the "Gutless 3.8" - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 52 Old 04-12-2015, 05:28 AM Thread Starter
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the "Gutless 3.8"

I took my 2011 JKU out to Assateague Island in Md. yesterday. First time on the beach,, turned out to be a nice day. My original Goodyear Wrangler tires Have 60,000 miles on them,, still legal though . Didnt have any problem with traction but when I got in deep soft sand the 3.8 was a real dog! No power at all, it wanted to spark knock if I didnt have in in that one "sweet spot" about 1500 rpm in 4 hi and in 1st gear,,, I made out ok , went about 24 total miles.

So I was wondering,,would it just be something as simple as running higher octane gas? I was running regular 87 octane. Or maybe a cold air intake to add a little more power? I dont want to do any major mod to get just a little more power and loose any gas mileage,, maybe a computer flash? Any advice would be welcome....
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post #2 of 52 Old 04-12-2015, 05:37 AM
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It's just a poor excuse for a Powerplant. Supercharger or a V8 swap. Cold air intakes are a waste. Some say they have had a little bit of success with a tuner.
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post #3 of 52 Old 04-12-2015, 07:09 AM
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It's a mini van motor. It can barley get out of it's own way.

POG MO THOIN
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post #4 of 52 Old 04-12-2015, 07:57 AM
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While the 3.8L isn't the strongest engine, the poor factory gearing is more to blame. The manual 3.8L should had came from the factory with 4.10 or 4.27 gears. The auto 3.8L should have came from the factory with 4.88 or 5.13 gears.
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post #5 of 52 Old 04-12-2015, 09:27 AM
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Try 4L.

When someone complains their JK 3.8L is a dog, my initial reaction (which I try to suppress) is "what's your point?" CJs, YJs, TJs, LJs...name your favorite dog. The Pentastar's HP & torque are a change of direction for Jeep. My '09 JKUR is nearing 48k miles, has spent most of that rolling on 37s with 4.88 or now 5.38 gears. Makes it to Moab several times a year and handled a trip to Denver and its traffic a while back just fine. Yeah, it screams going over mountain passes and ot sure could use at least one more gear in the automatic trans, but it has never failed to get over a steep obstacle or pass a slowpoke on the highway. And, compared to the highway performance of its predecessor, a '94 YJ rolling on IROK 36" radials & 4.88s, it's a missle.

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post #6 of 52 Old 04-12-2015, 09:37 AM
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I agree it could,should have more power. However, I never need more power when I'm in 4 low, and wheeling my Rubi. If I want to go fast on road, I drive my 61 Jeep wagon, it's a lot faster !
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post #7 of 52 Old 04-12-2015, 01:33 PM
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Quote:
Originally Posted by steevo View Post
I took my 2011 JKU out to Assateague Island in Md. yesterday. First time on the beach,, turned out to be a nice day. My original Goodyear Wrangler tires Have 60,000 miles on them,, still legal though . Didnt have any problem with traction but when I got in deep soft sand the 3.8 was a real dog! No power at all, it wanted to spark knock if I didnt have in in that one "sweet spot" about 1500 rpm in 4 hi and in 1st gear,,, I made out ok , went about 24 total miles.

So I was wondering,,would it just be something as simple as running higher octane gas? I was running regular 87 octane. Or maybe a cold air intake to add a little more power? I dont want to do any major mod to get just a little more power and loose any gas mileage,, maybe a computer flash? Any advice would be welcome....
If it was knocking, the last thing you want to do is add more air. It will throw the air/fuel ratio off even more, causing it to knock more/worst.

Running 91/93 when you're going out on the beach might help out. I don't have a 3.8 so I can't comment, but others can and the guys above seem to be willing to help you out.

Just in case you're wondering, the 3.6 is also a "mini-van" motor.

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post #8 of 52 Old 04-12-2015, 02:29 PM
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Quote:
Originally Posted by PKDailey4 View Post
It's a mini van motor. It can barley get out of it's own way.
yet that "minivan motor" still has more horsepower and torque than the beloved 4.0

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post #9 of 52 Old 04-12-2015, 02:35 PM
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Quote:
Originally Posted by steevo View Post
I took my 2011 JKU out to Assateague Island in Md. yesterday. First time on the beach,, turned out to be a nice day. My original Goodyear Wrangler tires Have 60,000 miles on them,, still legal though . Didnt have any problem with traction but when I got in deep soft sand the 3.8 was a real dog! No power at all, it wanted to spark knock if I didnt have in in that one "sweet spot" about 1500 rpm in 4 hi and in 1st gear,,, I made out ok , went about 24 total miles.

So I was wondering,,would it just be something as simple as running higher octane gas? I was running regular 87 octane. Or maybe a cold air intake to add a little more power? I dont want to do any major mod to get just a little more power and loose any gas mileage,, maybe a computer flash? Any advice would be welcome....
when driving in "deep soft sand" you should have probably been in 4lo. the best thing you can do is re gear your Jeep. as others above me said, Jeep really screwed up by running such high gears. they did this to help meet mileage standards.

I am running 37" tires with 5.38 gears and a Superchip in my 2011 and still get 19.5 mpg on the highway. being you have a standard transmission, you wouldn't need to go as low as I did with my gearing. 4.56's or 4.88's would probably do you just fine.

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post #10 of 52 Old 04-12-2015, 02:44 PM
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Iv'e always said that the 3.8 would be better tied to an anchor line .

It's weaker than any motor ever offered in the Wrangler line , with that said Chrysler really screwed the pooch when they mated the Dog mini-van motor to the 4-sp auto (Joe Biden of transmissions ) it has no idea of what gear it needs to be in on it's own , just a stupid trans.

Swap in a LS .
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post #11 of 52 Old 04-12-2015, 02:58 PM
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welcome !!!

SYNERGY, FOX,VKS,HUTCHINSON,
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post #12 of 52 Old 04-12-2015, 03:01 PM
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Quote:
Originally Posted by CamoCop View Post
when driving in "deep soft sand" you should have probably been in 4lo. the best thing you can do is re gear your Jeep. as others above me said, Jeep really screwed up by running such high gears. they did this to help meet mileage standards.

I am running 37" tires with 5.38 gears and a Superchip in my 2011 and still get 19.5 mpg on the highway. being you have a standard transmission, you wouldn't need to go as low as I did with my gearing. 4.56's or 4.88's would probably do you just fine.
I cant get 15 , but you are getting 19.5 really ?

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post #13 of 52 Old 04-12-2015, 03:54 PM
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Quote:
Originally Posted by IndyJLH View Post
While the 3.8L isn't the strongest engine, the poor factory gearing is more to blame. The manual 3.8L should had came from the factory with 4.10 or 4.27 gears. The auto 3.8L should have came from the factory with 4.88 or 5.13 gears.
My 07 3.8Lauto with 4.10s and 29inch tires lift up and hauls ass when gunned. Little two door with baby tires

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post #14 of 52 Old 04-12-2015, 04:33 PM
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Quote:
Originally Posted by tapcola View Post
I cant get 15 , but you are getting 19.5 really ?
Guess I shouldn't mention my 20.5mpg.

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post #15 of 52 Old 04-12-2015, 05:37 PM Thread Starter
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My JKU is actually an automatic,,My next trip to the beach I will run 93 octane and try 4Lo I dont know why I didnt try it in 4Lo I figured the engine would be turning a lot more rpm's,,but if I kept it in Drive it would go ahead and shift as needed. Duh....
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post #16 of 52 Old 04-12-2015, 06:22 PM
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High octane gas is for high compression engines and is not recommended for the 3.8. It'll run like shit on ethyl.

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post #17 of 52 Old 04-13-2015, 07:40 AM
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while this certainly isn't an engine that will impress anyone with it's power, I think your problem is more related to crappy gearing. I take mine out on the beach with no problem at all. I have 3.73 ratio though rather than the 3.21 or whatever they came with.

also at 60K your spark plugs are nearing the end of their life, could have a little to do with the knocking.

more air will definitely not help you. running higher octane may make the knocking and pinginng go away but it is really a "bandaid" fix rather than finding out what is really causing the problem.
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post #18 of 52 Old 04-14-2015, 06:45 AM
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my 2010 two door rubicon with the 6 speed manual runs comparable to my old 2003 rubicon with the 5 speed manual. I'm content with the power of the 3.8 in my jeep... now the 4 doors are another story....

Jeep sold 9/18/2015.
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post #19 of 52 Old 04-14-2015, 09:52 AM
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Sorry to state the obvious, but did you air down? Makes a big difference, more floating and less bogging.

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post #20 of 52 Old 04-15-2015, 12:55 PM
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Use 4Lo in the sand.

Those that complain that the 3.8 is underpowered really haven't tried underpowered or undergeared until they drive a 4 banger CJ, YJ, or TJ!

As for it being the worst engine in a Wrangler, again, they clearly have no experience with the carbed 4.2 in the first wranglers.

Too many lack experience and can only regurgitate what they read on the net!


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post #21 of 52 Old 04-15-2015, 02:25 PM
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Quote:
Originally Posted by Victim Of Pain View Post
Sorry to state the obvious, but did you air down? Makes a big difference, more floating and less bogging.
^^Zing, Bingo!!^^ I was going to mention that but I decided to read through. Yeah driving tires inflated will bring the dregs to your engine and overall performance in deep soft sand. Probably bring about some knocking also.

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post #22 of 52 Old 04-15-2015, 07:58 PM Thread Starter
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Speaking of spark plugs,, I

had a mechanic tell me to run a cooler plug to reduce the spark knock?

I deflated down to 15 psi which is what they recommended,, they didnt look like they were very slack though.

So I think I have a gameplan for my next beach trip,,Run in 4Lo and let more air out
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post #23 of 52 Old 04-15-2015, 10:08 PM
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Oh man, but 6 pots in a row just "feels" different than a V6. You feel the weight of the crank and the stoke of the engine and it just kind of gobbles up the road right off the line, even if it isn't fast.... 4Lo with a manual you just dump the clutch and it goes "blop blop blop" over everything at 500RPM.

The V6 Jeep just isn't the same.

The 3.8 is a total turd, I built many first gen JKs and was gearing them with 5.13's with 35's.
That being said the JKS JK has the 3.8 and the auto with a Sprintex Supercharger and the latest tune and it does alright. We're doing the newest intercooler/pulley kit with a complete reflash soon and Sprintex says that will hike us up into the 300's and will get us considerably better mileage. Bang for your buck the supercharger is still WAAAAY easier than an engine swap and does ok.

I'll do a little write up here when I do the upgrade.

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post #24 of 52 Old 04-16-2015, 12:13 PM
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Oh man, but 6 pots in a row just "feels" different than a V6. You feel the weight of the crank and the stoke of the engine and it just kind of gobbles up the road right off the line, even if it isn't fast.... 4Lo with a manual you just dump the clutch and it goes "blop blop blop" over everything at 500RPM.

The V6 Jeep just isn't the same.

The 3.8 is a total turd, I built many first gen JKs and was gearing them with 5.13's with 35's.
That being said the JKS JK has the 3.8 and the auto with a Sprintex Supercharger and the latest tune and it does alright. We're doing the newest intercooler/pulley kit with a complete reflash soon and Sprintex says that will hike us up into the 300's and will get us considerably better mileage. Bang for your buck the supercharger is still WAAAAY easier than an engine swap and does ok.

I'll do a little write up here when I do the upgrade.
Gotta call BS on that 500 rpm with a I6. At least you didn't exagerate as much as the guy that tried to tell me he cruised trails all day long at 300 rpm with the I6! "gobbles up the road right off the line", that's funny! All the way up to 2700 rpm when the torque curve falls flat on it's inline 6 face! At least the 3.8 keeps building torque up to 4000 rpm, and with more HP to boot!

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post #25 of 52 Old 04-16-2015, 12:41 PM
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Originally Posted by PKDailey4 View Post
High octane gas is for high compression engines and is not recommended for the 3.8. It'll run like shit on ethyl.
Octane is just the ability to resist detonation. The 3.8 can run just fine on higher octane, it just doesn't need it. Winds up being a waste of money. For the situation the OP spoke of, it might not have been a bad idea to have the good stuff in the tank.

Sand= low air pressure in the tires and RPM

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