So I am having an issue with my 1988 with the throttle body injected 3.9L engine...when I take it for a 20-30min drive it seems to misfire after a while (it looses some acceleration power and if I step on it the engine will cutout or backfire but not stall) once I start getting this problem my higher throttle range begins to vanish and I have to go easy on the throttle but if I shut it down after it starts acting up it will not start again for 10-20min it just cranks and cranks with no signs of wanting to fire. I replaced the o2 sensor, temp switch and temp sensor, checked the fuel pressure and replaced the plugs, wires do not look bad and the coil is 2 years old with about 7k on it. The issue does not happen when cold so I assume it is not a timing issue as for that would be an apparent problem right from the cold start?

All the time I spent on the side of the road I ran through the OBDI-CEL blink codes and I am now getting code 17 (low engine temp) which I never got before I did my engine temp sensor for the computer. I do not see how a low engine temp would be affecting my "long running time problems" so I may have two separate issues going on here because I am definitely getting cab heat.

My next approach is going to be ignition coil as I am talking to a friend as I am writing this, mine is factory mounted horizontally and there is some oil mist on the firewall around the coil so I am not sure if that was from the old coil or this one but I never really did understand why they mounted an oil filled coil sideways anyway??

 

The coil has been becoming very warm to the touch after 10min of casual driving then it starts misfiring, backfiring and when I shut it off it wont start for a while. A few years back when troubleshooting another ignition problem that turned out to be the pickup coil inside the distributor we installed a cheap possibly universal coil which has already seen its life within about 7k miles. I always kind of thought it was stupid of Chrysler to mount the oil filled canister style coils horizontally or sideways like this, granted mine did not leak that I know of even though the oil mist on the firewall is evident that may have been my old factory coil years ago that was working perfectly fine.



I am not even messing with another outdated oil bath coil this time I bought a universal E-core style ignition coil that is far more reliable and may even allow me to open my spark plug gap up a few thousands more, it uses the same dual terminal input setup seems pretty straight forward...but then there is the external resistor/capacitor/condenser controversial mystery haha



This little rusted canister attached to I think the positive side of the coil is what alllll my fuss is about; whether or not I am to use it with the new E-core coil!?



Some say it is strictly to reduce EMF interference in your radio from ignition switching and has nothing to do with the functionality of the ignition system. Some say it is resistor but that I am aware ignition resistors are ceramic blocks....however the coil in my truck now says right on it and you can see it in the first image "USE WITH EXTERNAL RESISTOR" but I see no resistor! Many claim it is a condenser/capacitor and I can not even find them in replacement parts or wiring diagrams, the closest I found was this for an 88-89 Dodge Van/D100/RamCharger as you can see here they are calling it a capacitor for the coil...guy at the part store said that they used to refer to it as a "resistor" as stated on the coil but they were stupidly referring to the capacitor/condenser!



They claim if it runs fine without it using the E-core don't use it, but I do not want to do long term damage...some say this unit is built into the E-core there is a LOT of confusion and I am ready to loose my mind! I can only guess that this little unit is malfunctioning which is WHY my coil is overheating because I do not see any leaking however the way the guy at the part store explained it to me was there is an inner and outer coil inside the oil filled units and hard bumps and vibration can cause them to move around and possibly touch or at the minimum shift position inside the canister (I live in the land of potholes).

 

Turns out the computer was the problem, however the new one I got from a junkyard with 225,000 on it doesn't look much better on the inside and it was used as a plow truck in cold winters so this must be a defect but the computer solved my issue! It was not easy to find for me all I could find were 87's and 90's all the 90's used a different computer; same large 3 row connector on top but with the smaller 2 row connector on the left completely absent with no additional wires entering computer, the new style computer seems to be used from 90-91 possibly even all through 89 too but I can't find an 89 to verify that. I started looking at 87's since I couldn't find an 88' and they were all carbed but I managed to find an 87' with my computer and TBI system so it was probably one of the very first few months at the end of 87' they installed this system. For all I know they stopped using my style computer in the middle of 88? What confuses me is where are they hiding a second mini computer because thats a big connector to just no longer use....also the white connector on the one I pulled was dirty/greasy just like mine...seems to be a common problem unlike the large clean one at top. Since I no longer use the snorkel tube cooling the computer I am going to install a small PC fan on my computer cover for reliability purposes.