HELP! Slow cranking/hard starting issue ..STUMPED!

87 jeep wagoneer, RENIX 4.0 , auto, dana44/35.

Replaced to try and find issue: battery, alternator, cables and terminals, added 4awg battery to chassis ground and put new 4AWG engine to firewall strap, cleaned sensors, refreshed grounds on dipstick stud and under ignition coil, new dizzy.cap n rotor. All of that is trying to find the slow crank hard start issue. And over the past.couple years I have put on a new CPS ,coolant temp. Sensor, IACx2 , complete tune up very recently as of last month plugs wires cap rotor. Fuel filter was done last tune up .new fuel pressure regulator, cleaned my cco1 connector, cleaned throttle body X100 , ran couple tanks of 94 octane, Injector O rings and exhasut manifold gasket. the most essential was listed probly a few things I'm missing.

So Ive been trying to figure out why I have a slow/hard start. It turns over.really slowly on all cold.starts(by cold I mean sitting for a few hours) and also on warm starts. every once in awhile it turns over how it should nice and quickly , and if I start it right after I shut it off it seems to be better/turn over bit quicker. But is slow/hard for the most part (mostly intermittent) Sometimes when its turning over.slowly, i get a grinding sound, the one when you turn your key when the engine is already running because its cranking slow and the starter engages then disenages again. Pretty sure cause of the slow.crank. so I've replaced and refreshed everything I can think of, a buddy at work says he thinks its "the engine" and a bearing inside but that's BS and he's out to lunch. What you guys got to say!? Lemme pick those jeep brains! Thanks,

Tired starter or battery?

I have just put in a new starter and battery no difference! But I unplugged my coil just to see how it cranks and I got it to crank good when I hooked it up to her jumpers.and.jumped it

Still no luck trying to figure it out. Where I got was if I o
Play with the battery cables while cranking it starts better but it was when I played with the positive and the negative. I hooked up jumper.cables to bypass the ground cable and also positive to starter but made no difference so my new cables are good...just puzzled on this one! Everything seems to be good I've replaced everything

Have you tried hooking up a "bump" starter switch between the starter solenoid and
the + battery terminal? At least that will clue you whether if it could be a dodgy
ignition switch or NSS (Neutral Safety Switch).

In fact, have you tried starting the car while the transmission is in Neutral?

Meter the battery,cold without engine running.
Do again with engine running.
Repeat while cranking.
Post results.

i did try the bump , i bypassed the posotive and also did the same thing for the negative with no difference, also tried starting it in neutral and it didnt make a difference. i will have to do the metering tests like marty said and see what that tells me/you guys.

You said you bypassed the coil and it started well? For $20 you might as well replace your ignition coil I used this one off Amazon and it worked fine in my 88 XJ RENIX 4.0 (dunno if the wagoneers use a different style...)

Buy/borrow a voltmeter and try out Cruiser's Tip #7

K, is this just slow crank and hard start? If so, it's not going to be a sensor issue... If your motor isn't turning over fast enough during cranking, you've only got two possibilities.
A. Starter isn't working hard enough.
B. Something is causing the motor to be way too hard to spin.

Assuming it runs well when it starts, I'd say A. is the most realistic. You said you put a new starter in, but didn't say if you checked or replaced the starter power wire. FYI, a starter will seem like it works great on a bench with just some booster cables, but that will not work to actually turn the motor over. You need a very good, low resistance connection to the starter for it to work properly.

I'd be looking at your starter power wire. Maybe even try adding another battery with booster cables to the starter itself to see if it turns faster with the extra juice.

When you bypassed the wiring with jumper cables, did you clamp the cables onto the bare studs? or the terminal lug? Reason i aski is, Ive had battery terminals lugs that fit nice and snug, yet somehow they had a bad connection to the battery. When twisting them, with the key on, engine off, you could hear relays clicking on and off... Had to retaper the battery lugs.

The jeep starts EVERYTIME, and runs PERFECTLY i might add. So when I replaced the starter I also replaced cables to the battery aswell. So I did replace.the battery positive.and negative leads to the starter if thats the "starter power wire" your talking about. That little green wire(for volt meter) I didn't do anything with. So just in case I bypassed the negative and posotive leads seperatly and neither made a difference... I thought maybe my new cable was junk. Tried a new battery didn't change . what gets me is randomly ...like some mornings even cold first start of the day it cranks perfectly...nice and fast. Also usually if I go for a drive then shut it off and start it up again right away it will crank perfectly... But most of the time it has a slower crank than those times where it cranks how it should ... From what I read , if its the ICM igniton control module or starter solenoid distribution box...it would not start at all..but myne ALWAYS starts.... And I'm just out of ideas except replacing that distribution box, starter relay!? Maybe!??sorry for late reply still an ongoing issue hasn't figured itself out lol. And I haven't either.