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Old 10-20-2013, 10:26 PM   #61
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Just curios w5kvv, did you change the ic module and other module on 4.0 throttle body

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Old 10-20-2013, 10:28 PM   #62
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Just curios did you change out the modules on the 4.0 throttle body with the 2.5 modules, or just bolt the 4.0 throttle body on with the modules that was already in it?

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Old 10-20-2013, 10:36 PM   #63
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Chris, my donor 4.0 TB didn't have any of the modules/ sensors on it. I reused my 2.5 TB stuff. My 4.0 TB did have a MAP sensor, which was absent on the original 2.5 TB. I simply removed the MAP sensor & used a rubber plug to block it off. Worked like a charm.
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Old 10-20-2013, 10:55 PM   #64
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Sweet, thanks I was wondering about that, plan on doing a 4.0 tb change soon on my YJ as well.
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Old 10-20-2013, 11:00 PM   #65
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Go for it! Very simple swap. It took me longer to clean the donor 4.0 TB than it did to remove the old one & install the new one.

I'm still in awe of how it woke my 2.5 up. Like I said, I've been playing with motors for over ten years & swapped out countless TB's & never has one made this big of a difference.
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Old 10-20-2013, 11:36 PM   #66
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Yes with a 4.0L TB swap on a 2.5L you swap out and keep the 2.5L sensors. Some models the map sensor or maybe the throttle position sensor might be the same part number as the 4.0 . But you defitnetly have to swap out the IAC housing .( Idle Air Control ). On the side of those housing they are marked with 2.5L or marked 4.0L. I do myself as mentioned before do run a 4.0L TB. The only thing I did is shave the top side of the throttle shaft for smoother air flow. Well for what its worth. O yes also bored out my intake manifold to 55mm match the bottom of the 4.0L TB. I just simply used a gasket to mark it, stuffed the intake runners with rags to prevent metal shavings from intering intake, used a drill with rasp and then finner sanding disk for smooth finish. Little by little round and round trying to stay as uniform as possible. Until reaching 55mm bore. Did use a measuring gauge for tight tolerance and measuring all around. Works great with the 4.0L TB, gsp throttle body spacer, and bored manifold. O yes for whats its worth I did wrap my intake tube with insulation to keep incoming air temps down.
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Old 10-22-2013, 03:47 PM   #67
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We have finished with the following mods and each one helped significantly, and were pretty cheap, recommend all of them;

Cat delete; did the same time as muffler, cost; 12.00 for 2.25 pipe from summit, Got 45.00 cash back for the old bad cat.

4.0 Throttle body, went on fine, big power difference, 45.00 at the boneyard (seemed like too much )

5.0 Injectors, (got them from a 5.0 Ford truck, Bosch yellow top, 60.00 for used from boneyard, 1 hr to do.

Efan; 30.00 fan, 35.00 sensor kit ("Derale") Big difference there too.

I am really happy with all these mods, and yes, were running 30x1050r15's with 4.10s. I fully understand with 33's will require gears, and poss SYE/driveshaft. Im happy weve stretched the 2.5 to be all she can be safely. Thanks to all for your input.
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Old 10-22-2013, 03:54 PM   #68
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On the Crank sensor mod, did some looking into; If we alter the crank sensor position without altering the CAM sensor position ( Which I believe is in the distributor) it stands to reason it would send the ECM a fault like a jumped timing chain. Would have to adjust both and guess they were the same amount?! The newer engines with variable valve timing have a fit with crank/cam correlation and Im not sure I want to go there... Thoughts anyone??
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Old 10-22-2013, 04:25 PM   #69
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We have finished with the following mods and each one helped significantly, and were pretty cheap, recommend all of them;

Cat delete; did the same time as muffler, cost; 12.00 for 2.25 pipe from summit, Got 45.00 cash back for the old bad cat.

4.0 Throttle body, went on fine, big power difference, 45.00 at the boneyard (seemed like too much )

5.0 Injectors, (got them from a 5.0 Ford truck, Bosch yellow top, 60.00 for used from boneyard, 1 hr to do.

Efan; 30.00 fan, 35.00 sensor kit ("Derale") Big difference there too.

I am really happy with all these mods, and yes, were running 30x1050r15's with 4.10s. I fully understand with 33's will require gears, and poss SYE/driveshaft. Im happy weve stretched the 2.5 to be all she can be safely. Thanks to all for your input.
Now that your cat is deleted have you noticed any power loss or exhaust popping?, my cat had been taken off prior to me buying my my 91 yj jeep and it pops almost everytime I let off gas also has flow master on it.
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Old 10-22-2013, 05:02 PM   #70
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2.5L Power Mods

Yea me myself I would not mess with the cam or crank sensor. There is safer mods to mess with if you decide to mess with any sensors. There is the IAT sensor mod. I believe one is a module you can buy that fools the sensor, which myself dont like. The second mod to the IAT is to actually and physically relocate it to a cooler location such as the intake tube or air filter box. This mod is supose to read cooler incoming air intake temps and therefore alter the timing a bit along with fuel intake. The other safer mod in my opinion is to alter the volts going to the map sensor. By increasing the voltage to map sensor it will slightly advance your timing along with giving you a wider and longer pulse width to the fuel injectors. I believe this mod is only good at wide open throttle. That can be a good thing.
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Old 10-22-2013, 10:10 PM   #71
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Thanks for keeping this thread alive.. after a year of not building .. its time to finish what I started. Picked up a hi flo exhaust system with hi flo cat.
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Old 10-22-2013, 10:43 PM   #72
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Is it installed ?
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Old 10-22-2013, 11:08 PM   #73
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Hmmm. How do you do this MAP sensor mod? Speaking of MAP sensor, where the heck is it on the 2.5's? Most of the time they're in the TB, but my original 2.5 TB didn't have provisions for one. I might give that one a try next.

I just finished up relocating the IAT sensor to the airbox. An old 2nd gen Dodge Ram trick I've been doing for years. Crude, but effective none the less.



As for the CPS mod. I'm not sure about it on the 2.5's. I haven't looked into it. I've done it on 2 of my personal 5.9 Rams & numerous buddies 5.2/5.9 equipped vehicles with good results. It won't cause any issues with the cam sensor/pickup coil since your not moving the timing out of it's threshold enough to trip anything. You can't mod it far enough to hurt anything on the Magnum motors. It's not physically possible due to the bell housing. None of this applies to the 2.5 tho. I haven't even laid eyes on the 2.5's CPS. It could have waaaay more room for adjustment than the Magnum motors.

It would be worth a VERY CAUTIOUS try IMO given the high success rate on the Dodge V8's. But, to be honest with you guys, my little 2.5 has responded well to the small amount of mods I've done to it so far. I probably won't even mess with it. I can't wait to ditch the fan & try some 5.0 injectors. I have long been anti TB spacer, but all the 4 banger guys say they help. I find that hard to believe given the engine is MPFI, but they're cheap enough on ebay.

Fun little motors to work on, Even if the return is small. The more the better I say.
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Old 10-22-2013, 11:15 PM   #74
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There you go there is a nice pic of the Intake Air Temp relocation. I just might try it one day, who knows. O as far as tweeking the map sensor take a peek at leigh performance.
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Old 10-23-2013, 12:50 AM   #75
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Hmmm. How do you do this MAP sensor mod? Speaking of MAP sensor, where the heck is it on the 2.5's? Most of the time they're in the TB, but my original 2.5 TB didn't have provisions for one. I might give that one a try next.

I just finished up relocating the IAT sensor to the airbox. An old 2nd gen Dodge Ram trick I've been doing for years. Crude, but effective none the less.



As for the CPS mod. I'm not sure about it on the 2.5's. I haven't looked into it. I've done it on 2 of my personal 5.9 Rams & numerous buddies 5.2/5.9 equipped vehicles with good results. It won't cause any issues with the cam sensor/pickup coil since your not moving the timing out of it's threshold enough to trip anything. You can't mod it far enough to hurt anything on the Magnum motors. It's not physically possible due to the bell housing. None of this applies to the 2.5 tho. I haven't even laid eyes on the 2.5's CPS. It could have waaaay more room for adjustment than the Magnum motors.

It would be worth a VERY CAUTIOUS try IMO given the high success rate on the Dodge V8's. But, to be honest with you guys, my little 2.5 has responded well to the small amount of mods I've done to it so far. I probably won't even mess with it. I can't wait to ditch the fan & try some 5.0 injectors. I have long been anti TB spacer, but all the 4 banger guys say they help. I find that hard to believe given the engine is MPFI, but they're cheap enough on ebay.

Fun little motors to work on, Even if the return is small. The more the better I say.
Here's a good link to do the map sensor mod you asked about, http://jeep-xj.info/HowtoMAPsensor.htm
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Old 10-23-2013, 01:03 AM   #76
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Sweet! I have most of that stuff in my ham shack. I'll give it a try. What the heck.
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Old 10-23-2013, 02:06 AM   #77
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Also check out this home built bad as# snorkel, im thinking doing it myself on my YJ, let me know what you think. http://www.jeephorizons.com/tech/snorkel/
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Old 10-23-2013, 02:44 AM   #78
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The MAP sensor is on the drivers side of throttle body. Looks like a little black box, about 1 inch x 2 inch, it should have 2 screws, 1 electrical plug and 1-vacuum hose toward the bottom end of it. Well it depends what year your rig is.
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Old 10-23-2013, 09:00 AM   #79
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Mine is a 95 & it's up on the firewall. The '98 model 4.0 TB I put on had provisions for a TB mounted MAP, so I just blocked it off with a rubber cap.

I might have to try a home brew snorkel myself. I don't thing I'd ever need it, but it would be a good project. One of the guys on here posted a pic of one that was built out of 3" exhaust pipe, bent on a mandrel bender. It looked very nice.
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Old 10-23-2013, 12:01 PM   #80
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Now that your cat is deleted have you noticed any power loss or exhaust popping?, my cat had been taken off prior to me buying my my 91 yj jeep and it pops almost everytime I let off gas also has flow master on it.
Usually the pop (backfire) on decel is you have an exhaust leak up front somewhere, and the unburnt fuel catches some air and creates the spontaneous bang. We replaced head pipe same time and manifold is good. Doesent pop but no leaks up front. If your nursing a bad exhaust manifold that could be causing it.
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Old 10-23-2013, 01:24 PM   #81
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Usually the pop (backfire) on decel is you have an exhaust leak up front somewhere, and the unburnt fuel catches some air and creates the spontaneous bang. We replaced head pipe same time and manifold is good. Doesent pop but no leaks up front. If your nursing a bad exhaust manifold that could be causing it.
Yeah I thought the same, checked header no leaks and tight and sprayed it with starter fluid to see if it revs up, checked new 4.0 tb as well i installed yesterday no leaks, checked header exhaust flange that bolts up to exhaust, i found the problem the retarded previous owner didn't put in any new or used exhaust flange gaskets back in when he bolted exhaust on to new header he installed, I paid $4.00 for some new ones and it stopped the backfire yesterday, thanks for response though.
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Old 10-23-2013, 01:28 PM   #82
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Yeah here it is, I seem it last night as well and thought it to be a better setup, however I think it would be better ran out of fender than hood. http://www.jeepforum.com/forum/f12/h...e-pics-909382/
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Old 10-23-2013, 04:48 PM   #83
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Well I have a 97 TJ so I could not say much on how to on a older model
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Old 10-23-2013, 04:50 PM   #84
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Hey do any of you guys know if there is a down side to relocating the IAT sensor to a cooler location such as air box or air tube ?
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Old 10-23-2013, 08:43 PM   #85
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Hey do any of you guys know if there is a down side to relocating the IAT sensor to a cooler location such as air box or air tube ?
Did the mod about 2 weeks ago, haven't noticed any downsides yet. Easy cheap mod, I'd recommend it.
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Old 10-23-2013, 09:14 PM   #86
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Hey do any of you guys know if there is a down side to relocating the IAT sensor to a cooler location such as air box or air tube ?
I've done it for years on numerous makes & models. No issues what so ever.
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Old 10-23-2013, 09:20 PM   #87
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Have you guys noticed good results with this mod ? O and your MPGs have not been affected ? All in all what affects did you guys notice ?
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Old 10-23-2013, 09:54 PM   #88
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The results are there, but nothing astronomical. You'll notice it better on a cold day if you have other mods that compliment it. TB, Kitty delete, that sort of stuff. It's worth doing. Pretty simple.
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Old 10-23-2013, 11:36 PM   #89
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Well if there is no downside, and on my Lil 4 banger I can feel 1/2 a pony increase or decrease then maybe I just might really consider this mod and ponder on it. My questions to this mod would be, do I relocate all the way to air intake box or a milder location such as the intake tube, further out or in the middle of air tube or closer to TB ? Humm ?
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Old 10-23-2013, 11:49 PM   #90
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As far away from the hot exhaust manifold as you can. In the airbox towards the front works best.

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