Dickinson County Comanche

2WD, 4.0, Tan on Tan auto fleet car? I wonder what it would’ve been used for?

Kind of an oddity, I think. It’s located at the same pick & pull yard I got my ZJ at. 4.0, AW4, 2WD. Thought it was a bit unusual that it had an Aux fan but no A/C.

I have had my cruise set to almost pegged on the dash (speedo gear is off but the truck can’t tell the difference) and it’s held it just fine. I’d say there’s an issue with the cruise control system itself. I’ve had to reach down and gently tap my control module a few times cause it would do the same thing, set at 55, then decelerate slowly to 50, then 45, then keep speed at like, 40. Tapping the module makes it go right back to the speed requested. Dunno why exactly but I’m too lazy to pull the module out while it’s still working so I shall continue to give it the occasional percussive maintenance.

I was driving in town and was coasting down to a traffic light but wanted to put in some throttle to make the shift nicer, only to realize my engine had died. It did pop out the exhaust a little, which makes me think it was spark-related vs fuel related, especially since it died so quickly and suddenly. It started back up and idled at like, 2,000 rpm for maybe 10-15s then has run fine. Not down on power, no missing, popping, nothing. Back to normal. My guess is CPS, it’s original, but I tested it a few years ago and it tested fine, above the minimum voltage. Maybe it’s finally going out? It hasn’t had any issues with long crank/hot starts, and it wasn’t particularly hot when it died. I’m also suspect of the ASD relay, but I think that kills fuel, not spark. Not entirely sure, figured I’d get some inputs before shooting the parts cannon.

I used the NTK EF0072. When I did the engine swap I relocated my sensor to the 91+ location.

Coming back after a while to say I have solved this, it was the coolant temperature sensor that was bad and causing it to not enter closed loop. My fault for using cheap Rockauto sensors, thing was probably bad out of the box.

Solved: after installing a new O2 and coolant sensor, it has seemingly vanished. Running better than before now as it also solved my idle circuit problems. IMG_0676.MOV

So I looked in my book and it shows the same thing. I couldn’t get the multimeter I bought to work (genius who designed it made the probes about 1/16” long so they’re impossible to get any sort of accurate measurement from a plug) so I’m just going to look at replacing the coolant sensor, intake manifold gasket (pretty sure it’s leaking) and the O2 sensor and check back. On the way back home, it acted up really bad again. Would immediately die when given any throttle from idle and it would only start when at WOT and it would studder for a split second after running. Then 30s later it was almost back to normal. I’m so confused.

I’m getting a nice multimeter to check for certain. I also have a 1989 electrical book so I’ll check in it as well

87-90 share the same part number for the sensor

I have voltage on both A & B, C is ground.

Both sensor and truck were 0 ohms. So sensor is defective but is that ohms for the truck normal or do I also have a fault there?

I got 0 ohms on both sides of the plug (truck plug & sensor plug)

That was on Wait so am I checking the sensor’s connector or the trucks connector? I got 0 ohms at the trucks connector since it was the one that matched the diagram

Great. Any leads as to where that would maybe be at?

I am showing 0 (or near 0) ohms between A & B. About 4 between C and B.

Now that I’m thinking on it more, I think it’s that O2 sensor. I was trying to delete my EGR valve and when I removed it I dropped it (about 3-4”) so I almost wonder if that didn’t break it. I don’t believe I remember feeling the issue before then, so it makes the most sense to me now.

Even with it running ok it’s almost never entered closed loop. I almost wonder if the computer isn’t faulty a little bit. Ive used it fine without it entering closed loop but having the iac disconnected is a bit annoying when it’s cold.

It’s in open loop, if that makes any difference. Very rarely does it ever enter closed loop. Wires looked fine going to the sensor. It’s a pretty cheap old thing, so it’s probably that coolant sensor itself that’s bad.

Seemed to react pretty snappy. Went from ~2.2V at idle/upon acceleration to ~4-5V upon decel

Pretty sure the Coolant temp sensor is no good. IMG_0299.MOV

What’s it’s supposed to be like? I have a snap-on scan tool hooked to it right now looking it over. Oxygen sensor was also new 2 years ago, it’s an NTK unit.

My idle circuit isn’t working properly so I have it disconnected. It’s been that way for ~2 years now.

It’s not down on power, and when I floor it when it’s doing it the truck picks right back up, so I don’t think it’s fuel system related. Pump is only 2 years old.

Hello all, my Jeep has developed the interesting quirk of a very intermittent issue where the engine falls on its face while under very light throttle inputs. If I give it more gas, it’ll rev up no problem, or if I go back to idle it’ll idle fine. I deleted the EGR believing it was the problem however it has remained afterwards. TPS maybe?