FYI--My handle used to be EsFourMe.

**If you're new to this forum and don't know what I'm babbling on about, click on the link at the bottom of the page, "DBW Experiments" to learn about the path I took to arrive at my conclusions.**

Disclaimers:
1) I am not an electrical engineer. Some of the terms I use might be incorrect. Sorry.
2) I have not reprogrammed anything. Any software flaws that may exist may still be there; they are just less noticeable.
3) All of my assertions are just that--assertions. They are not proven fact, as I have not done any formal data logging.
4) This fix applies only to cars with a manual transmission.


First of all, our car has two basic throttle programs (for simplicity's sake I will call them "maps", though unlike any map I've looked at, these maps change depending on conditions. But "map" is easier to write that "program"). Let's call them "Map A" and "Map B".

"Map A" is the primary map that is used in most driving conditions. It interprets your throttle requests and makes decisions according to many different factors. The most important factor is whether the throttle is already open to some degree or not. If the throttle *is* already open to some degree, then you will generally be rewarded with *some* response immediately. If you are completely off throttle though and request any amount of throttle, there is ALWAYS an approximately 0.4-second delay before ANYTHING happens. In addition to the delay, the throttle s-l-o-w-l-y opens and closes no matter how quickly you move your foot.

"Map B" is used in two scenarios: when the car is stationary and when the clutch is depressed. If either one of these is true, the car uses "Map B". As such, this map is a (more) linear, instantly-responding map. The reason for this map's existence is obvious--if there were a 0.4-second delay each time you tried to accelerate from a stop, things would get messy with clutch slip and all.

There are two sensors that are acted upon by the clutch pedal: a "home" sensor and an "away" sensor. In this first photo, the clutch is "away" (depressed).
<img src="http://pictureposter.audiworld.com/74193/picture_180t.jpg">

In the next photo, the clutch pedal is "home" (not depressed).
<img src="http://pictureposter.audiworld.com/74193/picture_181.jpg">

The "home" sensor (the white one) is tripped when the clutch pedal is fully released and the "away" sensor (the blue one) is tripped when the clutch pedal is fully depressed. These are simple plunger-style on/off switches. This mod deals only with the "home" sensor as the "away" sensor simply tells the car that it's okay to start, i.e., the clutch pedal is fully depressed--it doesn't affect the throttle map.

Here is the one catch that made things a little more complicated: if the car is moving, "Map B" times-out and the car returns to "Map A" after 10 seconds, no matter where the clutch pedal is. As a result, I could not simply unplug the clutch "home" sensor, as I would get "Map B" for only 10 seconds.

This circuit is normally closed, or N/C, when the clutch pedal is fully released (if it were a light switch, it would be on). So what I needed was an on/off switch (a.k.a. relay) that could switch itself on and off by itself at a preset interval.

This is what I found. I could go into the details, but basically the timing is fully adjustable.
<img src="http://pictureposter.audiworld.com/74193/picture_167t.jpg">
<img src="http://pictureposter.audiworld.com/74193/picture_169.jpg">

I have it adjusted so that the circuit is open (off/clutch pedal depressed) for 8 seconds, then it closes (on/clutch pedal released) for split second and immediately opens (off/clutch pedal depressed) again. After that it begins the cycle all over again. This setup tells the car that the clutch pedal is depressed ("Map B") for 8 seconds, then released ("Map A") for split second (to reset the 10-second timeout), then immediately depressed ("Map B") again. It performs this cycle indefinitely until the power source is unplugged. I cannot notice this cycling, other than the sound of the relay itself, during driving.

Now you know how it works. Here is how to do it yourself:

1) Buy the relay. Mine cost me about $15, shipped. Wire in a power supply (in my case a 9-volt I bought at Radio Shack wired in series with the 9-volt from one of my smoke detectors...for a total of 18 volts). My wiring setup is ugly, but I just wanted to see if it all worked.
<img src="http://pictureposter.audiworld.com/74193/picture_168.jpg">

2) Pull the fuse panel off
<img src="http://pictureposter.audiworld.com/74193/picture_174t.jpg">

3) Unscrew the noted bolt (use an 8mm socket)...
<img src="http://pictureposter.audiworld.com/74193/picture_175t.jpg">

...plus these two near the bottom of the panel (also 8mm).
<img src="http://pictureposter.audiworld.com/74193/picture_172t.jpg">

4) Remove the knee panel. Just pull it towards the driver, as there are a few clips that need to be removed HORIZONTALLY, not downwards.
<img src="http://pictureposter.audiworld.com/74193/picture_173t.jpg">

There is a light on the inside of this knee panel that needs to be unplugged from its harness, as well as the VAG port (at least I think that's what it is).
<img src="http://pictureposter.audiworld.com/74193/picture_171t.jpg">
<img src="http://pictureposter.audiworld.com/74193/picture_170t.jpg">

5) Unplug the clutch pedal's "home" sensor (the white one). Here is a picture of what you'll unplug (with my two white wires already shoved into it)...just squeeze the sides and pull it towards the driver.
<img src="http://pictureposter.audiworld.com/74193/picture_183b.jpg">

6) Insert two pieces of wire (maybe 3 feet long each) into the plug. There is no polarity to be concerned with here.
<img src="http://pictureposter.audiworld.com/74193/picture_183.jpg">

7) Insert the other ends of these two wires into the "common" slot and the "normally closed (N/C)" slot. Again, there is no need to be concerned with polarity.
<img src="http://pictureposter.audiworld.com/74193/picture_167t.jpg">

8) Set the timing of the relay as I stated above.
9) Put everything back together and go!

For those of you who just want to sample what your car is capable of without buying the relay and wiring it up, you can do the following: follow steps 2-6, hold the two wires in your lap (or give them to a friend), and go for a drive. Hold the exposed ends of the two wires together; you will get "Map A" and cruise control will work. Shifts will feel weird because the clutch pedal's "home" sensor is not active and you won't ever get "Map B", even when you put the clutch pedal in. Anyway, while traveling at a nice, constant speed in any gear, release the two wires and for 10 seconds you will get "Map B" and glorious muscle-car throttle response!

Note that this is not a polished, professional install. There is no on/off switch either. Feel free to improve upon what I have done as will be doing the same. Of course I will post accordingly!

 

Wow, I'm glad I'm going to have you explain it to me in person tonight!

 

- Where did the relay come from (what vendor)?
- Was this a pre-assembled part with the timing logic or is this someting you built?
- I'd like to add this info to the AW Tech section. Ok with you?

Pretty slick!

 

I admire your enthusiasm, but much of your results do not jive with the research I've done. First of all, in most cases, most of the data I collected showed that 95% of the time or better, the throttle followed the accelerator by less than 0.1 sec. The things you are describing, you claim happen every single time you press/ease the accelerator.

This makes me think something really was wrong with the callibration or adaptation of your specific throttle.

Second, I don't know where you get your information about there being "two maps," one for when you have your foot on the clutch, etc. You haven't quoted any sources, so I'm under the impression that you are guessing this. There are a lot more than two maps. There are temperature dependant ones, there are hard acceleration ones, there are crusing ones, etc. Furthermore, they control a lot more than just how the throttle responds to the accelerator pedal, they control fuel/air mixture, valve timing, and more things that I can't think of at the moment.

While the results you describe sound sensational, please don't be offended, but I wonder if it is relative. Maybe you did come up with an effective workaround for your situation, but maybe your situation isn't the standard one. In my data collection, once you are above 2000 RPMS and in gear, in general, you get WOT w/in 0.1-0.2 sec of pressing the gas, and you get idle throttle w/in the same timeframe from releasing the pedal.

The only standard cases I found that differ were below 2000, you get somewhere between 90% and 100% throttle depending on how close you are to 2k, and when cruising at low engine speeds, and you blip, then you do get the engine hanging high for a moment or two before it drops.

Where do you live? VA, right? Where in VA? I'd love to go for a ride on your car, I may be down there in a month or so.

As for your write-ups, I'd encourage you to either cite your referances for the design of the car's systems, or be careful how you phrase things. Your write-ups tend to say "this is how it is designed," but it appears all you are basing that on is the fact that you have a switch and notice a difference in behavior when you flip it - that's binary data. It's going to tend to lead you to binary conclusions regarding an massively more complex system.

As for doing this on my own car, I'd be terribly worried about the longevity of the engine. I think there's tremendous potential for you to be causing it to run lean or rich. All those maps take into account expected load, among other things. If what you are saying really is happening, you are using maps that expect there to be no load on the engine, and doing your daily driving with them.

The ME-Motronic EM system is constantly taking into account hundreds of variables, but many of them are predicted rather than measured. You are treating this whole thing like the engine only has one mode of operation, and the throttle is a standalone variable. It is not, it is coordinated with fuel delivery, valve timing, a/c compressor load, alternator load, knock sensing, and I'm sure much more that I've already forgotten.

 

Dude... you're like totally harshing his mellow...

 

After reading your impressions of the DBW issues and "playing" with the throttle on my car then driving my friends carberated big block '72 Camaro I agree 100% with your position that the software is second guessing our throttle inputs for the sake of smooth driving. And I also don't like it.
When letting off the throttle abruptly with a 350 HP engine at 4000 rpm one should instantly feel the brake HP. Does this engine do it? NOOOOOOOO! This software is second guessing me for the sake of smoothness at the expense of performance driving. I don't like that. Thats why I sold the TIP.
I don't need help to drive smooth, maybe some one else does and thats good for them but I prefer to have the exact response from the engine that my foot asks for with the pedal. Nothing more, nothing less.
DBW is OK for the most part but when it comes down to who has the last decision when I'm driving my car agressively get the software engineers meddling out of my way!
OK I'm done now...
BTW, thanks for sharing the info!

 

It's a great design, and I applaud his efforts! It definitely does away with the delay in throttle input while already cruising, it does away with the revs hanging (almost too much as we discussed!), but my only concern was about the other maps the car has.

How are they affected, if at all?

It was a great feeling to rev it up to 5k in first, let off the gas, nearly smack my forhead into the wheel, floor it again and it immediately taking off and smacking me back into my seat without any delay.

Even my little brother in the backseat said "whoa." Haha.

Nicely done Oliver. Please keep us updated on your progress with installing a switch etc.

 

The only valid point you raised was that the mixture might be different while operating under the "no-load" map as you call it.

Other than that I suggest you re-read my post a few more times, note that I qualified the whole piece with, "these are my assertions", and stop disputing a fact that you have no more grounds to dispute than I do to support (less, in fact).

The only work I need to cite is my own (as I did) because I acquired all of the information myself. I stand by everything I said, but I won't be upset if you don't believe me. In fact I couldn't care less.

The only other statement you made that I will dignify with a response was that I live in VA. I live in San Francisco. That being said, I would honestly love for you, The Greatest of All Doubters, to drive my car. I'm not sure where you live (Northwest?), but I would be happy to let you drive if we could meet. I would be happy to let anybody drive; in fact, somebody just did; he will probably post here shortly ;-)

 

Posted before you. Hah.

 

When I let off the gas now at high RPMs, I get THROWN forward.