2003 Jeep Liberty 3.7 engine (engine light)

We replaced the engine with a 2002. Ever since, when going down incline, the engine light will flash, and then stay on. Sometimes, it even goes into shut down mode until you turn the car off and back on. Car runs great otherwise. We have tried several sensors: cam, crank, knock. Plus replaced the computer. Diagnostic says random misfire. We have spent tons of money on this cheap car – help!

While it’s idling give the intake manifold, hose to the throttle body and vacuum hoses a wiggle.
I think you’ll find an intermittent vacuum leak.

I’m going to guess intermittent problem like circuitsmith, but I’ll guess loose connection having to do with ignition. Did you use a shop for the motor swap? And if so, what do they have to say?

Ironic oversight on my part, considering my handle.

I’m smirking - but in a friendly sort of a way.

“Wiggle”, or “wriggle” is correct; but, do it to ALL the wires in the engine compartment, WHILE the engine is running. When you wriggle a particular wire, and something happens to the engine, check THOSE wires more closely. Push and pull on the battery cables, also.
Concentrate MOST of your troubleshooting on wiring.

ANYBODY can do this simple procedure; just, keep hands away from moving parts and the spark plug wires.

How about checking the error code that is likely stored in the computer. Your car is tryiong to tell you something. Manhy autopart stores will do it for free. Come back and tell use the actural code (format= P1234)

Did not a vacuum leak. They all seem to be tight.

Thank you, I’ll see if i can get that tomorrow.

We tried that again today, with no luck. Nothing changed about the engine, and we tried wiggling all exposed wiring, and looked at wires coming out of harness.We also checked all wire end plugs again, to see if they were tight.The battery cable ends were good. Light is reset from removing battery cable end. It has reset itself before, when being started, and while being driven, but always comes back, while going down hill.

They said to get the computer checked, and i told them that the light was not on, on the old engine even when it was knocking. Never had a engine light before. They were not any help, A bad choice for the repair. I’ve had it to a couple of other shops, and it always comes back.

The code is PO 300. Random multiple cylinder misfire. PO301,303.304,306. Jeep does go into limp in mode, sometimes, after the light flashes going down hill.