That is incorrect once the vehicle is at operating temperature and is in closed loop the fuel is ran off the O2 sensor. O2 enters the vehicle and a MAF sensor and air temp sensor tells the computer how much O2 is entering the combustion chamber. The throttle positioning sensor tells the computer how open the throttle blade is and the computer goes to its fuel table the computer will check demand from throttle positioning sensor what gear you are in what load is on it and at what RPM to tell the injectors how much fuel they should spray. After the combustion cycle, exhaust runs over the Upstream oxygen sensor first the Upstream oxygen sensor compares the oxygen content of the exhaust with the oxygen content of the atmosphere if it notices a difference it makes adjustments by shutting the fuel injectors on and off faster or slower this is called closed loop if your vehicle is operating the way it was intended and efficiently the only way you're going to make a difference is by changing the computer's fuel table other than weight reduction and less wind resistance. Now if your vehicle is not running the way it was intended then the PCM will try to learn adjustments to get the fuel ratio that it wants to see basically if all your parts are running the way they're supposed to it the PCM won't have to relearn nothing it will just go into closed loop and run off of the O2 sensor the way it was intended
Very detailed. Thank you!. FYI - Petroleum jelly will degrade rubber over time causing it to harden and crack, a silicon grease is a better option for lubricating o-rings
I used k suspension 12 ports.. I sea foamed before hand did a tune up then changed them out post ecu reset and relearn I got about 14 to 16 mpg on 3 inch lift with 31s and a roof rack and trunk full of tools after adding a BBK throttle body and cold air I got about 17 running cruise control I’m happy with it mpg changes all the time so this was under best conditions
Just bought a 98 about 6 months ago. About to tackle this, replacing exhaust manifold and head gasket this weekend. Super high quality video, please keep them coming. I'm subbed.
This particular engine has the intake above the exhaust and the air temp sensor is in the intake. Heat from the exhaust heats up the intake and can cause the air temp sensor to read hotter air temperatures then whats actually going into your engine. My advice would be to switch to a header, wrap it and relocate the air temp sensor from the intake to the breather box. This should increase your performance and fuel economy after you have driven the vehicle for a while versus if you still had the air temp sensor in the intake
I get 13-14mpg on worn 33's with 4.88 gears towing a trailer. Stock injectors. The roof rack and lights must be really killing your mpg. I see others suggesting ideas to improve mpg. One not talked about a lot would be to install locking hubs. Allows you to diconnect the wheels from the drive train so the front drive train doesnt move when going down the rd in 2 wheel drive.
@@JeepinJimmythe 4.88 to 1 gearset has a really skinny pinion gear skinny to the point it becomes weak. 33in and 4.56 to 1 is known to be a great combination for power and efficiency and the pinion gear is still a massive chunk of metal
One issue you haven't addressed is your fuel filter. I've got a '93 ZJ with 123K and changed mine out at approx. 120K. The amount of black silt that poured out of the old filter was scary - I can only imagine the residue left in the tank itself. As everyone is probably already aware - • If your fuel filter gets clogged, it can reduce the flow and weaken performance as the engine has difficulties drawing fuel. • With a clogged filter, the fuel pump works much harder and you may have problems starting the car or notice poor acceleration or stalling... Because of its abrasive action, dirt and contaminants in the fuel can speed up wear and tear, damage expensive parts and even cause the fuel pump and injector to fail. • For most cases, the fuel filter needs to be replaced every 20,000 to 30,000 miles. • A clogged fuel filter can cause decreased fuel economy. I went from an average of 13-14mpg to 16-17mpg, just by changing the filter - even though I've been driving it a little bit more aggressively on the freeway. They're less than $20 for the 4.0 liter Jeep vehicles - some are less than 10 bucks. So, if you haven't changed yours yet, it may make a big difference in all around performance and fuel mileage. Thanks for sharing this content with us. - I Subscribed to your channel. 👊
I also have a 93 ZJ and did the 12 hole K-Suspension Injector upgrade about 1 1/2 years ago , I used the little adapters Instead of directly wiring in the new pigtail clips. Last week I ordered the new pigtail adapters and wired those into the harness , A night and day difference in how my little jeep runs now. Those adapters always were loose so I'm sure my injectors were misfiring Off and on at times. I also changed my fuel filter, which is an external filter on the drivers side by the rear tire above the axle, mounted to the chassis area. I have 127526.5 Miles on the little in-line six and she runs like a dream. But unfortunately my torque converter failed and ended up burning the transmission so I'm now replacing it as I write this comment, I certainly do love my little Jeep and can't wait to get her back on the road. Anyway, you're right about the fuel filter needing to be changed and diligently monitored, with today's fuels and all the additives and re-formulations of ethanol It's almost like the industry is quietly sabotaging gasoline engines all together. Stay safe brother and thank you for posting. Danny in Texas.
You mentioned heat soak at the end of the video, and it appears you do not have any type of intake manifold/injector heat shield. A company (Design Engineering) sells a heat shield kit for the Jeep 4.0L engine that protects manifold, fuel rail, and injectors from heat. For later TJs/XJs there is also a Mopar intake manifold heat shield (but to my knowledge no Mopar, fuel rail, nor injector heat shields). Also, please, what purpose do the cables running from your roof rack to your hood corners serve? Thx.
Hmm my 96 gets 16.5mpg (18.2 hwy) and it's 236k mi, only thing done was the accel tune up kit. I keep going back and forth on doing the 4 hole injectors. But might finally do it, chasing the 18/20mpg.
Man buddy you were doing such a awesome job right up to the point you used “Butt” connectors for the new wires🤷🏻♂️. Ya gotta know you are supposed to solder those wires and use heat shrink to protect the connection. But hey to each his own👍
Solder is actually known to get brittle over time and is less flexible than the original bundle of wire, in most automotive applications it's recommended you use crimped connectors with heat shrink that has glue inside it, especially in tight areas that experience high heat.
I’d shy away from soldering. High dollar heat shrink crimp connections with at least one or two layers of heat shrink tubing. It was probably my own idiocy trying to solder FI ends on, but I fried the ECU. I know I jacked up the soldering… but I wanted to use crimps and got talked into soldering …. Anyhoo. Peace
I don't solder those wires. I crimp connect, then paint with liquid electrical tape, then heat shrink. Same with my boat trailers. Unless the wire harness is subject to motion, like the harness that runs into the drivers door for the master window/lock panel, it'll never break.
Have you seen any better mpg after the MAP sensor ran a few more miles? I'm thinking of upgrading to the 4 hole, and adding a 62mm throttle body and a K&N air filter. I'd like to see how that works, if you haven't seen it. thoghts?
@@JeepinJimmy yeah, me too, I haven't seen any postins of this combo here on youtube, just individually done, although, i did see one where the Wix filter performed better on the Dyno than the K&N with the 62mm throttle body.
None of what you're doing is going to matter because your bottleneck is going to be your valves if you have a bad throttle body or a bad intake or bad injectors then replacing them with new ones will make the vehicle run as intended but the only way you're going to get more power is with bigger valves the air enters the engine through valves you would need bigger valves and they would need to stay open longer other than getting new valves a bigger can could help with this once you have that accomplished then you can Port the intake and run a bigger throttle body that will be the only way you'll see a benefit from doing that
@SethMoffitt-op3ng still not going to do anything unless you can force more air into the engine you can put all the fuel you want in there but all you're going to do is run rich without enough air, and the only way you're going to do that is with forced air induction , put bigger valves and stroke it, or fuel that has oxygen in it (Nitrous)you're forgetting the three things you need in the equation air fuel Spark
Thanks for the video, I was surprised you only got a half mile improvement, I was expecting a lot more than that and 12-13 MPG with a 6cyl isn't very good, I thought those Jeeps got about 16-18 avg.
nice video - well, several opinions about 4 hole injectors - fuel pressure and pulse width are given values - change in fuel economy and performance are not really noticeable.
@SethMoffitt-op3ng no you will not plus how you going to fit a set of headers on a Inline engine? Unless you're going forced air induction or bigger valves you're not going to see any increase
If your vehicle is running the way it should be the only way you're getting more fuel economy out of it is weight reduction and wind resistance also staying out of the gas and not being heavy-footed will save fuel. Motor vehicles have a sweet spot where they get the best fuel economy this typically is between 50 and 65 mph when the transmission goes into overdrive
You can lightly coat them using a qtip but I wouldn't recommend it. Jelly will start to liquefy on skin Lnn so anything above 98 F (like in a motor compartment) will end up dripping everywhere.
If the engine is running the way it was intended from the factory then you're getting the miles per hour you're going to get remember less fuel means less power so you can adjust fuel tables to where the injectors do not spray as much fuel but you're going to lose power vice versa if you want more power you're going to have to burn more fuel any increases to fuel economy you are seeing is because you replaced a part that wasn't operating efficiently
The short answer is no you won't get better fuel economy by switching to Bosch the gains in fuel economy you are seeing is because you had bad fuel injectors and now you're replacing them with new ones as long as a fuel injector is spraying a mist and not leaking or dripping the fuel economy is going to stay the same the only way to change fuel economy would be fuel tables but if everything is in working order the engine should run efficiently with the stock fuel tables
On my 2006 grand Cherokee Laredo, I changed the ignition coils, plugs, and fuel injectors at the same time with all high quality parts and I went from 12.8 to 16.6 MPG after I had a misfire on cylinder 4. My advice is if you’re going to go through the trouble of pulling the fuel rail do all 3, not just the injectors, because each one can improve mpg, one thing I saw in the video that I think may get people into trouble is to try to pull the fuel rail by hand like that, I think with enough resistance u may end up braking something. The way I did it was more controlled with high leverage by using 2 pry bars against each other little by little across the rail to raise it evenly because it can get really stuck, and don’t drop an O ring like did which is a PIA to recover
Should have got new pins and connectors. Those butt connectors are the worst. Atleast get the non insulated type crimp them with an actual pair of crimpers and heat shrink it...
Toss the petroleum jelly or use it for "none of your business" business and use silicone grease on them fuel injectors instead. Anything petroleum degrades rubber. So, young-un, don't use it on any "injector" that needs a "rubber" seal. Ya' hear!😉👍
The Chinese Bosch injectors are junk! I tried a set on my 2001 XJ and one was bad when I put it in. Withing days another failed. I pulled them all and put in a set of OEM injectors. The Chinese Bosch fuel pumps are also trash. "Botch" has never been a good brand in my experience. I didn't name then "Botch". That was an accepted description way back in the Sixties.
It may get better over time as well. I've heard the pcm can take up to 50 start ups to get the new fuel and air mixture perfect
Right on! Thanks, hopefully it does
50 starts? WTF? Why? How did you get this number? Please let me know because I am very interested.
That is incorrect once the vehicle is at operating temperature and is in closed loop the fuel is ran off the O2 sensor. O2 enters the vehicle and a MAF sensor and air temp sensor tells the computer how much O2 is entering the combustion chamber. The throttle positioning sensor tells the computer how open the throttle blade is and the computer goes to its fuel table the computer will check demand from throttle positioning sensor what gear you are in what load is on it and at what RPM to tell the injectors how much fuel they should spray. After the combustion cycle, exhaust runs over the Upstream oxygen sensor first the Upstream oxygen sensor compares the oxygen content of the exhaust with the oxygen content of the atmosphere if it notices a difference it makes adjustments by shutting the fuel injectors on and off faster or slower this is called closed loop if your vehicle is operating the way it was intended and efficiently the only way you're going to make a difference is by changing the computer's fuel table other than weight reduction and less wind resistance. Now if your vehicle is not running the way it was intended then the PCM will try to learn adjustments to get the fuel ratio that it wants to see basically if all your parts are running the way they're supposed to it the PCM won't have to relearn nothing it will just go into closed loop and run off of the O2 sensor the way it was intended
Very detailed. Thank you!. FYI - Petroleum jelly will degrade rubber over time causing it to harden and crack, a silicon grease is a better option for lubricating o-rings
Thanks! Right on, good to know
@@christhomas9300 .....or get some P-80, which basically dissolves away after the part is fitted!
I used k suspension 12 ports.. I sea foamed before hand did a tune up then changed them out post ecu reset and relearn I got about 14 to 16 mpg on 3 inch lift with 31s and a roof rack and trunk full of tools after adding a BBK throttle body and cold air I got about 17 running cruise control I’m happy with it mpg changes all the time so this was under best conditions
Not bad though! I might have to switch to 12 ports
@@JeepinJimmy I went from stock to 12s idk if you’d notice much difference from 4 to 12s though
BBK exhaust manifold helped a lot
Just bought a 98 about 6 months ago. About to tackle this, replacing exhaust manifold and head gasket this weekend. Super high quality video, please keep them coming. I'm subbed.
Right on! Thank you!
Awesome vid! Informative, educational and highly entertaining😁
Thank you for watching!!
This particular engine has the intake above the exhaust and the air temp sensor is in the intake. Heat from the exhaust heats up the intake and can cause the air temp sensor to read hotter air temperatures then whats actually going into your engine. My advice would be to switch to a header, wrap it and relocate the air temp sensor from the intake to the breather box. This should increase your performance and fuel economy after you have driven the vehicle for a while versus if you still had the air temp sensor in the intake
I get 13-14mpg on worn 33's with 4.88 gears towing a trailer. Stock injectors. The roof rack and lights must be really killing your mpg. I see others suggesting ideas to improve mpg. One not talked about a lot would be to install locking hubs. Allows you to diconnect the wheels from the drive train so the front drive train doesnt move when going down the rd in 2 wheel drive.
Hopefully ill be doing 33s with 4.88 soon. We shall see how it does! Manual locking hubs would be good too! Thanks for watching!
Do they make locking hubs for Dana 30?
@@moejr14 yes.
@@moejr14 They make a conversion kit but its pretty pricey. You could be well on your way to a one ton swap for the price of the kit haha
@@JeepinJimmythe 4.88 to 1 gearset has a really skinny pinion gear skinny to the point it becomes weak. 33in and 4.56 to 1 is known to be a great combination for power and efficiency and the pinion gear is still a massive chunk of metal
One issue you haven't addressed is your fuel filter. I've got a '93 ZJ with 123K and changed mine out at approx. 120K. The amount of black silt that poured out of the old filter was scary - I can only imagine the residue left in the tank itself.
As everyone is probably already aware -
• If your fuel filter gets clogged, it can reduce the flow and weaken performance as the engine has difficulties drawing fuel.
• With a clogged filter, the fuel pump works much harder and you may have problems starting the car or notice poor acceleration or stalling... Because of its abrasive action, dirt and contaminants in the fuel can speed up wear and tear, damage expensive parts and even cause the fuel pump and injector to fail.
• For most cases, the fuel filter needs to be replaced every 20,000 to 30,000 miles.
• A clogged fuel filter can cause decreased fuel economy.
I went from an average of 13-14mpg to 16-17mpg, just by changing the filter - even though I've been driving it a little bit more aggressively on the freeway.
They're less than $20 for the 4.0 liter Jeep vehicles - some are less than 10 bucks. So, if you haven't changed yours yet, it may make a big difference in all around performance and fuel mileage.
Thanks for sharing this content with us. - I Subscribed to your channel. 👊
Thanks for the suggestion, ill definitely do this!
Could be, but for the vintage in the video I believe the filter is inside the tank.
@@redtango75 Looked it up online and the fuel filter for the XJ's is external.
@@dawabbitt3079 The older Xj's are external but anything 97 and newer have the filter inside the tank unfortunately.
I also have a 93 ZJ and did the 12 hole K-Suspension Injector upgrade about 1 1/2 years ago , I used the little adapters Instead of directly wiring in the new pigtail clips. Last week I ordered the new pigtail adapters and wired those into the harness , A night and day difference in how my little jeep runs now. Those adapters always were loose so I'm sure my injectors were misfiring Off and on at times.
I also changed my fuel filter, which is an external filter on the drivers side by the rear tire above the axle, mounted to the chassis area. I have 127526.5 Miles on the little in-line six and she runs like a dream.
But unfortunately my torque converter failed and ended up burning the transmission so I'm now replacing it as I write this comment, I certainly do love my little Jeep and can't wait to get her back on the road.
Anyway, you're right about the fuel filter needing to be changed and diligently monitored, with today's fuels and all the additives and re-formulations of ethanol It's almost like the industry is quietly sabotaging gasoline engines all together.
Stay safe brother and thank you for posting.
Danny in Texas.
You mentioned heat soak at the end of the video, and it appears you do not have any type of intake manifold/injector heat shield. A company (Design Engineering) sells a heat shield kit for the Jeep 4.0L engine that protects manifold, fuel rail, and injectors from heat. For later TJs/XJs there is also a Mopar intake manifold heat shield (but to my knowledge no Mopar, fuel rail, nor injector heat shields). Also, please, what purpose do the cables running from your roof rack to your hood corners serve? Thx.
Right on! Ill have to look into a heat shield, thanks! They are for deflecting branches on tight trails!
You can wrap the header if you have a header but you need to move the air temp sensor to the breather box and off of the intake
@@UnderSprayedWhiteSkies I've got the DEI kit and it was definitely an improvement!
Why a lot other guys are getting like 17 mpg ?
I know it a year ago, but why is the check engine on?
A cold day 😉🙊
But thanks. I have a spare intake I plan to clean and put new injectors in. Been wondering what's holding them in. Nothing.
Yeah man! Yank em out haha
Hmm my 96 gets 16.5mpg (18.2 hwy) and it's 236k mi, only thing done was the accel tune up kit. I keep going back and forth on doing the 4 hole injectors.
But might finally do it, chasing the 18/20mpg.
DO it!!
.....and if you've got the 4.0L motor, make sure you get the DEI heat shield kit for the fuel rail & injectors, too!
Man buddy you were doing such a awesome job right up to the point you used “Butt” connectors for the new wires🤷🏻♂️. Ya gotta know you are supposed to solder those wires and use heat shrink to protect the connection. But hey to each his own👍
Yeah you’re probably right. Just working with what I got man haha
Solder is actually known to get brittle over time and is less flexible than the original bundle of wire, in most automotive applications it's recommended you use crimped connectors with heat shrink that has glue inside it, especially in tight areas that experience high heat.
I’d shy away from soldering. High dollar heat shrink crimp connections with at least one or two layers of heat shrink tubing. It was probably my own idiocy trying to solder FI ends on, but I fried the ECU. I know I jacked up the soldering… but I wanted to use crimps and got talked into soldering …. Anyhoo. Peace
I always use the heat shrink solder connectors
I don't solder those wires. I crimp connect, then paint with liquid electrical tape, then heat shrink. Same with my boat trailers. Unless the wire harness is subject to motion, like the harness that runs into the drivers door for the master window/lock panel, it'll never break.
"You mind yer damn business" 🤣😂
I would use dielectric grease on the connections and the o-rings. Look into an oil catch can for better fuel economy
Ill look into that, thanks!
@@bighookpgh Definitely not on the O-rings...
Have you seen any better mpg after the MAP sensor ran a few more miles? I'm thinking of upgrading to the 4 hole, and adding a 62mm throttle body and a K&N air filter. I'd like to see how that works, if you haven't seen it. thoghts?
I have seen a little bit of an improvement! I'm curious as to what your mods are going to do
@@JeepinJimmy yeah, me too, I haven't seen any postins of this combo here on youtube, just individually done, although, i did see one where the Wix filter performed better on the Dyno than the K&N with the 62mm throttle body.
None of what you're doing is going to matter because your bottleneck is going to be your valves if you have a bad throttle body or a bad intake or bad injectors then replacing them with new ones will make the vehicle run as intended but the only way you're going to get more power is with bigger valves the air enters the engine through valves you would need bigger valves and they would need to stay open longer other than getting new valves a bigger can could help with this once you have that accomplished then you can Port the intake and run a bigger throttle body that will be the only way you'll see a benefit from doing that
Gotta upgrade the fuel pressure regulator after the Bosch 4 hole upgrade
@SethMoffitt-op3ng still not going to do anything unless you can force more air into the engine you can put all the fuel you want in there but all you're going to do is run rich without enough air, and the only way you're going to do that is with forced air induction , put bigger valves and stroke it, or fuel that has oxygen in it (Nitrous)you're forgetting the three things you need in the equation air fuel Spark
Thanks for the video, I was surprised you only got a half mile improvement, I was expecting a lot more than that and 12-13 MPG with a 6cyl isn't very good, I thought those Jeeps got about 16-18 avg.
You bet! It definitely should have been more of an improvement. I think I got issues elsewhere haha
nice video - well, several opinions about 4 hole injectors - fuel pressure and pulse width are given values - change in fuel economy and performance are not really noticeable.
Need a good fuel pump and slightly higher fuel pressure regulator aka manual paired with a set of headers & cat delete you will see some power
@SethMoffitt-op3ng no you will not plus how you going to fit a set of headers on a Inline engine? Unless you're going forced air induction or bigger valves you're not going to see any increase
If your vehicle is running the way it should be the only way you're getting more fuel economy out of it is weight reduction and wind resistance also staying out of the gas and not being heavy-footed will save fuel. Motor vehicles have a sweet spot where they get the best fuel economy this typically is between 50 and 65 mph when the transmission goes into overdrive
question how did the 4 port fair better than the single port injectors?
For sure! I haven't had any issues with them yet
I get 14mpg in my 99 TJ with stock original injectors...
Yikes.
@revolutionday1 shit, I think that's pretty good, considering.
@jeepinjimmy what is the flow rate on these ?
"why do I have so much petroleum jelly?" "Mind your own business." LMAO
I just want all stock on my YJ. The problem is there's so much garbage out there.
You can stuff the wire conectors with petroleum jelly to make them moisture resistant as well.
Never knew that! Thanks!
You can lightly coat them using a qtip but I wouldn't recommend it. Jelly will start to liquefy on skin Lnn so anything above 98 F (like in a motor compartment) will end up dripping everywhere.
@@michaelgolliver4242 Do us all a favor and never attempt to give anyone such shitty and uneducated "automotive advice" again. 🤦
Awsome !
Thanks!
Nice vid. Thanks Where did you find those wheels
Found them on craigslist! They are turbine wheels from early XJs and MJs
What rims are you running?
Stock turbine wheels that I painted
Thanks god bless
If the engine is running the way it was intended from the factory then you're getting the miles per hour you're going to get remember less fuel means less power so you can adjust fuel tables to where the injectors do not spray as much fuel but you're going to lose power vice versa if you want more power you're going to have to burn more fuel any increases to fuel economy you are seeing is because you replaced a part that wasn't operating efficiently
The short answer is no you won't get better fuel economy by switching to Bosch the gains in fuel economy you are seeing is because you had bad fuel injectors and now you're replacing them with new ones as long as a fuel injector is spraying a mist and not leaking or dripping the fuel economy is going to stay the same the only way to change fuel economy would be fuel tables but if everything is in working order the engine should run efficiently with the stock fuel tables
On my 2006 grand Cherokee Laredo, I changed the ignition coils, plugs, and fuel injectors at the same time with all high quality parts and I went from 12.8 to 16.6 MPG after I had a misfire on cylinder 4. My advice is if you’re going to go through the trouble of pulling the fuel rail do all 3, not just the injectors, because each one can improve mpg, one thing I saw in the video that I think may get people into trouble is to try to pull the fuel rail by hand like that, I think with enough resistance u may end up braking something. The way I did it was more controlled with high leverage by using 2 pry bars against each other little by little across the rail to raise it evenly because it can get really stuck, and don’t drop an O ring like did which is a PIA to recover
Should have got new pins and connectors. Those butt connectors are the worst. Atleast get the non insulated type crimp them with an actual pair of crimpers and heat shrink it...
I have used the hell out of those butt connectors over the years. They work great.
Toss the petroleum jelly or use it for "none of your business" business and use silicone grease on them fuel injectors instead.
Anything petroleum degrades rubber. So, young-un, don't use it on any "injector" that needs a "rubber" seal. Ya' hear!😉👍
This is great😂😂 thanks🫡
If you draw a pizza, you don't have to pay for it. But you can't eat it, either.
Big facts
I dont think a mechanic should be driving around with an engine checklight on 😂
Its a Jeep though😂
Mind Your Damn Business, lolol
The Chinese Bosch injectors are junk! I tried a set on my 2001 XJ and one was bad when I put it in. Withing days another failed. I pulled them all and put in a set of OEM injectors. The Chinese Bosch fuel pumps are also trash. "Botch" has never been a good brand in my experience. I didn't name then "Botch". That was an accepted description way back in the Sixties.
What brand is OEM? Need new ones don't trust Bosch
@@KMRscoo Semens
you should’ve used more JELLY you would’ve got more miles
FO SHO
I couldn't imagine being a grown man and wearing chapstick, disappointed
😂😂 and PPE
Cute vid - but the little one is the star -
For sure!