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Should I attempt this Throttle Mod?

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T

TechBoyJK

Lifer
http://www.forteforums.com/forums/do-yourself-articles/1342-best-throttle-mod-ever.html

Basically, since my Kia Forte Koup is drive by wire, this article is suggesting by making a small, quick modification to your throttle, you can reduce the 'dead' range from when you press the pedal to when the throttle kicks in.

In my car, I do notice a slight delay that I don't remember having in my bmw. I drove my car around a bit after reading the thread, and I did find myself saying the car would be more fun if the gas pedal was quicker to respond.

Thoughts? Seems pretty easy to do.
 
most of the lag in autos IMO is due to auto transmission shifting 2 seconds after you decide you want to go. Hence slushbox.
but thats kinda unrelate
 
I've driven so many TBW cars, and have not once encountered 'lag' in a properly-functioning car. It's just not there. There is a difference between 'the throttle response is laggy' and 'I don't like the way the throttle is mapped.'

This 'mod' addresses the latter to some extent. It appears that you're tweaking the position of the potentiometer inside the pedal assembly. It seems quite weird that they built it that possibility, though.

Normal function in most all cars is something like: 5v reference voltage goes into TPS. Closed throttle sends back a ~.5v signal. WOT sends back a ~4.5v signal. Position of throttle blade relative to pedal input varies between those voltages, often in a fashion that would appear quite non-linear on a graph. I think this is where the 'lag' comments seem to come from. With pedal input on x and throttle output on y, you'd probably see a pretty slow rise at first to keep the car from being jerky or awkward at slow speeds. Then an increasing slope and then probably another taper near the end, accounting for the common 'deadness' felt at the end of many pedals.

Anyhow...all you're doing here is moving the rest position of the potentiometer forward. So where it may have rested at .5v before, it could be .6-.7v or some such now, and the voltage with max out quicker. Essentially...you've done nothing as far as actual performance is concerned. However, you MAY upset the idle circuit of the car, since there is a programmed cutoff voltage below which the ECM assumes that you are not giving any throttle input.

I dunno. Cliffs: I wouldn't fuck with it.

edit: I would be curious to monitor the voltage of the TPS pre- and post-modification. If you use a manufacturer-specific scan tool, there's probably also a PID that tells you if idle is being commanded or not. That would be relevant.
 
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I don't recall any lag in dbw cars I've driven either.

No lag in my 2008 dbw Jeep, although it has 2 different throttle response curves.
 
Making that mod might give you problems on slippery surfaces...? Too much throttle tip-in can cause you to break traction much easier. Just a thought.
 
my civic si has lag in the opposite direction - sometimes 1/2 a second of rev hang when I let off the gas.
 
iamwiz82 said:
Its more of an adjustment than a modification.
Click to expand...

This. There are CLEARLY adjustment slots in the housing. Just like setting base timing on some cars. It's meant to be adjusted. Futz at your own risk, but you could yield some good results.
 
Mark where you started and adjust away. It is clearly designed to be adjusted. On the Fusion we did something like this on we had better luck with remapping the foot throttle:TPS. This just looks like it will remove the early throttle dead spot where the voltage on the sensor is below the lowest value on the PCM table. As long as you don't go so far forward that that engine starts to rev and the fully depressed position is not above (and or breaks) the sensor, you should be fine and
 
Looks like you should be able to do it and revert it if necessary go for it.

Also many positive comments, it should be a no brainier.
 
Yea, I think I'll give it a try sometime soon when it warms up. My roommate is fairly mechanically inclined, especially with cars, so I figured we'd just play around with it one afternoon.

Sadly, its like 9f outside rightnow.
 
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