Altering Electronic Throttle Rates on E38

[C6Guy]

Can someone tell me how to go about altering the electronic throttle rates on an E38 PCM? When I look at the OEM tune, all the values are set to 99.99 in the table and there is a note that says not to mess with them.

Is it possible to adjust how the electronic throttle responds on an LS3 with an E38 using EFI Live?

[swingtan]

Is it possible? Yes.

Do you really want to change them? I guess you need to think about what you are trying to achieve. Normally people want to increase the response rate, be cause of a perceived "slowness" in response times of the motor. People put the foot down and feel there is a delay before the motor responds and assume that it's the ETC delaying the throttle opening. I've logged the relationship between the Applied Pedal Position and the Indicated Throttle Position and in the GM based cars you would be hard pressed to :feel" a difference. So if it's already set to near maximum values, I wouldn't bother changing it.

On the other hand, maybe you want to reduce the opening rates like they are on some other operating systems. Normally this would be to "soften" the applied power at small throttle movements to make driving feel smoother. I've never really tried this, mainly because of the warning about bricking the ECM. If you wnated to do this you could probably achieve the same thing with throttle tip in torque reduction.

Simon

[C6Guy]

I'd like to emulate the results of the Sprint Booster.

[C6Guy]

I guess what I'm asking is can I do this with the standard version of EFI Live 7.5 or do I need some other software package or upgrade? When I look at the throttle open rates table, this is what I see (attached). It seems like I'm missing something.

[swingtan]

You're kidding right?

Here's some real time data of the actual ETC TPS sensor. Note the elapsed time is 0.199mS for the throttle position but the MAP response (which gives a better indication of motor airflow) is about half that.



As I said previously, if the stock tables are maxed out, there's nothing to do here, apart from saving $300 on a device that will probably "slow down" the response. Check the How it works link and it indicates that the response would be slower.

Simon.

[C6Guy]

Yes, I understand exactly how it works and what it does, and I know it won't make the car any faster. I would like to play with the throttle tip in values just because I would like to change the response curve of the throttle and experiment with throttle feel. But what I really want to know is HOW to do it and what software do I need to make it happen.

The problem is not that the response rate of the system is slow. It is that when you press down 10% on the throttle, you don't get a 10% change at the throttle plates, but a much smaller percentage, due to the way it is mapped. I'd like to play with the throttle mapping, and make it closer to a 1 to 1 ratio of change like you would have with a standard throttle cable.

[C6Guy]

Do I need to buy the Professional version of the software to access the tables I am after?

[Boost]

no.

[swingtan]

Are you sure about that? Have you logged both Applied Pedal Position and ETC Indicated Throttle Position to compare?

I don't think you are looking at the tune as a whole, but may be concentrating on a single parameter. Normally, with the table set as you have shown, the actual throttle opening will always be "more" than the pedal position, because the throttle is never actually closed. You certainly do not want a 1:1 ratio in this case as the car would run poorly at low throttle openings. At idle, you have "0%" applied pedal, you don't want "0%" throttle, you are more likely going to have 7% to 8% throttle at this point. Here's a direct comparison of "applied" throttle, vs "actual" throttle.



Note that "most" of the time, the "actual" throttle opening exceeds the "applied" throttle. The only time it doesn't is during transients, where it nearly always matches. There a small section where the "actual" is lower than the "applied" but this has nothing to do with "throttle opening rates", it's actually throttle tip in torque reduction.

If you haven't logged the data, don't alter the table.

Simon.

[C6Guy]

Can anyone tell me what I need to do to gain access to the throttle mapping values?