LSA Tuning - Running Open Loop Lean at Cold Starts

[1bad68ls]

I am tuning my VVE tables on my LSA engine using a Wideband O2 sensor. The engine is running open loop fueling only.

When the engine is cold and I am at idle , I notice my EQ_Ratio_Error is significantly leaner than when the engine warms up (at idle).

I do not see a fueling correction factor for delivered fuel, which is a function of IVT or ECT (looking in the [Fuel],[General] tab).
Is there a calibration table available to correct the delivered fueling at colder temps?

Thanks,
Jeff

[Alvin]

One big thing to keep in mind is only the vaporized fuel is able to burn. So while the engine is cold and unable to vaporize the fuel for combustion on the intake walls, intake valve, etc its programmed to run richer than normal to saturate the charge.

So the ECU will be set to run mixtures as rich as like 6-9:1 initially on a very cold engine. 9:1 is black smoke rich. You won't see a cold factory car black smoke rich run at idle. They also will not report rich on a wideband. This is because while 9:1 was injected.. something closer to 14.7:1 actually burned. The rest comes out of the tail pipe as raw unburned hydrocarbons.

Long story short.. The commanded open loop AFR will look richer than what is intended to come out of the tail pipe. This will skew your calculators. The wideband will not work at 100% cold too. just keep this in mind.

Is it stumbling or anything while cold? [ECM] 12441 Open Loop IVT Gain vs IVT vs MAP is normally where I fix lean or rich cold engines.

[1bad68ls]

Is it stumbling or anything while cold? [ECM] 12441 Open Loop IVT Gain vs IVT vs MAP is normally where I fix lean or rich cold engines.

Thanks Alvin, I completely agree with all your feedback! I am aware of the [ECM] 12441 table, however this controls the "Commanded" fuel. I expect the production SW would have to have some temp correction factor to the "delivered" fuel (or burned fuel in the case of a cold start) because these vehicle need to meet emissions at cold temps and the fueling calculation needs to be dead on at all cold start conditions.

When I do my cold starts, I plug in the WB and get it to temp before starting the vehicle. In my experience with production vehicle calibrations, the WBs are pretty accurate for measuring burned fuel on cold starts too.

I do not have any stumbling issues, therefore it is not a big issue... it is more of a PITA because I have to wait for the engine temps to stabilize before I can continue my VVE cals.... which could easily be fixed if the temp table was avail to calibrate in HPTuners. Perhaps it is in the GM SW but it is not visible in HP Tuners?

Thanks for you help!
Jeff

[blindsquirrel]

Cold engines run dirty. They do all they can to get them up to temp and in closed loop ASAP, and get the converters lit up, etc., but there's no special software tricks that can change the way fuel behaves in a cold engine.

[Alvin]

I do not have any stumbling issues, therefore it is not a big issue... it is more of a PITA because I have to wait for the engine temps to stabilize before I can continue my VVE cals.... which could easily be fixed if the temp table was avail to calibrate in HPTuners. Perhaps it is in the GM SW but it is not visible in HP Tuners?

Thanks for you help!
Jeff

It sounds like your not actually lean then and you will be chasing a number without good feedback. This would be a garbage in vs garbage out type of situation.

[GHuggins]

You want trims to stay near 0 as soon as going into closed loop even cold. You accomplish this with the open loop in neutral and in gear tables. Just increase or decrease in the affected areas and keep them smooth. If cammed you'll want to look at injection timing as well. Even if pullied up...

[1bad68ls]

You want trims to stay near 0 as soon as going into closed loop even cold. You accomplish this with the open loop in neutral and in gear tables. Just increase or decrease in the affected areas and keep them smooth. If cammed you'll want to look at injection timing as well. Even if pullied up...

Thanks GHuggins!
I 100% agree I want the trims to be at 0. This is exactly my goal.
I was playing with the OL tables with my cold starts. My concern with changing these tables is they are the [commanded] fuel tables... so if I lean out the OL table, it will also lean out the [delivered] fuel from the injector... and the EQ Ratio Error will still be there.
I am pullied up with a BTR stage 3 cam for the LSA and I will look at the injection timing too.

I appreciate your help!
Jeff

[1bad68ls]

Greg/all,

I used the GenIV EOIT Excel sheet to review my camshaft and potentially update the Boundary and Normal ECT/RPM injection timing tables. I am looking for feedback on how best to calibrate this... In the attached file, I have 2 tabs (one at 750 rpm and the other at 2500 rpm. I entered my cam spec and looked up the actual pulse width (adding the short pulse an voltage offsets to the observed) in my last log file.

The green cells have the actual specs/cam data that I entered, and the yellow are the current "production" calibration for the Boundary and Normal ECT/RPM tables.

Question: What is the logic on how to calibrate the yellow cells (Boundary and Normal ECT/RPM tables)?

2500 RPM.jpgIdle.jpg
Thanks!
Jeff

[GHuggins]

You'll probably want to focus more on flattening your ect table then play with your open loop tables

[GHuggins]

The black charts file if you can find it works better too