CO MJ

$500 plus bits and pieces from the junkyard vs $2500 and unknown lead time from a remanufacturer is quite the difference though, I'll have to think on it. May attempt the jb weld and put some stop leak in it just to see how many more miles I can squeeze out of her

Definitely possible it was already there, we just had our first freeze of the year and I just assumed that was the cause since it also popped one of the expansion plugs. Either way, it's leaking just sitting in the drive so I guess I'll need to address it. If I can get that plug back in without pulling the intake/exhaust I may just try to keep it going for a while and just keep the coolant topped off until I can get around to swapping in a new block, but if it keeps leaking like this I think she's done for. Unfortunately I don't think my landlord would approve of a doner in the driveway so I think it'll have to be a reman long block or gamble on a junkyard unit

ah yeah water only That's also my concern since you can't start anything up in a yard, even with the 30 days or whatever they typically give you, what a nightmare it would be to pull and install it just to find out it has significant issues and having to bring it back to the yard. Unfortunately I don't have any space to take a doner vehicle, so i think buying a pulled and tested engine or a reman unit is the only way I'll be able to do it confidently, and the used engines don't seem to be significantly cheaper than a reman long block unfortunately

I was real confident I had antifreeze in my coolant, apparently not. Blew a hole in one of my freeze plugs, but the only leak I could see was coming out of the hole in the plug. I thought I got lucky and went to replace it today, started to press it in and noticed a drip on my shirt, put a light up in there and it looks like a nice big crack under the second freeze plug. Not sure why it only now decided to start leaking. I know for a fact I already had exhaust gas in my coolant already, presumably a crack or leak somewhere in the cooling jacket, and I planned on driving this engine into the ground, but it runs just fine and I was hoping it would be something less stupid than forgetting antifreeze that killed her. Is this even worth considering repair? In my head, if the engine comes out, I will only put a new one back in, but money is also a factor. If I'm really done and I need a new block, where are people getting reman engines these days? Does it matter what year or vehicle it comes out of? I have a renix 4.0 as is. Not sure I have it in me to pull an engine from a yard, but what are feelings about that? Worth rebuilding before installing?

In this photo, what is the cable on the right side, center of the image that runs from the firewall just to the lower right of the throttle body? I've read that maybe it's the transmission kick down cable? Really ought to go take a better picture of this one, but it's the blue thing in the bottle left beneath the coolant bottle. It has a vacuum line and a single electrical connector running to it. Just a little blue cylindrical object on a little bracket. I've never seen one in any picture, manual diagram, or any mention of it.

Removed! Looks like the PO Tried splicing in the TCU bits of another harness into the original manual harness instead of replacing it with the correct harness for whatever reason. Just need to go back and wire up the c115 connector to the dash (fingers crossed the manual came with that connector and I don't have to make my own harness)

I ended up pulling the engine control harness to remove the spaghetti mess the PO created while converting to an automatic transmission. Repinned a few things on a junkyard harness, still nothing. Checked all the ECU pins again, all looks as expected. Swapped the ECU with a reman unit, fired right up. Anything I should be looking out for that may have fried the original ECU? I checked all the pins at the ECU connector for shorts to ground, and nothing looked like it was getting voltage that shouldn't. All injectors have good resistance.

My PO did a very poor job swapping an auto trans into my 89 comanche. As far as I can tell, the engine control harness is the factory manual one, but for some reason the wires for the CPS go through their own grommet in the firewall next to the big one for the ECU. Anyone ever seen that before? the two CPS wires in the engine control harness are cut, and the original CPS connector is still there. Weird. Anywho, I have this other harness with all the TCU wiring that I pulled from the yard, but for whatever reason I did not take note of the year. It looks identical except for connectors c103 and c109 on the left hand side of the diagram. Shown in the photo are the connectors on the new harness. My plan is to trace these wires, and replace the connectors with the c103 and c109 connectors from my original harness (planning on tracing every wire on the ecu/tcu connectors as well to verify they are correct, but all the wire colors match so I'm hopeful). Colors on the c113 seem to be the same as my original harness, but in a slightly different arrangement. Between the c103 and c109 on the old harness there are 11 wires, but the new one has 13. Any features in newer years that might account for the extra pair? If anyone happens to know what year this new harness might be out of based on these connectors that would be super helpful! IMG_9057.heic

Put in a new map sensor just for giggles this morning, no dice. Also tried manually pulling a vacuum on the sensor in case maybe the outlet on the throttle body was clogged, still nothing. Tried disconnecting the TPU in case the ecu was maybe detecting WOP and looking for a higher rpm from the CPS, still nothing. Going to try to put together nicks engine monitor and see if I can get some kind of data out of the ECU. Maybe look more into the injector driver and see if that one transistor is blown. New ECU should be in tomorrow as well.

Fantastic! Looks like it is the 5v regulator that is getting the hottest, I didnt notice any of the ones labeled as injectors heating at all, but the one labeled in series with injectors seems suspicious to me. I can't imagine all 6 injector transistors failing at once but if that one effects them all, maybe that's the culprit

Diagnostic connectors checked out too. Opened up the ECU, nothing obviously burnt, but the big heatsink with all the power transistors was a little hotter than I would have expected, will try to see if I can find any info on the ECU internals tomorrow. I think I'm going to go ahead and order a replacement ECU as well. Hopefully I don't fry it too :|

It will fire on starter fluid, it has spark on all cylinders. Something is either causing the ECU not to fire the injectors, or the entire ECU or the portion that modulates the injectors is shot. The only things I see that explicitly will cause the ECU not to fire the injectors in the fuel injection manual is no cps signal, no throttle at high rpm (so heavy deceleration, but my throttle signal is fine and I'm not sure this condition applies the the ECU crank mode),

ECU is sending a signal to the latch relay coil, and battery voltage is coming through the relay to the ECU as expected, and the signal to the relay goes away a few seconds after turning the ignition off as expected

I have now checked everything I know how to check at the ECU connector as well. Neutral safety switch pin is grounded Injector wires have appropriate resistance Fuel pump relay is energized and injector feed pins on the ECU are receiving power CPS reads .5v Latch relay has power Start signal from the starter relay has power TPS reads the correct range Map sensor reads ~5v and drops with vacuum applied Battery pin has power Grounds all have continuity to the negative battery terminal It seems to me like the ECU has everything it needs, but still no signal to the injectors. I believe the ECU is on because it does output a signal to the latch relay, fuel pump, 5v to some sensors, oxygen heater relay, etc. but I don't see any definitive test to check if the ECU is working. No blown fuses, but I don't think there's any that could be bad with these symptoms. Unless the portion of the ECU that controls the injectors has melted a transistor or something, I'm absolutely stumped. None of the yards around me have a renix jeep, and I'm hesitant to buy one online just to find out it doesn't work either and no ability to return it. Can anyone confirm which sensors the ECU absolutely requires to power the injectors? I believe the sync sensor and maybe the egr and temp sensors will not prevent the ECU from starting the engine, but the map and cps sensors will, but I can't find any confirmation. Also if anyone has a renix code reader in texas, please DM :)

Checked all sensors again, everything seems to be behaving as expected, still no signal to the injectors. I think next step is to check all inputs at the ECU connectors and hope something is missing, and if everything is there, and ECU has all the expected power and grounds, then I must assume the ECU is shot? I also got the advice to check the resistance of the injectors to see if any were shorted internally and they all read good.