Wow!!! I hacked the OBD to increase max boost! A "free chip!"
04-01-2000, 08:14 AM
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Wow!!! I hacked the OBD to increase max boost! A "free chip!"
This is totally amazing. I was playing around with the FAQ on the On Board Diagnostics (see link below) in the FAQ section, which describes how to get all kinds of diagnostic information through the climate control display.
I noticed that one of the pieces of info you can get from it is Engine RPMs (code 28). So, it occurred to me that for testing purposes, there was probably a way to decrease the max turbo boost pressure (which would also be useful for when you have your car valet'd, but it's probably too much trouble). I knew it was a long shot - just finding it would be hard enough - but there was a chance that maybe you could even <b>increase</b> the max boost as well.
So, I started toying around with other codes & button combinations. You <b>don't</b> want to know how long I spent screwing around with this before I got lucky, but here's how you do it:
Follow the FAQ instructions to get to diagnostic display mode for engine RPM. Then switch to car speed (km/h) <b>without</b> leaving diagnostic mode. Then, hit the "down vent arrow" button, and hold it down for 45 seconds. Now, somewhere between 45 sec and 60 sec, press the "reset" button on the trip computer control stick button 5 times with about a 1 sec delay between each press.
If you get the timing right, the display on the climat control (while in OBD mode) will switch to 07.0. This is the current max boost in 1/10 bar. Now, you can use the up & down arrows on the trip computer control to increase or deacrease boost in increments of 0.5 bar. Be warned though, it does not have a limit. I didn't want to go past 1.0 bar myself b/c none of the chip makers are doing that, and I figure they know what they're doing.
My understanding is that this simply keeps the wastegate closed until a certain pressure is reached. Since the K-03 is only good for 1.2 bar, if you over boost it, I'm sure you'll eventually crack it, and won't get any more power along the way.
As for driveability, this does cause some interesting hesitations in the power delivery. From what I've read about chips, they take some time to "get used" to your engine. I'm not sure what the process is for training a new chip on your car, but I think this is the same effect. Also, the lag is the same as it ever was, you just get a lot more power once it's over.
I suspect it's a bad idea to drive around like this. I had already ordered my APR chip before I discovered this, and i plan to stick with it. Everyone says lag is decreased, and I know they do a lot more than just keep the wastegate closed longer. I'm sure what they do is much safer for the engine.
But if you're sitting at a light nex to a corvette, and you feel like giving him a run for his money - but don't have a chip yet - maybe this is your chance!
Legal Disclaimer: Anything you do to your car based on this information is your responsibility, and the associated risk is your liability, not mine.<ul><li><a href="https://www.audiworld.com/faq/faq_int/faq87.shtml">https://www.audiworld.com/faq/faq_int/faq87.shtml</a</li></ul>
I noticed that one of the pieces of info you can get from it is Engine RPMs (code 28). So, it occurred to me that for testing purposes, there was probably a way to decrease the max turbo boost pressure (which would also be useful for when you have your car valet'd, but it's probably too much trouble). I knew it was a long shot - just finding it would be hard enough - but there was a chance that maybe you could even <b>increase</b> the max boost as well.
So, I started toying around with other codes & button combinations. You <b>don't</b> want to know how long I spent screwing around with this before I got lucky, but here's how you do it:
Follow the FAQ instructions to get to diagnostic display mode for engine RPM. Then switch to car speed (km/h) <b>without</b> leaving diagnostic mode. Then, hit the "down vent arrow" button, and hold it down for 45 seconds. Now, somewhere between 45 sec and 60 sec, press the "reset" button on the trip computer control stick button 5 times with about a 1 sec delay between each press.
If you get the timing right, the display on the climat control (while in OBD mode) will switch to 07.0. This is the current max boost in 1/10 bar. Now, you can use the up & down arrows on the trip computer control to increase or deacrease boost in increments of 0.5 bar. Be warned though, it does not have a limit. I didn't want to go past 1.0 bar myself b/c none of the chip makers are doing that, and I figure they know what they're doing.
My understanding is that this simply keeps the wastegate closed until a certain pressure is reached. Since the K-03 is only good for 1.2 bar, if you over boost it, I'm sure you'll eventually crack it, and won't get any more power along the way.
As for driveability, this does cause some interesting hesitations in the power delivery. From what I've read about chips, they take some time to "get used" to your engine. I'm not sure what the process is for training a new chip on your car, but I think this is the same effect. Also, the lag is the same as it ever was, you just get a lot more power once it's over.
I suspect it's a bad idea to drive around like this. I had already ordered my APR chip before I discovered this, and i plan to stick with it. Everyone says lag is decreased, and I know they do a lot more than just keep the wastegate closed longer. I'm sure what they do is much safer for the engine.
But if you're sitting at a light nex to a corvette, and you feel like giving him a run for his money - but don't have a chip yet - maybe this is your chance!
Legal Disclaimer: Anything you do to your car based on this information is your responsibility, and the associated risk is your liability, not mine.<ul><li><a href="https://www.audiworld.com/faq/faq_int/faq87.shtml">https://www.audiworld.com/faq/faq_int/faq87.shtml</a</li></ul>
04-01-2000, 11:29 AM
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I wonder how many people will admit that they tried it?
I was just about to, when I noticed you mentioned that code 28 was engine RPM. The OBD code for engine speed is 27 not 28 on my 2000 S4. The FAQ you linked to was written in '98 for A4s.
But you almost had me!
But you almost had me!
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