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Discussion Starter · #1 · (Edited)
I had had the service engine and service 4wd messages come up, and took my TH in for service. I've now got enough miles on it and a couple tanks of gas to evaluate what changed and what did not. I debated putitng this in my original thread about the problem, putting it in the fuel economy sub, or here, but decided this was the most relevant place. So here's my impressions of what changed:

1) Previously, I had commented on how my TH was really aggressive/enthusiastic with engine braking whenever you try to coast. This has been largely eliminated. It now coasts much more like you expect a modern car to coast. This affects MPG in a positive manner.

2) They moved the target RPM for city driving. By this I mean, absent significant deltas in throttle position, where the ECU/TPM/other modules try to target engine speed at. Prior to the flash, this seemed to be barely off idle speed with idle being about 1100rpm and the target being about 1300-1500rpm. It now seems to aim for 1500-1800.

3) The shift it yourself mode seems even more useless now. Short version is that it overrides the human input much more often and the new rule reflect a similar desire to have more margin with regard to verging on lugging the engine as in 2 above. Previously, unless an upshift would put you into that 1300rpm or lower range and verge on lugging the engine, you could upshift, and under most driving conditions, I could make it upshift at least one gear. Now, quite often it forbids you from either or both. If you put it in manual mode, it is now more aggressive about forcing a downshift when coasting. I have yet to determine if they force an up-shift at a different point as somewhere around 5800 rpm, the whine becomes unbearable, and their limit is past that if there is one other than just bouncing off a rev limiter.

4) It's in the wrong gear more... kind of. The reality is that the previous shifting strategy was being in the wrong gear a lot for fuel economy. You now swap being in too low a gear frequently for occasionally being in too high a gear. The main difference being that the old strategy was happening very frequently but was only really a concern at the pump, but not so much while driving. The new strategy has you occasionally stepping on the gas and getting not much of any response until it decides to down shift after you apply a lot of throttle. It happens most often when trying to drive smoothly in city traffic without hitting the brakes constantly (i.e. coasting a lot with minimal brakes) and then want to accelerate a bit when the stupid people are no longer in the way (like when you finally hit the turn off where you can exit the long line of stupid).

5) It now has a weird intermittent "surge" when turning on the car. Vehicle is off, in park, e-brake applied. Turn on the car, and sometimes it give a little jump forward taking up the slack in the drive line. It's nearly 100% analogous to the feeling in other vehicles with an AT of starting the vehicle with foot on brake, car in P, e-barake on, then putting it in D while taking your foot off the brake to creep out of a parking space at idle but you forgot to take off the e-brake. Except in the case of the renegade it's not in D, it's in P, and none of that should be happening. It's very odd, and I'm trying to see if I can reproduce it consistently, but haven't figured out the right sequence yet.


6) Fuel economy. When I got the car it wasn't so hot. I started driving making an effort to be more deliberate about mileage and I was able to get
up to about 19 and change and then it fell off a cliff and I was driving the thing like I was hypermiling it to get 17.6 mpg. Post flash, making minimal concessions to mileage other than trying to keep aggressive passing to a minimum, high 18.X mpg comes pretty easy driving in nearly 100% city traffic. Also, pre-flash, AC on or off didn't seem to matter much. Post flash it seems ot have some impact, although I haven't made a serious test of it given the temperatures since I got it back form the dealer.

Given that the EPA mpg for city for all 4wd models is 21mpg, and it is pretty safe to assume that is in the lattitude with a kinder final drive ratio, better coefficient of drag and a tire that is 6lbs lighter with likely lower rolling resistance, likely without AC factored into 100% of the drive cycle, and I'm probably not far off what was promised on the sticker.

No feedback on highway MPG, because I haven't been able to take a long drive since I got it back.
 

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18MPG still seems too low to me. In my Wrangler 4-Door Rubicon with Auto and 4.10 gears I could get 17MPG pretty easy with mixed 50/50 suburbs/highway. I would expect a Renegade Trailhawk to average 22-24. I wonder if that's something that will continue to improve over time?
 

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Wow, I don't think I want to get mine flashed (haven't had any problems yet).

And my gas mileage is good; maybe 25 around town and at least 28 on the highway. Others on here have reported good gas mileage and still others have reported poor gas mileage.

How can FCA make one car one way, and the same model another way?
 

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How can FCA make one car one way, and the same model another way?
I have come across this before in the UK, so it is not just a one-off. Here's an example. Guy buys a brand new Ford Fiesta 1.4 S. Keeps it a couple of years and replaces it with an identical model. There is a difference in the two cars. First one was fantastic, pulled well, drive well, couldn't fault it. So he replaced with an identical model. Second one was gutless. No power, nothing. This happened back in the 1980s and is still happening. In the UK it is known as a Friday model. Thrown together quickly.
 

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Discussion Starter · #7 ·
18MPG still seems too low to me. In my Wrangler 4-Door Rubicon with Auto and 4.10 gears I could get 17MPG pretty easy with mixed 50/50 suburbs/highway. I would expect a Renegade Trailhawk to average 22-24. I wonder if that's something that will continue to improve over time?
My daily commute is 100% city driving with a nice chunk of traffic jam. The high 18s are a tank of 100% city traffic.
 

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My daily commute is 100% city driving with a nice chunk of traffic jam. The high 18s are a tank of 100% city traffic.
Oh, okay. I don't think you will get up into the 20's with that kind of driving no matter how easy you are on the gas pedal.

But the good news is that gas prices may drop below $2 per gallon at various places around the country.
 

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Discussion Starter · #9 ·
Oh yeah, I left out one thing that the flash did.

Previous to the flash, the cruise control would constantly have me driving about 2mph under the set speed. Now it behaves like cruise control has in every other car I have had it in, which is it holds dead on with a range of about -2 to +1 when correcting for uphill/downhill changes.
 
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