Throttle Calibration Tip!

[popthechute]

Greetings! Newbie checking in...picked up my R/T about two weeks ago and have put on about 700 miles. I have been very disappointed with the performance I was getting and it didn't seem to have the same get up and go as the car I test drove. I was suffering FROM extreme buyer's remorse.

I joined this forum a couple of days ago and have been reading non-stop. I came across an article describing throttle calibration which I did Saturday morning. WOW! What a difference! It's a totally different car...I'm fairly confident it's not all in my head. Can someone EXPLAIN why such a simple and quick tweak makes such a big difference?

Thanks!

[MagnumFreak]

Not sure anyone can EXPLAIN why. Although it may calibrate the pcm to move the throttle body opening in conjunction with the pedal position. In other words it is possible that FROM the factory 100 percent pedal position may have only been 85 percent throttle body position. After the recal, they may match up. Just my opinion though, not 100 percent sure.

[RT NOMAD]

Can anyone tell where the thread is that explained how to calibrate the throttle? I did a search but couldn't narrow it down enough to expedite finding it.

Thanks

[jco-MagnumRT]

Knowlege base.

I have an question about this...the post states that the various speeds of the pedal depression effects the throttle response....in what way??? Is it a direct relation?

Also for those of you not familier with Mercedes electronics..(.this has been discussed in other threads) all functions are "driver adaptic"...in other words you can "train" them.
the more aggressively you drive the more the memory holds and the drive train responds aggressively...start driving like a Grandmother and the car will start getting lazy and slow to react to both throttle and shifting imputs.

[popthechute]

Check out this link on DodgeBoy

http://www.dodgeboy.net/forum/viewtopic.php?t=2215

[chicano]

I still haven't done the calibration thing...i think i'll take the weekend to find a nice empty stretch of highway and experiment with different calibration speeds.

[IDSmoker]

Can someone EXPLAIN why such a simple and quick tweak makes such a big difference?

Well, here's my opinion, which is worth every penny you paid for it! <grin>

One fact that DC isn't making any noise about is that the LX vehicles are completely 'fly-by-wire' systems. In other words, unlike older cars, there is no mechanical connection between the accelerator pedal and the throttle body attached to the engine. I believe that there is also no direct link between the steering wheel and the front wheels. I'm not sure about the brake pedal, which is something I mean to CHECK when my technical manual finally comes in.

The whole 'fly-by-wire' (FBW) type of system has many implications, many of which can be kinda of alarming, if you let them. For instance, one of the first FBW systems was implemented on the F-117 Stealth fighter. To this day, there are rumors that during one of the early test flights of one of the early prototypes, an electrical 'glitch' in the FBW caused the plane to suddenly roll over onto it's back and crash, killing the pilot. I have no idea if there is any truth in this story, but a pilot buddy of mine says that the F-117 has a reputation of HAVING all of the flight characteristics of a brick if the FBW is turned off (or fails), and the pilot is forced to rely on the hydraulics.

While FBW can be more vulnerable to electrical issues, it also provides many benefits. Not only is there an owner-friendly procedure for changing the responsiveness of the accelerator, but I have also seen an equivalent procedure for changing the centering of the steering wheel (ask anyone with an older vehicle, what can be involved in fixing this kinda of problem with the mechanical linkage!).

I'm sure that the FBW systems in the LX vehicles are also part of the reason they are such "good values", since FBW is inherently cheaper than it's mechanical counterpart systems (once the initial R&D is paid off).

The simplest answer to the original question is that since the speed at which the accelerator pedal is pressed/released is no longer directly linked to the opening/closing of the throttle, it is relatively easy to change how the motion of one is related to the motion of the other.

Since that is probably way more than anyone wants to hear of my opinion, I'll close it there, except to say that if you really want more info on the theory and practices of FBW systems, try google.

[Tommy T.]

it is possible that FROM the factory 100 percent pedal position may have only been 85 percent throttle body position.

I think this sounds pretty reasonable and there may be a way to CHECK this theory.

For those with sluggish LX's, put the car INTO diagnostic mode, go to the screen that shows pedal position ("PDL POS") in percent. It should read 0% initially. If that theory is correct, my guess is that it will SHOW something like 85% when you mash on the gas pedal, and that it won't get to 100%.

Also, if that's the case, then does it change to something closer to 100% AFTER the throttle cal procedure? Seems like it should if the throttle calibration worked.

Any thoughts?

EDIT: I realize I'm putting a slightly different spin on MagnumFreak's theory, just a stab in the dark.

-- Tommy

[charliec]

TommyT -

You suggested in the discussion about FBW throttle recal procedure to, "put the car in diagnostic mode, go to the screen that shows PED POS..."

How do I get to that screen? Forgive my newbieness, my RT is less than 20 hours old, but it would be interesting (if and when I recal the throttle) to see where the RT thinks the pedal is!

BTW: Here is the procedure for those who can't find it:

Here's the steps you need to follow:
1. Find an unused section of road with a good spot to pull-off/turn-around. (make sure it's deserted or you could end up adding a ticket to the time/gas costs of trying this trick!)
2. Pull off of the road and shut your car off.
3. Turn your key to the "On" position (but don't start the car), and wait for the 'idiot' lights to go out.
4. Press down on the accelerator, and let it back up.
5. Turn your car off.
6. Re-start your car and cruise up and down the road testing your throttle responsiveness.
Depending on how fast/slow you do the 4th step, your throttle will either become more or less sensitive/responsive.
Repeat steps #1 through #5 as needed until you're satisfied that your throttle response is as good as it's going to get.


Thanks!

[AndyK]

Hold down "Note" and "Compass" (or sound and navigation, depending on how you look at it) for 10 sec, then page up/down with the up/down arrows.

Does not appear that min/max doesn't change, but 'smoothness' does; that is that the %ge appears to be more responsive to throttle position, IMHO.

[Tommy T.]

charliec,

Hey, we're all (well most of us) are newbies here!

Andy -- I think that makes more sense. So even with a sluggish hemi, you'll still see 100%. As you guys have stated, the throttle cal probably affects HOW the throttle body responds to pedal inputs.

In contrast to actually changing the range of the pedal as I had thought.

Oh yeah, here's the thread with details about diagnostic mode:

http://www.dodgemagnum.net/phpBB2/viewtopic.php?t=2027

-- Tommy

[mikeatw]

Did the throttle calibration on my 300C (900 miles) and nothing changed the first time. Did it again faster and it removed the slight rpm DROP during up shifts. Much smoother and controled acceleration! Glad I did it.

[MAGNUM8R]

Pedal% indication on my Magnum is is 100% with the engine not running. If I am actually driving, dunno, as at WOT, I probably would not want to look down at the display, rather the rear view mirror. I feel that I am actually getting 100% because of the seat of the pants feel of all of the torque and HP!!! I have only been able to do 0-60 runs with my G Tech because I don't have a place to run a full 1/4 without going to jail. My 0-60 on the G Tech have averaged 6.23 seconds. This was at about 68 degress and no torque braking on launch. I must say that I have only done the runs with CGS Motorsports intake installed. I expect slower times with the stock box, as the difference is very noticable.
I will post a photo of the intake set up when I figure out how to do that on this site.
Later,
'8R

[charliec]

Can someone EXPLAIN why such a simple and quick tweak makes such a big difference?

I believe that there is also no direct link between the steering wheel and the front wheels. I'm not sure about the brake pedal, which is something I mean to CHECK when my technical manual finally comes in.

Not only is there an owner-friendly procedure for changing the responsiveness of the accelerator, but I have also seen an equivalent procedure for changing the centering of the steering wheel (ask anyone with an older vehicle, what can be involved in fixing this kinda of problem with the mechanical linkage!).

Ummm - guys, the Magnum has rack and pinion steering. There is DEFINITELY a mechanical link between the steering wheel and the front wheels. Re-centering the steering wheel is a MECHANICAL procedure, according to my service guy. I ain't gonna drive no car that depends on a computer to steer (toyota prius?). It's one thing if, due to computer failure, the car becomes unable to accelerate. It's quite another thing if, due to computer failure, it becomes unable to steer or stop. (Think massive corporate liability). The throttle is definitely FBW though, which is why it doesn't surprise me that the ReCal procedure works. The car obviously has to have lots of computer action in the air/fuel/throttle/exhaust side of things in ORDER to monitor and control emissions, HP, "digital" trans, etc., but there's no compelling reason to make the steering or brakes FBW, since the rack and pinion and disc setup is about as simple, reliable, and cheap as it's going to get. And who wants to beta-test the new steering software? Not me!

[AndyK]

charliec:

See:
http://www.dodgemagnum.net/phpBB2/viewtopic.php?t=2434

The ESP does have a steering wheel angle sensor (to determine what angle you want to go to correct under/oversteer). After a battery reset, it does need to be reset.