Did you get the ground strap reinstalled on the back of the head?

 

I believe Jeep sent this out to the dealerships. I wasn't there so am not sure.

http://www.bc4x4.com/faqs/yj.cfm?cat=5&faqid=164

Idk your situation. I read of a guy taking an old points style dizy (w/condenser), and you know you power one side of the coil and ground the other through the points, holding that dizy on a ground and turn the rotor.
At hart it's just a coil, should spark. Suppose a guy could try it with nothing but a condenser.

Doesn't he have an ECU ground at the dipstick mount he might check as well?

 

You changed the head without breaking that MAP tube? Good Job!

I found this, another of Cruisers. If you did this all the sensors on your Jeep, and so your Jeep will he happier as you role it into the lake

Renix Ground Refreshin
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.

I added my ground from the AC compressor to a Radiator mount bolt.

 

yep the ground strap on the head was reinstalled..thanks DFlinstone i had seen that in another post and couldn't find it..that is the plan for tonight..

you guys rock! i really appreciate all the help. all this electrical stuff makes me appreciate my old late 60's chevy's..

 

Testing a coil by checking it's resistance is fooling yourself.
An Ohmmeter is LOW VOLTAGE - coils typically short out at HIGH VOLTAGE.

Use a scope or use the color of the spark!

Checking CPS resistance can also fool you. Just one little shorted turn in it does not change the resistance enough to notice, yet it internally shorts the pulse.
AND check to make sure it's not grounded internally.

Check output with a scope or swap it out.

 

Yea Brian, I'll give this thread a priority bookmark. Partly because of a bunch of Renix info, and partly because you are hauling your end so well.(V.there's more here!.V)
https://www.cherokeeforum.com/f51/he...ix-links-1397/

Agreed Rich. Just that coil resistance might tell you if it's bad. I have a bit if faith in the AC VOLTAGE test for the CPS. I just watched mine go from .3 something, down to .2 something, since Oct., as I got my worst mileage ever, (12.7, all stock)(actually had a no start one morning there, but a new battery, and it fired) , then went to .56 with a new Echlin , and got 19 on the Hwy, running smoother. Course there where other factors, but that was the only new part.......................V...other factor...V...

 

well i'm still on the problem...the pond remedy is starting to become an option..

to the gracious gents who have given links and advice..thank you!

i've cleaned grounds, terminals, replaced cps, cleaned stuff that i'm not sure what it is, tested parts that check out aok and still get a week spark...lots of fuel just no fire.

the only thing i haven't tested is the ignition module that the coil pack sits on..any thoughts on that being the problem?

 

It's beyond me. That's what Rich was thinking. I'd see what Cruiser has to say.

Past 400K eh? , Just quit..Rotor is past #1.....
Guess I'd check that it is indeed going around, and .020 past #1 at TDC.
Also I might be sure it had supper power to crank, a new battery or a good jump. Mine won't start, even cranking well, if the battery is weak. Not even a single chug or pop?

So you got over .5 volts on the AC scale from the CPS cranking. I think this writeup involves making sure that signal is making it to the ECM.
http://www.bc4x4.com/faqs/yj.cfm?cat=5&faqid=164
Wonder if Cruiser will suggest checking/tightening the connectors on the ECM?

This, from that link ^, gives the color codes and pin locations where the CPS connects to the ECM
It bypasses the c101 is the idea I think;



PROCEDURE

Disconnect the battery.

Replacing the harness:

Remove the ECM from under the dash. You can
remove the plug from the ECM without pulling it
but it will be difficult.

Unplug the 'top' or larger connector.

The blue clip on the connector will be labeled
"C1" through "C16" while the grey half will be
labeled "D1" through "D16".

Drill a 3/8 inch hole in the firewall. I can't
tell you exactly where but keep it as far from the
exhaust manifold as possible and as close to the
existing harness without contacting any vitals.
Thread the two terminals through the hole from the
engine side and plug in the grommet.

Remove the blue clip from the ECM connector by
squeezing the two 'hooks' together. Note which
side is "C1".

Now pull out the grey clip by inserting a standard
screwdriver in the notch and twisting. Note which
side is "D1". The black part of the terminal
block (plug) should still be labeled "C" and "D".

Locate "C1" (violet with a white tracer). Using
pliers gently pull out the wire at terminal "C1".
With the wire towards the center of the terminal
block slide the new wire labeled "C1" (White with
a black tracer) into the hole until it seats.

Locate "D1" (white with a black tracer). Pry the
wire out and install the wire labeled "D1" (red
with a green tracer) again with the wire toward
the center of the terminal.

Reinstall the grey clip and then the blue clip
into the terminal block. Plug the connector back
into the ECM. Reinstall the ECM. Route the plug
end under the hood up to the top of the wire loom
on the firewall. Use the tie wraps to secure it to
the wire loom. Trim the old wires to the loom on
both ends.

 

yep...just died and wouldn't start. the battery, cap, rotor, plugs and wires were brand new about 3 months ago when i replaced the head gasket..i've checked the battery and it is dead on at 12.6, the tree that the pigtail comes off of that all the other hot wires connect too is 12.6 as well along with the main pos cable going to starter.

the cps did range from .5 up to like .63 when i tried to start it..i tried some alligator clips to connect the male and female ends of the wiring harness to see if it was not making it past the connection but it was not what i would call a succesful mission...trying to hold it all without anything touching wasn't working to good.

when i turned the motor to tdc the rotor i thought was past #1 more than .20 but then again i never measured it to see how far the trailing leg was actually past.

i even rechecked fuel level, pulled injectors and shot fuel to be positive (maybe i was hoping to catch it on fire) then i installed new plug wires as a final before i turned the shop lights off and called it a night.

 

400,000K+ Wow.
I can only say what I might try. A coil is just that. With it out I might power the +, ground the --, and with a condenser, (grounded), the lead on that ground side wire, break the circuit. Disconnecting the ground side with that condenser connected to it should make it fire. (just duplicating what a dizy with points does)(actually pos and neg don't matter here). Wonder what a JY coil costs.

You wrote; ".5 up to like .63 when i tried to start it." Tried to start it? You do know it won't start with the CPS unplugged, and the test is done [U]with[U] it unplugged, probing just the CPS, cranking.

As far as "making it past that connection, I might be interested in that "violet with a white tracer" @C1, and "white with a black tracer"@D1. Thankfully I've never been there, but I'm looking at an 88 with a C101 and might end up there yet!

 

Flintstone suggested this and I'm with him on this. I've never done a write-up on it but I have bypassed the C101 regarding the CPS wiring.

 

i savey the cps test is done in a no crank mode and it was a crisp .5...the cranking situation was to turn it over as see what type of reading i would get, playin with a new tool and tryin some shade tree process of elimination.

i think i have a condensor on a shelf somewhere. my father in law has a 87' renix. i'm going to get his rig and swap out a few parts before i start replacin with new ones.

 

"""""i've cleaned grounds, terminals, replaced cps, cleaned stuff that i'm not sure what it is, tested parts that check out aok and still get a week spark...lots of fuel just no fire."""""

You've said it several times WEAK SPARK!

Look in a FSM - look up your symptoms - COIL!

 

thats what i'm gonna do..just wanted to get all my other bases covered before i spent $50 on a new coil.

 

its fixed...bad coil

rrich was correct about testing the coil with the low resistance test that the manual says..

old coil tested 15.83 new coil was 16.51
the other test was about the same..not much differance

lots of good info in the post and the connectors seemed to like the cleaning they got, fires up real strong, much more responsive..

thanks for all the help fellas, you guys rock!