Newbie help.

[Rocketdog]

Good morning,
I'm brand new to tuning and have been using a combination of YouTube videos from Chopper Doc and Goat Rope Garage to muddle my way through. I'm currently VE tuning my LS-swapped Jeep. The engine was originally a 5.3 from an Isuzu Ascender but I have recently swapped it to an LS1 block and heads. Everything related to the ignition and fuel system came from the 5.3. ECU, Injectors, sensors, intake etc. The engine has a BTR stage II truck cam. The original tune on the Jeep was done by a local guy. After learning from this forum, Chopper Doc and GRG I realized some of the things he did were somewhat questionable. I have attached the as found tune which is what I started with. I also attached my last tune and scanner log. The last tune is the current tune. I have not run it with the scanner yet.

My questions are;

Have I completely disabled my LTFTs? Looking at the scanner the STFTs are reading nothing. The LTFTs are still populating data.

Why are my o2 sensors reading so different? Possible exhaust leak?

Am I on the right track? I have been working my way slowly up the table doing small sections of the VE table at a time. My main goal with tuning this is for drivability and not necessarily max power. Thank you for your help.

[SiriusC1024]

In order to go SD, set Engine Diag>Airflow>MAF Frequency Fail High to 0Hz and ...DTC>P0103 to MIL on First Error to correctly fail the MAF.

During SD or MAF tuning, should have Engine>Fuel>Cutoff,DFCO>DFCO>Enable ECT set to 248. Fuel>Power Enrich>Min MAP to 85kPa.

Investigate Engine>Airflow>General>EGR Airflow.

Clear LTFT's through VCM Scanner>Vehicle Controls & Special Functions.

[horsepowerguru427]

Your STFT isnt reading because you have them disabled STFT disabled.jpg change that back to enabled and they will populate again. I assume since youre trying to disable fuel trims that you are trying to tune with strictly a wideband? Youll find you will get better driveability if you use the fuel trims until around 4000-4500RPM and when you start getting into WOT & PE youll need a wideband for that. Sirius suggested the PE change so you can get more accurate data with the fuel trims, since that would make PE not kick in til later (85kPa).


Heres something you can start with if you want. I took your base and made some changes, set it up for SD tuning for you. I know Sirius tunes CL and if youre going to use CL when youre done with everything, then Id suggest the same. Collect trims in the histogram using LTFT+STFT. I Usually tune OL with LT+ST depending on what the setup is on the vehicle.

Looks like youre using vac-ref regulator (factory return system)? Youre also using a DBW throttle body? DBW is enabled in system options, if youre using a DBC that needs to be disabled. I already removed Brake TQ in the same system options. Dont worry too much about timing until you get your air model lined out. Correct idle conditions after air model is correct and then move on to timing. You can use your provided "base tune" to view changes i made to that file through the compare feature. I DID set it up cor OL LT+ST tuning.

Let us know if you need anymore help.

[Rocketdog]

Your STFT isnt reading because you have them disabled STFT disabled.jpg change that back to enabled and they will populate again. I assume since youre trying to disable fuel trims that you are trying to tune with strictly a wideband? Youll find you will get better driveability if you use the fuel trims until around 4000-4500RPM and when you start getting into WOT & PE youll need a wideband for that. Sirius suggested the PE change so you can get more accurate data with the fuel trims, since that would make PE not kick in til later (85kPa).


Heres something you can start with if you want. I took your base and made some changes, set it up for SD tuning for you. I know Sirius tunes CL and if youre going to use CL when youre done with everything, then Id suggest the same. Collect trims in the histogram using LTFT+STFT. I Usually tune OL with LT+ST depending on what the setup is on the vehicle.

Looks like youre using vac-ref regulator (factory return system)? Youre also using a DBW throttle body? DBW is enabled in system options, if youre using a DBC that needs to be disabled. I already removed Brake TQ in the same system options. Dont worry too much about timing until you get your air model lined out. Correct idle conditions after air model is correct and then move on to timing. You can use your provided "base tune" to view changes i made to that file through the compare feature. I DID set it up cor OL LT+ST tuning.

Let us know if you need anymore help.

Thanks for the response.

To answer your questions Horspowerguru.

Yes to the DBW
Yes to the wideband
Yes to the vac-ref fuel pressure regulator.
I do plan to run it closed loop when I'm done.

I knew I had the STFT disabled and it was intentional. My concern was that LTFT was still populating data and the STFT was not. I was worried I had done something wrong and the LTFT was influencing my data collection.

My other concern is the delta between Bank 1 and Bank 2 O2 sensors. I noticed it when scrolling through the data. Is this an issue? If it is a issue, do I need to stop and diagnose/repair before I continue with tuning the VE table?

I have attached my latest scan from this morning's drive to work. I apologize for my ignorance. Thanks for the input.

[Rocketdog]

In order to go SD, set Engine Diag>Airflow>MAF Frequency Fail High to 0Hz and ...DTC>P0103 to MIL on First Error to correctly fail the MAF.

During SD or MAF tuning, should have Engine>Fuel>Cutoff,DFCO>DFCO>Enable ECT set to 248. Fuel>Power Enrich>Min MAP to 85kPa.

Investigate Engine>Airflow>General>EGR Airflow.

Clear LTFT's through VCM Scanner>Vehicle Controls & Special Functions.

I understood everything you said except for the comment about the EGR airflow. Could you explain? Thanks

[Rocketdog]

Here is my latest scan from this morning.

[SiriusC1024]

I understood everything you said except for the comment about the EGR airflow. Could you explain? Thanks

Have to be careful about commenting on emissions equipment. All I can say is your EGR DTC's and EGR spark tell me one thing, but the EGR airflow tells me another.

[Alvin]

That STFT tab disables open loop STFT.. Kinda of confusing but a lot of truck OS's will start trimming the fueling within seconds of startup. Cars are typically not setup like this.

For heavily modified trucks (decent size cam) the open loop STFT should be disabled and the OL fueling should be setup more like how the F-Body/ Vettes came factory.

[horsepowerguru427]

That STFT tab disables open loop STFT.. Kinda of confusing but a lot of truck OS's will start trimming the fueling within seconds of startup. Cars are typically not setup like this.

For heavily modified trucks (decent size cam) the open loop STFT should be disabled and the OL fueling should be setup more like how the F-Body/ Vettes came factory.

Interesting. Comparing my stock Z28 file to my stock Yukon file i see what youre saying. Thank you for the input, Alvin. Its much appreciated!

[Rocketdog]

Have to be careful about commenting on emissions equipment. All I can say is your EGR DTC's and EGR spark tell me one thing, but the EGR airflow tells me another.

I figured it out. Thank you

[Rocketdog]

Here is my latest VE tune and scan. Do I need to continue massaging the areas on the edge of the table or is this sufficient? The scan is normal driving.

[SiriusC1024]

You're doing pretty well. Still have to factor in transients when you're shaping the table. Follow trends across the splines of the VE surface to estimate. Like those edges you're talking about might only happen for a moment, too brief for the wideband to get a complete picture. Look at the cell counts. Forecast the lower end of the table downward just like it shapes across the higher rpm/low MAP areas. Confirm through your logs.

Throw it into CL and see what the fuel trims are like.

Speaking of counts look at the 400rpm/100kPa cell. Notice that the table is still populating data after key off. Try to stop the log before shutting it down next time.