throttle by wire; can it modulate at wot WITHOUT showing up as TPS changes?

[camcojb]

05 GTO twin turbo at 8 psi. I've picked up a new issue. At wot the car surges, like it's running out of gas, or someone is moving the pedal back and forth. I have a bigger pump and BAP. Logging shows everything staying the same, 88% TPS steady, fuel pressure is steady and normal, maf hz steady (slight movement but due to the surging). Timing isn't moving, injector dc is around 65% tops.

Feels like it's some sort of torque management that I've missed removing in the tune. But I would think if the throttle blade is moving some the TPS% would change on the datalog, true? It is smooth as silk at 3/4 throttle, only wot.

Jody

[EC_Tune]

What about spark advance? Is it steady?

If not it could be a multitude of things. AFR Advance, IAT advance,
Coolant spark, or like you mentioned, Torque mgmt.

BTW: did you get the new trans in? Update to 2.1.10 yet?

EC

[camcojb]

What about spark advance? Is it steady?

If not it could be a multitude of things. AFR Advance, IAT advance,
Coolant spark, or like you mentioned, Torque mgmt.

BTW: did you get the new trans in? Update to 2.1.10 yet?

EC

The trans and converter are going in now. Along with the 402 turbo build (LS2). Hopefully the swap gets rid of this.

The timing isn't changing at all, heck I can't find anything that's changing. I have applied the update (2.1.10). It acts just like you were flooring it, pulling back, flooring it in succession. Thing is not a single piece of data I'm looking at says that is happening. Everything from timing, fuel pressure, a/f, TPS is all dead steady. Maf HZ not hitting 13000 yet either.

I read an older thread that the LS2 computer doesn't allow high HP, actually will stop the car from exceeding certain amounts. This was an older thread though and figured that tuners hadn't figured out how to tune around it yet.

Jody

[EC_Tune]

I think that was an operating system problem with the MAF. If you hit 11.5Khz the OS dropped the airflow to 0. Bad GM! Bad! It hit just like a rev limiter only a bit harsher.

[camcojb]

I think that was an operating system problem with the MAF. If you hit 11.5Khz the OS dropped the airflow to 0. Bad GM! Bad! It hit just like a rev limiter only a bit harsher.

OK, been there, done that with this one before I applied the 15000 maf patch. I do have a couple questions you may be able to answer. If I hit 15000+ HZ now with the patch will it shut off or "0" out like it did without the patch, or will it hold the last number it sees? Also, I have the patch in but the scale still only goes to 12200 HZ. Any way to change it or does the number at 12200 hz hold from there on up?

Jody

[EC_Tune]

If it's normal GM stuff, it will pick the last line of the table, 12.2KHz.

If you go over 15KHz it may roll over to 0. I don't know for fact as I haven't run over about 12.5K on anything, ever, but it may just pick 15K & stay.

EC

[camcojb]

If it's normal GM stuff, it will pick the last line of the table, 12.2KHz.

If you go over 15KHz it may roll over to 0. I don't know for fact as I haven't run over about 12.5K on anything, ever, but it may just pick 15K & stay.

EC

Thanks. I may find out and I'll post what happens. I am re-installing my 402 with 11 degree ET Performance heads. I can run a lot more boost and since I was seeing high 12000's HZ with the stock LS2 and 7-8 psi I'm guessing it may see over 15000 HZ with the larger engine, better heads, and more boost. The plan is to get in the 650 rwhp range or so which should let me stay low boost and not break other things on the car.

I can't wait until HP Tuners figures out 2 bar speed density for the LS2's!

Thanks again for your time, much appreciated.

Jody

[rmitchell242]

i am having similar problems with my ls2 maf when sprayin. I did the patch to 15000hz but there seems to be no way to tell what its at I just set up the scanner to read hz on the maf so tomorrow i will log that and see what i go to exactly but it is definatly getting funny at 511.99g/sec