ETC, Reduced Power Mode & Boost

[GMPX]

Hi All,

We seem to get alot of questions about the Electronic Throttle shutting down and going into reduced power mode on boosted engines.
Does anyone care to share their tricks with everyone else and we can make this a sticky if it rurns out good.

Thanks,
Ross

[SinisterSS]

Can't remember the table off-hand but one thing that is in the ETC section of the Engine Diagnostics - one needs to increase the table or actual air flow will exceed the predicted and put it in reduced power mode.

[jfpilla]

C6101 ETC predicted airflow. Raise the table 10% at a time until the code no longer comes up. I copied the Z06 table to mine and the code has never reappeared. It's been years and bigger heads and 2 bigger cams.

[GMPX]

That is the one I tell people, but everynow and then we get ones that still do it. On a blown car some have found you just need to set that to maximum.

Cheers,
Ross

[SinisterSS]

In addition to C6101, one also needs to raise C6102.

[dfe1]

One of the functions of the C6101 table is to prevent over-revving caused by a failure of the electronic throttle control. If the entire table is raised to maximum values, that safety net is lost. I usually go to the column that's 500 rpm above anticipated max rpm and bring the values down to 400 or 450. In theory, the rpm limiter should catch things before the engine over-revs, but we all know limiters are occasionally set too high or forgotten entirely. It's also a good idea to leave some of the values at the lower end of the table- zero to 12.5 TPS-- close to stock, to catch an ETC problem. Since the engine never uses a lot of air at light throttle settings, these values won't instigate reduced reduced engine power unless there is an actual problem.

[Redline Motorsports]

I have have added 200% to the predicted airflow table under those conditions and solved the problem. I am definately getting my fill of ETC tuning as 90% of the cars we work on are Vettes.

[GMPX]

DFE1, all good points, I should add, I do usually also suggest the tuner revisits that table once the tune is done to keep reducing it until reduced power is hit, then increase it by 5 - 10%. I am not a big fan of turning everything off until the problem goes away.

Cheers,
Ross

[madprof01]

I was succesful with setting the highest single square to the max then highlighting the entire map and smoothing. Both produced a clean linear graph and I have not had any further issues. However I did just have an incident tha I got crazy with the ETC tables and locked up a pcm beyond repair so be careful!
madprof01

[hpcubed]

Let me tell you, I had a mind blowing experience when i forgot to update that table when I went into speed density with my new 402. When I exceeded the value in those tables without the maf plugged in my car went wacko. I lost all controll of the throttle body until I turned the car off and re-started it. The car sounded extremely strange - like the throttle body was wide open but the computer was limitting the rpm by some other method. Sounded like a car that has an exhaust pop off. Woke up the next morning and remembered I had not adjusted that table. Bumped it up 50% and issue solved. Short lived nightmare.:Eyecrazy:

[GMPX]

However I did just have an incident tha I got crazy with the ETC tables and locked up a pcm beyond repair so be careful!
madprof01

Well, we do put a warning in ;) .
But seriously, I contemplate removing those tables at least once a month.
Interestingly, on a Holden, you can't get away with much change at all or it will limp the engine (though recoverable).
On some vehicles you can make BIG improvements on throttle feel without any limping.........the down side as you found out, you can push your luck and go too far.

Cheers,
Ross

[SinisterSS]

But seriously, I contemplate removing those tables at least once a month.


Don't make baby Jesus cry. :bawl:

[fyi]

The F/I airflow characteristics are vastly different from say a positive displacement-type supercharger like the Magnuson compared to a centrifugal-type supercharger like Vortech or Procharger.


The Mag. airflow table needs to be VERY aggressively ramped up, very early in the RPM band, since that supercharger produces so much intake pressure, so soon in the airflow curve and held nearly flat across the board until right at the end of the RPM curve, where it runs out of steam. Once that table is done correctly, it will not resemble the O.E. configuration at all...

The Vortech-Procharger table will resemble the O.E. curve somewhat early on, but will need to be ramped up heavily in the mid-range and VERY heavily ramped up in the high RPM area, due to that type of supercharger producing little intake pressure until 2000 RPM or so, but then it ramps up *massively* throughout the entire curve~ rapidly ascending all the way to redline. You'll also need to add a bit down in the lower also, but in higher RPM areas for those times that someone is in 2nd or 3rd gear at say, 3000-4000 RPM and then smacks the throttle to WOT. That event will produce a huge airflow spike like the Mag. does, which will set the code if the predicted table doesn't match (or exceed) actual in that location. Once this table is complete, it will look similar to the O.E. table, only fatter everywhere in the mid-range and high RPM areas of the table.

It works quite well. :)

Whewww! Sorry so long winded and I hope that helps... :banana:


-john

[Travis@FIR]

Well, that explains why I am having partial throttle/boost issues.. I get Reduced Power Mode if I'm cruising at 2500rpm or so, and get into boost at anything less than 1/2 throttle. However, I can go 100% throttle, and I don't have any issues. Hopefully, I can adjust my C6101 tables once the I6 software comes out. :)

Travis

[GMPX]

Travis, it might be a bit more challenging on the LL8, that PCM uses a 2nd CPU for some ETC control, I 'hope' the main ETC predicted air flow table is in the main flash and not in the co-processor

Cheers,
Ross

[Travis@FIR]

Travis, it might be a bit more challenging on the LL8, that PCM uses a 2nd CPU for some ETC control, I 'hope' the main ETC predicted air flow table is in the main flash and not in the co-processor

Cheers,
Ross

Ross, is the second CPU located within the PCM? Or, is it located in another box?

Travis

[GMPX]

It's in the PCM, it's like a 'sanity' check on the main CPU I guess is one way to describe it. Programming it is another story!!
GM basically got rid of the TAC module that was used on the LS1 motors. In some applications just did like the LL8 and made the PCM do everything including ETC motor controls directly.

Cheers,
Ross

[Travis@FIR]

So... is this something that we're going to be able to control? Without control over this feature, we're in deep doo-doo.. ;)

Also, I wanted to ask... will we have control over shift-firmness and shift-points? Our trans slips between shifts, which I'm hoping will be fixed with some tuning.

Travis

[joecar]

Our trans slips between shifts, which I'm hoping will be fixed with some tuning. You mean it slips while running in each gear...? :bawl:
Yes, some "In Gear Pressure" tables would be usefuel. :beer:

[Travis@FIR]

Yeah... it's wierd... it's like something is modulating the line pressure.. I'm not too familiar with the 4L60E or it's control systems, though. I assume that the CPU can control the line pressure?

The trans slips when it shifts into 2nd gear.. and 3rd.. it won't slip in 1st gear, however. It's very mushy between shifts, too... Can't wait to fix it.

Travis

[joecar]

The TFM/PCS pressure is dependent on PCM calculated engine torque which appears to me to depend on airflow (among other things);

Log TRQENG (ftlb), TFMPRS (psi), DYNAIR (g/s) and see if these track each other and see if DYNAIR goes up at the right times; if DYNAIR stays low, then the problem may be incorrect airflow calculation (from VE table, MAF or combination of both) keeping TFMPRS (psi) low.

[GMPX]

Most of the trans controls for the LL8 are the same as what you see in the LS1 (which is a good thing).
On the ETC airflow thing, it will be something we will try to get around.

Cheers,
Ross

[Travis@FIR]

Yeah.. we'll have to figure out something.. Otherwise, we're dead in the water. :(

Do you have any ideas? Maybe we're being overly-worried too soon?

Travis

[joecar]

...Maybe we're being overly-worried too soon?
Slipping trans is a major concern not to be taken lightly.:bawl:

[Travis@FIR]

Slipping trans is a major concern not to be taken lightly.:bawl:


Oh.. I wasn't saying that.. I was saying that maybe we're over-reacting about tuning this ECU.. Since we haven't really gotten into it, yet.. maybe we're getting ahead of ourselves.

Travis

[joecar]

Oh.. I wasn't saying that.. I was saying that maybe we're over-reacting about tuning this ECU.. Since we haven't really gotten into it, yet.. maybe we're getting ahead of ourselves.

Travis
Oh, I see, yeah maybe we are, the new PCM's are very complex and sophisticated. :Eyecrazy:

I was just trying to say don't drive around when it's slipping or it will have a short life. :bawl:

Hopefully the answer will be found soon. :cheers:

[Travis@FIR]

Oh.. I hear ya... I've blown out my fair share of transmission's... ;)

I just hope that we can get this nailed down.. I'm ready to see what kind of potential this engine has..

Travis

[C3vette75]

Earlier in this thread it was recommended that Table C6101 be increased to prevent setting code P1514 on blown cars. Another recommendation was to increase Table C6102. Does anyone know exactly what function each of these tables perform. According to the EFILive description in Table C6101 it sets the code but it doesn't say it cause the throttle to close and the description for C6102 doesn't say much of what it does. From tunes I have downloaded of professional tuners I notice that none of them have changed Table C6102. Which of these tables cause the throttle to close once the tables limit is exceeded. I also notice that the max limit for each RPM range is higher in the C6102 Table than the C6101 Table on a stock tune.