90 cherokee HELP!!!!
01-13-2010, 03:44 PM
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90 cherokee HELP!!!!
Ive got a 90 jeep cherokee 4x4 4.0L with a new rebuilt jasper engine that a few friends and i just installed, its the second engine we have replaced in this jeep cuz im jus a lil hard on em. 
But anyways, we started it for its first time in the new jeep, and it fired!!! wow thats a first lol, but anyways during the "fine tuning" part to get everything str8nd around and running right i noticed that it wont rev past 2000rpm while slightly on the throttle, it kind of acts as if it has a rev limiter but i kno that isnt the case, but if i punch it to the floor it runs like a raped ape, just like it should. lol it backfires and kind of "bounces" at that certain rpm until i open it up completely and then it clears up, but it isnt even driveable on public roads, wont go over 25mph without backfiring and sputtering unless i floor it and it runs puuuurfect idleing, weve tried rerouting vaccum lines, unhooked the egr valve, new cap, rotor, plugs and wires, its getting constant 32-35lbs of fuel pressure on the fuel rail while idleing or revving, new crank position sensor, new coil, new map sensor. the engine came from a 89 jeep cherokee, we havent tried swapping the computers yet, but the wierd thing is is that i can completely unhook every wire from the "throttle body", and it will run the exact same way, no change. idk where to go from here. HELP
But anyways, we started it for its first time in the new jeep, and it fired!!! wow thats a first lol, but anyways during the "fine tuning" part to get everything str8nd around and running right i noticed that it wont rev past 2000rpm while slightly on the throttle, it kind of acts as if it has a rev limiter but i kno that isnt the case, but if i punch it to the floor it runs like a raped ape, just like it should. lol it backfires and kind of "bounces" at that certain rpm until i open it up completely and then it clears up, but it isnt even driveable on public roads, wont go over 25mph without backfiring and sputtering unless i floor it and it runs puuuurfect idleing, weve tried rerouting vaccum lines, unhooked the egr valve, new cap, rotor, plugs and wires, its getting constant 32-35lbs of fuel pressure on the fuel rail while idleing or revving, new crank position sensor, new coil, new map sensor. the engine came from a 89 jeep cherokee, we havent tried swapping the computers yet, but the wierd thing is is that i can completely unhook every wire from the "throttle body", and it will run the exact same way, no change. idk where to go from here. HELP
01-13-2010, 08:12 PM
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?
Idk, maybe, but like i said above, i can completely unhook the throttle body without it changing the way it runs, its wierd, lol it shouldnt even run with all of that stuff unplugged. lol
01-13-2010, 10:54 PM
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yup, we pulled the engine out of another daily driver jeep, and we didnt touch the distributor or the intake, or throttle body, or exhaust downpipe, its open exhaust, well straight pipe anyways, AND we replaced the map sensor with the 1 that was on the other jeep (89)
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