Swampdawg,
This is a very common issue with the 80's AMC Engines. These are feedback and self adjusting systems. AMC used a Ford Duraspark Ignition during this time period.... so this is true for AMC and the FORD units for the late 70's, 80's too......... so this would be true for you Ford Mustang from this period.
When the feedback Carter Carb, knock sensor, Distributor Mechanics, O2 sensor, computer do not work properly, talk to each other, or are removed..... the computer and carb go into limp mode.
LIMP MODE..... will lock the feedback pins on carb to a limp condition, fixed, and the ignition will also be in limp mode. Poor running situation, lack of pep, pooor mileage, poor idle. Will still run
Good info on the mileage.... before I rip stuff apart and make purchases this is great info to have. 130, 000 Miles is a fair amount. Recommend a compression test and record to see what you base line is.... Poor compression could cause poor idle issues and give you a good idea of what results/improvemnt would be attainable. I would do this before you do any major work on a 130k engine.
Spark Plugs...
What do you spark plugs look like? Front cylinger is #1 and firewall one is the #6 on the
AMC 258 i6 / 4.2l and
AMC 232 i6 engines. Write down what they look like and record in a note book and I take pictures too. Use std copper AUTOLITE spark plugs and gap to .032. All plugs need uniform gaps and good quality wires and caps.
IMPROVEMENT AREAS.....
The Ford DuraSpark Ignition
Uses the distributor for ground for the ignition. It is a weak link and causes major issues. Alumium body distributor gets ground from the locking foot on its mount. Galvonic Corossion (aluminum/steel) is not conductive and its a DC circuite so the electrons go out from the battery and make a complete loop back to battery. The spark energy and the operation of the inductive pick up to see position of distributor to signal the spark release for each cylinger can be affected by this WEAK GROUND. The way to fix this is cut the BLACK/Ground wire goinging into the spark modual......
I cut the black wire on the harness side vs the spark modual side so the aux ground stays with the engine bay if the spark modual every needs to be changed/replaced. Solder in a 12-14 awg black wire, cover with heat shring. and ground direclty to battery or the fire wall. The spark modual is on the passenger fender, so I used the firewall and added aux ground to the firewall. This is a HUGE UPGRADE.
(future topic) aux grounds needed for firewall, dash, grill, alternator, starter, block, frame, CJs have very weak grounds.
Carter Carb BBD, idle tubes so plug up...
You did mention the idle tubes were cleaned out...... good step and the BBD tube do need to be cleaned out to correct poor idle.... Many write ups on this you carefullly look down the throat of carb while running. If the idle tube dribble / drops of fuel vs a stream of fuel they are plugged up. These are often drilled out to .032" to solve the pluggs. The BBDs need rebuilds every 2-4 years or when there are issues.... just part of this carb. Feedback BBDs can also have the feedback pins set fixed position when the FULL SYSTEM is not going to be used.
WHEN POOR IDLE is the issue.... look to the CARTER BBDcarb first.
Swampdawg said this was done or some of it was done.... The next ck would be the ground for the ignition as said above.
MORE IGNITION
After compression ck, add igniton ground & maybe other aux grounds, ck spark plug results.
There is a very good igntion upgrade using TUNE UP PARTS.... this uses a better quality distributor cap and rotar. Uses a adapter for larger diameter and taller distributor CAP with brass contacts. Few buck more but a major upgrade FORD developed and its backward compatible to the CJs of 70s and 80s. Alumium Terminal CAPs are JUNK if you have one and have issues replace it with a brass terminal cap. The larger diameter taller cap cuts down on cross fire, ionization issues, and grounding out the distributor weights and body (another path to ground vs spark plugs). This is a huge HUGE HUGE HUGE>>>> upgrade>>>>> we all need to do this on you next tunes..... This gave me 20% more preformance on a rebuilt long block.... I use the BBD cap and rotar and Oriley has lifetime warranty and good prices. Also like the MSD version but it is a bit more money. Only issue is the UPGRADE CAP uses male terminals and the spark plug wires are going to need changing also. My yields were:
20% more preformance
pep increased 20%
MPG went up about 4mpg, I get 24 mpg with my set up at 60mph
Max RPMs went from 3200 range to 4500 range
Better Starts, smoother idle
Spark plug wires are junk if you buy the ones from the auto stores. They can fail out of the box as well as the sprark plugs. If you drop a spark plug on the ground... throw it out... the carb stack crack and fail if you drop them... could have been mentioned above.... The best wires are the MSD wires they last longer and work better they run about $75 from summit racing. The other wires I use but not as good are the NAPA Belding Dark Navy Blue wires they work well and have lifetime warranty.
The spark energy needs to get to the spark plug gap to the fire. Timing, cap, rotar, plug wires all need to be excellent to get the energy to cylinder.
The next step is overlooked often....
80s Computer CJs have a very Limited mech advance in distributor..
The duraspark distributor is 25 to 35 yrs old and still working. ....its what I have still.... get 24mpg, 80-90 mph speeds, 650 idle speed, strong pulls from 650 - 4500 rpms... it works fine is set up correctly.
The computer control CJ's distributors are a bit different. There are two mech advance slots with limits of 5 and 8 degrees. The PREcomputer versions have two mech advance slots of 13 and 18 degrees. Usually factory has them set on the smaller slots. Swampdawg is (guess) likely set on 5 deg mech advance. This is one of the more advance corrections but the slot can be opened up in width to equal the 13 - 18 slot of the 1970's. This is a huge short comming.
When you remove the Carter BBD Feedback, computer, knock sensor, or O2 sensor or they fail the engine control goes limp and operation suffers.
This can be corrected by
Open the limit slot to the 13-18 deg range
Purchase a Cardon Rebuilt Distributor with the larger slots (need to look) $50 with lifetime warranty
Purchase the MSD Distributor, true upgrade, for the CJ $200 est
Modify the stock distributor with a larger slot.... free
I do not like the HEI distrubtors for the AMC Engines.... many short commings with hard starts, too much advance, advance curves that need to be correct, hardened gears, and many failed AMC engines. I am sure more will be published on the HEIs. I do not like the HEIs on AMC they cause more issues then they solve and the user should be very well read before using.... ONe of the most heated topics on the CJ
COIL ISSUES.......
Coils like to fail and get weak..... When plug wires are pulled, fail, spark energy does not have goood ground, etc, the coil wire spark out internal to coil and over time these short will make the coil and engine work poorly. If your FSM, Field service Manual, there are resistance measurements published for the primary and secondary coil windings...... If you have never replaced your coil this is a good time to do it or atleast take the resistance measurments. Coil will generate 35,000 to 50,000 volts at the plug gap if working well. The high voltage is why good plugs, plug wires, and premium carb large & brass are needed or this voltage will find the easiest ground it can reach.
I have been using the Ford E coil used from the junk yard and have had great results. I also use a MSD capacitance multspark ignition.... This gives me 3 full energy spark discharges for each cylinder.
Sorry for the long posts.... This is a huge issue for the CJs. IN the next few months I would like to put a few tech articles with more info on this. I learned most of this from JeepHammer and he is a igntion god.
