Hello from France / Need help on my 2018 DENALI

L86 All Terrain · October 11, 2019

On 10/8/2019 at 12:30 PM, lolpops said:

I would have liked GMC to answer to my only question but it seems to be so difficult with them

One thing is sur it's my first and last GMC, I don't want to give money to some one who don't care about their customers any more...

You have to remember than they probably get about 5,000 emails per day from customers asking questions rather than going to talk to the dealer or consulting a forum. Try to email Citroën, you will get the same silence. They aren't going to respond to you, they aren't going to respond to me either who has spent over $200,000 at my dealership. Its not that they don't care for the customers its about operating a multi-billion dollar corporation. That is why they have dealerships, you go to them with your problems or concerns, the dealer will relay to GM when a reoccurring problem is noticed. GM does not have the human resources required to be answer phone calls on a case by case basis. Unfortunately for you France does not have GM dealerships so you cant take that route. I have emailed GM with questions in the past with no luck either.

The proper way to look at it that you did not fully research the product you were buying, you took someone's word for it. That is on you, not General Motors. If you get your issues sorted out, I am sure your opinions will change, you bought a hell of a nice truck. Have you given it more thought? Are you going to convert it or sell it or just run SP98? As I said earlier, the L83 5.3L engines are E85 capable and can be spec'd in a Denali as well. E85 unlocks a good chunk of power in the 5.3L as well but only around 45% efficiency compared to 87 octane.

wforrest08 · October 11, 2019

1 hour ago, L86 All Terrain said:

On 10/8/2019 at 12:30 PM, lolpops said:

You have to remember than they probably get about 5,000 emails per day from customers asking questions rather than going to talk to the dealer or consulting a forum.

I’ve had good luck getting responses from [email protected] usually within 48 business hours.

lolpops · October 21, 2019

On 10/11/2019 at 10:32 PM, L86 All Terrain said:

The proper way to look at it that you did not fully research the product you were buying, you took someone's word for it

Loool ! You're a nice guy !

First I'm not a car dealer, I'm not working with cars, I'm not a "car professional"

Second I'm in France, things are not the same that in USA

So now I needed a pick-up running E85 for 3 reasons, 1 is that it's considered as an hybrid car in France, so you can go everywhere same in case of "polution alert", and you don't pay taxes for the papers, otherwise it cost about 10k€, 2 is that you don't pay taxes on E85 for a firm and 3 is that E85 in France is 0,60€/L and SP98 is 1,6€/L, that's not really the same things...

When I call a seller, a professional, and he says "the car is E85 from origin" and he wrote this everywhere on his adverts I don't need to check it, this wouldn't be the same with a particular seller

Now they took the car back and reprog it, I run E85 and the "check engin" light doesn't go on anymore

They didn't put any sensor under the truck, when I asked them they told me it doesn't need, there is a sensor in the fuel pump (I know, I should take the pump down to check it too !!!!)

Well, today I haven't got problems anymore with the truck, but my fear is to get problems in 3 or 4 years, when the truck won't be under warranty

So, to get my fear away, I need that GMC tells me if MY truck is E85 capable or not, and if it is, what they recommend to add/change/make

For the end, in France if I'm the owner of a Citroen car, I go to a Citroen dealer and I ask him to give me all the options about my car, if he doesn't want a lawyer can force him to to it...

Thank you wforrest08, I'll try to send a email to [email protected] and I will tell you back

TJay74 · October 22, 2019

On 10/7/2019 at 10:02 AM, L86 All Terrain said:

The 2015+ 6.2L CAN NOT run E85 as it is set up from the factory.

You CAN make it run on E85, but you will need 8 new E85 capable fuel injectors, and a custom tune for the ECU.

This route will cost you thousands of dollars, I would expect it to take 5+ years to pay off the cost of the upgrades in fuel savings from utilizing E85. Additionally, it may be difficult to find someone in France that can reliably tune modern Gen5 GM LT V8's.

It would be cheaper, safer and easier to purchase SP98. These trucks can run on your blended E10/SP90, but the ECU will retard the timing to prevent pre-detonation of the cylinders and you will lose some power, but it wont hurt the engine.

Your best bet is to forget about E85 unless you are going to mod the truck for performance anyway.

The info about the injectors is wrong, you dont need any injectors or fuel pumps to run E85 in the 6.2 trucks. I have a 2016 6.2l / A8 truck, all I did was plumb the sensor into the fuel under the drivers side of the truck, plugged the sensor in and then went into my tune and turned the E85 on in the tune. All of the tables are already populated in the OEM for E85 flex fuel.

GM has a couple of sets of injectors for the 6.2l engines, the ones the trucks, Camaro SS and the Corvette use and the injectors for the LT4 engines (ZL1 Camaro, Z06 Corvette and the Cadillac CTS-V). The way the truck sits now the OP's truck will run E85 with zero issues for any bolt on mod the OP every throws at it if she converts it over to E85. I have been running E85 on my truck for 2 years now with zero issues. Even my 17 Camaro SS I converted over to E85 and ran it when it was a bolt on only naturally aspirated and even now that it has a Procharger D1SC supercharger on it making 650 to the wheels.

OP since your truck is only set up for gas I would run what ever you have in France that meets the 93 octane US minimum or the 95/98 RON that you all use in Europe that is the equivalent to Us 93 octane. You can run 93 octane E10 with zero issues and it will give you even more protection against detonation, I have ran as much as 15% E85 in the gas tanks with zero issues, I do this in our 16 Audi SQ5 that is fully modded on a Stage 2 tune with a pulley that makes around 470hp at the crank. Zero issues at all. The only is it takes some math in order to figure out how much E85 to add the tank on each fill up.

TJay74 · October 22, 2019

21 hours ago, lolpops said:

Loool ! You're a nice guy !

First I'm not a car dealer, I'm not working with cars, I'm not a "car professional"

Second I'm in France, things are not the same that in USA

So now I needed a pick-up running E85 for 3 reasons, 1 is that it's considered as an hybrid car in France, so you can go everywhere same in case of "polution alert", and you don't pay taxes for the papers, otherwise it cost about 10k€, 2 is that you don't pay taxes on E85 for a firm and 3 is that E85 in France is 0,60€/L and SP98 is 1,6€/L, that's not really the same things...

When I call a seller, a professional, and he says "the car is E85 from origin" and he wrote this everywhere on his adverts I don't need to check it, this wouldn't be the same with a particular seller

Now they took the car back and reprog it, I run E85 and the "check engin" light doesn't go on anymore

They didn't put any sensor under the truck, when I asked them they told me it doesn't need, there is a sensor in the fuel pump (I know, I should take the pump down to check it too !!!!)

Well, today I haven't got problems anymore with the truck, but my fear is to get problems in 3 or 4 years, when the truck won't be under warranty

So, to get my fear away, I need that GMC tells me if MY truck is E85 capable or not, and if it is, what they recommend to add/change/make

For the end, in France if I'm the owner of a Citroen car, I go to a Citroen dealer and I ask him to give me all the options about my car, if he doesn't want a lawyer can force him to to it...

Thank you wforrest08, I'll try to send a email to [email protected] and I will tell you back

Laruent the guy who is selling you this truck is lying to you, flat out. There is no E85 sensor in the fuel pump at all. There are 2 fuel pumps in the truck, the electric one in the gas tank is the low pressure pump that pumps the fuel to around 60psi and the high pressure pump under the intake manifold that pumps the fuel to as much as 2900psi. Neither one has any type of E85 sensor built into them, I have touched and installed both of these pumps at one point.

"IF" your dealer reprogrammed the truck and told it to run E85 without an actual ethanol sensor that is actually required then the truck is using a virtual E85 system to determine if it has E85 in the fuel system. The virtual E85 tables try to use the short term and long term fuel trims to calculate if the truck is running regular ole gasoline or E85. It isnt accurate nor is it the correct way to do this.