'MURICA

I know there's quite a few members here with tuned 3.7s. It sounds like it's the single best mod that you can do to liven up the engine and increase power, and there seem to be a number of really good tunes out there. I really like my engine, and while it doesn't keep up with my friend's Ecoboost, it still never fails to impress when I need to pass on the highway. However, I wouldn't mind a little extra oomph and especially am interested in the modified shifting.

My one question is the effect that it will have on reliability. I know there's lots of people saying that it's already tuned more aggressively in the Mustang, but the Mustang weighs a couple thousand pounds less and the engine isn't working as hard all the time to push around that added weight. From what I've heard the 3.7 is about as bulletproof as you can get in a truck engine and is incredibly reliable. I just turned 100,000 miles yesterday (in a 2013! Yeah I drive a lot) and haven't had any issues, and hope to keep the truck for many more years.

So I'm wondering what everyone's experience has been with their 3.7 tunes. I know there are quite a few people that have blown up their Ecoboosts with tunes, but I haven't heard any comments about the 3.7. I'm hoping this is a good sign. Anyone had a tune for more than a couple years? Do dealerships care at all when you go in for maintenance? I don't think I would do anything more aggressive than an 89 octane performance, especially since I live in Utah where the highest octane you can get is 91... And have any of you noticed any real gains in MPGs with the economy tunes? With my 33s the gas mileage is less than optimal.

Thanks in advance and sorry for the novel of a post!

RLXXI

Can't compare naturally aspirated engines with those that are forced induction. Tune and enjoy.
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antony1103

FYI, I don't have any fire hand experiences with the ecoboost, but in general, like any significant power-adder, you are going to reduce the reliability of the engine. The significance of this reduction depends on your driving habits, as well as how diligent you are on preventative maintenance. With any forced induction engine, I would be worried about increased blow-by around the pistons if your tune increases boost. The PCV system helps mitigate this, but i would always stay on top of your oil changes. And degradation in oil quality will directly effect the life of the major mechanical components in the engine; not only the pistons and cylinder walls, but also wear on the timing chain/tensioner, cam phasers, rotating assembly, etc.

My next major concern would be the transmission. If your tune adjusts transmission pressures in any way, you could see accelerated wear. Firmer shifts may help keep transmission temperatures manageable, but will put additional strain on the power train as a whole. Looser shifts or extended operation with an unlocked torque converter will ultimately raise transmission temperatures, reducing the effectiveness and life of your ATF.

There are tons of other possibilities, but the two above would be my major concerns. YMMV. For the most part though, any reputable tuner is keen to these issues and will give you a good mix of performance and reliability. IMO, get a good tune, keep up on your PM, and monitor the quality of your fluids as you change them out. I highly recommend Blackstone labs for keeping track of wear indications in your engine/gear/transmission oil.

GrasslandHVAC

Only have 15,000km on my tune, so cant speak for reliability. No issues so far. Only and off the shelf 87 octane tune tho.

Mattwrotethis

If you do a search of this forum, other F150 forums, and Mustang forums looking for 3.7 problems, you find almost nothing. I just replaced the first non-maintenance part on a 3.7 for me in my career as a technician (and I worked for a Mazda dealer when these engines debuted in the CX7). I did a crank sensor on a 2011 Mustang this morning. The 3.5L version of this engine seems to have water pump failures just often enough to be a known issue in FWD applications. Tune it at your own risk, but I doubt you'll have issues.

GNR22

I have some 5 Star tunes on my 14 F150, 3.7L. No reliability issues thus far. It was -20F here this morning and it still fired right up. Currently using 87 Octane Performance/Tow.

I'm very pleased with the tunes I got from 5 Star. The shift strategy and power down low is astounding. Like a whole different vehicle.

The truck holds back from up shifting so early. You'll no longer lug through town at 30MPH in 5th gear while the truck struggles to go up hills before downshifting.

As for the performance aspect, the truck will do belligerent burnouts. The shifts are much firmer, very noticeable under heavy throttle. The performance difference is more noticeable at lower RPMs though. It doesn't seem like such a dog when you try to take off. 5 Star also lets you totally disable the Advance Trac system when you press the Traction Control button. So if you feel like doing donuts in the middle of your yard, Ford's nanny programming can't stop you any longer.

I haven't gotten to pull any trailers since I got the tunes, but I'm looking forward to seeing the difference the tunes will make.

I haven't noticed any difference in MPGs. I'm right at 21 where I was before I got the tunes. In all fairness, I've spent a great deal of time with a lead foot playing around, so I can imagine that the economy has improved slightly.

I've impressed a whole lot of people with the "little 3.7" in my truck. It's much more peppy than anybody, including myself, expected it to be. I have ZERO regret on purchasing the tunes from 5 Star. The improvement of the shift strategy alone was well worth the money. I would do it again in a heartbeat. I was also very leery on how much of a difference the tunes would make, but take my word for it. It's a world of difference.

'MURICA

Thanks for the replies, guys. Sounds like it would be tough to go wrong with a tune. I think since I've hit 100K I'll go have the tranny fluid changed, spark plugs replaced, and then I'll tune him up. The extra power down low really appeals to me. I still worry just a tad about what the tunes will do to the transmission. It already isn't shifting as smooth as it used to, and feels like it kindof needs to work to get into gear every once in a while. I don't know if that's because of wear and tear, or just a software thing that might work itself out after loading the tune. I wonder if the transmissions are slightly different on these 3.7s, because back when I was test driving them they all seemed to shift pretty rough, whereas the Ecos and 5.0s were a little smoother... Maybe they all were just work trucks treated badly though.

GNR22

When I first got my 3.7 the shifts were mushy. I didn't much care for it. Firm shifts save the clutches within the transmission from slipping. If your fluid is well aged, that could well be some of what you're feeling.

'MURICA

Well guys, just a quick update. I went ahead and tuned him up w/ some 5 star tunes. Just barely threw on the 91 perf/tow and took him for a spin, not 30 minutes ago. I'm having mixed feelings. I don't want to get into the power too much right now, but I can certainly tell that the throttle response is different. And the shifts are nice and crisp. My one concern is the 1-2 shift. Maybe like I said the tranny is starting to wear out just a tad, but before, while you could feel the truck shifting from 1 - 2 (3-6 pretty much were too smooth to feel the truck shift), now it's a total thump into gear. Like unless I get my foot into it a little bit, it's an almost audible and extremely uncomfortable shift that lurches you forward. I understand that these tunes are not ideal for city driving, which is alright because I don't only drive in the city. But it's not a race tune, nor is it the 93 octane tune, and yet I don't think I could live full-time with the 91 on there. If I'm just driving around alone on the street it's bearable, but if I'm stuck behind someone at a light who's accelerating slowly, I grit my teeth and then THUMP, since there's really no way to avoid it.

Anyways, thought I'd share my thoughts. I'll go with the 91 for a while longer and see what I think, and then I'll try out the 89. I might just be a wuss and this might be totally normal, but there IS something to be said about a nice ride. I guess there's some give and take, huh?

blue5.0

Reach out to 5 star and tell them exactly that. They will update to your liking. They may have you data log but it's not a very hard process.