1990 Performance question

[Sly8795]

RE: Newest, Youngest Jeeper, Its a Girl!!

I'm looking to add a little performance to the jeep that I have. So far i have a K&N 6x9 intake and a catback exhaust system. I was wondering if anyone has found a header for the 1990 jeep cherokee automatic 4.0L. I have found a few but some wont work with the automatic. Has anyone had any luck finding a header or any other performance mods that can be suggested. Its more of a hobby of adding performance to my jeep so any suggestions would be great.

Thanks guys

 

[MudderChuck]

Re: RE: Re: RE: Spare on the roof made for some excessive ro

Just an opinion, I added the K and N you have, got the biggest 2 1/4" cat I could find and a high flow (though not loud) muffler. Header most ways is good for a few horses on the XJ.
The most horses to be had, is actually getting what you got to run well. Add ons most ways aren´t worth the money. Marginal results, unless you get serious.
Try this site, http://www.jeep4.0performance.4mg.com/

 

[Sly8795]

RE: Fuel Gauge

Thanks for the response. If i run across extra money i was gonna look into the header. I was also looking to get it for maybe some added volume to the exhaust. Does it help with that at all? Also i want a muffler thats a little more throaty but doesnt sound stupid. I have a dynomax right now not sure what series or anything does anyone have suggestions? And finally what do you guys think about bored throttle bodies and possibly a spacer? I finally found one for the 90'. Any input would be helpful.

 

[MudderChuck]

Thanks for the response. If i run across extra money i was gonna look into the header. I was also looking to get it for maybe some added volume to the exhaust. Does it help with that at all? Also i want a muffler thats a little more throaty but doesnt sound stupid. I have a dynomax right now not sure what series or anything does anyone have suggestions? And finally what do you guys think about bored throttle bodies and possibly a spacer? I finally found one for the 90'. Any input would be helpful.

Got to think about what you want when you get done. XJ is kind of heavy for a street racer. Headers IMO really don´t help much, in the lower RPM band. Mine will run, near stock, well over a 100 MPH. Don´t street race much and rarley get over 35-40 MPH, when dirt roading.
Most of were I need my power is grunt, and you find that in the lower RPM band and torque is actually improved when the exhaust is resticted a bit. The stock 2 1/4" pipes work well, as does the stock header, might want to think about replacing the exhaust manifold with an after market header, when your stock exhaust manifold cracks, they all do sooner or later.
I was thinking about a bored throttle body, but you really don´t get much gain, in the Renix years TB. And I´ve heard the HO throttle body bored out, can really mess with your sensor values (MAP).
I´ve got a dynomax now, I like it and if/when I smash it, it´s cheap. Had a Edelbrock muffler, way too loud.
Most of my HP gains, were in getting what I´ve got to run well. A good tune up, cleaning all the grounds, cleaning the throttle body, making sure what sensors I´ve got work well and adjusting the TPS. I´ve got a pretty used up 88 4.0, that runs pretty well, wifes 96 HO isn´t much quicker actually.

 

[Bounty__Hunter]

Re: Simple Axle Question...

Throw on a 4.0L HO head, good for quite a few more HP.

 

[Sly8795]

What did you tune up to get yours running good? Along with what sensors because I'm looking to do that over my winter break from school so she runs like a champ and thats when i will actually have money and the time to do so.

 

[Sly8795]

RE: Re: RE: Jeep Gladiator Concept Truck

One other thing. You mentioned that would mess up the MAP sensor possibly. I've sorted looked into that already and theres diagrams I've found where you can build a MAP sensor adjuster and if I did this i was going to find a Air/Fuel sensor so I could adjust properly for the new mods. I guess you could say this is sort of a hobby right now a learning experience for the future when I get a new vehicle and want do make the performance on that much better. Any ideas on the MAP sensor adjuster?

 

[MudderChuck]

I´ve been thinking of an air/fuel sensor mayself, seems like a good idea, madxj has a right up on an adjustable MAP. Personnaly, I spend most of my time and money getting what I got to run good and/or repair what I´ve broken. Let me know what you find out about a good, air/fuel gauge, I´m wanting to install one also.
Two or three biggest improvements in performance, where cleaning the grounds really well at the dipstick holder, the ECU and TCU modules ground there. Also the ground at the fire wall drivers side near the rear of the head. I also added a ground from the battery negative, to the front clip, could actually see that the headlights were brighter.
Really check out the vacuum lines well, seems I´m continiously finding, very small vacuum loss, here and there adds up, makes for poor performance.
Adjusting the TPS to 86-88% instead of the recommended 82-83%. Standard tune up, paying special attention to the cap and rotor. A little tip, the plug cables aren´t that critical, after market works well, but the coil to cap high voltage wire, should be close to OEM resistance.
Like any computer, garbage in barbage out, most of the sensors, work on very small voltages, there is often a little resistance in the connectors, due to oxidation and/or moisture.
The Renix is designed to run things with certain imputs and expectations. I read the manuals on the Renix when they first came out, pretty primative stuff, not a very adaptable computer.
If you decide to tear into something, like the TB and clean it, I can probably save you some headaches. And try and help you avoid my mistakes.

 

[Sly8795]

Guess that arcade sound

Hey MudderChuck thanks for all your information. If you could give me some tips on cleaning the TB that would be great. I'm just starting to learn about this stuff and am eager to get the jeep running in tip top shape. I hate when its not. Also how do you change the TPS position and what exactly does that do? Ive also been planning on changing the cap and rotor just havent gotten around to it who knows the last time it was done. Im wondering there if a novice like me could figure that out. Thanks again
Sly

 

[MudderChuck]

Novice, what´s a novice. I´ve been playing with XJ´s for about 17-18 years, still learn things. Upsets me when I hear of someone else, making the same mistakes I´ve made. Much easier (an cheaper) to learn from somebody elses, muck ups.
Best to have a book to adjust the TPS, have to have a digital multimeter. If your gonna clean the TB, the safe way, your gonna have to remove every sensor from the throttle body to do it. You can cover the TPS, with a piece of plastic, but if you get spray cleaner in there it´s pretty much junk. The IAC has to come off. I use spray carb. cleaner, nasty stuff, most any plastic or rubber it touches can cause damage. Gonna need a new TB, gasket, old one gets too hard to seal again, from the heat. The IAC is often caked with crud, better not to spray the rubber stopper or any of it with spray cleaner, use your finger nail to clean it off and put a drop of oil behind the piston (without moving it) if you pull the piston out by hand you can strip the little gears in there.
If you remove/loosen the screws for the TPS, have heard of many people snapping them off or striping them. I always put a torx socket in the end of the screw and tap it with a hammer, too loosen things up a bit and a little penetrating oil (remember the sensors, don´t like chemicals or water).
I can tell you the quick and dirty way to adjust a TPS. You adjust the TPS with a digital meter at the square four pole connector at the TB (for the transmission) the three pole connector is for the ECU (it adjusts with the transmission together/two part TPS and is a bit more forgiving in adjustment). The four pole connector is lettered (have to remove a little cover to read some of the letters) should have 5 volts between A and D, never do, most times it´s closer to 4.63-4.66. After loosening the screws a bit, you twist the TPS, until you get around 4 volts between poles A and B. Book says you should multiply the reading between A and D by .82-.83 (82-83%), gives you the value for the adjustment reading at A and B. But have found a .86-.88 (86-88%) works better, around 4 volts. I usually run the TPS wires over the top of the TB rubber intake hose and make a little cut lengthwise in the insulation (just enough to see the copper) with an exacto knife, got to do the test with the connector connected and the key in the run position. When I´m done I cover the cut with a dab of silicon. They also make special leads for the meter that pricks the wire.

 

[t3chn1c0]

I also have a 1990 4.0L. I added the 7120 casting HO head from 91-95 models. I ported and polished it according to an article I found by Dino Savva. I have also added the newer intake manifold. I had to create a kit to adapt the Renix TPS to the newer style throttle body. Now I am waiting for a flometric 66mm throttle body to get here, as I hate the whistle from the bored stock TB. I have built the MAP adjuster from the other articles I found, and it does work well. And now, thanks to this thread, I have found out that I have been mis-adjusting my TPS at .82 - .84. I am hoping that will help with the issues with mileage, and transmission shifting I have been having. Otherwise this 4.0 runs quite well. Makes my F150 4.6 jealous...

 

[jeeps for pimps]

Re: Fuel Gauge

Thanks for the response. If i run across extra money i was gonna look into the header. I was also looking to get it for maybe some added volume to the exhaust. Does it help with that at all? Also i want a muffler thats a little more throaty but doesnt sound stupid. I have a dynomax right now not sure what series or anything does anyone have suggestions? And finally what do you guys think about bored throttle bodies and possibly a spacer? I finally found one for the 90'. Any input would be helpful.

If you're looking for add-ons on your jeep, go check this link jeep parts, that's where I bought my header top bikini for my wrangler. With a much affordable price, hope I'd help somehow.