How to get better throttle response

Chandar8

Chandar8

3rd Gear Poster
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Sep 28, 2023
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Las Vegas
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1995 Thunderbird, 4.6
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Okay thunderbird hive mind, please help me with this. On both superbirdo and shitbird the throttle response is a bit lacking. When I floor it it takes half a second or so before the car revs up and responds. Shitbird has a 75mm throttlebody and a PI engine, superbirdo has the PI intake with trickflow heads on an npi engine. Both take about the same time.

So my question is, is this just inherent to the 4.6l? Is it a tuning issue? Is it rotating assembly weight? I suppose i dont fundamentally understand what increases or decreases the throttle response in the car.


In the video at the start you can hear me slam my pedal to the floor.... wait.... then response

 
Ok, I'm no expert with things other than shift knobs...but isn't this a stall speed thing?

From all I've been reading, this is the expected behavior with a stock torque converter. It revs up to stall speed rpm, then you get a moment of lackluster response until revs climb into the engine's power band, then it really takes off. And you can resolve that by getting a torque converter whose stall speed falls right into the power band.

Again, this is just from trying to understand what I read about these powertrains. If I'm totally wrong, please correct me.


In your video, it's hard to see the initial rev climb (shaky camera), but it seems pretty instant (?).

Side note regarding the throttle cable: I recommend this small mod to position the pedal closer to your foot.
1997ThunderbirdLXV6

Thread 'How-To: Throttle Cable Slack Reduction'

Since I'm all out of ideas around suede, wood, and lighting, but I felt like writing another how-to, I decided to document my solution for throttle cable slack.

This mod affects a major drive control, so I think I should start out with my usual web disclaimer:
I am not a professional; this is for entertainment; I am not making any recommendations for your vehicle.

The Problem

Slack in the throttle cable causes the throttle pedal so sit low/forward. In my case, under full throttle the pedal was pressed deep into the carpet and insulation underneath. It also makes for a slightly...
  • Like
 
1997ThunderbirdLXV6 said:
Ok, I'm no expert with things other than shift knobs...but isn't this a stall speed thing?

From all I've been reading, this is the expected behavior with a stock torque converter. It revs up to stall speed rpm, then you get a moment of lackluster response until revs climb into the engine's power band, then it really takes off. And you can resolve that by getting a torque converter whose stall speed falls right into the power band.

Again, this is just from trying to understand what I read about these powertrains. If I'm totally wrong, please correct me.


In your video, it's hard to see the initial rev climb (shaky camera), but it seems pretty instant (?).

Side note regarding the throttle cable: I recommend this small mod to position the pedal closer to your foot.
1997ThunderbirdLXV6

Thread 'How-To: Throttle Cable Slack Reduction'

Since I'm all out of ideas around suede, wood, and lighting, but I felt like writing another how-to, I decided to document my solution for throttle cable slack.

This mod affects a major drive control, so I think I should start out with my usual web disclaimer:
I am not a professional; this is for entertainment; I am not making any recommendations for your vehicle.

The Problem

Slack in the throttle cable causes the throttle pedal so sit low/forward. In my case, under full throttle the pedal was pressed deep into the carpet and insulation underneath. It also makes for a slightly...
  • Like
Click to expand...
Im not entirely sure. I mean it sounds reasonable, but the nice car superbirdo has a fully built jerry spec trans with the marauder torque converter in it. Shit bird has just a stock torque converter.


I'll definitely give that mod a try for sure, and get a better video for both cars if possible
 
Yeah I think it’s a combination of the low stock converter stall speed and the 4.6 just not being a particularly strong engine below 3000rpm, plus heavy car, heavy converter, plus 3.08 final drive gears. I wouldn’t define it as throttle response(actually it’s cam response if anything) throttle response to me is more how it responds to your foot at part throttle, not WOT, bigger Throttle bodies add that sort of throttle response because it’s creating a bigger opening than previously for a given input from your foot

A higher stall converter (marauder is higher stall than stock but even still not what I’d call a high stall) will essentially “skip” that lag area to roughly the RPM the cam comes alive. Steeper rear gears will also make it spunkier. Also a roots supercharger 😆
 
XR7-4.6 said:
Yeah I think it’s a combination of the low stock converter stall speed and the 4.6 just not being a particularly strong engine below 3000rpm, plus heavy car, heavy converter, plus 3.08 final drive gears. I wouldn’t define it as throttle response(actually it’s cam response if anything) throttle response to me is more how it responds to your foot at part throttle, not WOT, bigger Throttle bodies add that sort of throttle response because it’s creating a bigger opening than previously for a given input from your foot

A higher stall converter (marauder is higher stall than stock but even still not what I’d call a high stall) will essentially “skip” that lag area to roughly the RPM the cam comes alive. Steeper rear gears will also make it spunkier. Also a roots supercharger 😆
Click to expand...
Also, also, also …. :ROFLMAO:
 
Maybe see how it feels getting into it at a higher rpm? i mean my 96 coug was stock aside from pi intake, resonator/ muffler delete.

It was no rocket ship but i felt like it had some good response. Granted in this vid the altitude is like 300? and i think that was the best conditions that car has seen lol. speedo also wasnt accurate 3-5mph off high



 


So I think this is a bit better video for that, still seems to lag almost a whole second behind
LukesCougar said:
Maybe see how it feels getting into it at a higher rpm? i mean my 96 coug was stock aside from pi intake, resonator/ muffler delete.

It was no rocket ship but i felt like it had some good response. Granted in this vid the altitude is like 300? and i think that was the best conditions that car has seen lol. speedo also wasnt accurate 3-5mph off high



Click to expand...
 
XR7-4.6 said:
Yeah I think it’s a combination of the low stock converter stall speed and the 4.6 just not being a particularly strong engine below 3000rpm, plus heavy car, heavy converter, plus 3.08 final drive gears. I wouldn’t define it as throttle response(actually it’s cam response if anything) throttle response to me is more how it responds to your foot at part throttle, not WOT, bigger Throttle bodies add that sort of throttle response because it’s creating a bigger opening than previously for a given input from your foot

A higher stall converter (marauder is higher stall than stock but even still not what I’d call a high stall) will essentially “skip” that lag area to roughly the RPM the cam comes alive. Steeper rear gears will also make it spunkier. Also a roots supercharger 😆
Click to expand...
Yeah I have the 3.27 trac loc waiting for install, that should feel a bit better in that area.

For converters basically the only other option we have is circle D right? Or is there another go between?
 
Chandar8 said:


So I think this is a bit better video for that, still seems to lag almost a whole second behind
Click to expand...

What lag though?

I'm sorry, but that looks pretty instant to me. 🤷‍♂️

I mean, some electronic stuff is happening. Throttle position sensors tells PCM WOT; PCM tell injectors to inject more fuel...all of which is likely a matter of milliseconds (?).

It seems there's one initial small rpm jump when you first hit the throttle, maybe about +500; then it jumps to redline. Is that a shift? Or are you locked in 1st or 2nd?
 
1997ThunderbirdLXV6 said:
What lag though?

I'm sorry, but that looks pretty instant to me. 🤷‍♂️

I mean, some electronic stuff is happening. Throttle position sensors tells PCM WOT; PCM tell injectors to inject more fuel...all of which is likely a matter of milliseconds (?).

It seems there's one initial small rpm jump when you first hit the throttle, maybe about +500; then it jumps to redline. Is that a shift? Or are you locked in 1st or 2nd?
Click to expand...
When I say foot is when it's on the floor, so it's about a full second before the car responds to me.

I just let off the throttle mostly.


Maybe this is just instant and it feels incredibly anemic
 
Chandar8 said:
When I say foot is when it's on the floor, so it's about a full second before the car responds to me.

I just let off the throttle mostly.


Maybe this is just instant and it feels incredibly anemic
Click to expand...

So to be clear did you have your foot on the floor BEFORE you said “…alright … and … foot on the floor” or somewhere between (I kind of had the impression from the video it was within or towards the end of the …and…)?
 
XR7-4.6 said:
So to be clear did you have your foot on the floor BEFORE you said “…alright … and … foot on the floor” or somewhere between (I kind of had the impression from the video it was within or towards the end of the …and…)?
Click to expand...
It was at the end of 'and' and foot
 
When I watch the video back with the time I press my foot down at the 3 second mark, doesn't do anything for about a half a second and finishes at 4.5 ish seconds
 
Chandar8 said:
It was at the end of 'and' and foot
Click to expand...

Thats what I was thinking but it actually seems pretty responsive for the combo, having had basically that very combo. Converter, gears, PI heads/cams, tune, all gradually nip away at it.
 
Can you connect a dongle and read out throttle position? Someone correct me, but iirc idle is 16% and full throttle is 80% or so? I'm wondering if your PCM gets the correct reading.

And now that I'm writing this, I question if that's possible pre-97/OBD2. What year is your car?


Also, regarding that throttle cable mod, when you do WOT, is the pedal actually touching the carpet? If so, the cable may be stretched, and you're not actually applying  full throttle.
 
Chandar8 said:


So I think this is a bit better video for that, still seems to lag almost a whole second behind
Click to expand...
Was that locked in 1st? or a 3-2 shift? I had mine locked in 1st so it was ready to trail.

If that was a 3-2 looks pretty good to me

as lxv6 said the throttle cable mod.

I find that every one of these cars ive bought had a floppy pedal that felt awful to get onto, and it probably added a bit of delay

i mean if your cable is just freestyle tickling your toes that is probably your answer as other have said it looks to be running good
 
Our cars do have a lag, as do all cars. It's set by the advance; how fast the car can gain rpms. but. It's restricted by physics, how much it can accelerator the motion " of the connected masses" In the beginning, it's the engine, as the shift progresses, so does the mass. so it slows.
 
1997ThunderbirdLXV6 said:
Can you connect a dongle and read out throttle position? Someone correct me, but iirc idle is 16% and full throttle is 80% or so? I'm wondering if your PCM gets the correct reading.

And now that I'm writing this, I question if that's possible pre-97/OBD2. What year is your car?


Also, regarding that throttle cable mod, when you do WOT, is the pedal actually touching the carpet? If so, the cable may be stretched, and you're not actually applying  full throttle.
Click to expand...
Yeah, I gotta figure out what the sct means cuz its doing it from like 0-1000 in unknown units to me at this time
 
LukesCougar said:
Was that locked in 1st? or a 3-2 shift? I had mine locked in 1st so it was ready to trail.

If that was a 3-2 looks pretty good to me

as lxv6 said the throttle cable mod.

I find that every one of these cars ive bought had a floppy pedal that felt awful to get onto, and it probably added a bit of delay

i mean if your cable is just freestyle tickling your toes that is probably your answer as other have said it looks to be running good
Click to expand...
Yeah it's the 3-2 shift. I am starting to get the feeling I'm being really nit picky and asking for on demand power where our cars kinda just doesn't have it
 
Grog6 said:
Our cars do have a lag, as do all cars. It's set by the advance; how fast the car can gain rpms. but. It's restricted by physics, how much it can accelerator the motion " of the connected masses" In the beginning, it's the engine, as the shift progresses, so does the mass. so it slows.
Click to expand...
Yeah, I suppose I just want to minimize that lag. Because watching the video back it doesn't feel as bad, but sitting in the hot seat it really is palpable
 
Chandar8 said:
Yeah it's the 3-2 shift. I am starting to get the feeling I'm being really nit picky and asking for on demand power where our cars kinda just doesn't have it
Click to expand...
I mean do you know what it runs to 60? or 1/4. Has it been dynod? I havent personally driven a pi car, but when your car gets up in second it doesnt seem to be pulling much harder than mine, but if your in la with ungodly temps and im in illinois at a low altitude that very well could make the difference between a half stock npi and a pi swap.

I just would want to say its running rough, but in reality you are probably 1700ft higher at sea level, and im comparing a run in 30 degree weather to what was probably high 80s?

edit: cars just feel like shit in the heat. imo. even if its not a boosted car
 
LukesCougar said:
I mean do you know what it runs to 60? or 1/4. Has it been dynod? I havent personally driven a pi car, but when your car gets up in second it doesnt seem to be pulling much harder than mine, but if your in la with ungodly temps and im in illinois at a low altitude that very well could make the difference between a half stock npi and a pi swap.

I just would want to say its running rough, but in reality you are probably 1700ft higher at sea level, and im comparing a run in 30 degree weather to what was probably high 80s?

edit: cars just feel like shit in the heat. imo. even if its not a boosted car
Click to expand...
I mean the question i am posing is persistent through both of my cars. Shitbird is just the one out of the garage atm, superbirdo, the black and silver car in my Pfp has trickflow heads, PI intake, fully built trans and a marauder converter and still has this hesitant moment to it. Granted it pulls a whole lot hard but it's still there
 
Chandar8 said:
Normal relative to our cars. It's just mildly annoying to feel it and then not know how to make it better lol

I guess making it better requires money
Click to expand...

The issue here is the W in 4R70W. The wide ratio part, meaning that there are fairly large ratio jumps between gears. Benefit is that you get a pretty short 1st for take-offs and a pretty long overdrive for cruising; downside is that there can be some gutlessness before a shift.

We actually had a similar conversation recently in my thread about the WOT 3>2 shift. Ultimately, what I concluded was that you'll enjoy the car more if you plan ahead. Just going from cruising straight to WOT indeed isn't enjoyable. Instead you work  with the car when you anticipate needing speed: you turn overdrive off, and you ease into the throttle just enough to prompt the 3>2 shift, and then you push it to the floor and it'll move!

I know it sounds tedious, but it's a matter of learning how to "shift" in an automatic, meaning how to make the car behave the way you want it to behave.

1997ThunderbirdLXV6

Thread 'How hard is a WOT 3-2 on the 4R70W?'

How hard is the full (or almost full) throttle 3>2 shift on the transmission?

Just curious because it's a pretty common scenario (with the stock calibration).

Imagine a highway crossing, a tight ramp at around 35 mph. I'm in 3rd at this point because I turned O/D off during the ramp, in anticipation of speeding up.
Coming up to the straightaway, I push the accelerator, the TCC unlocks, which puts me to about 2,000 rpm - which simply isn't enough to accelerate at a decent rate.
So I push the accelerator down further...still nothing...further...and finally I get a 3>2 shift and the car...
 
For faster acceleration, change the diff to a 4.11 or 5.13 :1 and That will improve that a bunch.
 
Grog6 said:
For faster acceleration, change the diff to a 4.11 or 5.13 :1 and That will improve that a bunch.
Click to expand...

From a standstill, I'd agree with you. But that's not really the OP's concern.

His concern is the delay caused by a WOT downshift. If anything, that sounds like something more likely to be resolved by a tune than a hardware change. Can you tune what percentage of throttle position prompts a downshift? If that was tuned to a lower percentage, it could reduce that delay.
 
1997ThunderbirdLXV6 said:
The issue here is the W in 4R70W. The wide ratio part, meaning that there are fairly large ratio jumps between gears. Benefit is that you get a pretty short 1st for take-offs and a pretty long overdrive for cruising; downside is that there can be some gutlessness before a shift.

We actually had a similar conversation recently in my thread about the WOT 3>2 shift. Ultimately, what I concluded was that you'll enjoy the car more if you plan ahead. Just going from cruising straight to WOT indeed isn't enjoyable. Instead you work  with the car when you anticipate needing speed: you turn overdrive off, and you ease into the throttle just enough to prompt the 3>2 shift, and then you push it to the floor and it'll move!

I know it sounds tedious, but it's a matter of learning how to "shift" in an automatic, meaning how to make the car behave the way you want it to behave.

1997ThunderbirdLXV6

Thread 'How hard is a WOT 3-2 on the 4R70W?'

How hard is the full (or almost full) throttle 3>2 shift on the transmission?

Just curious because it's a pretty common scenario (with the stock calibration).

Imagine a highway crossing, a tight ramp at around 35 mph. I'm in 3rd at this point because I turned O/D off during the ramp, in anticipation of speeding up.
Coming up to the straightaway, I push the accelerator, the TCC unlocks, which puts me to about 2,000 rpm - which simply isn't enough to accelerate at a decent rate.
So I push the accelerator down further...still nothing...further...and finally I get a 3>2 shift and the car...
Click to expand...
I actually read this entire thread before posting this. I am making a semi auto type trans thing in the near future and I wonder if being able to manually select gears will remove that gutlessness. For context I have the Silver fox manual valve body with a lightning shifter going in soon
 
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