Official Interest In COBB Flex-Fuel for the Legacy GT Platform - Please speak up

[utc_pyro]

Can bus for everything isn't that much diffrent ether. The earlier ECU's used can bus to talk to everything else. The newer ones just had to comply with a law change that required using CAN for diagnostic tools. From the limited testing that's been done, the highspeed canbus messages appear to be more or less the same on ether side of the split.

 

The CPU inside the ECU is the same between the '05-'06 cars and the '07-'09 cars. The code running on the CPU is quite diffrent. The newer cars uses a much improved code architecture that's similar to the cars they first developed the flex fuel stuff for. As the architecture is closer it's easier to port the flex fuel patch over to it. For the older ECU's it'll take a lot more work.

 

It'd probably be easier/cheaper to convert your car to an ECU that supports it. There is a little surface mount 8pin EEPROM chip you can transfer over to fix the immobilizer stuff. You'd also need to check that the CANBUS messages are the same (they should be, ish). '05-'06 STI ECU and '06 WRX ECU's look to be a good candidates.

Edited October 15, 2017 by utc_pyro

[Sparkey]

Can bus for everything isn't that much diffrent ether. The earlier ECU's used can bus to talk to everything else. The newer ones just had to comply with a law change that required using CAN for diagnostic tools. From the limited testing that's been done, the highspeed canbus messages appear to be more or less the same on ether side of the split.

 

The CPU inside the ECU is the same between the '05-'06 cars and the '07-'09 cars. The code running on the CPU is quite diffrent. The newer cars uses a much improved code architecture that's similar to the cars they first developed the flex fuel stuff for. As the architecture is closer it's easier to port the flex fuel patch over to it. For the older ECU's it'll take a lot more work.

 

It'd probably be easier/cheaper to convert your car to an ECU that supports it. There is a little surface mount 8pin EEPROM chip you can transfer over to fix the immobilizer stuff. You'd also need to check that the CANBUS messages are the same (they should be, ish). '05-'06 STI ECU and '06 WRX ECU's look to be a good candidates.

 

If that was doable, wouldnt it be possible to just get a WRX ECU and then WRX flex fuel kit and be good?

 

Ive read some people attempt a swap but havent come across a completed swap and the conversation goes over my head with a lot of this.

[utc_pyro]

It's on of those things that in THEORY should work, but very few people try it out.

 

The immobilizer stuff makes it a bit of a pain, but it was discovered a while back that's stored on a separate chip. That can be transferred between ECU's, but I havent seen a lot of information about what ECU's you can move what ones between.

 

You also need to make sure the CAN bus operates more or less the same between cars. If the ECU is expecting to hear messages from a device or field on a device that isn't there, it gets pissy. Missing modules are spoofable without much effort (an Arduino and can bus interface). Modules that talk differently are are going to be a much bigger pain unless you intercept the entire CAN bus and reformat things how the ECU wants to see it. If you're going that far, Merpmod is probably more up your alley.

[m sprank]

In other words... not feasibly doable without hardware modifications that 99.9999999999999999999999999% of users will not/can not make. Changes that Cobb will not make internally (too much risk). Leaving you with... one current option and a "dont hold your breath" from the peanut gallery.

 

There is more than one way to skin a cat. Someone could figure it out, but most people want to be paid for their hard work and investment.

 

It could happen with Cobb. But they should have bigger fish to fry.

[Con.Harr91]

Whole lot of speculation going on here. From my talks with Cobb it IS doable on 05-06, and is on there R&D "to do" list. Best ETA was that it won't be weeks, but it won't be years.

[m sprank]

This thread is 2 years old. LOL. SEMA is in 2 weeks. I would bet money Cobbs SEMA announcements will not include Flex Fuel capability for the 05-06 LGT.

 

My shop sells, installs and tunes Cobb. I wish they had something so I had options. But they dont. The DT kit works just fine.

[Con.Harr91]

That's great, I'm glad we're hoping for the same thing. Your relentless optimism is always appreciated.

[Shutoburner]

Just curious but why are folks hesitant about DT flex fuel kit if that's the only legit option on the market? It seems that only certain tuners are willing to work with the DT kit.

 

Also, I've been in contact with a few tuners and they all seem to tune for e85. I read multiple threads on variable e85 content etc. I'm just curious how the cars get tuned to account for that.

 

 

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[Con.Harr91]

Typically the car won't be tuned on the bleeding edge of performance if it's just a straight E85 tune, simply because E85 itself is more of a category of ethanol content fuels than a specific one, meaning that ethanol content can vary from ~60-90% typically. With flex fuel that senses the precise ethanol content in your tank, you don't have to be concerned about it.

 

The DT flex fuel kit hijacks the IAT compensation tables in your ECU to make flex fuel capability work, this effectively prohibits your ECU from accurately adjusting for differences in intake air temp. From my personal experience in trying to find a tuner for this kit, the half dozen reputable tuners in the Chicagoland area that I approached (several of whom are listed on the DT website) told me that they would not touch my car if I had this kit installed. If DT didn't require their tuners and vendors to sign an NDA about their kit then I think we would be able to have a more open and honest discussion.

 

In the meantime, I suspect we will see something new on the market in the near future.

[m sprank]

Typically the car won't be tuned on the bleeding edge of performance if it's just a straight E85 tune

 

This is why the DT kit works just fine even though it uses the IAT compensation tables to make the FF "magic" happen (which is ONLY in the 05-09 LGT kits as all other kits made by DT do not use this method). Dont push it to the bleeding edge. You may be leaving 10whp on the table, but with the 40+ whp gain already (depends on supporting mods) its nothing to really lose sleep over. You tune a little conservatively rather than push the edge.

 

Someone figured out a solution for the cars, tested it and brought it to market. There are forum members with the kit installed and tuned and operating in their cars for some time now.

 

It is an option. Possibly there will be more in the future. But there is an option.

[Sammyshoe]

Hello flex-fuel curious members! Just thought I'd chime in here since I've had a DT Flex-Fuel kit on my '05 LGT for about 6 months now. Yes, this kit hijacks the intake air temp sensor, but it does seem to work just fine. It's a very noticeable difference in power between E85 and 93. Like m sprank quotes above, +40whp is what I got by using E85 from a close to stock setup. The tune changes to whatever combination of gasoline and ethanol is in the tank. It's been pretty much set-it and forget-it for me.

 

The only issue I have noticed is that cold starting can be bad. I talked to my tuner and he said that there isn't really any way to tune a solution to this with my old '05 ECU. He suggested adding a couple gallons of 93 when it gets cold, especially if you've still got summer blend e85 in the tank.

 

My car has never failed to start or anything, just has taken a lot of cranking to get started, then runs rough for maybe 30 seconds. For instance, I had 70% ethanol in the tank yesterday morning (38 degrees) and the cold start was very difficult. I added a few gallons of 93, and today it started much easier (55% ethanol, 37 degrees). That's really my only annoyance so far though.

[hadvw]

Sammyshoe, what are your mods (specifically injectors)? 5eat or 5mt?

[gkinslow]

And who did your tuning?

[m sprank]

We do not recommend running more than 55% ethanol when it is below 40deg outside. Cold starts can be an issue with high concentrations of e85. There is no way to preheat the engine or fuel for a better burn during cold start. Chevy hides a small heater in the injector just for cold starts on e85. No way to do this with a Subie.

 

There is no solution to this other than reducing the concentration of ethanol in the fuel to compensate for the cold temps. You could park in a heated garage, lol.

[xtea]

We do not recommend running more than 55% ethanol when it is below 40deg outside. Cold starts can be an issue with high concentrations of e85. There is no way to preheat the engine or fuel for a better burn during cold start. Chevy hides a small heater in the injector just for cold starts on e85. No way to do this with a Subie.

 

There is no solution to this other than reducing the concentration of ethanol in the fuel to compensate for the cold temps. You could park in a heated garage, lol.

 

Im in mn and ran E85 all last year but sneaked a gallon of 93 on cold days. What damage do I risk? Right now Ive got a pretty good cold weather tune and have not had any issues at 32 degrees.

[Th3Franz]

E70 cold crank at 1F with optima yellow top

[cryo]

Yup^

 

I have tons of customers that start thier car down to -10 here in co with only an extra couple seconds of cranking.

 

Just need to make the proper adjustments but its 100% possible

 

Dave

Edited November 2, 2017 by cryo

[xtea]

I also have a block heater for when it gets below 10.

[utc_pyro]

The DT flex fuel kit hijacks the IAT compensation tables in your ECU to make flex fuel capability work, this effectively prohibits your ECU from accurately adjusting for differences in intake air temp.

 

Well that's an interesting (and fairly clever) way of dealing with the issue. 100% hack job, but still interesting.

 

In theory you could use a AEM Wideband Flexfuel gauge to do do this out of the box, and add safety. Just wire it's E85 content analog output to the IAT sensor input. That only cost $300 or so, and you get a wideband and on-boost failsafe with it.

[xtea]

Well that's an interesting (and fairly clever) way of dealing with the issue. 100% hack job, but still interesting.

 

In theory you could use a AEM Wideband Flexfuel gauge to do do this out of the box, and add safety. Just wire it's E85 content analog output to the IAT sensor input. That only cost $300 or so, and you get a wideband and on-boost failsafe with it.

 

I live MN but I really want to do this. If my iat gets hijacked my car won't be able to adjust with temps that flucuate between -20 and 110.

 

How does the AEM guage provide a failsafe against this?

[utc_pyro]

It wouldn't be any diffrent for the DT kit on dealing with IAT swings (or more correctly: NOT dealing with them), but you can wire it to kill boost and/or kick off failsafe mode if it detects Lamba or Boost outside of a mapped range.

 

ECUTeck or porting Merpmod to our ECU is the only non-hackery option keeping IAT working.

[cryo]

Hope is not lost. Thank you all for your continued support as I am still in constant contact with COBB on the subject. Lets cross our fingers and see what 2018 brings. Gotta think positive.

 

 

Dave

Edited November 12, 2017 by cryo

[gkinslow]

Thanks for your continued support, hope is not lost. Thank you all for your continued support as I am still in constant contact with COBB on the subject. Lets cross our fingers and see what 2018 brings. Gotta think positive.

 

 

Dave

 

Agreed. The folks at Turn in Concepts say its just a matter of time. Not if but when.

 

I hope our patience pays off. Until then I'm only running ethanol.

[cryo]

Agreed. The folks at Turn in Concepts say its just a matter of time. Not if but when.

.

 

 

I would tend to agree.

 

Dave

Edited November 12, 2017 by cryo

[WRX USA]

Agreed. The folks at Turn in Concepts say its just a matter of time. Not if but when.

 

I hope our patience pays off. Until then I'm only running ethanol.

 

I would tend to agree.

 

Dave

 

I agree that both of you agree.