1st idle run with 1227747 ecm and modded bin.

[damanx]

Ok, so the spare 7747 ecm is good.

Reinstalled the original 7747 with the modified ASDU bin that Mark provided called "damanx".

I was kind of confused at first about this, but it makes sense now since I saw first hand that closing the throttle plates to reduce the amount of air flow through the blades caused the ecm to open the IAC while in drive from 0 to around the 20's.

Idle is sitting at about 550 and it seems kind of rough. I think pushing it to about 650-750 area would be great, but I am guessing that is a setting in the bin that needs to be changed?

Had to reset the TPS as it dropped from .590 to .490

Now, upon restart, the idle isn't so high.

Here are the various files recorded.

File "orig7747....." is log prior to any adjustments.
File "thrstopscrew..." is log while adjusting the throttle stop screw.
File "tpsreset...." is log of tps range with engine off.
File "aftertpsadjust" is log with engine running after all adjustments.

EDIT to add:

The last file I just did. I readjusted the throttle stop screw to get to about 10 counts on the IAC in idle drive. TPS readjusted back to .590 vdc. That file is "iacreadj....".

[EagleMark]

Now your getting the hang of it! Last log looks like good idle control by IAC. When there's no IAC counts the ECM has no control of idle.

There is a desired Idle in XDF, this paremeter get's it pretty close to RPM during Closed Loop in drive. Open Loop and Park will be closer then they were. I usually adjust the entire table by same amount, it's higher when cold. Just add what you need, 50, 100... from the looks of those charts the smaller engines had a higher RPM idle then the V8, except the 7.4L which most are Open Loop Idle, commercial and another animal as far as engines and emissions were concerned.

[EagleMark]

EDIT to add:

The last file I just did. I readjusted the throttle stop screw to get to about 10 counts on the IAC in idle drive. TPS readjusted back to .590 vdc. That file is "iacreadj....".

10 is going to help when you raise idle by 50 , 100 or? As you raise idle it will increase IAC count. See ECM now has control of idle.

Just make sure when you turn the screw or adjust the TPS voltage that you turn vehicle off for... IIRC timer is 5 seconds, then restart. When key is turned on ECM set's TPS% to 0, so making any adjustments with key on makes TPS% for closed throttle change.

There is a TPS hack for this to see actyual TPS%. But do not leave it on as it takes the place of a knock count and knock sensor no longer works. I use this hack just for the purpose of idle as you are doing. It's a lot easier with an emulator then burning chips though...

[damanx]

Thanks again Mark, your help in me learning this has been priceless.

The table for "IAC - Desired C/L Idle Speed" shows the following:

55 - 600.00
65 - 600.00
75 - 575.00
85 - 525.00
95 - 525.00
100 - 525.00
105 - 575.00
110 - 625.00
115 - 650.00

I am confused to the drop in rpm from 75 - 105.

So, I think upping each number by 75 rpm would be a good start.

Thoughts?

ETA:

Oh, I don't think I have ever mentioned that I am at about 2900 feat above sea level, if that makes a difference.

I've programmed another chip with the +75 rpm added across the table. Will post the results of that shortly.

[EagleMark]

Click on the top of column to highlight all, then use the tool to add 75 to all.

If you look at the table to temps it has total warmed up area 85,95, 105, when colder it's a little higher and if it's getting to hot it raises idle some to increase coolant flow to cool. You don't have to follow this routine but it works well.

[damanx]

Ok, having played around with it for a bit, this to include a 51 Prom error, I am going to run a datalog to work and see how it goes.

Right now, the Idle rpm's are as follows in the bin:

725.00
725.00
700.00
650.00
650.00
650.00
700.00
750.00
775.00

Get about 45 seconds in and you will see where the IAC settles out in drive.

[EagleMark]

Nothing counts if it has a Error 51...

[damanx]

Here is the test drive.

What the heck happened to the knock count? And, what is considered reasonable?

Also, it seemed to idle much better after the drive and the IAC seemed pretty solid at about 15 counts.

Edit to add:

So I was a little confused about the procedure in regards to setting the idle speed via the throttle stop screw and having the IAC disconnected per the instructions here:

http://www.gearhead-efi.com/Fuel-Inj...-Fuel-Pressure

I had read this a while back:

http://www.gmcmidwestclassics.org/We...0the%20TBI.pdf

I've been thinking about this for a bit since the log attached in this post since I did not actually set the IAC to 0 position by shorting A&B and disconnecting the IAC connector and then adjusting the idle speed to about 125 below the desired speed on the IAC RPM table.

What I did, after upping the desired target rpm in the "IAC - Desired C/L Idle Speed" table to the values listed above, let the engine run, with the IAC connected and the engine in drive I think, I then tweaked the throttle stop screw very very slowly to get the steps to about 15 while the ecm seemed to maintain the rpm at about 625-675.

It seems that I accomplished the same thing since it appears that the charts attached in this post http://www.gearhead-efi.com/Fuel-Inj...ll=1#post22350 seem to correlate.

ETA to add drive home log, (drivehome041513 file). This drive was without the a/c running. Not sure if the 3 knock counts were due to the a/c not being on.

[EagleMark]

You can do it the way described in both those links, or the short way I told you. In the end the IAC counts end up the same as you found out.. If you turn screw with key on you need to turn off before driving or logging. ECM set's TPS to % percent when key is turned on.

Knock counts are accumulated, so when you have 3 or 10 then they are all 3 or 10. It's hard to find knock in these because of this, have to watch data frame by frame and if you see knock continue to climb in a cell or cell to cell this is knock counts you need to worry about. Remember this data is only every 1.2 seconds... For frame by frame pause data and use SHift + ] or [ to move ahead and back.

[damanx]

The drive home file was started before starting the engine, after it had been off for about 7 hours.

So that I am clear, the way I had adjusted pretty much is the same result?

Also, what is reasonable for knock counts?

[damanx]

I am purely guessing right at this moment, but it appears my knocks are occurring before the water temp reaches 160 and I am in gear. This morning in particular, I had a total count of 22, 16 of which occurred during a 2nd to 3rd gear shift and the water temp being being under operating temp.

I think one of the reasons I may have had very low knock counts as seen earlier in this thread is due to the IAC counts at idle not being correctly adjusted for by the throttle plates being opened a little too much.

Will review that data after some sleep.

[EagleMark]

That's where the small amount of knock counts were in last log. Under high MAP, low vaccum in this table "SA - Coolant Comp Spk Adv" Take some spark out there.

You must do night shifts?

[damanx]

Yeah, I do night shifts.

I do have a question about the BPW though. It's set to 135, as you had told me that would not make much difference from the 144 that the math actually comes out to.

Would changing that BPW in the bin from 135 to say 140 make any difference?

[EagleMark]

It would add a little more fuel and raise BLM even more. Because of your ever so slightly rich BLM I left it low.

Go back to 144, and see what BLM does, should make them lower. Then forget it and do some VE tuning

[damanx]

Ok, that clears up the question of whether the spark advance hack is affecting the timing.

Now set to 0 per the bin.

I feel like i'm doing freaking circles right now trying to get the idle rpm / iac count situated.

I'm not sure what scalar exactly is commanding the idle rpm, so I am going by the Max RPM Hot Pk/N in the bin for 900, but, I can't get to that because the throttle plate has to be opened up too much and the IAC counts drop to zero. The best I can get is about 650 rpm with the IAC counts running about 15, which seems to idle ok, but could use another 100 rpm.

I'm confused.......maybe....

I've got the Closed loop idle rpm's set around 700. Correct me if i am wrong, but it appears I need to tweak those up another 100 rpm to get to the 700 actual rpm with the IAC counts at about 15?