stonehands Posted October 27, 2008 Share Posted October 27, 2008 1987 4.0L 4x4 D44 rear Lacks power. Motor seams to run well. Trainy seams to shift up ok. From dead stop will not break a tire loose. Steep hills the truck will slow down and doesn't seam to shift down like it should. Fluid level good. Does any one have any Ideas? Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 27, 2008 Share Posted October 27, 2008 Get an HO engine or stroke what you got! :cheers: Seriously, is this lack of power a sudden thing, or was it gradual? And what gears are you running in the D44? 3.55s? Link to comment Share on other sites More sharing options...
Pete M Posted October 27, 2008 Share Posted October 27, 2008 What size tires? Still have the original cat? Link to comment Share on other sites More sharing options...
deziped Posted October 27, 2008 Share Posted October 27, 2008 You didin't mention it but do you have an auto tranny? Is it starting out in 1st gear or 3rd? Maybe it's not engaging 1st when you come to a stop for some reason. MJ autos don't shift down on deceleration , per-say, to 2nd gear like a manual tranny from 3rd, or even to 1st unless you almost come to a complete stop & the solenoids are working properly. You can shift it manually from 3rd to 2nd gear at any speed & eventually it will slam into 1st with a jerk at about 32-35 MPH if the electronics are working as they should. Not knowing what your MJ has for loco motion it hard to discern what your problem might be. And if it not shifting down going up hill , probally solenoids again Link to comment Share on other sites More sharing options...
Eagle Posted October 27, 2008 Share Posted October 27, 2008 Clogged catalytic converter. Link to comment Share on other sites More sharing options...
stonehands Posted October 27, 2008 Author Share Posted October 27, 2008 It has an auto with overdrive. Another jeep owner tooker for a spin and said that it shouldn't do what it is doing. It has 30x9.5x15's for tires. How do you check a cat-conv? Do these tranies realy not shift down when put under a load going up hill? That just doesn't make sense. Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 27, 2008 Share Posted October 27, 2008 there are many things that could be causing this. when was your last tune up and what oil do you use? has anything been replaced in the past 20 or so thousand miles? Link to comment Share on other sites More sharing options...
stonehands Posted October 27, 2008 Author Share Posted October 27, 2008 Ive been replacing lots of stuff. Plusgs, cap, rotor, ICM, KNOCK SENSOR, COOLANT SENSOR (BOTH), CLEANED TB, PUT K&N AIR FILTER, CLEANED INJCTORS. Runs just a little bit smoother since, but same power to wheels problem. I haven't changed oil yet but will soon although I don't know what that will do for power to wheels. It does not consume oil or leak it. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 27, 2008 Share Posted October 27, 2008 I have the same issue with my 87 the engine hadn't run in 8 years before I got it, and before I got it a bunch of illegals tried to fix it and screwed it all up. I attribute it to sitting and shrugged it off..far as I'm concerned, renix is pretty much crap so I'll be dropping a H.O. stroker with 1995 H.O. wiring and all in the truck within a month or two. I haven't got a "real" cat... the only main things that would cause the dogginess (since the 4.0 is in general a decent motor) would be clogged catalytic converter, or bad shift solenoids/TCU. Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 27, 2008 Share Posted October 27, 2008 I suspect the clogged cat too, especially if it's the original. Only sure way to tell is cut the inlet pipe off and look thru. Mine was obviously clogged. Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 28, 2008 Share Posted October 28, 2008 possibly poor timing? Link to comment Share on other sites More sharing options...
stonehands Posted October 28, 2008 Author Share Posted October 28, 2008 Thanks guys. I will check the timing before I cut any pipes. I'll repost after. :doh: Link to comment Share on other sites More sharing options...
summerinmaine Posted October 28, 2008 Share Posted October 28, 2008 Thanks guys. I will check the timing before I cut any pipes. I'll repost after. :doh: Timing is not adjustable IIRC. So unless you did something wrong in the tune-up, your problem lies elsewhere. I just started to have a similar problem, so I'm going to replace the ignition bits, and probably the Cat as well. Link to comment Share on other sites More sharing options...
deziped Posted October 28, 2008 Share Posted October 28, 2008 I think you miss read it, I didnt say it wouldn't shift down going up hill, I said "if it don't/doesn't" or something to that effect. Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 29, 2008 Share Posted October 29, 2008 Thanks guys. I will check the timing before I cut any pipes. I'll repost after. :doh: Timing is not adjustable IIRC. So unless you did something wrong in the tune-up, your problem lies elsewhere. I just started to have a similar problem, so I'm going to replace the ignition bits, and probably the Cat as well. can't you spin the distributor for a base timing and the ecu/vacuum/mechanical will advance it? Link to comment Share on other sites More sharing options...
Pete M Posted October 29, 2008 Share Posted October 29, 2008 The distributor has no factory adjustment. The ECU does whatever it feels is required. Link to comment Share on other sites More sharing options...
summerinmaine Posted October 29, 2008 Share Posted October 29, 2008 can't you spin the distributor for a base timing and the ecu/vacuum/mechanical will advance it? Not so far as I know. The timing is determined by the ECU responding to the CPS, and the ECU decides when to inject fuel, how much fuel to inject, when and how much spark to be at the optimum efficiency, so the distributor fits into position maintained by dowel pins and has nothing to do with timing. Link to comment Share on other sites More sharing options...
Eagle Posted October 29, 2008 Share Posted October 29, 2008 can't you spin the distributor for a base timing and the ecu/vacuum/mechanical will advance it? Nope. Pete and Summerinmaine are correct. The distributor has locating ears on it. The position is fixed and timing is not adjustable. Timing is manipulated by the ECU based on inputs from the CPS and the cam position sensor in the distributor. Let's keep in mind that this is an '87 MJ, with stock gearing and running oversized tires. The Renix 4.0Ls engines were torque engines, not drag race engines, so the owner's expectations may not be realistic for the way these engines work. Automatic won't be as horrible as a 5-speed, but putting larger tires on a Renix MJ without re-gearing does make a very noticeable difference in (lack of) acceleration. And the '87 was rated a few horsepower and foot-pounds lower than the 88-90 versions. If it won't shift going up a hill, the downshift cable probably needs to be adjusted. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 29, 2008 Share Posted October 29, 2008 you can index the distributor though... if the distributor gears are set off by even one tooth, it will either not run, or run like absolute crap. Link to comment Share on other sites More sharing options...
WahooSteeler Posted October 30, 2008 Share Posted October 30, 2008 you can index the distributor though... if the distributor gears are set off by even one tooth, it will either not run, or run like absolute crap. Tell us why you know this Pat? ;) Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 30, 2008 Share Posted October 30, 2008 you can index the distributor though... if the distributor gears are set off by even one tooth, it will either not run, or run like absolute crap. Tell us why you know this Pat? ;) because the mexi-cannots who had my truck before me fawked up the dizzy index when they swapped the used decrepit friggin distributor in the truck.... which is why I got it for trade in scrap value :D :clapping: Link to comment Share on other sites More sharing options...
ejndssn Posted October 30, 2008 Share Posted October 30, 2008 you can index the distributor though... if the distributor gears are set off by even one tooth, it will either not run, or run like absolute crap. Tell us why you know this Pat? ;) because the mexi-cannots who had my truck before me fawked up the dizzy index when they swapped the used decrepit friggin distributor in the truck.... which is why I got it for trade in scrap value :D :clapping: not only that but the stroker's have the tabs filed off the distributor so that they can be properly tuned :brows: Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 30, 2008 Share Posted October 30, 2008 because the mexi-cannots who had my truck before me fawked up the dizzy index when they swapped the used decrepit friggin distributor in the truck.... which is why I got it for trade in scrap value :D :clapping: What's a "mexi-cannot" Pat? That sounds politically uncorrect to me. Shame on you kid............ :dunce: Link to comment Share on other sites More sharing options...
ejndssn Posted October 30, 2008 Share Posted October 30, 2008 because the mexi-cannots who had my truck before me fawked up the dizzy index when they swapped the used decrepit friggin distributor in the truck.... which is why I got it for trade in scrap value :D :clapping: What's a "mexi-cannot" Pat? That sounds politically uncorrect to me. Shame on you kid............ :dunce: he stole it from the movie :rotf: Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 30, 2008 Share Posted October 30, 2008 Clever. Link to comment Share on other sites More sharing options...
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