Effective Area Min Question

[ZZMike]

I am experimenting with a TPIS 102mm throttle body on a 2008 turbocharged LS7 with the 2 BAR OS. At startup, I cannot get enough airflow to get the car started. Using my foot to modulate the throttle, I can get the car to run, but if I remove my foot, the car dies.

If I increase the Effective Area Min value up from zero, will this allow more throttle opening at startup? At the PCMs commanded start and idle positions, the throttle blade to bore clearance is tighter than stock, limiting airflow.

I have experimented with both small incremental changes and large value adds to both startup and minimum idle airflow with no success in getting the car to start and run without assistance from my right foot. It is reminding me of the pre-ETC days when a hole in the TB would fix the problem.

If I change the ETC Scalar and put the stock throttle body on, the problem immediately goes away.

Just looking for a sanity check.

ID2000s are used on this car, car runs on E85 and does not have the actual timing tables in this shared tune.

[DSteck]

Uhh, add base running airflow and startup airflow, or lower the area scalar etc.

[ZZMike]

Doesn't work, those values in the idle RPM cells for BRA and SUA have been as high as triple the values you see in that tune (small increments at a time), with no change in performance. ETC Scalar has been as low as 5100 with no change.

Any other ideas?

[ZZMike]

It is like I cannot get the throttle open any farther at idle, it is just so strange...

[DSteck]

How the hell did I miss you saying that... Long day.

Try reducing cranking VE more than you have. A lot of people fail to reduce that when scaling, and it makes a huuuuuuuuge difference on startup.

[ZZMike]

Thanks, I'll drop it. The cam in the car is not that crazy, but at this point, I am willing to give it a shot before I send this thing back to TPIS along with a tube of K-Y.

Thanks again

[DSteck]

Having to scale for those injectors, I can tell you from experience that cranking VE needs to drop to at least 50%. I'm not saying that will fix it, but see what it does for you.

Lol on the return suggestion. Not the first time I've heard of people having issues.

[ZZMike]

I am off tomorrow and I am going to give it a shot. I will update this thread with what I find.

The crazy thing is, with everything idle and cranking related staying the same in this tune, change the scalar, put the stocker on it, and it starts right up and idles perfect.

I am convinced if I could get a few more percentage points of rotation, I could get it to work, but kicking up the startup and base running values do not seem to change the number of ETC % the PCM will give me.

[IDRIVEAG8GT]

Oh! That's an easy fix. If you haven't already, go to idle>airflow and set the TPS MAX FAIL up to 200 or so, considering its probably set at 60 right now. Haven't looked at your tune so idk. Problem solved otherwise if Dave's solution didn't help.

[ZZMike]

OK, so here's the latest.

Scaling the cranking VE closer to 50% made the car start much faster, thanks Dave.

However, the car only starts if I put the Percent Max and the Percent Max Brake at around 10% or so in the Effective Area Tables (independent of what I ask for in SUA or BRA). But as soon as I do that, the car immediately throws a P0606 code and puts the car in REP.

IDRIVEAV8GT, unfortunately, your suggestion didn't help.

Any ideas?

[DSteck]

Have you tried more airflow while knocking down the cranking VE?

[ZZMike]

Yep, started adding a g/sec at a time until the numbers were just ridiculous.

[IDRIVEAG8GT]

OK, so here's the latest.

Scaling the cranking VE closer to 50% made the car start much faster, thanks Dave.

However, the car only starts if I put the Percent Max and the Percent Max Brake at around 10% or so in the Effective Area Tables (independent of what I ask for in SUA or BRA). But as soon as I do that, the car immediately throws a P0606 code and puts the car in REP.

IDRIVEAV8GT, unfortunately, your suggestion didn't help.

Any ideas?

Ok glad Dave got you going there. Anytime the MAF/MAP is failed the ECM looks at that table to reference how far it should open the blade at its maximum to maintain consistent idle.

As for adjusting the ETC scalar, set it back to 7800 or so and adjust accordingly. In my experience the startup airflow numbers always look high to get it to start correctly.

[ZZMike]

Still working on it, will keep everyone updated.

Adding insane amounts of airflow in the BRA and SUA tables do not do anything. Removing insane amounts of airflow in the BRA and SUA tables did nothing, either.

The only positive thing so far I have come across is Dave's suggestion of dropping the cranking VE. While it did not help the car to start without the idle percentage I added (that threw the car into REP ), it did start much faster when I cheated the throttle into opening using those tables. I will be using Dave's suggestion going forward, what a cool trick.

I have experimented with the ETC Scalar between 1000 and max, in 200 step increments as well with no change, though it did want to try and start when the ETC Scalar was below 2500

As these TBs become more common, since they cure the blow-close, suck-close and flutter problems under boost associated with another brand of 102 TB, (and after firsthand experience, the reason I sprung for the TPIS), I would like to have a solution folks can search for.

Additionally, it appears the P0606 I alluded to earlier comes from the possibility that there are associated tables that also need to be modified when you change Percent Max and the Percent Max Brake that we do not have access to, currently. It errors as an incomplete flash.

I have about 11 hours in it today. Anyone feel like talking me into drilling it?

[desmondshea]

effective area min is 0
change to 50 try it then ajust 50 up or down should work if car runs fine after your foot is needed to start car now .

[ZZMike]

Thanks, desmondshea, yesterday I had it as high as 500 in 10 sq/mm increments (while increasing the other related values correspondingly) with no joy.

Still fiddling with it...

[DSteck]

Return 1:1 fuel system? Base pressure? Stock cam? MAF?

[wadelieck]

post up your latest tune so we know where your at now.

[IDRIVEAG8GT]

post up your latest tune so we know where your at now.

+1

[ZZMike]

Thanks to everyone who has taken time out to look at this and assist me with ideas. Car runs now, but has a distinct hesitation when the throttle is stabbed before the car revs. I had to bring the scalar down to get the car to act right, with huge increases in Effective Min Area (see screenshot below).

Return 1:1 fuel system? Base pressure? Stock cam? MAF?

Cam in the high 240s @ .050" with a 115 LSA, return fuel system using a 1:1 regulator set at 44 psi static, which pulls down to around 38 when the car is running. MAF is card style Hitachi in a 4" housing, with a 6:1 airflow straightener in front of it.

post up your latest tune so we know where your at now.

Here is the only area that has changed from the first tune.