Tuning Help Please, 2.0 LSJ

[jahorgos]

Attached is my current tune with the log file. The log file is from a drive to work. I'm new to tuning so I just want some opinions on what some experienced people see that I don't?

I have a:

2006 Cobalt SS Supercharged, bored .020 over and put special ordered diamond pistons in. I have an engine torque brace, poly trans mounts and an exedy hyper single clutch which I believe is giving me false knock due to the very intense vibrations from acceleration, but please let me know if you do not believe thats the case.

Mostly my changes are to mass airflow frequency to adjust for the increased air due to the large cylinders and I pulled some timing in my high octane spark map to rid some knock which worked well. All of this was done in open loop mode with LTFTs disabled in case you are questioning. The posted files are all back to normal closed loop mode and I don't know what I should be looking for at this point to see if the computer is correcting more then whats normal, I assume the big hints would be in my LTFT values?

Thanks for your help as I don't want to blow it up like my Intense Racing tune did

[SJSchafer]

Attached is my current tune with the log file. The log file is from a drive to work. I'm new to tuning so I just want some opinions on what some experienced people see that I don't?

I have a:

2006 Cobalt SS Supercharged, bored .020 over and put special ordered diamond pistons in. I have an engine torque brace, poly trans mounts and an exedy hyper single clutch which I believe is giving me false knock due to the very intense vibrations from acceleration, but please let me know if you do not believe thats the case.

Mostly my changes are to mass airflow frequency to adjust for the increased air due to the large cylinders and I pulled some timing in my high octane spark map to rid some knock which worked well. All of this was done in open loop mode with LTFTs disabled in case you are questioning. The posted files are all back to normal closed loop mode and I don't know what I should be looking for at this point to see if the computer is correcting more then whats normal, I assume the big hints would be in my LTFT values?

Thanks for your help as I don't want to blow it up like my Intense Racing tune did

Interesting tune. Wondering where you got the numbers for the offset table. They look better than most I've seen. Ah, stage 2. I see it now. Your IFR table needs some work though and your MAF is a bit crazy. VE is stage 2 as well.

MAF will not change because your pistons did, so you are trying to compensate for someting else with MAF. First of all you need to change the cylinder volume to reflect your bigger bore. Second (and I am no expert, but...) I believe it will effect your volumetric efficiency. Not sure about that. I would start with getting your fueling tables a bit more in line, adjust your cylinder volume, go to a stock stage 2 MAF and start building your adder table. Then dial in your MAF and VE using AFR error %.

Just my $0.02.

[Sunburst_SS]

I actually mentioned changing the cylinder volume in his first thread.....he said he would just adjust the fuel tables to make up for it....I think it would be a good place to start by changing that....it's a quick change, not hard to make

[SJSchafer]

I actually mentioned changing the cylinder volume in his first thread.....he said he would just adjust the fuel tables to make up for it....I think it would be a good place to start by changing that....it's a quick change, not hard to make

Yea, I agree. Changing one table to "make up for" incorrect data in another is never a good idea. The fuel tables are not really changed except for the IFR table which is not done correctly. It looks like the bulk of the changes were made to the MAF, which is not a fuel table, but an air table. I see a lot of tunes done like that and most of the people driving the cars with those tunes complain of poor or rich idle, lean spikes, rich decel, etc...

You are also correct that changing the volume is not hard, just need to do some basic math.

[jahorgos]

Interesting tune. Wondering where you got the numbers for the offset table. They look better than most I've seen. Ah, stage 2. I see it now. Your IFR table needs some work though and your MAF is a bit crazy. VE is stage 2 as well.

MAF will not change because your pistons did, so you are trying to compensate for someting else with MAF. First of all you need to change the cylinder volume to reflect your bigger bore. Second (and I am no expert, but...) I believe it will effect your volumetric efficiency. Not sure about that. I would start with getting your fueling tables a bit more in line, adjust your cylinder volume, go to a stock stage 2 MAF and start building your adder table. Then dial in your MAF and VE using AFR error %.

Just my $0.02.

Alright I will try and change my cylinder volume to match properly. But even then I still need to tune my MAF as I did using AFR error %, correct? As for the VE table I have not touched it and would like a bit more info on how to tune this using afr error %? What do you mean by adder table? Is the VE a preset histogram or do I need to set it up?

[SJSchafer]

VE is a bit harder to tune than MAF, but the principal is the same. You should be able to find the histo in your histos folder. Yes, you still have to tune MAF, but there is a difference between tuning your MAF with correct volume and fueling tables and tuning your MAF to make up for other tables that are not correct.

The adder table is there because injectors have a minimum linear PW. I believe the siemens 60s are at 1.1. We still need the injectors to work under 1.1ms, so we need to use the adder table to help the injectors get linear below 1.1 ms. To do that is a long process that requires almost as much majic as logic, but it can be done. You also need to get your IFR table better in line. One way to do that is to figure out what the true numbers should be, divide them by 1.25 and put the resultant numbers in your IFR table. Then use your modifier vs volts to multiply the entire table by 1.25. This makes up for the ceiling in the ECM of 63.49 (in theory).

[jahorgos]

VE is a bit harder to tune than MAF, but the principal is the same. You should be able to find the histo in your histos folder.

Is the file "VE - AFR Error" ? Which gives me a graph of Mainfold Absolute Pressure (kPa) vs. Engine Speed (rpm) ? I assume I have to tune my maf first then correct this VE table?

Thanks

[SJSchafer]

Yes, that is the histo. The order that you do it is not that important. I prefer to do MAF first, but it's a personal preference.

[Turbocharged LSJ]

Chris,

What kind of failure did you have on the old setup? Were you using nitrous on your mail order tune or did you have it tuned for it?

[jahorgos]

Yes, that is the histo. The order that you do it is not that important. I prefer to do MAF first, but it's a personal preference.

Alright, thanks. I will look at doing that this weekend. Does the VCM use this table during normal open loop operation? I was under the impression that the MAF would control all my afr problems. I can tell so far that if I do get on it some that at some points its going too far rich or lean thus killing my power band. This is after I readjusted my cylinder volume and did some more maf tuning.

As well I have been doing all my tuning in closed loop mode at wide open throttle using the afr error%. Do you think this VE table could once tuned could help with this?

[Sunburst_SS]

well, at WOT the vehicle will not stay in closed loop. Do you have a wideband hooked up on the car?

[jahorgos]

well, at WOT the vehicle will not stay in closed loop. Do you have a wideband hooked up on the car?

Yes I do and my current WOT is only to 4500 rpms because I'm in the break in period for about another 4 days. I thought if I disabled everything to keep me from going in to open loop it would stay there, at the 4500 rev limit its just at/before PE enable. I don't understand how else you would tune the maf with out being at WOT?

[SJSchafer]

You do not want to tune in closed loop because when you go WOT whatever trims you had will stick with you. Always tune in OL if you have a wideband.

The VE is used for transitional fueling as well as a baseline for your ECM to check and make sure everything is as it should be. Some say that tuning VE doesn't help, but it does. It helps for smoother transitions.

[jahorgos]

You do not want to tune in closed loop because when you go WOT whatever trims you had will stick with you. Always tune in OL if you have a wideband.

The VE is used for transitional fueling as well as a baseline for your ECM to check and make sure everything is as it should be. Some say that tuning VE doesn't help, but it does. It helps for smoother transitions.

Alright yeah thats what I meant to say is that I always tune in open loop.

I disable my LTFTs and closed loop mode when I am tuning to keep the ECM from correcting my mistakes so that I could see what I was doing wrong.