my car feels like it is absolutely dead in the low rpm range. Im thinking that my 75mm tb is too big. my friend has the same car and also an 2002 but his pulls in the low end and he has a 70mm tb. the only thing i can think of is that he has gears or when my rear end was rebuilt they installed smaller gears what do you think. I have a video of me launching it and it just doesnt sound right. any ideas?
NO low end torque
99gt95
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my car feels like it is absolutely dead in the low rpm range. Im thinking that my 75mm tb is too big. my friend has the same car and also an 2002 but his pulls in the low end and he has a 70mm tb. the only thing i can think of is that he has gears or when my rear end was rebuilt they installed smaller gears what do you think. I have a video of me launching it and it just doesnt sound right. any ideas?
i purchased the car with it. as far as i know its not tuned. its my second gt so i wasnt sure if i just got used to the power but my friend has the same car and his pulls harder in the low rpm.
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Well, first things first you need to know if your friends has gears and if yours is stock. That would make the biggest difference I believe. I can't imagine a bigger TB would have enough effect down low to do much of anything. What mods were on your old one, vs. this one? How fair of a comparison is it?
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i have a 75mm Accufab TB and it pulls great. Much better than the factory one. I would say it's either the tune or another issue entirely. Any other mods done to the car?
my old one just had an exhaust. this has exhaust, intake, plenum, and tb. the old one felt like it had more torque low end like my friends.
---------- Post added at 12:30 PM ---------- Previous post was at 12:29 PM ----------
catless x pipe with lm2. bbk intake. tb and plenum.
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Maybe just do a tune up on it? You'd be surprised how much a difference a nice fuel/air filter change and some fresh new plugs can make on a older motor. Maybe some fuel injector cleaner too. Depending how much miles it has i'd suggest changing the coil boots too as these degrade over time and cause the spark to arc and make the car sluggish and miss. As others have said, the throttle body isn't going to make that much of a difference.
air filter and plugs are clean, ill do the fuel filter next and see if that helps and btw the car isnt throwing any codes.
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Change the coil packs as well, if you got the money.
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I wouldn't change the coils unless you have a misfire myself.
Is the car a five speed or auto? Was your old one the same?
From the video, it seems to run strong, gets up and runs pretty well.
How long has it been since you've driven one between your old one and this one, and what have you been driving in between? Also what year is the current one vs. the old one?
I know when I had my 99GT, when I got in my 2002 Crown Vic after driving the Mustang it felt like everything was in slow motion. And after driving the CV awhile, the Mustang seemed much faster.
Perhaps it's a perspective thing?
Is the car a five speed or auto? Was your old one the same?
From the video, it seems to run strong, gets up and runs pretty well.
How long has it been since you've driven one between your old one and this one, and what have you been driving in between? Also what year is the current one vs. the old one?
I know when I had my 99GT, when I got in my 2002 Crown Vic after driving the Mustang it felt like everything was in slow motion. And after driving the CV awhile, the Mustang seemed much faster.
Perhaps it's a perspective thing?
old one was a 99 gt sold it 8 months ago and purchased this 2002 a day later. both are gt's in manual. when i first drove mine i realized it was slower only to find out my clutch was slipping. i just replaced the clutch so its better than before however i let my friend drive my car and right after we drove his and his has noticeably more torque in the low end . his is also a 2002 gt and he has the same exhaust, and intake, however he has a 70mm tb instead of my 75mm. his car also has 150k miles compared to my 126k.
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Well, find out if your friend's has a tune, find out if anything has been done to yours, and go from there. There will be differences between the cars, no matter the mileage, one may be closer to spec than the other, the new one you have may have one issue or another, who knows. I know my 99GT with a mail order 87 Octane tune surprised the heck out of a local ford dealership's salesman, he thought I had done head work or cams when my motor was fully stock, so you may have a motor that needs a little more help. Check the obvious, make sure your friend doesn't have gears in his car (see what RPM he is at when he shows 60mph in 5th gear and compare that to yours), make sure you have the correct size tires, etc. A 5cfm increase in throttle body won't make a huge hit on low end torque for a car already noticeably low on low end torque (the 4.6 doesn't start making good torque till around 3000rpm), and heck, if you have a racetrack nearby, do a side by side and see how they do in real world vs. seat of the pants.
we already raced them he pulls on me on a second gear pull. hes taking his rear apart either way so ill see if he has gears or ill just go get a tune. we both also have 17in rims. thanks
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Looks like it launches decent for a GT, it doesn't sound like it's bogging down at all. I'd do a tune up on the car and see what happens.
You shouldn't have to take the rear end apart to see if you have gears either.
You shouldn't have to take the rear end apart to see if you have gears either.
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A 75mm TB is not too big. That is the old volume vs. velocity argument which doesn't really apply to our cars unless you change the plenum and intake manifold. The biggest restriction to air flow on our cars is the plenum. CliffyK, an engineer who occasionally post here, calculated the maximum air flow that our motors (stock) can use. Its around 475 cfm. On his website (link below) he has posted Accufab test data. Except for the C&L plenum there is very little difference in air flow between a 70mm and 75mm TB on each of the plenums (including stock). In several cases the 70mm TB flowed a couple of cfm more than the 75mm TB. This is probably a result of turbulence inside the plenum. Here is the link: PaladinMicro If there is a difference in your cars its not caused by the TB.
Gears are an entirely different matter. They make a big difference. If you are comparing speed to rpm it is always best to do in in fourth gear. All of our transmissions do not have the same 5th gear ratio. Since you both have 2002s then 5th might be OK (assuming no one changed the transmission). To compare gear ratios this way you must absolutely make sure both speedometers are correct. The PaladinMicro site also has a rpm/speed calculator you can use.
A better way which eliminates speedometer error is to jack the rear end of the car off the ground, put a mark on the drive shaft and tire, and count the revolutions of the drive shaft for one revolution of the tire. Three and a quarter drive shaft turns is stock 3.27 gears. Three and three quarters is 3.73s. A little over 4 turns is 4.10s. You do not have to take the rear end apart to know what your gear ratio is.
Gears are an entirely different matter. They make a big difference. If you are comparing speed to rpm it is always best to do in in fourth gear. All of our transmissions do not have the same 5th gear ratio. Since you both have 2002s then 5th might be OK (assuming no one changed the transmission). To compare gear ratios this way you must absolutely make sure both speedometers are correct. The PaladinMicro site also has a rpm/speed calculator you can use.
A better way which eliminates speedometer error is to jack the rear end of the car off the ground, put a mark on the drive shaft and tire, and count the revolutions of the drive shaft for one revolution of the tire. Three and a quarter drive shaft turns is stock 3.27 gears. Three and three quarters is 3.73s. A little over 4 turns is 4.10s. You do not have to take the rear end apart to know what your gear ratio is.
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:bow
hes rebuilding the rear either way so hes just gonna check. thanks a lot.
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Did you drive your buddy's car or were you a passenger? For me, being a passenger ALWAYS feels faster than being a driver because it's harder to anticipate what's going to happen next (not your foot on the throttle) and you aren't in control should something go wrong.
I'm having the same issue. I've had a '99, '00, and an '01 in the past. However my current mustang is a '00 and doesn't have much power in the low end. Top end feels the same across the board but it just doesn't have any guts down low. I've replaced spark plugs, fuel filter, cleaned the MAF, cleaned the K&N filter, checked fuel pressures, and tested the RFI suppressors. Eventually I'm going to do a compression test and check the camshaft timing. Camshaft timing varies a lot with these engines stock.
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