LLY: my truck's weird issues...revisited...again

[duratothemax]

The ECM limits fuel based on the measured airflow in order to maintain the proper air/fuel ratio (Yes, this does apply to a diesel) to prevent smoke.?

yes, we already realize that.

but thats to limit fuel when airflow is too LOW (ie, the turbo isnt spooled, so to prevent smoke before its spooled).

Obviously my defuel is happening when airflow/RPM/turbo 'spool' is HIGH.

What Ben is trying to tell us is that there is another airflow table somewhere in the ECM that has not been retrieved and decoded by the crew at EFI Live. I am thinking something along the lines of "airflow torque limit" I'm thinking that if this table exists perhaps it falls off at higher RPM similer to some of the other "stock" tables in the ECM...Now this can be worked around using the torque tables much like using the MAF voltage table in lue of the other MAF tables being present in the newer ECM's. Ben, have you talked to the folks at EFI to see if they'd be willing to look for this possible table?

I wont bother them with this right now; obviously not many people are running my configuration (or are running into this problem) so its probably not really worth their time tracking down something that only seems to affect me.

Plus, now that the LLY's are "old" I dont think theres really much priority to revisit it, which I understand.

ben

 

[Mike_S]

I know your problems are in the high rpm/airflow range ben, I was answering the question from the other dude.

On a side note, I seem to find some odd things happening with mine as well, due to the fact that I am trying to run the engine at a significantly higher RPM than the stock fueling was set up at. So far, I have been able to either find a table that isn't mapped out far enough, or figure out a workaround if I cannot find a troublesome table. I'm thinking that the workaround may be the only option in your case.

 

[GMC_2002_Dmax]

Havent been able to work on my truck at all; ive been too busy with customers trucks and stuff here.

I have a completely stock tune in my truck and I it will still defuel and randomly fall on its face at higher RPM's.

Yes, I have twins. The only thing this effects is airflow (or MAF). The truck doesnt throw any overboost codes or anything (remember, this is a stock tune, all DTC's are enabled), it JUST DEFUELS!!

It throws EGR codes and thats it. But it still defuels. Someone tell me there is not some other hidden airflow-related limiter/defuel table....

(im not talking about B0751/0752, thats to control LOW BOOST fueling and limit smoke before turbo spool up)

If there is a table it does not place any limits if the tune is done properly. I know you want to blame it on a table you don't have, but I am telling you your problem can be resolved with the available tables in EFI-LIVE.......:thumb:

Forgive me but I don't think I understand what your saying. Are you saying the ecm will pull fuel if it doesn't see the maf maxed out at 66.14 lbs of air a minute? Or that it will pull fuel if it does see the maf maxed out at 66.14 lbs a minute?


Thanks.

What I am saying to Ben and anyone else who wants to know is this, the MAF table is a limiting table for fueling, it is there for smoke control as others in this thread said, it will limit fuel mm3 based on measured airflow. If MAF goes out of range it will code and reduce fueling.

There are other inter-related tables that all reference one another, miss a related table and it can place a limit on you.........

If you write the tune properly and follow all the tables you can remove the problems.

 

[duratothemax]

my truck defuels when the MAF is well within range. The highest airflow ive logged is 63lbs/min. I have rescaled the MAF many times. I am going to try to mess with this tomorrow.

 

[TrentNell]

my truck defuels when the MAF is well within range. The highest airflow ive logged is 63lbs/min. I have rescaled the MAF many times. I am going to try to mess with this tomorrow.

My truck with the old twins would peg what can be logged, 66lbs/min by about 30 mph ?

 

[Mike_S]

If there is a table it does not place any limits if the tune is done properly. I know you want to blame it on a table you don't have, but I am telling you your problem can be resolved with the available tables in EFI-LIVE.......:thumb:



What I am saying to Ben and anyone else who wants to know is this, the MAF table is a limiting table for fueling, it is there for smoke control as others in this thread said, it will limit fuel mm3 based on measured airflow. If MAF goes out of range it will code and reduce fueling.

There are other inter-related tables that all reference one another, miss a related table and it can place a limit on you.........

If you write the tune properly and follow all the tables you can remove the problems.

Yes, the table that we HAVE is a low airflow limiting table. What you fail to acnowledge is that there could be a table thats not been retrieved and decoded that limits at HIGH airflow. Don't know whats so hard to understand about that.

 

[TrentNell]

Yes, the table that we HAVE is a low airflow limiting table. What you fail to acnowledge is that there could be a table thats not been retrieved and decoded that limits at HIGH airflow. Don't know whats so hard to understand about that.

If thats the case why isnt every LLY truck defueling That in itself is why i dont buy the hidden theory .

 

[GMC_2002_Dmax]

my truck defuels when the MAF is well within range. The highest airflow ive logged is 63lbs/min. I have rescaled the MAF many times. I am going to try to mess with this tomorrow.

I think you are looking in the wrong place..........

Yes, the table that we HAVE is a low airflow limiting table. What you fail to acnowledge is that there could be a table thats not been retrieved and decoded that limits at HIGH airflow. Don't know whats so hard to understand about that.

I am telling you that in my experience I have not had a problem tuning a truck and getting it to NOT defuel and NOT lay over with the available tables we already have. I will acknowledge that there may be tables EFI-Live has not found but at this point based on what I do with the tables I am not having the problems Ben is...........:thumb:

If thats the case why isnt every LLY truck defueling That in itself is why i dont buy the hidden theory .

EXACTLY !!!

:angel:

 

[IOWA LLY]

If there is a table it does not place any limits if the tune is done properly. I know you want to blame it on a table you don't have, but I am telling you your problem can be resolved with the available tables in EFI-LIVE.......:thumb:



What I am saying to Ben and anyone else who wants to know is this, the MAF table is a limiting table for fueling, it is there for smoke control as others in this thread said, it will limit fuel mm3 based on measured airflow. If MAF goes out of range it will code and reduce fueling.

There are other inter-related tables that all reference one another, miss a related table and it can place a limit on you.........

If you write the tune properly and follow all the tables you can remove the problems.

So if I was Ben, I would start by setting the sensor voltage back to stock. Then log the truck creating a map of actual airflow as read by the maf sensor. Then put that table I created into the expected airflow table.

Am I heading in the right direction?

 

[dmaxfireman]

you need a real life airflow number of the twins to start dialing in the maf. do you guys have the maf sensor not fitted option on lly's?

 

[GMC_2002_Dmax]

So if I was Ben, I would start by setting the sensor voltage back to stock. Then log the truck creating a map of actual airflow as read by the maf sensor. Then put that table I created into the expected airflow table.

Am I heading in the right direction?

You can head in any direction you want, there are many ways to get to where you want to go, some take longer and some are dead ends.........

I will try one more time to explain it, the MAF tables that are used to limit fuel mm3 do just that, they limit mm3 based on the MAF sensor data ( lbs per minute of air ) the ecm looks at all sensor data and then compares that information to the hard limits that are set by the tables.

So then, "If" the sensor sends a voltage signal that is indicating a certain airflow it will look up the correct mm3 limiter for the actual airflow it sees, that does not mean that it is actually that low lbs/minute of air flow it just means that is what the sensor is reporting based on the way it is calibrated.

If you allow that sensor to limit you it will, if you raise the mm3 limit vs. air flow it won't. It is just as simple as raising the maximum timing limit table to above 20 degrees to whatever you want to cap timing to, it is a hard limit table. I am not saying you max it out to the hard limit what I am saying is you have to know where to change the limiters and where to leave them alone.

Ben's troubles are not being caused by the MAF sensor IMHO, I never change the MAF voltage scaling, some may disagree with me but I have never found the need to do it.

Most likely the problem is a table that does not seem important or has been changed and is now affecting another table, you have to know how the look-up is done and in what order the tables are referenced and when you miss one or have one not quite right these weird issues pop up.

:thumb:

 

[duratothemax]

Ben's troubles are not being caused by the MAF sensor IMHO,

then how come with the LBZ-airbox calibration my truck does the massive defuels and with the LLY-airbox cal it does not defuel? The only thing thats changed between those two tunes is the MAF sensor scaling.



EGR codes will also cause a defuel. When P1401 and/or P1402 are set, you are limited to exactly 30psi on the MAP sensor (or about 15psi of boost)

 

[TrentNell]

then how come with the LBZ-airbox calibration my truck does the massive defuels and with the LLY-airbox cal it does not defuel? The only thing thats changed between those two tunes is the MAF sensor scaling.



EGR codes will also cause a defuel. When P1401 and/or P1402 are set, you are limited to exactly 30psi on the MAP sensor (or about 15psi of boost)

I rescale the MAF in my truck for the twins , but thats not really a fair comparison Ben , your truck /airflow is not stock so why compare a stock table ?

 

[GMC_2002_Dmax]

then how come with the LBZ-airbox calibration my truck does the massive defuels and with the LLY-airbox cal it does not defuel? The only thing thats changed between those two tunes is the MAF sensor scaling.



EGR codes will also cause a defuel. When P1401 and/or P1402 are set, you are limited to exactly 30psi on the MAP sensor (or about 15psi of boost)

Does your log show consistent MAF flow in lbs/minute during the defuel you see ??? Did you do a dead stop to WOT log with the truck with the square box MAF scaling and the round one and compare ???

If you see similar WOT lbs/minute with both and one defuels and one does not look elsewhere.

It is a process of elimination, you are stuck on one thing, take your blinders off and look around, the answer it there.

Get the logs done and get back to me.



Oh, one more thing, are you logging ECT, IAT and Fuel Temp.

 

[TrentNell]

05 LLy log snap shot , from a truck i tuned today , no hidden tables so far .................................................................

 

[05_LLY]

then how come with the LBZ-airbox calibration my truck does the massive defuels and with the LLY-airbox cal it does not defuel? The only thing thats changed between those two tunes is the MAF sensor scaling.



EGR codes will also cause a defuel. When P1401 and/or P1402 are set, you are limited to exactly 30psi on the MAP sensor (or about 15psi of boost)

Only tried it once but when i put the LBZ MAF in my truck it was a big laggy turd and would just smoke if you tried to get intot the throttle, but had no power, this was nothing changed other then the maf scale. obviously my truck wont defuel from the trans, but it just would not run with the lbz MAF, truck had a full 4" intake running a 4094r.

Just thought id share,
Caleb

 

[duratothemax]

trent you have email

 

[duratothemax]

more stuff I logged last night.

ben

 

[GMC_2002_Dmax]

Did you look at B0745 and B0746 ??

 

[TrentNell]

trent you have email

replied ,couple quick things to try , and will look a little closer when i have a sec .