Comanche MJ build thread.

I just found this on a truck forum. No idea the truth but multiple people agreed with the guy:

Quote:
RV cams are those having specs in these ranges: 250-270 degrees advertised duration and lifts ranging from the .470's to .515 (give or take an extra .010) The @.050 duration is typically about 200-215 degrees duration.
 
thanks gene, this is a big undertaking for me,

I don't know much of anything about working on motors or wiring. Im more of a fab kind of guy.

I've been online reading all day on tuned port injection wiring diagrams, and what all the sensors do.

you are correct, that no knock sensor causes a retard in timing, it was slightly advanced in the video to compensate. I will be trying to get the chip reprogrammed to eliminate the vss, and egr. a vss on the t case is 75 bucks online, and I hear its not that important on a trail rig anyways, so moneys better spent getting the chip reprogrammed.

I bought a knock sensor at napa today, and will be wiring that in tonight. well see how that works out this weekend, I am also getting the alternator rebuilt and turned up to 120 amps, the guy suggested against turning the amps up too high, (he said he could do 160 or even 200 amps)
we had to charge the battery every time to start it up, but the alternator wasn't recharging it. even after letting it idle for 20 mins.

I also found a dust cover for the trans in a junkyard today. Finally been searching forever, I was about ready to make one.
 
Mike, get that alternator taken care of before you do anything to the computer. Lack of juice to the ingnition system could be a huge part of your problem.

I have been on thirdgen.org and those guys make me think that cam is not near different enough from stock to bother that computer. I looked around for five minutes and I was overwhelmed with information.

Check your plugs out also. Running rich, plus assymbly lube, and oil will all do bad things to your plugs. May get a couple box's of cheap champions for a 350/TPI car. I don't know for fact, but I have been told once a plug is fowled it is always fowled. You can clean it off, but it's still not good. <--just what I have been told.

i'll keep researching.
 
just put the knock sensor in, the alternator will be done tommorrow,

I'll go check out that site and see what I can learn,

shutting off is smooth, no extra idling or anything. the plugs looked a bit rich on sunday, but not that bad. I'll have to get some new ones anyway though.

Even if the computer is fine for the modifications, the check engine light will still be on for no vss, or egr.
 
just read this on classictrucks.com. I know its the internet and no different than any other website but some of these older guys really seem to know their TPI facts. I know you don't want to starve it, but can' you back down to 38, or maybe even 35 and see how it runs?

quote:
29. How much fuel pressure do I need?
You need 38 to 48 psi for a 300- to 400-hp engine. High horsepower engines need 40 to 48 gallons-per-hour of fuel. You don't want to use a racing-type pump because they push too much fuel, and the TPI regulator cannot push it back to the tank fast enough.
 
just got this off of ColoradoK5.com. This guy seems to mention some really important details, especially the TPS voltage and properly setting the timing. We may need an Admin to move this to the "other tech" forum so we don't fill up the picture showcase. Then move it back when the MJ is running like it should.

quote:
Hey dude. sorry to hear yer troubles.
Are you Speed density or mass air flow?
What wiring harness did you go with? I see you have a cam, who burned you a chip to match your setup?
What are your cam specs? Duration @ .050 and LSA?
What is your base timing at? Did you set the timing by unplugging the EST connector, set timing, then turn off the engine, hook back up the EST and fire her back up again? Check timing with it unplugged, should be something like 0-6 degrees, then with it plugged back in the timing should advance quite a bit more maybe 10 or more degrees.
What is your fuel pressure at? have you hooked up a gauge and see what happens at idle then when you romp on it? When i've had issues with my tpi in the past, i've hooked up the fuel psi gauge and duct taped it to the windshield so i can see it while i take it for a test drive.
Is your gas tank full? My setup surges for gas below 1/2 tank. I had some driveability problems when i first got the tpi running, finally figured it out when i filled up the tank!
Did you set the tps at ~ .54 volts when the throttle is closed?
Have you jumpered the A to B terminal on your ALDL and see if you have any trouble codes?
Is it going into closed loop after a couple minutes of warm up?
 
thanks for the help gene, I've got a list of things to try now, I'll stop posting in here till monday so the mods don't have to move it, I'll let you know what we find out this weekend

btw, I'll try turning the fuel psi down, it is loading up and getting too much fuel, so that is a definite probability. I like the duck tape gauge to windshield idea, it may be getting more pressure when its moving.

also looking at doing a rear mount radiator, cause Ive come to the realization that a stock cherokee is just not big enough, and the only way to fit a bigger one is in the bed.

be back monday:cheers:
 
jeepmike887 said:
thanks for the help gene, I've got a list of things to try now, I'll stop posting in here till monday so the mods don't have to move it, I'll let you know what we find out this weekend

btw, I'll try turning the fuel psi down, it is loading up and getting too much fuel, so that is a definite probability. I like the duck tape gauge to windshield idea, it may be getting more pressure when its moving.

also looking at doing a rear mount radiator, cause Ive come to the realization that a stock cherokee is just not big enough, and the only way to fit a bigger one is in the bed.

be back monday:cheers:
Click to expand...

Probably wouldn't set the fuel pressure until you are getting a constant voltage to the fuel pump, That could increase or decrease what you are getting. Also make sure you are getting enough. Pressure and Volume are very different things. Not sure what size fuel line you ran. Good Luck, I'll keep researching.

On the radiator thing... I've seen guys mount stock radiators in the beds of other vehicles and the additional tubing alone is enough to not let the engine warm all the way up. Also you will never worry about running a stick through it. Maybe modify the grill so a winch sits way back.

Gene
 
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didn't get it running again this weekend, instead spent most of the day saturday wiring in a new knock sensor, and building a slick little mount for the rear mounted radiator. turns out I was pretty busy doing other stuff sunday and didn't get to running rad lines to the back. got most of the materials though, decided to use aluminized pipe, (conduit from menards) 1.5", and Im gonna see if I can pick up so 90 degree rad lines for the bends underneath tommorrow. should turn out pretty sweet. and Im figuring it should hold an extra 3 gallons of coolant. Also have a ton of room to work on the motor with the radiator out of the way.

heres some pics of what I did.

started with the stock comanche crossmember, cut it up a little bit, now I need to get another one for the front, this one was already pretty bent up anyway.

100_0771.jpg


was looking through my scrap parts and noticed I had a stock tj front bumper, checked it and it fit damn near perfectly flat across the top of the bed. drilled some holes for the posts, added rubber grommets, welded the crossmember to the bottom of the bumper, welded some mounts to bolt to the bed in 4 places. and wallah,

100_0772.jpg


100_0773.jpg


in this shot you can see the mounts I made to bolt to the bed, and the little mounts that hold the shroud on.

100_0775.jpg


overhead view

100_0777.jpg


turned out pretty sweet, and it doubles as a great place to sit. Also when I put a cover on for the bed, it will be a great support, and I think I might only make the cover go back to that mount.
 
also forgot to mention, the wiring is all hooked up for the fans as well, an we found out the its gonna be a great way to cool off on a hot summer day, those fans kick A#$, just stand behind the jeep.

and I will be turning the radiator around so the lines go out towards the front, but will leave the shroud facing towards the back with the puller fans.

I feel bad cutting this bed up so much, but thats what has to be done, so. . . . .

Im just happy that everything back their is looking good and not hacked.
 
super nice Mike. I'm just waiting for this thread to turn into a 4 link with d60 front on FOX air shocks thread. This thing is going to be nice. Thanks for the instant updates.
 
lol, I know, I just can't leave anything alone. I really want this thing to be a great rig. not just thrown together.

Ive got some buddies gonna help with running the radiator lines tomorrrow night, so we'll see what happens.
 
update on yesterday, I didn't get much done at all, got to working on it around 4:00 flipped the radiator around so the hoses face toward the front, which will make it easier to run the pipe underneath, took a few hours cause I had to modifiy the mounts a bit for the shroud and the upper support. nothing picture worthy. started running the coolflex lines I have on the front and had to rearange all of those and re glue all the fittings so their water tight.

I saw that I wanted a different type of clamp/ support to hold the hoses up than I had, and I got called in to work an over night/ demo job 3 hours away in peoria. needless to say, I gave up early and just got home at 9 this morning. got 3 hours of sleep, now I gotta get some hw done and go to class tonight.

on a positive note, my classes for friday were all cancelled and Ive got no plans for the weekend.
 
So I hope you don't mind, but I'm "steeling" your bed design.

slightly modified of course (fenders, complete bed all the way back, tailgate, etc.
 
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