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Making the LE5 a Flex Fuel engine...

18K views 88 replies 12 participants last post by  Robotech 
#1 ·
Okay, so as many of you know (and some may not) my LE5 2.4 is fairly modified and I am on the verge of adding even more power. It's turbocharged and will have forged rods, reduced compression forged pistons, head work...you name it. The one thing I would like to do is give it the ability to run on E85 for even more power but considering how few gas stations around here carry it I never wanted to HAVE to use E85.

Today, I ran across a post on Facebook (see, this is why I'm on both) and found that the e67 ECM that runs the LE5 engine can be used in a flex fuel application!!!!!

For those not understanding what this means, a true flex fuel vehicle can detect the alcohol content of the fuel going into the engine and adjust the fuel and timing tables accordingly. This means, if you only have access to 91 octane regular gas you will have the tune run in the proper settings for that but if you fill up with E85...even if you still have considerable 91 octane in the tank...the ECM will transition to the tune for E85 as the alcohol content of the fuel going to the engine increases to the proper levels (not sure if it gradually increases or if there is a certain threshold and then it just switches immediately...still researching).

The modification necessary? Install a GM flex fuel sensor between the fuel rail and the fuel line and wire this into an empty pin spot on the ECM FOR THIS SENSOR! Yea, that's it. About $30 in parts. Then, of course, the tune which I'm still figuring out all the changes necessary but really I'm totally stoked about this. On E85 I should be able to hit 500 whp with this new setup! Just need to make sure my injectors can deal with it, my pump can flow enough (or if I need to install a boost-a-pump...had one in the Grand Prix), and that my fuel rail fuel line is flex fuel compatible (current one is but I think it is interfering with the rail fully seating and the new one I was going to make is not alcohol compliant fuel line). Then the tune, of course.

They do this on Caddies and other LS based vehicles that use the e67 ECM so I don't know why it wouldn't work on our e67. Still researching so anyone who wants to follow this I will be updating it.
 
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#3 · (Edited)
That seems to be the question. The ECM has an OS and from what I can tell, some OS have the options and some may not. Same with HP Tuners. Seems the newer versions have the tables unlocked so I'm hoping that at least that much I have. I may have to upgrade to a newer version of HPT to make this work. Just have to make sure my OS is good. Considering I had the ECM reinitiated by the dealership in 2016 or so I should hope the OS is recent enough.

I'm going to go home tonight and dig into this further with HPT since I don't have it or a copy of my tune here.

Other platforms have done this successfully with this specific ECM so it makes me wonder why ours hasn't.
 
#4 ·
What version of HP Tuners do you currently have?

The V-8 platforms had a factory Flex Fuel options in the SUVs/Trucks, which I assume has the same OS as the cars. Was there an Ecotec Flex Fuel option using the e67? IIRC, the 2.0Ts used a different ECM which did have factory flex fuel available in other GM vehicles.
 
#5 ·
I have an older version of HPT but I can download the latest beta version of the software if necessary. :D

The e67 is used by many different platforms and many of these have been successfully converted to flex fuel. The sensor used in the trucks will be the same sensor used in this application. Believe it or not, there are a ton of different OSs for the e67. That's part of the problem, figuring out which is which and which ones may have the flex fuel capability.

The 2.0 LNF did not use the e67 ECM. The direct injection uses completely different logic.
 
#6 ·
Are any of those platforms Ecotec motors, though? The OS is very likely different between the V8, V6s and I4s. I know that's the case with the '0411 ECMs that came before. The hardware was the same between the 4.3L V-6 versions and the other V-8 versions, however the OS was not and they weren't compatible with each other.
 
#7 ·
So far not that I can tell but there is a shop here locally that has put the Ecotec platforms into desert racers and have successfully done flex fuel on them. The HHR also came in a flex fuel variant with the Ecotec engine but used the e37 ECM instead.

I have also figured out OSs that are compatible with my ECM but not what each of those OS are for and whether or not they are Ecotec friendly.
 
#8 ·
I understand what you're trying to accomplish Robo, but I'm not certain it's possible in a 4 cyl. I know I questioned Trifecta a lot about an e47 tune for my GXP and it basically came down to the simple answer...there was no way to switch between e47 and a 93 octane tune for my car. I would have to drain the tank every time I wanted to switch and the tables were so precise for the e47 that if the mix was off by a 1/2 gallon either way the car wouldn't run good.... I was told later by a tuner at work that it's all or nothing with e85 on a 4cyl. He was a drag racer and used to tune the 2.0L Dodge turbo motors to run on e85 for drag racing. He told me to with a 4cyl, that tuning for both was impossible.... I will watch this this thread in case you find something because I would love an e47 tune in my car and over 400hp!! (can't use true e85 in mine...without different injectors or hpfp).
 
#9 · (Edited)
Ghost, the LNF (engine in the GXP) is a completely different beast than the LE5 (which is what I have). The ECMs are totally different due to direct injection (LNF) versus port injection (LE5). I can up injectors, increase the voltage going to the in tank pump, and run true E85. I can do that with what I have now...I just want to be able to switch fuels without hassle.

The E67 (model number of the ECM in the LE5) is used on other cars and has settings for flex fuel use. I can go into HP Tuners and actually switch on the Flex Fuel feature. The issue is with the Operating System (OS) that is on our ECM, that's the ONLY table I have access to. If you pull up the E67 for a 2007 Cadillac CTS-V, there you will find it has all the Flex Fuel tables you need to make this work. Problem is the OS on the Caddie is not compatible with the OS on the Kappa so you can't just write the Caddie tune onto a Kappa ECM and have it work.

I have been told that when you turn on flex fuel, you have two tables, the "regular" gas table, and what equates to a E100 table. There is a virtual way for the ECM to determine what fuel is going to the engine but I would rather use the GM sensor that monitors the fuel going to the engine and then reports this to the ECM to allow the ECM to "blend" the two tables together for whatever the alcohol content is going to the engine. That sensor just has to be pinned into the ECM (and I know what pin it goes to...woot!). It actually is pretty simple to add the sensor.

The hard part is changing the OS. Lucky for me I have someone that knows how to do that sort of thing. LOL I just don't know if his skill set includes this ECM. If anyone can do it though, it's him.

I also found a thread talking about EFILive and that they had created a tune like this for the 2007-8 HHR (uses same engine and ECM). They did it on that car because the 2009 HHR WAS flex fuel enabled but on the E37 ECM and the LE9 engine (not really that much different from the LE5...basically the same motor with some alcohol friendly parts). I have reached out to them as well to see if they did do that and what I would need to do to get an ECM set up that way where I could still tweak it. They guy I met on FB (putting the Kappa drivetrain into a Miata...LOL) is looking to do the same and has reached out to HP Tuners to see what they say. We're also checking their repository to see if we can find the elusive needle in a haystack where someone may have accomplished this and shared their tune there.

For those that may be reading this and don't know what the heck I'm talking about (because I know Ghost knows this stuff) when we talk about a tune on our cars, we are changing the data that goes into the OS, not the OS itself. What we're talking about here is a whole new level of modifying the engine management system.
 
#12 ·
Interested to see what you come up with. I have a Chevy Cruze and the same thing is done to them. The ECM already has the setup for flex fuel just needs to be turned on and a sensor installed. With the factory turbo you can take advantage of the higher octane.
 
#13 ·
Our ECM is KIND of the same way. You can add the sensor (even know which pin to do it at) and then there is a setting in the ECM that will activate the Flex Fuel option.


Problem is our ECM OS doesn't have all the other tables you need to adjust after turning that switch on...rather HP Tuners doesn't currently access those tables if they are there. Other cars that use our ECM DO have these additional tables and for them it's kind of like how it is for your Cruze. Chances are in your Cruze, you may not need the sensor. One of the tables I can't see in our ECM is what kind of Flex Fuel detection you wish to use, Virtual or Sensor. Virtual does it based off the data it's already collecting and would require no additional sensor. My understanding is this is the kind of Flex Fuel function they put into the GM cars around 2008.
 
#14 ·
My understanding is the sensor is a much better option. Wonder if the tables for our Sky is there just not editable at this time. Will be interesting to see what you come up with. If you need to do any comparison let me know I have turbo on mine also. Should be out of deep freeze storage in the next three weeks or so. I have access to E85 as soon as my warranty on my 2015 Cruze runs out going to go to E85.
 
#15 ·
Keep in mind the ECM in the LNF (2.0 Turbo car) is not the same as the one in the LE5 (2.4 NA car). I'm working on the one in my LE5 car. (The ECM is a E67 ECM...can't remember what the LNF uses.) So IF I solve this for the my car, it won't help you Redline folks. Besides, the bigger issue for the LNF is the HPFP and injector volume when it comes to spraying E85. For the 2.4, we can just up the size of the in tank pump and the port injectors.
 
#18 ·
Not yet. First fire up of the engine should be this weekend. Sucks not having more time to work on it. Once we get it running, then we need to tune it on 91. Once that's done I can start messing with the E85.

I have got the sensor wired up mostly...have it tied into power, ground and the pin on the ECM...just need to wire in the pigtail once we figure out the exact position of the fuel rail so we can cut wires to the proper length and route them the right way. So getting closer.
 
#19 ·
Have you got an update on this setup? I am looking at doing a flex fuel setup for a 2.4L Cobalt race car project, and I'm curious what has to be done otherwise with the software. Wiring a sensor up seems like the easy part... but I haven't dove into the software yet.
I have C1Pin5, a continental sensor 13577429 sensor and 13352241 pigtail to plumb inline.
 
#20 ·


So a bit of an update to this. The sensor is in and wired. I just did the initial startup and the engine runs well but there are a couple other issues we need to sort out before driving it. Once we get there though, we are tuning it to 91 first then getting to the flex fuel tuning. So MilestoneMotors, no info yet on the tune, but will post it when we get there.
 

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#23 ·
We are still working on the 91 tune. Fueling has been a bit of a headache. We are getting that sorted first and once we have a good 91 tune I'll be working with the flex fuel tuner to dial that in. I drove the car to work today...first long drive with it since I got it home from the shop. That's some good progress.
 
#27 ·
I do but the laptop it's on has an issue with the power connector so I can't start the thing. LOL Too lazy to tear it open and get the data off the HD. You can download a stock LNF or LE5 tune off the HP Tuners repository last I checked and then just copy the differences over to an existing tune and save it.
 
#31 ·
There aren't any. 2008 and later there is a different ECM in the 2.4s but 2006 Solstice 2.4 tune is the exact same as a 2007 Sky.

Remember 2007 Skys where built alongside 2006 Solstices from December 2005 until July 2006. In July 2006, the 2007 Sky production continued while the Solstices went from 2006 to 2007 production.
 
#35 ·
Thanks to Josh@ Hp Tuners these are added to the beta:


20220 - Flex Fuel Sensor
330 - Flex Fuel Sensor Diag
3144 - Flex Fuel Fail%
4140 - Flex Fuel Diag Delay
2424 - Power Enrichment Mode Threshold
2401 - Power Enrichment Ramp Out Rate
2464 - Power Enrichment Mode Timer

I have tried this using the beta like they said but it is not showing any fuel composition frequency in the logger. Not sure if I am missing something.
 
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