Impala Forums banner

1 - 20 of 29 Posts

·
Registered
Joined
·
68 Posts
Discussion Starter #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.
 

·
Registered
Joined
·
97 Posts
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.

Sent from my SM-N960U using Tapatalk
 

·
Registered
Joined
·
68 Posts
Discussion Starter #3
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.

Sent from my SM-N960U using Tapatalk
Yeah the only thing that may get eaten away Is the fuel pump and Injectors. Tank and fuel lines are the same as the 3.5 and 3.9 and there both flex fuel. But I will keep a close eye on things.
 

·
Registered
Joined
·
1,028 Posts
The ECM for the LS4 doesn't have fuel maps for E85 so it's not going to run well on it.
 
  • Like
Reactions: Fred9505

·
Registered
Joined
·
68 Posts
Discussion Starter #5
The ECM for the LS4 doesn't have fuel maps for E85 so it's not going to run well on it.
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.
 

·
Registered
Joined
·
1,028 Posts
My buddy that drag races a 440 in a Dodge Colt burns through a set of rings and bearings in one season on alcohol fuel.
I don't think I'd run something as nasty as 85% raw alcohol though my LS4.

It's your rig so have at it.
 

·
Registered
Joined
·
68 Posts
Discussion Starter #7
The engine Itself Is e85 safe as every Internal engine component Is Identical to a flex fuel model with the 5.3.
 

·
Registered
Joined
·
1,028 Posts
The engine Itself Is e85 safe as every Internal engine component Is Identical to a flex fuel model with the 5.3.
The LS4 has different pistons, different cylinder heads with different combustion chambers, and the LS4 doesn't have variable valve timing like the flex fuel V8 even tho it's classed as a Gen IV engine.
 

·
Registered
Joined
·
294 Posts
E85 in normal fuel

We have 10%< E85 in our fuel in New Mexico. What % is considered damaging for chevy? (mine is flex fuel)
 

·
Registered
Joined
·
1,028 Posts
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.
 

·
Registered
Joined
·
294 Posts
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.
Thanks for being patient Hatzie. You know if you put this information if front of us oldsters long enough we (or at least me) finally figure out what E10 and E85 really mean.
 

·
Registered
Joined
·
411 Posts
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.
So does that mean we shouldn't run E85 or we should always run what has always been used in it?

I was thinking about letting my tank get close to empty and trying some E85.
 

·
Registered
Joined
·
68 Posts
Discussion Starter #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.
 

·
Registered
Joined
·
294 Posts
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).:|
 

·
Registered
Joined
·
1,028 Posts
So does that mean we shouldn't run E85 or we should always run what has always been used in it?

I was thinking about letting my tank get close to empty and trying some E85.
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.

Up to 2005 or so Flex Fuel vehicles had a $$$$$ Flex Fuel Sensor to determine the ethanol percentage in the fuel... No way that could end badly is there?

The 06 and later Flex Fuel vehicles are somewhat better. The Ethanol level is supposed to be detected by the ECM/PCM by examining fuel trims called for by the O2 sensors over time... it's called VFFS (Virtual Flex Fuel Sensor). The VFFS is based on the fuel trims. The ECM/PCM selects the proper fuel map based on the VFFS recommendations. The sensing seems to get confused at times and it sticks on one Ethanol level. Again. 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.

There's a service bulletin about the VFFS (Virtual Flex Fuel Sensor) getting confused and sticking on several vehicle families.
Service Campaign Bulletin 06162C includes at least 2006 & 2007 Impala Flex Fuel vehicles. The fix requires an ECM/PCM programming update. If you have a laptop and a Tech 2, MDI, or GM VXDIAG... get a 24month $40 TDS subscription, fully charge your battery, and update your ECM/PCM to the latest and greatest. Flashing the PCM/ECM with a low battery is a good way to brick it.
 
  • Like
Reactions: plano-doug

·
Registered
Joined
·
143 Posts
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.
 
1 - 20 of 29 Posts
Top