Park idle rich, in gear at same rpm/map not

I've got a strange problem with the Suburban in my signature(or at least seems strange to me, but maybe is normal)where the 800/30 cell(I think the 800/40 does too) runs down to 108blm when in park. This same cell when in gear however is tuned to, and registers when logging to be around 128. I've gotten everything dialed in, but these cells at idle in park. Biggest reason I am concerned is that I've got an emissions test coming up in early May, and here they do a parked idle, and a parked 1200 rpm test, and I'd prefer to have the fueling where it should be. So is this something that is normal, and either way, is there something I can tune to fix this?

Always do your idle at end of log after engine was warmed and driven, not at beginning when there's choke, cold intake, running Open Loop etc... it's a wet intake. You should be in different VE area in P/N then in Gear. RPM is higher in P/N, and lower in Gear. By a little in this low resolution table. Then it does not use just that cell, it interpolates a VE number from that cell and four surrounding cells, interpolation. So Smoothing the VE table helps.

There's usually 16 cells for BLM Learn and one is separate for idle, this is why you get a change sometimes.

Code:

; LD2AB FCB 11 ; Freq of blk learn update, (600 Msec) ; VAL = (N * 20)+1 ;--------------------------------------------- ; ; _______|______|_______|______ ; | | | ; 12 | 13 | 14 | 15 ; _______|______|_______|______ HI MAP 81 Kpa ; | | | ; 8 | 9 | 10 | 11 ; _______|______|_______|______ MID MAP 58 Kpa ; | | | ; 4 | 5 | 6 | 7 ; _______|______|_______|______ LO MAP 18 Kpa ; | | | ; 0 | 1 | 2 | 3 ; _______|______|_______|______ ; | | | ; 750 LO RPM ______| | | ; | | ; 1800 MID RPM _____________| | ; | ; 2600 HI RPM _____________________| ; ;---------------------------------------------

There is no BLM Cell number in $42 data to tell. After tuning I like to disconnect battery to clear the BLM Learn to see what my new adjustments are doing immediate. Then instead of seeing what's stored and waiting for INT to move enough to adjust it I see BLM raising or lowering. Do all this warmed up as well. 108 is an issue because that is as low as it will go, it's still trying to take out fuel. Don't get stuck on everything having to be a perfect 128, can't do it! Even if you could it'd be different when weather changes.

If all that fails look at "O2 - Idle AFR Bias Value" = Bias used to lower AFR at idle.

Quote:

Originally Posted by EagleMark

108 is an issue because that is as low as it will go, it's still trying to take out fuel.

I actually never do any VE tuning without letting the truck warm up first. I usually let it warm up some in my driveway, and then take it out. Once the closed loop kicks in, I wait a little longer, and then clear the blm table to start fresh with a warmed up engine. I do realize that the in gear and park rpms are different. I'll have to do another log to be absolutely sure of the cells that are off, as I am currently thinking back to when I tuned in January. I just know, that thru several runs, I got the VE table in gear to be around 128, only to return home, and park in my driveway, and see the blm drop out to 108. It would concern me less if the number was even at 109. But as you said, 108 is as low as it will go, and thus why I think something has to be amiss.

Also, as a completely different question, but one that could be relevant here...I know it is possible to adjust the low end of the blm scale to be lower than 108. What I am wondering is, if I lower that, can the computer actually read below the 108, or is that as low as it can effectively work, and the real reason the number is adjustable is due to the fact that the same programming was used in multiple vehicles?

You could lower the BLM min, but realistically you need to pull some fuel from the idle cells.

What bin? BCC code?

You sure it's in Closed Loop when reading 128 BLM? You can post a log if you want us to take a look?

Quote:

Originally Posted by EagleMark

You could lower the BLM min, but realistically you need to pull some fuel from the idle cells.

What bin? BCC code?

You sure it's in Closed Loop when reading 128 BLM? You can post a log if you want us to take a look?

$42 ASDU. The low blm question was more of a curiosity than anything. It's definitely in closed loop. It's not a dead on 128 just around there due to my tuning. I'll get a log posted up here soon and see what you think.

Post your bin too.

I am about to do some datalogging, and while check my bin used for tuning to my bin that is normally used I noticed two differences that I wasn't sure of. I'm pretty sure it is but....is the checksum different based on every little change in a bin? My tuning bin has everything turned off that would affect the logging. Does this then make the checksum different? The other that I am less sure on is the ----Fuel---- scalar. My tuning bin is 121, but my regular bin is 119. Is this setting one that is different due to the certain scalars being off for tuning?

Also, back to the BLM, just for a initial recheck of the fueling, how low can I drop the low end of the blm? IE: How low can the ecm read the blms?

Checksum will change every time you make a change to the bin and save it in TunerPro. Automatic nowadays. Used to have to add hex...

I'm not sure how low min BLM can go? Really this is not a tuning tool, if your rich at idle take out fuel from VE table. 128 is the half way point of 156 bit so should be able to lower it? Honestly I don't know how it will effect the rest of algorithm of the ECM...

The " ----Fuel----" I think your looking at a title to separate things, not a paremeter, don't change it! In the next version of $42 they are marked as "Do Not Change!" Right click on it and Edit XDF, if the hex address is 0x00 it's a title, does it look like this? "-= FUEL =-"

Quote:

Originally Posted by EagleMark

Checksum will change every time you make a change to the bin and save it in TunerPro. Automatic nowadays. Used to have to add hex...

I'm not sure how low min BLM can go? Really this is not a tuning tool, if your rich at idle take out fuel from VE table. 128 is the half way point of 156 bit so should be able to lower it? Honestly I don't know how it will effect the rest of algorithm of the ECM...

The " ----Fuel----" I think your looking at a title to separate things, not a paremeter, don't change it! In the next version of $42 they are marked as "Do Not Change!" Right click on it and Edit XDF, if the hex address is 0x00 it's a title, does it look like this? "-= FUEL =-"

I'm just worried about maybe having to adjust from 108 flat... which means multiple adjustments before fine tuning can begin.

The ----Fuel---- is a title to separate. I just don't ever recall seeing it show up when using the difference tool.

Hex address 0x00 is actually first part of Checksum. So if Checksum changes then so will all Titles...

I guess the real solution would be ask Mark Mansaur at TunerPro to add a new XDF object.

Quote:

I'm just worried about maybe having to adjust from 108 flat... which means multiple adjustments before fine tuning can begin.

Multiple adjustments are part of the learning to tune game. I still can't get it right first shot.

Quote:

I've got a strange problem with the Suburban in my signature(or at least seems strange to me, but maybe is normal)where the 800/30 cell(I think the 800/40 does too) runs down to 108blm when in park. This same cell when in gear however is tuned to, and registers when logging to be around 128. I've gotten everything dialed in, but these cells at idle in park. Biggest reason I am concerned is that I've got an emissions test coming up in early May, and here they do a parked idle, and a parked 1200 rpm test, and I'd prefer to have the fueling where it should be. So is this something that is normal, and either way, is there something I can tune to fix this?

I think I told you this but idle in park and idle in drive should change cells, it changes RPM and load so it has to move some. Also it's not one cell, it is that one cell and four surrounding cells interpolated to come up with the number used. This is why smoothing helps so much in tuning. Also Park/Neutral uses a different BLM learn cell then if in drive, so BLM will be different.

If the tune is that close and all your worried about is idle for emissions and the BLM is bottomed out? Try this, "O2 - Idle AFR Bias Value" I believe this is subtracted from O2 sensor voltage to produce a lower AFR for idle, so raise it. Let us know what the resulting BLM does.

Also always base your data on a totally warmed up and driven truck, especially for idle! I've found to dial in a perfect idle on TBI to do it at end of a data log run.

Thanks for all the info as usual. I'll post again once I datalog and let you know how it goes.

Well, I went out and logged, and the problem is no longer there. Worst number was a 117.5. This got me to thinking about why it's not doing it now, and I remembered that my old ecm died on me due to unknown reasons, and this problem was showing up when I was using it, so there's a good chance that it was on its way out when I logged the problem. I just had completely forgotten about having to put in a new ecm. On that thought, is upgrading to the 7427 worth it in your opinion?

The only question I have left is how much should I smooth out the fueling table? Do you have a picture of what your tuned fueling table looks like, or could you post a bin that you've smoothed out the fueling on so I can check it out myself?

Quote:

Originally Posted by TheApocalyptican

On that thought, is upgrading to the 7427 worth it in your opinion?

Not in a stock motor and truck that came with 1227747, unless you were going to an E trans...

Quote:

Originally Posted by TheApocalyptican

The only question I have left is how much should I smooth out the fueling table? Do you have a picture of what your tuned fueling table looks like, or could you post a bin that you've smoothed out the fueling on so I can check it out myself?

Ahhh, you want my perfect tune from my 90 Suburban? :innocent2:

If your BLM are in order leave it alone. Smoothing the tables makes tuning the VE so much easier.