Cold startup parameters w/90mm TB

[Redline Motorsports]

Because you only have limited time to adjust cold startup conditions I want to hit the right parameters the first time. I have a H/C F-body with a 90/90 setup. Idle both on cold startup and warm are a bit off but in gear (its an auto) its good.

I was looking at the following tables;

B4307 Desired Airflow

It definately seems like it wants more air as when I have my foot on the throttle slightly it fires right up. If I raise the values in this table I assume this lets more in through the IAC based upon coolant temp? Or does the PCM still play with the IAC to give the desired idle speed?

What about the IAC effective area? This table I just realized is based upon air temp NOT ECT.

Finally with the 90mm does the PCM really need to know the
desired idle effective area and what does this mean?

Thanks

Howard

[ArKay99]

I don't know if you've seen this but if not, try this: http://forum.efilive.com/showthread.php?t=149
You can log cold and input those values.
Set the IAC effective area according to the info in the above thread for an F-Body. This should be a good start.

[Redline Motorsports]

Regarding B4403 IAC Effective area; the write up mentions to move the values 6 places towards the higher values. Does it mean to raise all the values not noted as 0 by 6+?

After logging the MAF gms/sec at idle it states to input those values into the desired airflow (B4307) table. I assume you just match the logged values based upon coolant temp number for number?

[minytrker]

I have adjusted the same table you mentioned B4307 Desired Airflow and also when thecar gets to a point where I just need to barley touch the gas for it to start I will turn the throttle set screw just a hair. I have really only run into this with the fast 90/90 setups on auto's.

[ArKay99]

Regarding B4403 IAC Effective area; the write up mentions to move the values 6 places towards the higher values. Does it mean to raise all the values not noted as 0 by 6+?

After logging the MAF gms/sec at idle it states to input those values into the desired airflow (B4307) table. I assume you just match the logged values based upon coolant temp number for number?

For IAC Effective Area select the first cell, the one at the top of the column, and all the cells below it except for the last 6. Then hit ctrl-C to copy them to the clipboard. Then clear the highlighting and highlight the 6th from the top of the column to the bottom cell and hit ctrl-V. This will put the cells from 0 to n-6 into 6 to n, effectively moving the entire selection of numbers down 6 cells.
---
Regarding B4307 you are assuming correctly. Take your logged MAF values at the ETC temps and put them in at the corresponding temps. For example: if you log 8.43 gs/sec at 32 degrees C ECT, then put 8.43 into the 32 C cell in B4307.

[Redline Motorsports]

If I do that correctly that should put zeros from 68 to 92 square mm. Did I do that right?

I wish I had better explainations for the idle parameters as it would make it easier to understand what I am touching!

Even some of the idle scanning pids need further clarification.

What am I doing by moving that table down 6 spots? Also what is the explaination of "desired air flow" and why should it match the maf grams/sec? I made a map to log maf/grams/sec with coolant temp going up the left and rpm across the top from a cold start. Now that I think about it, I should of made the map coolant temps match the coolant increments in the table! . By copying those values into the DAF table is telling the PCM what?

Also what is the DEIAC b pid??

Thanks

Howard

[ArKay99]

If I do that correctly that should put zeros from 68 to 92 square mm. Did I do that right?

I wish I had better explainations for the idle parameters as it would make it easier to understand what I am touching!

Even some of the idle scanning pids need further clarification.

What am I doing by moving that table down 6 spots? Also what is the explaination of "desired air flow" and why should it match the maf grams/sec? I made a map to log maf/grams/sec with coolant temp going up the left and rpm across the top from a cold start. Now that I think about it, I should of made the map coolant temps match the coolant increments in the table! . By copying those values into the DAF table is telling the PCM what?

Also what is the DEIAC b pid??

Thanks

Howard

Howard, I'm sorry I confused you. I didn't have the program in front of me and I was going by memory, usually a bad thing for me...
For IAC Effective Area do this:
1) Select all the cells from 0.0sq mm through 108 sq mm. and hit CTRL-C.
2) Scroll back to the top and click on the 12.0 label to highlight the 0.00 cell next to it.
3) scroll to the bottom
4) while holding shift click on the 120.0 label to select all the cells above it inclusive.
5) hit CTRL-V to paste the values.
What you will be doing is shifting all the values down the row of cells.

I understand about the idle parameters, I'm just figuring them out myself.
The good news is to get the car to idle you shouldn't have to touch any of them. They are handy for tweaking.

Maybe we can get a sticky with explainations of idle pids going. But I wouldn't be the one to define them.

Make a map that looks just like the DAF table. The column should have the ECT increments, and for the row just have the number 500 above it.
For the ECT column select the ECT pid.
For the Airflow row select the MAF gs/sec pid
For the Data select the Desired Air Flow (grams / sec) pid
Set up your column to look like the desired air flow table and make the labels the same

Desired airflow is the amount of air the IAC 'desires or wants' at certain coolant temperatures.
As I understand it. DAF is calculated from other factors and used to control the IAC motor to get the idle running well. What I have found as important as MAF and IACDES_B agreeing is DYNAIR. I think DYNAIR is calculated and used as an estimate for fueling and spark. So if they are all in agreement then you know the MAF is calibrated properly and the DAF table is set up properly. Remember, you won't be able to get the pids to match, just get them close.

Read about RAFIG, if you have that it is a big help in nailing down the DAF values.

By copying those values into the PCM those are the values that the PCM will try to shoot for by using the IAC to control airflow. If the PCM sees 68 degrees C as the coolant temp it will try to get the IAC to let in through the IAC, and being measured by the MAF, the amount of air that has been entered into that cell.

The DESIAC_B pid is the pid I told you to log above and use as the Data portion of the map you should make. That pid reflects the Desired IAC air amount.

[Rich Z]

Yeah, I know this is an OLD thread........

I've been having an intermittent startup problem with my tune whereby I will get a REDUCE ENGINE POWER issue that flashes alternating messages about TRACTION CONTROL, etc. I can normally get it to start up if I keep trying, but still, it's disconcerting.

From what I understand there are several things that can cause this, among them problems with the throttle body blade positioning. So I've been looking at tables related to the throttle body. I have a custom 427 engine in my C5Z06 with a 90mm LS2 throttle body on a F.A.S.T. 102 intake. So pretty much nothing in the tuning for a stock Z06 will be relevent, I presume.

First thing I did was to raise the values in tables C6101 and C6102 40 percent in case this was a contributing factor. Since the problem is intermittent, I won't know if this made a difference or not till enough time and number of startups have elapsed to be comfortable. But in the meantime, I'm looking elsewhere for other possible causes.

While looking at other tables, I tried fiddling around with B4349. Mine is set for 0.0330 where stock, I believe is 0.0255. Some writeups concerning this value indicate that it should be LOWER for a 90mm throttle body, so I tried setting it to 0.0192. Car would start up fine, but just blipping the gas pedal would have it fall on it's face and stall. Scratch this change...

Now I'm looking at B4403 mentioned in this thread, since the values I have in my tune are identical to what is in my stock Z06 tune. Which I doubt should be the case. But I'm puzzled about this recommendation above earlier in this thread. If I slide all the values down 6 cells, it will push out the 310 step values at the high end of the scale. Can this be correct? Are we talking about the number of steps the PCM will command of the throttle body blade stepper motor? Does this change mean that the throttle body blade will NEVER be opened fully because the PCM won't command the full 310 steps needed to do that?

I also found another writeup in another thread about this B4403 table and the replacement values suggested topped out at 140 steps. That CAN'T be correct, can it?

[joecar]

Hi Rich,

B4403 is used for idle air control (IAC), which with DBW is done by PCM manipulating throttle...

step 310 does not correspond to throttle opening wide, but it corresponds to the maximum IAC airflow (which is at idle)...
so with DBW, it is how far the throttle would open (within the idle-range of throttle openings) if PCM requested max idle airflow;

with correct idle speed you would not see the steps anywhere near 310, they should/would be in the range 30-80.

140 might be too low... but maybe you can shift and scale the slope so the max is higher.

[Rich Z]

OK, that makes sense. And it actually might be relevant in my case since I am getting that REP fault at startup, so maybe the PCM is getting confused when it goes through the motions of testing the throttle plate movement. Of course, this is all assumptions on my part as I haven't actually found a checklist description of what exactly and when the PCM does during the first few seconds of engine startup.

But this raises another question. Aren't the calculations of how much airflow is being delivered per throttle body play step needed for off idle driving? And if so, where is this table located?

BTW, I'm running with the MAF disabled using the hybrid speed density using table B3647. Been meaning to update another thread here concerning the tuning efforts I have made so far.

Anyway, when I checked error codes, I had P0102, P0103, and P1516 logged. That REP fault is real sporadic. I've been pecking away at possible causes, both tuning wise and hardware wise and then waiting to see if the error just never comes back. I just hope it doesn't strand me somewhere if I can't get it to start at all. Otherwise I'm real pleased with how the car is running.