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Received the estimate for the parts, thank you. Forgot to ask when we spoke, but will there need to be a fuel/ethanol sensor installed to truly run FLEX tune? Can we select different tunes once programmed or have to stay with only the one flashed tune?
As far as a sensor goes we do not need one on the Trackhawk we are able to do the flex fuel tune off the current computer,now if you wanted to add a flex fuel sensor to tell you ethanol content we can make an elaborate set up for that or just grab an Ethanol testing tube and test your ethanol when you fill up always an option.

As of now we do not have any device to hold several tunes for the end user to select we can only bench flash the 2018 model vehicles as of now. If you run the S1025 package that will give you the most flexible fuel options out there and we can set that for 91 or 93 octane to run with the E85.
 

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thats awesome :) so the tune will automatically adjust based on the detected e85 content? what would happen if the truck was at the dealer and they reflashed the pcm as some sort of update?
 

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thats awesome :) so the tune will automatically adjust based on the detected e85 content? what would happen if the truck was at the dealer and they reflashed the pcm as some sort of update?
Do not do that!!!That would be very bad.

You must be very upfront with the dealer and let them know what is done to your veh. and emphasize do not plug in anything to the OBD port and do not let Johnny Jackwagon go out of sight with it we have all seen Ferris Buellers day off.

Yes the tune will automatically adjust based on E85 content or 93 content or any mix that is encountered with the two fuels.
 

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Hmm. that would pretty much rule out any sort of dealer diag no matter what they are doing. not preferable. this is why I would like the ability to flash/return to stock/reflash as needed. i fully understand that there are redundant systems in the new vehicles that will alert them to flashed pcm. There are almost always circumstances where certain modules require updates and would be silly not to be able to connect the witech and do needed updates jus because the pcm is flashed.
 

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Hmm. that would pretty much rule out any sort of dealer diag no matter what they are doing. not preferable. this is why I would like the ability to flash/return to stock/reflash as needed. i fully understand that there are redundant systems in the new vehicles that will alert them to flashed pcm. There are almost always circumstances where certain modules require updates and would be silly not to be able to connect the witech and do needed updates jus because the pcm is flashed.
As of wright now that is a fine line of separation for adding performance parts and modding the 2018 models. We are still in product development to create a tuneing device to hold a stock file and your modded file. Until then the only option is to have a stock pcm and also a modded pcm just so you can have a stock file and your modded file.
 

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I am having my TH dropped shipped near Sealy TX so Hennessey can preform there 850HP upgrade, I have secured serial #1. Is any one else considering Hennessey?

I am. But also looking at Zero Dark Thirty out of Houston.
I have visited with Alec at Hennessey and liked the package.
Thought that another PCM purchase and leave one stock....just in case.
 

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Well Hennessey is progressing with my Trackhawk nicely. here is a link if anyone is interested. https://www.youtube.com/watch?v=n2ObRr-cEyQ
Glad you are happy with the progress at the end of the day. That is all that truly matters.... I know you said when you dropped it off it would be 4-6 week turn around.... Mid april now.... How happy are you with that? Have they kept you in the loop at all? Do they send you updates? Just trouble with securing parts as its such a new car?

Thanks hope you enjoy it man! Its gonna be a beast... It was hard enough for me to drop off my truck to get xpel put on it for 2 days. I dont know how you are leaving your car for so long!
 

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Is it me or are only the back wheels spinning in the Hennessy video?
You saw right. They disengaged the front for this dyno. They first did a RWD baseline test before they tested it with the mods. I think they will then apply the percentage increase as a rough estimate as to what the AWD increase will be. I've seen this done before...seems like it is an acceptable way to accurately estimate AWD gains.
 

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Discussion Starter · #56 ·
I was surprised as well to see it in rear wheel only, but as this article below states, they did a before and after on the dyno so the comparison should be close. I will be picking it up Friday the 27th. it was a long wait, but I'm sure it will be worth it. I ordered it Aug 10th and had it shipped to Hennessey in January.it has been a long 8 months.So I really am happy to get it back soon. Hennessey like Livernois motor sports was only able to crack the ECU just recently, so I have to give Hennessey some slack. I have been in constant contact, and have had several updates during the 4 months it was there.

https://www.roadandtrack.com/new-cars/a19756953/jeep-grand-cherokee-trackhawk-hennessey-hpe850/
 

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Hopefully Mark didn't get Henniscrewed, but his experience is like many others that have...

* When you cut the cheque the kit is "ready to go", but suddenly there are many issues that "need ironing out" and that 4-6 week delivery turns into 6+ months. Reality is they're doing R&D on your vehicle, and hopefully he isn't using it as a parts car for things they've broken trying to build another
* "Communication" on how your build is going is mainly various marketing videos which you're encouraged to post to drum up more potential customers. Occasionally you'll get a vid of your vehicle "on the dyno" but its always chopped up into a marketing style video so you can't really get any detail from the runs.
* Customers local to Hennessey talk about what a great experience they had, customers from out of town talk about how they got screwed

John is a great marketer and hype-man, and smart enough that he doesn't crap where he lives when it comes to screwing over customers. Personally I got screwed on a "new from the factory performance ECU" for a Viper I had, which turned out to be nothing more than an ECU from a customers car that was 2 model years older and at Hennessey for a build (tracked that on the forums by matching the VIN that they never even bothered clearing from the PCM). While selling a used ECU as "factory new" was bad enough, the "tune" had the fueling so fat that it just puffed black smoke at anything more than 70% throttle. The supposed 50hp gain and better responsiveness on the track turned into a 100+hp loss with a boggy, bucking motor at 100% throttle, and having the cats overheat and melt from excessive fueling.
 
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