THIS SHOULD BE EASY

GREG91GT

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Jun 3, 2004

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Jul 1, 2004

#1

• Jul 1, 2004

• #1

my? is when i race my mustang up it revs very quick, but it dont rev down very quick, very slow going down whats my problem guys?

 

85_SS_302_Coupe

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#2

• Jul 1, 2004

• #2

Heavy drivetrain, such as a heavy flywheel, heavy tranny gears and clutch equipment. If you're in neutral and revving down, it's a combination of the heavy flywheel and heavy internal engine parts such as the pistons/rods/crank. It's sort of a fact of life...lol Unless you build a motor of primarily aluminum parts, including the flywheel, it's just going to be this way. It just takes less time to rev up because of the power of the combustion.

 

cardudeusa

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Jul 1, 2004

#3

• Jul 1, 2004

• #3

85_SS_302_Coupe said:

Heavy drivetrain, such as a heavy flywheel, heavy tranny gears and clutch equipment. If you're in neutral and revving down, it's a combination of the heavy flywheel and heavy internal engine parts such as the pistons/rods/crank. It's sort of a fact of life...lol Unless you build a motor of primarily aluminum parts, including the flywheel, it's just going to be this way. It just takes less time to rev up because of the power of the combustion.

Click to expand...

Never thought of it like that.

 

GREG91GT

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Jul 1, 2004

#4

• Jul 1, 2004

• #4

no i no all of that, i mean its kind of like somthing is keeping it reved up for a while before it comes back down, in neatral

 

cardudeusa

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#5

• Jul 1, 2004

• #5

It is designed to stay revved a little bit like 1500 until you come to a stop.

 

85_SS_302_Coupe

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#6

• Jul 1, 2004

• #6

Could possibly be a fuel delivery type of thing, like maybe your throttle stick a little? Or if you have a fuel pressure regulator, maybe it's running too rich or something...

 

85_SS_302_Coupe

it sucks (I know) to be on the receiving end

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#7

• Jul 1, 2004

• #7

cardudeusa said:

Never thought of it like that.

Click to expand...

Rotating mass is just plain fascinating....the weight of something that's spinning is (i dont remember the percentage) MUCH more than the actual weight of the object....sort of like taking a weight and tying it to a string, if you swing it around over your head it actually feels like it gets heavier the faster you swing it. If you get an aluminum flywheel and a small diameter clutch, your car will actually clime RPMs much faster and in effect will make your car gain speed faster, while at the same time will take more throttle to keep you at that speed, since the normal weight of the rotating mass will keep things spinning for a longer period of time, but with a higher amount of force required to get you there.

 

GREG91GT

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#8

• Jul 1, 2004

• #8

i thought it might be a idle air control problem, how does it act when this messes up?

 

jrichker

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#9

• Jul 1, 2004

• #9

Mustangs will drop RPM from 1500 down to idle speed very slowly when you come to a stop. It is part of the computer design to keep the engine from stalling.

Sometimes the IAC which controls air bypassing the throttle butterfly will gum up and cause problems. Removing it and cleaning it with throttle body cleaner will often help.

 

GREG91GT

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Jun 3, 2004

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Jul 1, 2004

#10

• Jul 1, 2004

• #10

mods

well this problem did not happen until i put all of my mods on like i have a 80mm c&l for 30s i have edelbrock heads,systemax intake, 75mm throtle body and spacer, and 1inch intake spacer,255lph holley pump,dss dish pistons,no ac,no ps,no smog pump,electric water pump drive,1 3/4 mac long tube headers, and a vortech s trim and fmu, s-trim not bolted on yet and a built c-4 with a 8inch ptc converter and pro stick shifter

 

Mavrick

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#11

• Jul 1, 2004

• #11

I thought that the computer kept the engine from dropping revs real quick, so that in between shifts your revs will still stay up?

On that note, I heard a video of an 85-86 mustang, and when shifting the revs would drop right down (im guessing 2000rpm or so from 5000), and man did it sound like crap.

 

GREG91GT

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#12

• Jul 1, 2004

• #12

any one else have any ideas

 

B

blk92stangg

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Jul 1, 2004

#13

• Jul 1, 2004

• #13

Maybe vacuum leak.

 

GREG91GT

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Jul 1, 2004

#14

• Jul 1, 2004

• #14

i have checked for all vacum leaks and found none, i did find somthing today i am kind of inbaresed to say but my upper intake was loose well the bolts were any body ever had that to happen and how did your motor act i still have my problem after tighting it up

 

cjman15

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Apr 15, 2004

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Jul 1, 2004

#15

• Jul 1, 2004

• #15

yeah mine drops a good bit when shifting too... i know what u mean

 

HISSIN50

"How long does it take to get help in here?

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Jul 2, 2004

#16

• Jul 2, 2004

• #16

stockish motor should pull between 15-20 inches of vac at idle.

good luck.