me and my wife own a j. love it. a few months ago it started to surge and chug I have replace the maf, injectors, fuel pump, fuel filter, timing belt, spark plugs, and the list goes on. basically my fuel system is all new along with spark and air now it starts up fine but when it gets to operating temperature it completely shuts off and I have to wait for it to cool down it start it back up. I was told it could be the ecu with open loop?. Can someone please help out with my j. I love her but she is costing me too much money.

Have you replaced the temperature sensor? There are 2 sensors on the coolant pipe the smaller one is for the gauge and the larger one (2 wire) goes to the ecu.

I have clean egr and valves, punched cats, replaces all hoses , clean fuel rail, iac . how do I test the ecu to see if it's bad

I have replaced the sensor bc it was a code being thrown now it reads 55

I think code 55 means no malfunction??? Make sure your not losing ground. You can take a jumper cable and run from the engine block to a good ground on the body.

Also make sure the crank sensor is connected good and not rattling loose. I would also ohm test it per the manual. If it has any chips or cracks replace it.

then check ecu for codes?

I'm out in front of my car which is crank sensor?

the cas? it's good no shakes replaced it a while back

The crank sensor is on the back of the engine below the egr. You kinda have to do it by Braille. The cover that holds it in is a 10mm. I can't understand why it wouldn't throw a code though unless that is indicative of a bad ecu.

I'll check it and respond l8tr

Can a car run without the crank sensor being connected?

I wouldn't think so but idk it may get multiple signals from somewhere else that allows it to run. . The trouble with the crank sensor is the location. Dirt and grime and hard to get to people will often break the tab getting it unplugged when that happens it can rattle loose. If the tabs are broken you can hook it up and tape the connection then reinstall.

One thing to remember is that you may be running with a sensor when cold but cracks open up when it gets warm and shuts it down. So when you pull the crank sensor not only test it and look for obvious cracks but also for lines that look like someone drew on it with a pencil. Those can be cracks as well.