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The SS running on E85.

11K views 28 replies 10 participants last post by  Mr312712 
#1 ·
A few days ago I decided to try out E85 In my SS. Even though they never equipped the SS for E85 I decided to try It anyway. Since It has the same engine as the pickups and SUVs have and they were equipped for E85 I figured why not. Anyway I had half of tank of 87 and filled the rest with E85 and have been topping It off with E85. So far I've noticed the Idle Is smoother, the throttle response Is better and It feels alot more powerful. But I have noticed I lost about 3 MPG's as the PCM Is giving It more fuel to compensate for the lean condition as E85 has less energy. But It's still worth It as gas has skyrocketed around here. It has no starting or drivability Issuse at all so I'm assuming that means the fuel pump and Injectors have no problem keeping up with the demand of E85. But It does throw code P0171 for Bank 1 lean, obviously since the E85 tables aren't enabled In the PCM. But I'm gonna add the sensor to the fuel line and tune It so It can run both fuels reliably and not throw the lean code. I checked the fuel lines coming from the tank to the engine and they are the same across all engines so there E85 safe. But just thought I would let other SS owners know of my experience. As of right now I'm gonna keep running the E85 unless I start to have drivability problems or I go somewhere that doesn't have E85. Will keep this updated.
 
#2 ·
Hope you talked this over with your dealer or a ASE Certified shop. Seals, gaskets, injectors and other things are made differently. I'd definitely be checking with the dealer because as I understood it is the corrosiveness of the fuel with all the stuff in it that eats away at the non E85 engine stuff.

Max I use in my impala or Tahoe, 2006 (v6 3.9 impala) and 2004 (4.8 v8 Tahoe) respectively is 10% but that's only been a few times. No matter the price of gas I've always ran 91 octane. The wife has been known to forget on occasion and put 10% Ethanol in.

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#5 ·
Yeah I didn't think It would either. But It's been a week and It's running great. It burns a little more fuel but that's normal with e85. It's running straight e85 now as I've filled the tank up a few times now. Fuel pump and Injectors have no problem keeping up. The car seriously runs better on e85 than It does on Premium as I couldn't even tell a difference when I ran Premium other than my wallet getting lighter. But the ECM Is adjusting as It's running lean because of the e85 by giving It more fuel to keep the engine running correctly. Long term fuel trim Is around 19-24% higher which means the ECM Is adjusting and setting the code because It's programmed for 87 but e85 has less energy and requires more fuel and the ECM thinks theres a big vaccum leak when there really Isn't. I would leave It the way It Is but I'm tired of looking at the engine light, which Is why I'm gonna get a HP Tuner so It can run both.
 
#12 · (Edited)
We have 10%< E85 in our fuel in New Mexico. What % is considered damaging for chevy? (mine is flex fuel)
Real gas (0% Ethanol) is E0.
10% Ethanol is E10.
E85 is 85% alcohol.

Flex Fuel rigs can run E0 - E85. The ECM is supposed to adapt to the level of Ethanol in the fuel. GM Flex Fuel SUV and Pickup trucks have issues with the ECM getting confused about the Ethanol level and running badly.
 
#17 ·
Giving another update. Engine Is still running fine but be warned It will kill your catalytic converter unless It's e85 safe. My factory catalytic converter died back In January after 150k and I had a universal Flowmaster put on. But since I switched to e85 It killed the Flowmaster pretty quick as I'm getting a p0420 code again. So Im gonna order a cat for a 3.9 flex fuel since they have the same exhaust but the 3.9's cat Is safe for e85 and the 5.3's Isn't. But other than that the engine Is happy. Took It out and played with It and let It go Into the higher RPM's for awhile and It performed great. Other than my power steering pump dieing everything's good.
 
#18 ·
When I first got my Impala (had 23,000 on it) and I took it to the dealer for minor interior fix on the back seat belt. So they said they re-flashed the computer for the E-85 stuff would work (mine has a "K" in the VIN so I know it will work). Anyhow, since then the car runs terrible on anything less that 89 octane. If I try running anything less in octane the valves clatter when the car is first started and it's idling (fast idle) and power is pitiful. Is a re-flash in my future and how long does it take? Will a tech 2 tool do the trick? All this talk about E-85 got me thinking (sometimes that's good and sometimes it's not).:|
 
#20 ·
That's the best way to go about it. The ECM confusion seems to be most prevalent on vehicles that don't make a sharp change over from one to the other because they're re-fueling on partial tanks. Re-fueling changeovers to E10 or E85 at low fuel levels avoids that problem.
My Flex Fuel Terrain owners manual is pretty clear about the change over. As much as possible, but a minimum of 3 gallons and drive a minimum of 7 miles after re-fueling.
 
#21 ·
My 2014 limited did great on E85, with the exception of lower MPG. It was especially great when the price difference between E85 and 87 octane was almost a $1. Then they jacked the E85 price up and made the difference negligible. I have not run E85 during the winter because I feared my MPG would be worse yet. I am considering going back in a few weeks when it warms up consistently... cost difference last I checked was about .65 cents.
 
#22 ·
Another update. Been 3 weeks now and things have definitely changed. At first long term fuel trim was the only one that Immediately changed but after about a week and a half short term followed. Everything Is still running great. On cold mornings after It's sat for about 10 hours or more It will start fine but stall Immediately (unless you give It gas) but start right back up. Another thing If It's running and you shut It off and Immediately try and restart It. It will do a long extended crank and crank over for about 5-10 seconds. While It's cranking over It try's to catch and fire. Sometimes It will fire after a few seconds and sometimes If It cranks too long the ECU will kill the starter to prevent damage to It. Idk If It's getting too much fuel or not getting enough but It's never failed to start or have drivability problems. Fuel range and Instant economy have also adjusted. Before this trip fuel range on a full tank was only around 170 miles. That's city driving and me gunning It every chance I get. Also before when It would go Into 4CYL MODE It would switch back to 8CYL MODE when the Instant MPG dropped to 18-17. But now with e85 In 4CYL MODE It will drop as low as 12-11 MPG before switching back to 8CYL MODE. I actually drove It to zzperformance to get the dog bone poly mounts set as I only live an hour away from them. State Troopers were all over the highway so I couldn't speed too much. So with the cruise set between 70-80 MPH according to the car I averaged 15-16 MPG. I drove It gentle but did get on It at times when passing people. I started out with a little over 3 quarters of a tank (75% full) and ended with a little under a quarter of a tank (25% full). Round trip was about 80 miles both ways so 160 miles In total. But It still consumed quite a bit of fuel for as gentle as I was driving. Anyway I just put another $30 bucks In the tank (e85) and that almost filled It up and now fuel range Is at 240. Obviously fuel range goes up the more efficient you drive.

Bottom line Is when I first started this little experiment I just wanted to see how the LS4 reacted with e85 and If It would run correctly. So It's good to know that the ECU can compensate for e85 and make It run correctly and the pump and Injectors have no problem keeping up with e85. Im not saying I won't ever go back to normal gas but It's just good to know that I can run either fuel without problems other than a check engine light for lean conditions. I also stated In a previous post that I thought e85 killed my catalytic converter. Apparently It didn't kill It as the computer was just adjusting and the p0420 code only appeared one time and has not been back after 2 weeks. So In the end Im happy with the way the engine runs on e85. It has great performance but you do pay for It In MPG's. And to top It off I added these... Automotive exterior Red Bumper Automotive tail & brake light Vehicle


Yellow
 
#23 ·
I filled mine on Friday morning because I saw the one station was almost a $1 cheaper on E85... $1.59 a gallon... $21 to fill it. I drive fairly conservatively but work called and bumped my start time by 45 mins so I had to hustle in... almost 80 the whole way in... so there goes this weeks real mpg test. Looks like the weather is going to stay 60° to 70° pretty consistently here.
 
#24 ·
Giving this another update. Been about a week now since I switched back to 87. I ran the tank very low and filled with 87. Fuel trims went Into negative obviously. But power went up. I Immediately noticed an Increase on 87 vs the E85 as at WOT the PCM Ignores the 02 sensor's and defaults to the factory programming weather It's running lean or rich. The reason I switched back was It started hiccuping anytime I would put It to the floor as It was going Into open loop and taking away that extra fuel and It was starting to have trouble starting up when sitting overnight. So now everything Is back to normal and the power Is back. 0-60 on E85 on a cool morning with a perfect launch was a tad over 7 seconds. 0-60 on 87 with a bad launch was dead at 6 seconds. So even though E85 Is cheaper It's not worth It without a tune. I filled up about 4 days ago and just hit the half mark.
 
#25 ·
Why do you think things started acting up? Will be curious to see how things go on from there. The alcohol in flex fuel is not good for cars not designed to run on it, think some here said as much. With seeing the after effects of small engines run on gas "with less than 10% ethanol", I have my suspicions.
 
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