2.5L performance?

[Skulljeep683]

hey everyone im new to this forum(first post what what) and basically just read this entire thread fishing for information (which there is no shortage of here, good info too) on doing the 4.0TB swap and adding a TBS. ive noticed that quicksand has a pretty extensive tb experimentation past so i guess ill direct this question at you (but anyone else feel free to chime in): if i add the TB/TBS, will i need to bore out my intake mani or is this all just a bolt-on operation?

Well the 4.0 has a little notch on it that i simply removed (with some pliers then sanded smooth) which prevents you from using it on the 2.5, it doesnt affect it in any way. You dont have to bore out the intake but its recommended for ideal airflow. I have to get rid of the helix in my spacer and im going to be boring out my manifold and spacer a bit and doing the same to the underside of my tb. making it all one flush and smooth air travel. thats the goal, smooth airflow transitioning, my narrow point for air charge will be the tb itself, so it willl maintain velocity through the intake. Just be sure to reset the cpu when your done so the motor can relearn how to run with more air, or you'll burn the valves up on cylinders 2 & 3 and lose compression... also after that mod best to run a high flow exhaust so you can get more power at lower rpms and watch your mpg go up. when i first commented on this thread i took notes down on everything that was said, my notepad doc on this thread is a novel. lol well hope that helps, happy wheeling.

 

[quicksand97]

I havnt been around for awhile been taking care of ill wife. Anyway I think thats a great answer in my opinion. Yes thats right it is best to macth the manifold bore size to the same size of the bottom of the throttle body. Also like it was said before it is best to reset the pcm. There was a couple times in the past, after I made adjustments and did not reset pcm and it would take longer to learn and during this process I would get backfire or misfire at random times then it would go away. I did not disconnect battery because they where small changes in bore size. But in my opinion and experience on a 2.5L even the smallest changes make a difference in performance and MPG. I am currently still making fine tune adjustments to my air intake box to get the best balance for power and MPG. You all take care and happy 4 wheeling.

 

[NalinMFG]

how big is the bore on a stock 4.0 throttle body. i've seen them bored out to 62mm.

I've gotten the intake manifold to 64mm for a 2.5L guy before. 62mm works better for the gasket/rtv though.

 

[Skulljeep683]

thats the intake bored out to 64mm? or 62?

 

[NalinMFG]

that picture is right before the finishing cut...so more like 63.95mm.


here is 55mm from the factory:

Side note: I have 1 YJ and 2 TJ intake manifolds sitting next to the mill if anyone else is interested.

 

[Skulljeep683]

that picture is right before the finishing cut...so more like 63.95mm.


here is 55mm from the factory:

Side note: I have 1 YJ and 2 TJ intake manifolds sitting next to the mill if anyone else is interested.

I'll take an intake if your offering? how much and how much for one bored out?

 

[NalinMFG]

I bored all of the intakes at once so I don't have any stock ones left. I've been doing $120+ship with $50 refunded upon the arrival of your old core in remanufacturable condition.

Just started a thread on JF this evening.
2.5L Bored Intake Manifold - NalinMFG - JeepForum.com

 

[Skulljeep683]

i hope you got my private message. Just a few questions about purchasing and such.

 

[NalinMFG]

replied

 

[quicksand97]

If I was to use a 63mm bore on manifold would I still use a stock 4.0L TB. Also would I get any performance gains ?

 

[Bounty__Hunter]

If I was to use a 63mm bore on manifold would I still use a stock 4.0L TB. Also would I get any performance gains ?

No performance gains as the stock 4.0L TB would still be the choke point of the intake.

 

[quicksand97]

No performance gains as the stock 4.0L TB would still be the choke point of the intake.

Hey Mr Bounty Hunter there you are, Its been awhile hope you been doing ok and that bussiness has been good for you. Yes I believe you are right. I was thinking about since I posted the question and should have known that. Yet its good to get a confirmation from someone like you with experience in air intake knowledge. Yes I have some knowledge to, but never say or think I know it all. O yes your one I could ask about spark plug gap. I do run cold air intake, bigger TB and spacer, catback, accel coil and wires with NGKs gapped at a mild .038. It starts bucking with the first take off of the day only at take off. The bucking happens when the plug gap is set at .039 or above. I use to be able to gap at about .041 with the accel coil, which is rated at 42,000 volts. Correction from above I currently run a coil from CRT performance, which is rated at 45,000 volts. and the bucking happens at a gap set about .039. I think I just repeated myself. Is it possible it could be the coil. I did look up the specs on my old accel coil and it has things listed as primary resistance and secondary resistance. I forget the exact numbers. But the max output is 42,000 volts. I guess my main question could my current CRT coil have poor primary resistance? even though its max output is 45,000 volts? O I did get new accel 8mm wires as mine were older than what I thought. I was also thinking is it possible that it is my distributor sensor? Thanks

 

[White Buffalo]

I'm doing most of the engine upgrades on my 99 TJ. What I have left to do is the Ford 24 pound injectors and the e-fan for the engine mods. For the axle mods to save money I'm doing lockers and upgrading my gears to 4.88's all at once. This will make it easier so the re-install will go much quicker. Always remember this when you change out the gears or put larger tires on you have to change the speedo gear or your gas mileage will suffer. Looks like I have a lot of work in front of me.

 

[Bounty__Hunter]

It's really hard to say what is causing your bucking, and it's my opinion that a change in plug gap from .039 to .041 is insignificant and you're looking in the wrong place.

I do know the Champion Truck plugs are more highly recommended for the Jeep 2.5L with performance mods. Maybe give a set a try.

 

[Kyle Beckman]

I put a headman header on my 92, along with the 4.0L tb, tbs, ram intake, turbo muffler and noticed a pleasant difference. Ran all over the sand dunes and the highway with my 33"s.

 

[quicksand97]

Yes Sir Mr Bounty Hunter I believe your right on the plugs, I did a few different gaps on my plugs and same thing, I will keep those champion plugs in mind on next change. I did replace my distributor pickup plate also known as the camshaft sensor. Jeep feels better and more responsive, I guess equal to a real good tune up like. As far as my rigs bucking at first start of the day its still there then goes away after its warmed up. The bucking happens not when I start it up or sitting at idle. It happens when I take off real slow just letting my foot of the clutch and not evening hitting the gas pedal yet. She will buck for a couple of minutes as I coast out of parking lot and then when I give it a lil gas bucks harder for just a second then it stops bucking and acts normal. It happens more often when its cooler out. I also swapped out TPS and still same. cleaned TB, air filter, TB. Its acts like its staved for air or fuel for those first few minutes. Is it possible its the IAC ( idle air control ) ? O yea I also cleaned my IAT sensor and no change. As far as the IAC could it be sticking closed till it warms up and not letting enough air pass around the throttle body plate at crawl speed. Because the bucking goes away just as soon as I apply the pedal a bit. Yes does buck for a second when pedal is applied for the first time, then its fine. Wierd. Any ideas ?

 

[quicksand97]

O yeah one more question could it be a faulty TPS ( throttle Position Sensor ) even if I already replaced it ?

 

[JPNinPA]

O2 sensor.

 

[quicksand97]

Well I got rid of 90 percent of the bucking I was having at crawling speed without steeping on pedal. I cleaned my IAC real good, including the housing. I have clean it before with just a rag and It looked pretty clean to me in the past. But this time I used a spray cleaner and was surprised how much more carbon built up in the came out. Then I noticed that mine has a black plastic sleeve over the spring part of the pintal , at first I thought I broke it and then realized it was stinking shut or open, whatever position it was in. Well Duh right. Now it moves freely back and forth and my lil rigs bucking is hardly even there. I also noticed she was much more responsive at take off and idling pretty smooth. I happy it feels like I got my jeep back.

 

[quicksand97]

Well I got rid of 90 percent of the bucking I was having at crawling speed without steeping on pedal. I cleaned my IAC real good, including the housing. I have clean it before with just a rag and It looked pretty clean to me in the past. But this time I used a spray cleaner and was surprised how much more carbon built up in the came out. Then I noticed that mine has a black plastic sleeve over the spring part of the pintal , at first I thought I broke it and then realized it was stinking shut or open, whatever position it was in. Well Duh right. Now it moves freely back and forth and my lil rigs bucking is hardly even there. I also noticed she was much more responsive at take off and idling pretty smooth. I happy it feels like I got my jeep back.

O no you mean It could be a 02, Ah man, well I am not throwing any codes but I did have the exhaust manifold replaced about 2 months ago, and with the old one I had it all getto with exhaust sealer,puddy and bubble gum. Could it be the 02 has residue on it ? Do I just replace it or can it be cleaned?