Pontiac G6 2.4L Ecotec LE5 convert to LE9 flex fuel

[Dominatorstang]

I worked out a nice buy on a 2008 G6 2.4L for my daughter turning 16 in a month. I notice it recommends 91 octane, so my brain goes to thinking, I wonder if it would be worth making it flex fuel.

After much research I find the only G6 model offered with a flex fuel 2.4L (LE9) is in 2010 and not all those 2.4L's were. Researching what is different between the LE5 and LE9 in forums and looking at parts on Rockauto, It honestly looks like just the injectors...

Now to get the tune file, the HHR and Malibu also offered the LE9, so I start searching like crazy for any of these LE9 stock tune files in the repository and forums, but no luck. Next thought was salvage yard, but I don't want to buy the whole ECM. Then I just decided to look around me for one for sale and sure enough the best choice I could have asked for, being a 2010 G6. I took it for a test drive and read out the ECM and TCM.

Posting my stock 2008 G6 LE5 file and the 2010 G6 LE9 for anyone else that needs them.
LE5 injector AC delco number 2173158 and LE9 number 12613163.

Anyone else who has more information or tips on this please chime in here. Also I can certainly see where a 6 spd trans would help this engine out, but this is just the 4spd. So I will probably tune the shift points and TCC some to help it out. Any tips on that are appreciated too.

[Dominatorstang]

Searching for injectors I am actually finding the the larger LE9 flex fuel injectors were put into LE5 engines on the same vehicles and years that offered the flex fuel. So now makes me wonder if those LE5's that have the injectors in them, just do not have flex fuel turned on in the ECM? I mean because of emissions or something in certain areas, but all parts are exactly the same?

[tunerpro]

This is certainly the case on the newer direct injected engine. E.g. the LFX V6 engine was offered in several models in both "flex fuel" and non "flex fuel" trim. The way you know is whether it has a yellow gas cap or not (or to look at the RPO code list). The engine itself and all its components are the same, the only difference is the non "flex fuel" models didn't have an alcohol composition sensor, and also used a different factory calibration.

And, yes, you're also correct that emissions tiers and certification are different for "flex fuel" versus non. Automakers, especially during the late 2000s and early 2010s were given various incentives to produce a certain number (percentage?) of "flex fuel" vehicles. They would want to take advantage of those incentives while incurring the least amount of additional cost as possible, which means using a common set of parts and components wherever possible.

[Dominatorstang]

Thanks for the info and confirmation tunerpro. My wife's SRX has the LFX flex fuel with the sensor you mentioned, I had just not given much thought to the non flex fuel LFX's previously. Now that you say it, that makes even more since because my 17 sierra 6.2L only needed the sensor added (already had the plug for it) and enabled in tune. I wish the stock LFX gained more from the E85 like my 6.2L does, but my experience says the ones with recommended 91 octane stock will see bigger gains in low end torque with E85 and then around here E85 is just over half the cost of premium.

I have a set of the flex fuel injectors coming for the 2.4L out of a 98k mile 2011 malibu. Will be a bit before I get to test the E85 on the G6 though since the 4T45E needs a shift solenoid (split trans case for it) and I am doing a timing chain kit on the engine since it has 160K. Also doing a cat since acts a little plugged and manifold is black and cracking from previous heat.

[Vasquezz1228]

That flex fuel file will help a lot. I have a ecotec swapped Miata that I added LE9 injectors too but could not find the data for them. thanks!

[Dominatorstang]

@Vasquezz1228, I am glad this file is helping you too. Let us know how it goes.

I am adding a stock 09 G6 and stock 10 malibu(not FF) file that I had gotten from the repository. The G6 used a different fuel pump assembly part number in 09+ and had some global tune changes even though it did not yet get the larger injectors in 09. comparing the G6 09 file to the 10 flex fuel file will probably narrow down further what was changed when enabling flex fuel on these vehicles.

[Dominatorstang]

Here is a tip I learned on purchasing used injectors. Try to find a set that has not been sitting on the shelf too long... The set I got in from ebay had been sitting for at least 2 years and had issues. one injector would not fire and another injector was constantly dripping out into the engine. Maybe could have gotten them to clean up, but I returned and have another set that is a newer listing. Best way I can find to see how old a listing on ebay is, look at the main description area and click on "revision history", found to the far left of "ebay item number". Some listings drop the price a little each month, so you can see the dates and tell when it was first listed.

Otherwise spend the extra coin to purchase new or refurbished.

[gtstorey]

Better yet, don't buy injectors from ebay or amazon period unless you are familiar with the seller.

[Dominatorstang]

after pulling the differences in from the 2010 flex fuel G6, to my 08 G6 file, I added E85 today. That probably made it around 25-30%E in the tank. The ECM was already calculated at 9%E before fueling, but after some driving the power felt to come and go and I was seeing some off STFT blips, just random odd behavior. After driving a bit the ECM then showed 6%E, so yeah that is not going to work out this way.

Came back home and did a write entire for ECM and TCM using the 2010 flex fuel G6 file that had a newer OS on both those. I did verify they were both E37 ECM's, but still understood it was a risk of bricking it or at least having issues...

All looked well with KOEO so started it and it idled just fine. Did a crank relearn and then went to add more E85. ECM calculated at 0.0% since it was a fresh write, so after adding more E85 to try and trigger it to recalculate, drove a few miles and then seen it hit 9%E, then 26%, then 39% and pretty well stayed there. Drove good and the E% looked about right.

came back to the house and read the ECM and TCM back out to have a good copy with new OS for editing.

[Area57]

Thinking about doing this to my 2010 Equinox with a 2.4. What fuel sensor did you use?

[Dominatorstang]

It is virtual so needed nothing more than injector change, write entire and go. My 16 year old daughter has been driving it on the daily for over 3 months with E85 and it is doing great.

[Area57]

Interesting. For the Equinox, flex fuel was only available for the 2.4L after 2012, but it also has a sensor.

https://www.rockauto.com/en/catalog/...l+sensor,10766

I downloaded a 2012 Equinox 2.4 flex fuel file from the repository and under fuel /flex fuel/ it is "enabled" and fuel sensor is set to "sensor" below it. I noticed on your 10 G6 LE9 2.4L 4A stock (flex fuel) file that it only has the option to enable flex fuel but not a setting to change between sensor or virtual below it. I'll have to look and see if the connector for a fuel sensor even exists on the 2010 or not. If not, I guess virtual it is. Do you know where your readings are coming from with the virtual setting? One would think the computer would still need to make adjustments when going between different fuels/mixtures.

BTW, thank you for making this topic. I found some older discussions on various forums, but most of the time the discussion ends and I'm still guessing.

[Dominatorstang]

With virtual my understanding is the ecm uses a programmed strategy to determine the ethanol percent. I am content with virtual depending on the use case. All stock or not switching back and forth with gas and ethanol often works well. Even some 3/4 ton use virtual, but on stock tune then i do not see the gain over 87 octane on a 6.0.

For my L86 pickup with a cam and long tubes that I tow with often wand pulling up to 12k I prefer the sendor. But the truck was pre-wired and I found a quick connect hose that made it easy. Like $60 for sensor and hose then an hour or two since I had to extend the sensor connector cable.

[Area57]

So I looked under the Equinox and there doesn't seem to be a connector anywhere for a fuel sensor. How far did you have to extend your sensor connector cable on your L86, and was there a connection somewhere closer to the ECM that you found? I'm wondering about that for my 2010 as it has the same ECM as the 2012. First 4 numbers in the software are identical as well.

I have compared files and there are definitely some changes. Under MAP sensor config NA-MAP on my 2010 vs NA-MAP-TIAP on the 2012. Flow rates on the injectors are a bit less on the 2012. I guess experimentation with comparing is all I can do now. At least I'm heading in the right direction. If it ends up being the virtual sensor then so be it.

Thanks for sharing your info, Dominator.

[blindsquirrel]

Virtual flex is not a good system. Anything that causes the long term trims to be off will eventually bleed over into the learned alcohol % - it functions like a third stage of fuel trims, short term, long term, and super long term (alc%). They're also goofy about under what conditions they do that LT -> alc% shift, differences in nothing more than trip length and how frequently the tank is filled can make it absolutely freak out. This all happens on bone stock trucks that came with virtual flex enabled from stock. If you get virtual flex to work dependably, all it means is that you got lucky.

[Area57]

I thought that most of the virtual flex related problems had to do with not following the proper fueling procedure for E85 vehicles equipped without a fuel sensor. It was my understanding that when the system detects 3 or more gallons of fuel added, it will automatically recalculate the ethanol content. The procedure also indicated refueling AFTER the engine is warm and driving for about 10 mi without shutting off the engine. This was especially important when switching between E85 and gas. Good luck getting my wife to follow those fueling procedures. I had a 2010 Chevy work truck that was inaccurately displaying alcohol % and having hard starts. ECM update from the dealer and a reset fixed the problem at the time. Obviously a fuel sensor is the best way to go when possible.