ETC question for Ross/Paul (and anyone else who knows ;))

[turboberserker]

I'm working on this whole 90mm tb not opening 100% thing, and have been playing around in the ETC settings. I've gotten a small bit of success by changing when the PCM commands 100% open, but am road blocked.

I'd like to command 110%, but there is a limit being set to cap it at 100%.

Is this limit in EFI or is the parameter itself hard capped at 100 by GM? I'm guessing the former, as it is probably a calc'd param in EFI?

Is there a way I can bypass this that you know of (be it hacking the param file or hacking the OS -- if the latter, can you give me a hint of what to look for)?

Thanks!
E

[Blacky]

It is absolutely limited by the PCM from 0.0% to 100.0%. There is no way to change that within the calibrations.

Just for your info, if we allowed greater then 100% to be entered into that table, then the values greater than 100 would wrap around to 0%. i.e. 110% would actually mean 10%.

If mechanically, everything is operating correctly, then 0% means closed throttle and 100% means WOT. If the blade is not moving through 90degrees of rotation from 0% to 100% then there is something else wrong (probably mechanical).

Regards
Paul

[turboberserker]

Hey Paul,

Thanks for the response.

For more background info, this applies to us 03 DBW guys who have converted to a 90mm GM TB and an 02 TAC module which can support the different TPS configs. If we put these TBs on different cars, they open 100%, just for use they hit 80-85% at WOT.

It must be a voltage issue in the TAC by your description above -- at least we have eliminated the PCM

[turboberserker]

Seems like its even more screwbally. I just heard from Richard@WCCH that people with an 02 use the same TAC, TB, and harness adaptor and DON'T have the trouble at all.

Is there some kind of voltage cap for the TB motor in the PCM?

[DrX]

Seems like its even more screwbally. I just heard from Richard@WCCH that people with an 02 use the same TAC, TB, and harness adaptor and DON'T have the trouble at all.

Is there some kind of voltage cap for the TB motor in the PCM?

I believe that voltage is constant. Motor position is controlled via pulse width modulation according to the GM manuals.

Can anyone compare what PW the motor is seeing at 100% commanded TP/sensor TP on the various applications(stock LS2 setups, 02, 03, 04 and 05 stock setups, 02 conversions, 03-05 conversions using the 02 TAC)?

Also, does the TAC module convert TP sensor voltage to % TP then report this to the PCM as such. Or does it just relay the voltage to the PCM and the PCM does the conversion to % TP?

[turboberserker]

Some additional info from pt.net:

It has to be a tune issue on the SSR and now Trailblazer SS. We can reprogram a GTO Computer and install it in an SSR and you will lose the full movement of the throttle blade. The GTO and Corvette report 88% TPS for 100% ETC for full throttle movement while the SSR and now TBSS only report 83% and are shy of 100% on the throttle movement and yet it shows 100% ETC. There has to be a table that we are missing that can break down the correlation between TPS% and ETC%!!!

Do not let this little bit discourage you from installing the better throttle body because they do flow more air then even the Stock SSR 90mm throttle body. We had to add more fuel to compensate for the change on my SSR.

[DrX]

Is there any way to put a 2002 OS/Custom OS(512K) into a 2004(1 MB) PCM? What OS are the 2002s that are working with the 90mm TB? I was considering the 12212156 OS(actually the corresponding custom OS 0202003).

[GMPX]

Sorry, that cannot be done.

[DrX]

I'd settle for a swap of only the appropriate segment, unless there is something in the hardware of the 02 PCM that allows the LS2 TB/02 TAC/02 PCM combo to work. Would a 04 to 02 PCM swap work? Do I need that extra 512K? Anything essential on there? The main difference I see in the tunes is the absence of the E85 stuff which doesn't affect me. Think I noticed a missing fuel gauge calibration table also(F0501). Don't recall anything that looked critical.