfer through the gears, I noticed.


I never noticed any "improvment" by this mod, beside the deceleration was slightly improved at certain rpm ranges, and the noise of it when decelerating.
 

rocketman461

New Member
Aug 19, 2005
12
0
0
Bensalem, PA
Apr 2, 2006
#133
  • Apr 2, 2006
  • #133
Noise

wht03GT said:
Bringin it back....

Does anyone have a hiss after installing this when pressing the gas, or at idle?
Click to expand...

I have a "back-pressure" noise when I decel, but I don't have any constant hissing noise.
 

01GTSTANGER

Member
Feb 19, 2006
100
0
17
Pasadena, CA
Apr 3, 2006
#134
  • Apr 3, 2006
  • #134
WillDuhhBeast said:
I recently took mine out because it started to bug me. The rpm's would drop too fast from time to time then it would make it harder to shift smoothly. The rpms would drop down to 1500 and i'd have to ease out the clutch really slowly to not bounce it a little. It started to get really annoying. Having the rpm's "hang" for just a second allows a much smoother transfer through the gears, I noticed.


I never noticed any "improvment" by this mod, beside the deceleration was slightly improved at certain rpm ranges, and the noise of it when decelerating.
Click to expand...

I totally agree....I took mine out for the reason that my RPMS would drop so fast that when i would release the clutch I would hear a pop or something like that coming from my tranny. Took it off and my shifts were alot smother and no more popping. Loved the snap crakel and pop but dont want to damage anything. Just in case.
 
G

GettinThere

Member
Jul 29, 2005
553
1
19
Central Texas
Apr 3, 2006
#135
  • Apr 3, 2006
  • #135
sgarlic said:
I just made one of these puppies up today, and installed it...
Click to expand...

That settles it, I'm making one too.

Thanks for your in-depth account.
 
M

magnum347

Member
Jun 4, 2002
31
0
7
Texas / Ft Hood
Apr 26, 2006
#136
  • Apr 26, 2006
  • #136
Awesome... just returned from Iraq again and this thread is still alive. I quit making these for awhile because of the new job in Balad Iraq. I'll make a bunch when I get back "over there" and will sell them again. And I will sell them cheaper than anyone.... with free shipping.
Oh yeah.... Finally got a Paxton Novi 2000 Mongoose kit in my Bullitt from MPH.
 

Warrior 102

New Member
Jan 22, 2003
231
0
0
Macomb MI
Apr 27, 2006
#137
  • Apr 27, 2006
  • #137
I machine one from solid aircraft aluminum,I install it, and the car defiantly running the way supposed to run,nice mod.....
I have left over material and I machine one more piece......now I have one extra...... here is some pictures.....
 
R

rs-turbo

Founding Member
Aug 14, 2001
397
0
16
Orlando, Florida
May 18, 2006
#138
  • May 18, 2006
  • #138
Just thought I'd throw my five cents in here. I read this thread and liked the idea. I was going to replace my IAC since I suspected it was causing a stall issue now and then and figured I'd add this plate while I'm at it. I made a simple plate from a sheet of aluminum I had left over from another plate I once made for a different car to block off the EGR. My hole was a little smaller, turns out I didn't have the right drill size out of all the bits I've got. Once installed I had a high idle. It would vary between 1200-1500, which helped the AC and electrical with my underdrive pullies, but still annoying running so high. Everything seemed tight so it didn't seem like a leak past the plate. From what I've read with a smaller hole than mentioned here, I should have more of a stalling problem than high idle. The car did feel a lot more responsive and I loved the tougher sound of the popping. I intended to open the hole up a bit, but ran it "as is" for about two weeks when my Service Engine light came on. This past weekend I pulled the plate and reset the light by disconnecting the battery and right now all seems normal. Back to the standard idle, but now that I drove for a while the other way, I really miss the popping and the responsiveness. I now notice the idle staying high too. I don't recall it hanging this long before. This could be because the old IAC wasn't working right anyway and/or I just never paid that much attention to it. I've thought about trying the Mr. Gasket one on eBay, but figured an actual metal plate might be a better and more durable solution. Are you guys still putting a gasket on both sides of this plate, or just IAC/plate/TB? For now I'll see if my Service light stays off, or if I have another issue going on, and then probably buy one of the plates sold here when they are available again.

Here's an idea for those making this. How about a screw or something in the side of the plate that extends into the hole. Then while installed if our idle is too low or high, we can simply turn the screw to open or close the hole some until idle become normal.
 

loosescrew79

New Member
Dec 18, 2004
313
0
0
May 18, 2006
#139
  • May 18, 2006
  • #139
WillDuhhBeast said:
I recently took mine out because it started to bug me. The rpm's would drop too fast from time to time then it would make it harder to shift smoothly. The rpms would drop down to 1500 and i'd have to ease out the clutch really slowly to not bounce it a little. It started to get really annoying. Having the rpm's "hang" for just a second allows a much smoother transfer through the gears, I noticed.


I never noticed any "improvment" by this mod, beside the deceleration was slightly improved at certain rpm ranges, and the noise of it when decelerating.
Click to expand...

I have been thinking about taking mine out or maybe makethe hole a little bit bigger
 

gtstangau

Member
Jan 9, 2006
133
0
16
Alabama
May 18, 2006
#140
  • May 18, 2006
  • #140
loosescrew79 said:
I have been thinking about taking mine out or maybe makethe hole a little bit bigger
Click to expand...

I had to make the hole bigger, because the rpm's were sticking at 1500. Seems to work fine with the bigger hole. I love the crackling sound when I shift now!
 
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