MUST Have Jeep Wrangler/Cherokee 4.0 Upgrades?

In this video we talk about your options for upgrades for your Jeep Wrangler TJ, YJ, Cherokee XJ, or your Jeep Grand Cherokee ZJ, WJ, WG, Jeep Comanche and probably others I am missing 4.0 Engine. I show you the Intake and exhaust, and header i have on my Jeep and then we install a 62mm throttle body from eBay and a performance ignition set from CRT performance. Is it really worth spending $200-$500 or more on engine upgrades.
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[@seniorxj2931]

As far as motor upgrades on my 98XJ; Banks Header, Hi-flow cat, Flowmaster 44, true cold air intake, 62mm throttle body w/1" spacer, 703 four hole injectors, MSD Blaster coil pack, MSD ignition wires, cap & rotor w/iridium plugs, Mechman HO alternator w/two XS batteries with all 1/0 wiring. Also, all sensors are new & are Mopar and I have an on board OBDII that streams live data to my phone!! Now I didn't do all this for power, I did it to let her breathe and be more efficient especially with 170k on the OD. 😉

[@merylpelosi1704]

To quote Stevie Wonder from over 50 years ago: " When you believe in things that you don't understand, then you suffer". A bigger throttle body will only make more noise. MAP will not be affected, partial throttle response will suffer. Bigger plug wires won't increase ignition secondary voltage or current. Your big-assed cat and turbo muffler get choked down by the stock sized exhaust pipe that now runs precariously close to the rear driveshaft. Your air filter now gets to suck in heated under hood air and is restricted by the primary filter, thus negating the bigger throttle body to begin with. Other than that, great job!

[@ke4gbe]

As a long time YJ owner, putting on an aftermarket header made some improvement, but the big gain came with replacing the stock air filter. After many miles, I replaced everything but the coil in the ignition system and was surprised how much it smoothed out the engine. One additional fix - adjust the throttle cable to get out the slack. It gave me a much more responsive engine.

[@rayzielonka7856]

I got my injectors from Ksuspension. Noticeable difference. Ran smoother, more pickup. Eadier starting. The best benefit was gas mileage. I used to get 170 miles from a tank. With the new injectors, I got 250 miles from a tank of gas.!

[@MuddyBeards4X4]

I am definitely going to get a set👍🏻

[@anythingwithplanes]

@@MuddyBeards4X4 I’ve done several sets of injectors on my 4.0s. fake. K susp. Stock. Only noticed gains if the stocks were leaky or work out. Currently got a set of Chinese 12 holes running on one and k susp 4 holes on the other. Don’t notice anything different not even in the fuel trims. K susp does warranty theirs and I’ve exchanged a set before. Easy company to work with no regrets but never saw gains

[@claytonsaxton6757]

Hey ray, which injectors did you end up getting? The 12 hole?

[@rayzielonka7856]

@@claytonsaxton6757 I got he 4 hole injectors. I think the 12 hole needs a different pig tail connector.

[@stevens-garage]

@@rayzielonka7856 12 hole use the same connectors, at least on my 2000 they do.

[@robertl9065]

In my experience, matching your axle gear ratio to the tires being run will is pretty much the best thing you can do for power. All of the throttle body mods, plugs, wires, programmers might get you a little. But it won’t even compare to having proper gearing. Unless you spend thousands and many hours swapping in a 4.6L Stroker or adding a supercharger.

[@Mark622111]

Totally agree, got to change axle gearing if you plan to slap on 35" tires. I built a 4.7 engine for my 98 Jeep Wrangler 4.0L which helped Her to reach freeway speed on 35" tires, but still lacking, then did an axle upgrade to match 35" tires. Long story short, She runs down the freeway at 75-85 mph on 35" tires, crisp starts from red lights, etc... It's a Jeep at the end of the day / not a sports car. I may try the larger throttle body matched to an enlarged intake ID as 4.7 sucks more air.... Please don't take my comments as critical as I've learned a few things and we all learn from each other. And yes, building a 4.7 stroker is not cheap per muddy and only adds some torque, go with axle gearing if your slapping on larger tires. I respect those that share and take their time to share via videos.

[@skylarfugate7346]

doesn't help he's running heavy 40 inch tires if he put a lighter tire on it might be a little better yes gearing will help but then you always have to have those tires

[@stephendockray6698]

I have a completely stock 05 TJ sport with 3.73 gears on a Dana 44 rear/Dana 30 front. What gears do you think I need for 33 inch tires. Stock tires are 30x9.5x17R.

[@GIFTOFGVME]

@@Mark622111 hey dude, where do you typically get the axle gear ratios done? im more than competent on doing little things to my jeep, but dont think I could handle that job? is it a tough thing to get done? thanks!

[@chriswhitehouse9764]

The greater plug wire diameter really only buys you more silicone for greater ability to resistance to loosing slight spark energy if routed near grounding items. I used to manufacture and test ignition systems back in the day. 8-)

[@devenstone7449]

Great info to know.

[@denniscosban6145]

One of the greatest motors ever made. The only flaw. The fuel injectors are right next to the exhaust manifold. The fuel gets hot. After a while you go through catalytic converters, or mufflers. My suggestion. Buy fuel injector boots. They go around the fuel injectors. Solved my problem. ✌️

[@MuddyBeards4X4]

Yup, I did that years ago, I have a video on it. It definitely helps 👊🏻

[@timmyl2005]

I changed the Fuel Rail to a Billit Fuel Rail and Insulated to Reflect the Heat. I need to drive it and ill report back. I know this is not a new Post. Duh. Just

[@nathanmccumber8965]

​@@MuddyBeards4X4link to video please and thank you about the boots.

[@maxdicus7846]

Recommend replacing intake manifold with a post '97 intake. The updated intake allows more airflow to the ports, and will take advantage of your new throttlebody.

[@scottbutts6703]

One other thing: if you change to an electric fan you can gain almost 30hp at the top end. This has been tested and proven. The only drawback as far as I'm concerned is that the mechanical fan moves more air, and sometimes that's what you need when you're moving slow out on the trail

[@unique-daann6098]

Why not have both?! I gotta fix my wires for my electric fan.

[@zachsheffield1325]

Then why not have two electric fans?!

[@kingwiththeax6880]

@@zachsheffield1325 because the relays can burn out. you can carry spares, but sometimes they are difficult to access to replace. mechanical is far more reliable.

[@davidschlarp1606]

Where are you going to run 2 fans?

[@kingwiththeax6880]

@@davidschlarp1606 lots of vehicles have 2 fans. Specifically, my WJ 4.0 has a mechanical fan and an electric fan. Electric was standard on that model, but if you got the factory tow package, they added the mechanical fan for “heavy duty cooling”. The WJ electrical fan was controlled by a relay, so it only operated when called for, usually when running the AC. The relay is located behind the headlight, where it would get hot and burn out, frequently.

[@rhyelince8277]

I put a 62mm tb and a spacer on my 2.5... Lost low end torque, gained high end power, but I have a sweet intake whistle now

[@motownXJdad9565]

there is a 4 part interview with Rick Mudge on youtube on the AMXJ channel i highly recommend every 4.0 owner take a listen. Rick Mudge was the engineer in charge of AMC- Jeep & Chrysler cylinder head, intake amd exhaust development from 1976-2001, hes the godfather of the 4.0 and knows more about them than anyone i suspect.

[@oscarbear7498]

Link pls, I'll take a look

[@ashtonmariefranklin725]

Tune the EFI for even better results. Not jeep related but. I put a 75mm ported TB on my chevy s10 4.3 factory was 75mm necked down to 70mm with a restriction plate on the butterfly. After opening up the factory TB. It has instant throttle response and noticeable difference. But then took hp tuners and tuned it for the extra intake flow and got even more noticeable performance increases. Im sure if you tuned the pcm you'll definitely have a bigger performance gain then from just doing bolt on mods.

[@litz13]

I put the 4-hole Mustang injectors in my 97 XJ something like 22 years ago. Still in there. Honestly not sure they really made any difference, but I always figured better misting can't hurt things.

[@christophernava6685]

I installed the k suspension 4 hole, not sure if it helped my mpg but it did help my starting.

[@leefhead1]

Great video. Next time you want to “machine” or “lathe” a fitting down, chuck it up in a drill and run it against some sand paper or a bench grinder. Keep on keepin on brother

[@MuddyBeards4X4]

Good idea, I have sanders that would have worked great but I couldn’t figure out how to hold it. Drill chuck would have been perfect. 👍🏻

[@TimmayFilms]

One more setup you may want to try. a Holly Capacitive ignition system with tri-fire sparkplugs. Both create a tri-leg spark to ignite all fuel, and the capacitor (energy storing) ignition also creates, generates high/fast enough firepower to keep the juice flowing. I used a blaster coil and 10mm sparkplug wires, a Holly performance distributer cap and rotor; and Jeep oem style injectors with a four hole design.

[@TimmayFilms]

My 97 TJ 4.0 is the last model year with the single, primary coil setup. According to a couple of racecar builders I confer with regularly, my dreary throttle response, especially at the lower end was more about the explosion trigger and completeness, than the air and fuel content, which i had already addressed, similar to this video. They suggested that in order to prevent a "slow/low" firing condition, the ignition system needed a "middleman" to develop and maintain enough voltage for a sufficient amount of spark, firing consistently within the prescribed/preset timing intervals. I needed something between potential and execution that could/would manage the process. The primary reason that the (single) "coil over (spark) plug" is now the industry-standard is precisely for control and bottleneck elimination. The ECM can precisely control the voltage discharge level and timing consistency at each cylinder. This was less important in "the olden days" before the emergence of automobile standard and attachable, electrical gadgets and devices. Every time a device is turned on or off, there is a corresponding surge or drop in the direct-current loop. The residual effect is absorbed or lost within the succession of other devices powered at that time. There are only two ways to resolve the condition, "coil-over-plug" so the ECM can regulate it, or if that's not possible, then installing a regulator, one-step past the ECM, would be the next best thing. With that "regulator" you also get the additional benefit of an RPM "limiter" (in case you snap something within the drivetrain during high acceleration) The CDI prevents major damage to the engine from the ensuing spike in RPM's, while the uncontrollable bottleneck is also avoided, thereby eliminating the loss of performance from primary voltage-lag (slow) and/or a lowered, constant throughput (low). I used the Holly (MSD) Street-fire CDI. This essentially replaces the primary function of the ignition coil, while providing as much voltage as needed, when needed by the sparkplugs, to ignite the fuel, while also protecting the engine, (offroad) if say you bottom out and snap a u-joint during an up-hill climb.. Additionally, in order to fully and more effectively utilize the 3-legged spark, produced by the Street-fire CDI, I installed the E3 Tri-Fire sparkplugs (E3.58), which are made to split the spark into three legs. Then, in order to insure against any other bottlenecks, I installed the following: Taylor 36271, 409 Spiro-Pro Spiral Core 10.4mm Spark Plug Wire, a high-0performance Accel 120330 Distributor Cap, and a "Borg Warner D228" Rotor (better build). I also replaced the coil with an "MSD Blaster 8228". All other engine mods described in this video, are already installed and modified for optimum performance. The difference in performance is truly "night and day". One other thing I want to mention concerning "mods": I recently installed a "Spal 30102049 16" Curved Blade Performance Fan", but I am planning on switching back to mechanical. It's just way too, dang loud and the pitch is irritating and as obnoxious as heck. The Jeep is completely customized and that one aspect repels any would-be observer, coming within about a 20 ft radius.) I'll just keep a spare fan-clutch onboard; 'Cuz in the Jeep world. as we all know: "Two is one and one is none!"

[@NB-yn7dv]

Over the course of the three 4.0’s I have owned including an early 90’s xj and two late model tj’s I can tell you that the best way to have a “powerful” 4.0 is to use factory mopar or ngk sensors and keep everything stock mopar as much as possible including the intake and exhaust systems. From my experience there are no “add-ons” or combination of add-ons for the 4.0 that will amount to anything more than a placebo feeling that there is more power. The only real way to get more power is to stroke it and I’m not convinced that is a good option either.

[@alale923]

Facts.

[@frankieoffroad]

The turbo I put on my 4.0 as an "add-on" made for a more powerful 4.0. 😆

[@remingtonnewkirk8981]

I mean…. My 4.7 stroker with intake, exhaust and upgraded fuel injectors definitely made for a massive improvement. Much more drivable at freeway speeds with all that added torque and horsepower. Not necessarily cheap though…..

[@motownXJdad9565]

theres a great 4 video interview with Rick Mudge on the youtube channel AMXJ i believe. hes the godfather of the 4.0 i highly recomend veiwing, alot of what the the internet and social media thinks about the 4.0 isnt correct.

[@Truckerdaddy]

Look up Newcomer Racing. He's an engine builder that primarily does 4.0s. He's even built a record breaking 4.0 engine that made over 800hp if I remember right.

[@altereddisposition4827]

A banks header pipe and 3" free flow exhaust hot coil low resistance wires made a big difference for me

[@russellalbro6600]

I did the banks header .. Bitchin isn’t it , but I have the stock exhaust, but I have a cherry bomb sounds great and works wonderfully

[@xSKOOBSx]

I read a long time ago that some good power can be gained by swapping a TJ air intake manifold into a YJ. they basically redesigned it for better flow to make up for the power loss due to emissions regulation changes.

[@chrismulhauser333]

I hate to say it for us with the older 4.0s with many miles but the best way to get more HP and torque is a head job recently did mine and it’s like a completely different animal now

[@katm983]

What all did you do?

[@robertdepyssler2769]

Raffy at K Suspension is outstanding. I put his Viper coil and plug wire conversion kit, his power wire kit and his rebuilt 4hole injectors in my 4.0 TJ and I was impressed. Let's face it, we're not in a race vehicle, so the wide open HP isn't important but the torque is and mine picked up more torque. You'll be pleased with His injectors. They are worth the money.

[@MuddyBeards4X4]

Great to hear 🤟🏻

[@keithlea6804]

Had a 258 that was built by Clifford and a ford 300. Both put out 300hp and around 485 foot pounds of tork at the rear wheels. Always liked to see a built straight 6 under the hood. Clifford research was the go to guys in the 80s for building straight 6 engines. Not sure who is today.

[@Gungie00]

Newcomer racing has a few options for the 4.0

[@connor3288]

Unless they had forced induction those numbers cant be right. N/a engines are doing really good to be in the 80s for ft/lb of torque per liter, and thats almost always 4 valve head dohc engines, and rated at the engine. I do love inline 6's as well, and have a 04 rubi 5spd. I wish the banks turbo kit was still available. Another thing im gonna research is the gm atlas 4.2, much superior to the jeep 4.0 imo. If it can be adapted to a manual trans that would be an amazing swap

[@onefastcyclist]

I placced a Banks Header on my 4.0 with a K&N intake - Banks claims a 12 hp bost on his dino with that combo

[@learner099]

So I’m running the 12 hole injectors from K Suspension and I’m super happy with them. When I swapped the new injectors in I also swapped in a billet fuel rail as well.

[@bhooks21]

MyTJ has an actual tuner on it. I had a jump from 133 HP to 145 HP with everything else stock. This was done on a dyno. It is the biggest bang but its is expensive. With HPtuners now supporting the Jeep 4.0 it is fully tunable just like an LS. Now saying that I still want/need more power and I am looking into a turbo. it needs just a little more power to run down the highway.

[@crashtke]

Eh, it is much less refined and has many less tables and options as they just have not put much into developing it like they have the LS.

[@dandahermitseals5582]

I don't need a sragstrip engine. Just dependable low torque to sucessfully climb up to my cabin.Dandahermit

[@stevenreyes9209]

I got an 01 cherokee and used 12 hole injectors off a chevy hhr from a junk yard and they swap right in

[@nathanmccumber8965]

Good to know. I just 2000 Cherokee sport will those work for me what year was HHR.

[@tomtheman91]

Had a 99 cherokee put dodge neon injectors the 4 hole ones in it noticeable better mid range power o er the single holes.

[@trakkerp4202]

I already had the 62mm throttlebody on my 4.0 when I got the Jeep, decided to do some other mods too. Cause its an 01 WJ I have electronics so ended up with Ksuspensions Viper coil mod and love it, also did a 12 hole injector swap. Injectors were el cheapo used so I'm expected a CEL soon but my mileage and power difference is noticeable over stock. Cold air intake, KSuspension 12 hole injectors and battery wire kit are next followed by skid plates. As for your throttlebody missing the sensor nipple the ones from the stock TB come out easily with a torch and, at least on the ones I worked on, can be pressed into the new with a bit of sealer on.

[@tira_otro_cambio]

I have an 01 wrangler 60th anniversary will be doing a complete tune up soon this was a good video these 4.0 are real offroad warriors 💪 there's so many cool things you can do to these beauty's 👍

[@MrAllyWow]

How did it go? any updates i have a 1 wrangler 60th anniversary also, curious what you did and the difference it made?

[@tira_otro_cambio]

@MrAllyWow my transmission failed I haven't had a chance to do anything but should be up and running soon

[@thousandoaksauto1696]

good info, fix the exhaust leak, then recheck your performance!

[@barbe-rousse5775]

One way or the others, you need to change the spark plug sometimes. From what I heard the in-line 6 should be change every 50 000 km. So it's just regular maintenance.

[@russellalbro6600]

what is 50000 km in miles.... this is America so we need miles :)

[@brianmiller6340]

@@russellalbro6600 Roughly 30000. That seems a bit excessive to me.

[@dorsk84]

Look on The Horsepower Monster channel. They have done a few vids on getting power out of the 4.0. Like 800+ HP levels. (Bore/stroke, turbo,....) I don't think you need that, but some of the mods would definitely help better then just a throttle body and some sparkplug wires.

[@CallMeAdam2023]

Yes! Good to use regular plugs, never Iridium. The 4.0 is an older designed engine, its happier with copper

[@matrixbikes]

Iridium spark plugs are the best on any engines! I have great improvement with my 4.0l Jeep wj! Get it right!

[@terraforge_motorsports]

Hey Kelly love the content! I’d recommend reaching out to Keith at Newcomer Racing if you have any questions on the 4.0s. He’s “the guy” when it comes to building out these dinosaurs

[@johnthegiant320]

1000hp with stock bottom end.. yeah he's the " guy "

[@terraforge_motorsports]

@@johnthegiant320 yeah I know! Definitely a smart choice using the fully counter balanced crank. I can’t believe it made multiple dyno passes and still held up

[@TheGersh13]

Do a stroker kit on the channel man! High quality/modern videos for that subject aren't something that's really common. I'd be interested to see how you like it!!!

[@MuddyBeards4X4]

I think that is the direction I will go. Since I just built this transmission, doesn’t make sense to go LS. I don’t want a bunch of power anyway, don’t want to break my 1/2 ton axles.

[@markdenenberg9110]

Picked up ksuspension 12 hole injectors and the ripper coil and plug wires also the 7 large wire upgrades. Most noticeable change was the idle smoothed out. Also a better throttle response and picked up about 4 miles per gallon. The starter spins must faster and lights no longer flicker. Best money ever spent. Looking at selling my suburban and getting a 4.o stroker.

[@swatscorner]

Wish I’d seen this and had your advice before I changed plugs and injectors and fuel pump and fuel tank. Can’t start and no idea why! Thanks for a great video.

[@MuddyBeards4X4]

Yea… that’s a tough one. Start at the easy stuff, fuel and spark and work backwards

[@swatscorner]

@@MuddyBeards4X4 thanks. Took to mechanic. Timing was off. So distributor must’ve been installed wrong, though I don’t know how that happened.

[@zaninenterprises9003]

I did a 4.0l swap into my 82 CJ. I connected my MAP sensor to an extra port on the intake.

[@jack-nv3ty]

Never increase the gape on your plugs. I have played the that game for years with random misses then tried to lowering the gap by a couple of thousandths and all the engine I have done this run the better and over time the gap opens anyway. I’m 56 and and done this on Toyota Jeep Chevys

[@MuddyBeards4X4]

With a stock ignition coil absolutely. This is a higher power coil that can produce a spark that can handle a bigger gap. So far it runs great. But I guess we will see.

[@jack-nv3ty]

Even with coil on plug it works better to be tighter. I first started to over gapping plugs when I bought a Jacobs ignition in 1993 For a 1991 4Runner to try to get a little more power it didn’t work I also used all the snake oil plus to get a little more power on many different engines. Till I noticed that I would get random misses and took the plugs out of my 5vz fe and cleaned and set the gap tight by .003-.005 closer and yes that engine has duel ground plugs and it worked grate. I also only use the cheapest plugs I can find and through them every year. Oh ya i just replaced a broken piston on my 97 XJ and did the same thing it runs great. It will be getting a SBC in the spring though. Oh if you run Magnetos I think you could gap the plugs 2 feet😃 good luck 🍀👍 I have to fire up the death wheel to make room for 35” Milestar patagonias M/T i got Facebook market place cheap let the spark fly

[@fun6243]

Those inline filters are good for diagnosis. If you have "running" issues and have gone the mile. Go ahead and throw in a fuel filter. It could be dirty fuel. It usually is not the throttle body, kinda nice of em.

[@poker8193]

Iv learned over the years that a daily driver slightly modified does not benifit from expensive ignition but heavily modified non pump gas engines do just my opinion

[@Adrenalineoffroadad]

I think you will be able to get a better throttle body and get better results.

[@garywilliams7484]

Great video, Happy to see you back to working on your TJ. Throttle body is my next planned upgrade. I have already done the ignition and fuel injectors on my 98. waiting on you guys to take a trip down to Cross Bar in Oklahoma.

[@MuddyBeards4X4]

Thanks, it feels good to be working on it again!

[@BadmunkyWRX]

Nice video man! I have a 62mm TB sitting here for mine right now. That said don't bother with a stroker build. I did that to my last Jeep and it was the biggest waste of money! It makes very little extra power for the money. Do a 5.3 LS swap and the trans to go with it. Its not much more expensive than a well built stroker, and you have plenty of power. Don't mod the 5.3 or tune the crap out of it. just a box stock 5.3 is all you need. Plenty of power, much better MPG, sounds great, and way more reliable than the 4.0 is.

[@connor3288]

"way more reliable than the 4.0". I am curious, why do you say that? Only problem areas i have heard of with 4.0s is the early 00s or late 90s bad heads and the 05/06 oil pump drive gear thing. I have had 3 2004 jeeps, 2 wranglers with 5speed( currently have rubicon with 230k+ miles) and a grand cherokee. Never had any issues. Only electrical issues, one ecm on a wrangler went bad, and suspect a bad cluster on grand cherokee, those wjs are known for electrical issues, ended up getting rid of. I know ls engines are pretty good but not perfect, probably quite a few have died from the oil pickup orings going bad. Not sure if 4.0 has an oring, i will look into it. Might paint or replace my rusty oil pan, would be a perfect time to change.

[@BadmunkyWRX]

@@connor3288 I hate technology! I typed a nice reply explaining why I hate the 4.0 and them it was just gone. Short version, they have a lot more problems than you think. Piston skirts like to crack, they eat cam shafts often, oil pumps fail often, timing chains have problems, oil pump drives fail on 99 and up with 05-06 being the worst, ODPA on 99 and up like to fail often, head gaskets fail often, lifters fail and tick on every year of the 4.0, every year has rear main seal problems, the early ones had one of the worst fuel injections systems ever built, later ones had a coil pack that fails constantly, exhaust manifolds crack or the gasket at the head fails or both constantly, and I had bunch more typed out but I don't have to add all that back in. I have owned over a dozen of these things over the years. It has time and time again proven to be one of the least reliable engines I have owned. At one point I had 32 blown 4.0s behind my shop. (I only blew up 2 of them, the rest where customer engines, of the 30 customer engines only 2 were something the customer for sure did. One was hydro locked, the other ran with no oil in it do to a leaking rear main seal.

[@keniferusxj7047]

4.0 will out last any 5.3 if taken care of..remember it’s a jeep not a hot rod

[@BadmunkyWRX]

@@keniferusxj7047 LOL Not even close! 5.3 will outlast a 4.0 every day of the seek if they are both cared for the same. At one point I had a massive pile of 4.0s behind my shop. 32 of them to be exact. There where 4 5.3s back at in the same time frame. I get a call for a blown 4.0 every other week. I get a call on a blown 5.3 every 3-5 months and at this point they have sold a LOT more 5.3s than 4.0s. The 5.3 is well known to go 400k and I have seen over 50 of them above 400k. I have seen 3 4.0s make it that far. No place but in Jeep fan boys heads will find any data showing the 4.0 to be a longer lasting engine than the 5.3 is. Jeep dropped this engine in part because it was not reliable enough and the warranty claims were to high. They looked at updating it to meet the higher 2007 emissions standards and keeping it in the JKs but the cost to fix all its problems and get it to do that was higher than the cost to just adapt the 3.8 and run that. So the 4.0 was killed off for what its. An outdated, under powered engine with average reliability at best.

[@seanfrank4158]

Uhhh....WAY more reliable than a 4.0? I think you don't know much about 4.0's if you think that....

[@chev500l8]

It may sound weird but the best upgrade is a 258 american motors inline six( 4.2L) they can be built for off-road use and if you use the right parts can be made to belt out 250-85 hp before having to worry about breakage. The only downside is the engine is all cast iron so a 258 weighs about 275 pounds more than a typical 4 liter (from 1996-06,end production year)

[@YouTubeDoxedMyRealName]

Fuel injectors are the best and most important upgrade you can make to a 98 and older Jeep. Chrysler put the oldest crappiest injectors they could on them from the factory. I pulled injectors at the scrap yard and they even had a lower flow rate then stock and the difference was night and day. The first thing I noticed was that I actually had engine braking in 4 low unlike before. The other thing was I got 5 more MPG. I did later pull higher flow injectors for it and they work great to. Funny story Chrysler invented the the fuel injector. Also funny story Dodges and Chrysler of the 90's years had ev6 injectors while Jeep had ev1's....

[@andrewchristiansen8311]

7:48 Looks like a small blow-by filter I've seen on CAT engines in semi's. Some of the renix Jeeps had for crackcase vents that prevented oil in your air box at high rpms. Kinda like an air dryer in compressors. That was the upgrade fix for it I believe.

[@davidchappelle6480]

Look up Newcomer racing an see what Keith did to a 4.0 !!!

[@MuddyBeards4X4]

I definitely will👊🏻

[@4x4ManiacBadTimeGarage]

i have the CRT kit in my 5.9 jeep, works good so far

[@harvestblades]

Great video & picking up 15hp & 20 trq is actually really significant considering where you started.

[@vishibalo1]

For the throttle body modification. I don’t know if this was mentioned. But why didn’t you use a threaded hose fitting? Tap the throttle body and get a brass fitting with thread on one side and barbed end on the other?

[@bensfixitpage341]

Your mpg will likely improve when you fix the exhaust leak.

[@chev500l8]

The TB comes like that to allow drilling and tapping for the map sensor, before 1995 you can plug it, as those 4 liters used a different fuel injection system.

[@harvestblades]

Whike the upgraded injectors are a good call there has been a lot of debate whether the majority of the increased performance is simply coming from new clean injectors & not as much the improved Squirt. I woukd love to see someone throw on just new OEM single hole run those for a month & dyno if possible to see the mpg, hp & torque they are getting & then throw in the Bosch & test again.

[@nathanwoten6236]

Ive had a 4.6 stroker kit and also a 4.0 with centrifical supercharger and they both gained alot of power over stock and i liked them both but if i was goimg to do it a gain id say id have to pick..... LS swap lol.... but really id take the stroker kit again it toom less tuning and both were reliable but the charger i had to do alot more to get it dialed like more heat protection under hood and i ended up doing i think 3 completely diffrent custom intake setup untill i got one that flowed right and kept intake air temps down ( was my first time ever doing something like that so i had a learning curve). But i liked the stroker more i ordered it threw it in i added a good clutch and a bigger radiator and hit the trails i think from when i got the motor till i was loading my cherokee on the trailer headed tof the rubicon to test it out (i live bout 3 hours from the rubicon) was 4 days only working at night after i got off work with just my cousin helping and 1 friend on the last day. But since then i drove my friends ls swaped cherokee with just a stock truck motor and it feels almost as powerfull as the 4.6 and was much chealer and if he adds a few parts l ike a cam and intake and a holley sniper kit instead of the carb set up he has it would kill my 4.6 . And i forgot to say both my motors were in a 99 cherokee 4 door, manual! 38s and tons, with a advanced adapters doubler, and a homebuilt 4link long arm front and rear.

[@MuddyBeards4X4]

Nice, good to know 👊🏻

[@MarkShinnick]

Seems like more time, money and effort than worth the actual results compared to temperature shielding and a better flowing air filter fed by the original front cold air intake hole. Nice you determined up to .06 gap is ok. Very true is very few other things, beyond a good header and great intake and exhaust flows, can realistically be done.

[@danhambrick6331]

That's why I'm going with a 4.7L stroker for my 2001 XJ...💪😁😁

[@MuddyBeards4X4]

Let my know how it goes. I will definitely be interested in this at some point.

[@thecrazych1cken575]

@@MuddyBeards4X4 it's definitely worth it. My 4.6 has plenty of torque right off idle. It's very snappy and is a blast too drive!

[@jonarment1229]

If you want more usable power, you're FAR better off spending your money on lower gears, than on engine upgrades. My 99 with an automatic transmission is running 4.10s with 33" tires. It's a little revvy on the highway, but on 37"+ tires it's probably just right.

[@jackiejoe8930]

Thanks for sharing that simple problem solving sorting out issue from adding new parts

[@MuddyBeards4X4]

Thanks 👍🏻

[@jackiejoe8930]

@@MuddyBeards4X4 that simple step will save someone a big headache.

[@thelonewrangler1008]

I was honestly dissapointed at the end of the vid but then you posted the #s from the test and I actually enjoyed the vid knowing that putting all that $ and non factory stuff on is not worth the minimal hp gain. I do think that you need to get the right injectors because I have heard good things about those

[@ibrigs19]

These are all supporting mods, they're not going to do much without a cam and a tune.

[@windedwarriorsracing9722]

heads up- in our first race with the ebay 62mm throttle body like this, the throttle stuck in wide open twice. luckily our driver was able to get it to the pits and we had to lose a few hours coming up with a fix. the problem is it wasnt machined perfectly, and once it got hot the butterfly expanded more than the housing and caused it to hang up. beware.

[@MuddyBeards4X4]

Good to know, I have already taken it off… don’t plan on putting it back on.

[@zacharywhitlock3130]

@@MuddyBeards4X4 why did you take it off?

[@billykurtz]

Bro, you need to check Newcomer Racing and his videos on The Horsepower Monster's channel. Your opinion that 'the straight six 4.0L isn't a very tunable engine' will be forever changed. The mods you did in this video are definitely worth the cost, considering if you replaced those items with OE equipment it would be about the same cost. The only thing you're missing in the equation is remapping the ECU, it's completely necessary when modifying for gains and is the reason you weren't very impressed with the HP/torque improvements, if it was even 10-15hp you would notice it immediately on WOT.

[@michaelcanto6175]

Who doesn't want more HP, but realistically considering your use highway/offroad, trail speed and torque is more important.

[@user-jd4nt4ie4c]

Man your a STUD... Got these parts and the throttle body didn't have the right shit but you kept going and Jimmy rigged the MAP sensor and got'r done!

[@johnmohanmusic]

Great video. Just one thing: at 11:37 I believe your wording is backwards. You are not "discharging the Positive out the Negative". The negative side of the circuit contains more electrons (which are negatively charged, hence causing that side of the circuit to be the Negative side). When you hooked up the jumper cable from the positive terminal to the negative cable to erase the ECU's learned parameters, you induced electron flow from the Negative side toward the Positive side. So you are actually discharging the Negative out the Positive. I am so glad I spent $37,000 a year studying Biomedical Engineering and taking classes such as Circuit Analysis so that I am relatively qualified to leave unnecessary critiques on KZbin videos. 🤣

[@MuddyBeards4X4]

🤣 all I know is you hook the thingy to the other thingy and then it does stuff….

[@codeyalan]

The 62mm throttle body isn't going to help unless you need with the head. That's where the restriction really is. And adding newer parts will make a difference because most of the time the parts we replace like this have over 150k miles. Just an FYI.

[@gixrman]

I swapped the injectors for used ford 5.0 injectors and pigtail adapters. Much better idle and TR.

[@johnsheetz6639]

Interdasting.... 🤔

[@jeremypalmer5950]

They have 12 hole injectors. Work better then the 4 hole.

[@elisalazar3097]

I got an aluminum radiator for my 99 tj 👍runs cooler 😂

[@MuddyBeards4X4]

I have one as well, with a electric fan, works awesome 👊🏻

[@thomasmcgovern2431]

Get some ford 4.2 injectors,already to flow more fuel and are plug and play to jeeps harness.

[@off-roadtimes8930]

You really need to check out newcomer racing. He tunes and builds these engines and he works winders with them.

[@MuddyBeards4X4]

I will, thanks 👊🏻

[@jimmiebroadbrook1057]

I think if you would have cleaned your old throttle body put new sensors in it I think that would be enough because your intake manifold is still .50 or 55 whatever it was

[@gregscherf9385]

What about the edelbrock aluminum head? Could increase some efficiency. Maybe a mild cam swap too

[@rickmarquart3277]

Great video, Kelly. You get a new camera? Really clear video. Thanks 👍🏼💪🏼🇺🇸🇺🇸🇺🇸

[@MuddyBeards4X4]

Thanks man, same camera I have been using for about 2 years. Just good lighting I guess.

[@KSuspension]

Please do give us a call before you order. We’ll get you set up! Happy Trails!

[@MuddyBeards4X4]

Thanks, I definitely will 👍🏻

[@bonespur2728]

Can you do a little update when you get those injectors? They definitely helped my old renix xj, but those injectors were 35 years old.

[@nate4036]

I have the Kenne Bell on a 4.6 “poor man” stroker….. that’s a really huge difference from stock🤷🏻‍♂️😂

[@louiscypher4275]

You forgot 671 blower with rock crusher and Dana rear.

[@messix7768]

Kelly can you go into more detail on the method to have the ecu to relearn? it looks like you have used a jumper cable to connect the positive and negative together at the battery!? that might go boom!!! [ i know what you did but it's unclear and others might actually do what it looks like.]

[@MuddyBeards4X4]

Haha, I did say I disconnected the ground and isolated, lol. But yea I can see how people might be confused

[@messix7768]

@@MuddyBeards4X4 ah i missed that you did say that the ground was disconnected at the battery.

[@cjplol6589]

Cracked header tube will mess w the O2 Sensor, causing bad data back to ecu

[@williamgauntt1164]

Depending on where it's cracked...but yes very easily can affect drivabilty...should been done first...

[@mohameddabous3781]

Can you please explain how you make the computer learn

[@MacsSpecialitiesMotorsports]

4:58 Great Advice!! 🙌

[@MacsSpecialitiesMotorsports]

8:40 Also a great move!! 👈

[@schizzultz]

Don't forget an Amazon light bar. That'll give a fella an extra 27 hp

[@adambatchelder4121]

You have just done some of the suportmods for the real power adders to work and breath. A stroker will add torque, a super charger will add more torque and help make up for poor flowing intake side of the head.. Is it worth it ? Vs a real v8? Depends on a few things smog being one . Personally if I'm going big power like I did with my sb 400. I started with 3/ ton axles than a atlas, nv 4500 , than the eng.

[@deadspeed6679]

My throttle body had a vac leak from the center shaft that caused a rich condition

[@julianbyrd4232]

I highly recommend the CRT Performance HEI for the 4.2 (258) if you want to go that route. I've had my 85 CJ7 HEI'd with a CRT Performance unit for a couple-three years now and it's been rock solid and so far, bomb-proof.

[@Mattmazz77]

It never hurts to have an extra in line fuel filter. Which the clear filter let's you see how dirty you fuel is.

[@bobbysenterprises3220]

I can't see the throttle body really helping airflow without an intake manifold and valve/cam upgrades. The 2000 TJ has distributer less ignition. Not sure when they started it though. Ngk makes platinum plugs also.

[@brianwilson5666]

I think if I’m when I do a motor upgrade on my jeep yj I think I’m gonna go with the Chevy 4.8 Ls V8 it’s about 100 hp and torque more then the stock 4.0L and I don’t think I’ll kill the stock drive train

[@graemedalgleish8944]

Jeep comes stock with the 318 and 360 dodge v8. Either engine, with head work and camshaft, would give you the power of the 340.

[@brianwilson5666]

@@graemedalgleish8944 I just got a 318 magnum motor from a friend and going to do that instead of the Ls

[@graemedalgleish8944]

@@brianwilson5666 I think staying within the same brand will cut down on the parts problems.

[@graemedalgleish8944]

@@brianwilson5666 I run a 340 back in the 70s, the power was incredible. I had my duster up to 145mph. Before you install that engine, I would recommend you do some head work and a camshaft change.

[@shortbusmj]

MUST HAVE UPGRADES “Im not convinced it was worth it for $200” Cmon.

[@JeepTJWheelin]

Jerry Bransford aka the TJ guru "who knows a few things" on the Jeep TJ forums said these upgrades including those 4 hole injectors are a total waste of money. Many others on these forums who have done these so called upgrades agree, time and money wasted. Like you said, these 4.0's are already tuned as well as they possibly can be. They're built for longevity and durability, not high speed performance. What has given me a smoother running 4.0 has been using Valvoline 10w30 150K+ miles Synthetic Blend oil and a few oz of marvel mystery oil at fill ups and about 500 miles before oil changes. Routine maintenance and doing our due diligence is key with our 4.0's. It's seems nowadays a lot of "Jeepers" want the muscle car performance of a '68 Camaro SS in their 4.0's. I don't recall this foolishness from '97 - '06. The aftermarket has been feasting on off roaders in shaming them who keep their rigs stock or close to it. When knowledgeable wheelers know full well, our 4.0's are plenty capable and just require a 2" lift and 32's - 33" ko2's or MT's to have a blast off road! The aftermarket has really done a number on people targeting the not so sharpest tools in the shed.

[@bretthibbs6083]

I totally agree. I use the Valvoline 10w30 conventional oil since I bought it 6 years ago and it runs great. I have 115000 miles on it.

[@jeffmckc2081]

Your Assometer is lying to you. That throttle body added no power in the range you where in RPM wise. The Stroker will add power across the board if you do that.

[@Mattmazz77]

The 4.0L is notorious for cracking headers. Had 1 on a grand cherokee at 1 point it cracked. I had it replaced with the warranty and then it ended up cracking again...lol.

[@danieljohnson8437]

Knowledge is power. Thank you.

[@richfarfugnuven6308]

A 6 speed manual would be the way to go IMHO...

[@Ryan_Tidwell]

Kelly, great video. I'm wondering why you are sinking money into performance upgrades for this old engine. If it doesn't have enough juice you should do a swap. What am I missing?

[@JeepTJWheelin]

I love the bulletproof 4.0, but some have put on insane lifts and unnecessary enormous tires putting an extreme toll on them and the axles that they weren't designed to handle. While others have bought TJ's where the previous owner neglected to do routine maintenance, and that's when our 4.0's lose their longevity. Then people start to bad mouth the 4.0 and swap them out for a 4.7 stroker or a V8. This is bs. I wheel at a moderate to high level on 32" ko2's with a 2" lift with my '05 TJ Rocky Mtn. But I'm not rock crawler, I'm an adventurer hitting mostly moderate to occasional difficult trails. In my opinion, the 4.0 is the best engine ever put in any Jeep. But to each their own.

[@Ryan_Tidwell]

@@JeepTJWheelin I think if Kelly was happy with his engine I doubt he would have spent $250 in performance mods that had negligible results. He's not running 32" tires either. My question is why would he not save that money for an engine swap?

[@JeepTJWheelin]

@@Ryan_Tidwell Good point, he threw $250 out the window. Maybe he sells the 4.0 and tells the new owner about those "upgrades" and gets some or all of it back. I've known rock crawlers who wheeled with 33's - 35's with the 4.0 and regeared and did very well. And they were highly skilled off roaders like Kelly.

[@MuddyBeards4X4]

Thanks, I would like the 4.0 to perform at its full potential, power and efficiency. Also I do have a KZbin channel where I need to make content that people will watch and comment on. So thanks🤟🏻

[@bonespur2728]

In what world does 250 bucks contribute a meaningful amount to a swap? At the end of the day he swapped some old parts for stuff that are new and may help performance. I’m sure he likes wheeling and not having a project sit in his garage for a year too lol.

[@19961djs]

I had issue with those so called Bosch injectors they didn't work worth a shit half of them I believe didn't work at all

[@asusreviews]

Is the ignition upgrade worth it if your distributor, plugs and wires need to be changed out anyways due to age? Or should I save $50 and just go with something thats similar quality to OEM?

[@MuddyBeards4X4]

If you are replacing some parts anyways I would definitely do it.

[@ujayet]

That is the throttle body I got from ebay as well.. looks like yours missing that tube sticking out mine didnt..but the hole on mine where one of the module goes in was slightly smaller and I could fit it in..i had to sand down that module..makes me wonder if these manufacturers ever tested or measuring anything before they machines them.

[@zurn56]

I would imagine it would be amazing if you had a 5 speed trans in a Grand Cherokee it might help. You have more gears & better aerodynamics to get more out of the engine. Other than that I don't see much of a reason unless you are after torque

[@christophernava6685]

not that much better lol I have a 93 xj with the ax-15, stock tires, stock lift, k suspension 4 hole injectors, post 97 intake manifold, banks header. fairly new tune up and only get like 12-13.