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Cold start symptoms.


NAXJA Forum User
I've got some issues when the motor is cold and figured I'd ask around to try any find possible causes before throwing money at it.

Symptoms are as follows
Hard to start, takes 3-4 tries before it will stay running.
Dies if I touch the throttle
Shakes a bit

After about 1 minute I can start to rev it without it dying, but it will stumble and hesitate.
After about 2 minutes it revs normally, maybe a bit sluggishness.
Once it reaches 50c on the temp gauge, it's at full power.

So far I've checked for vaccum leaks, couldn't find any.
Compression is a little low on one cylinder.
I've read that the egr might be the issue, how do I test it? Also, how does it work? It runs on vacuum, does that mean that if it's bad it can cause a vaccum leak?
Are all the tune-up parts fresh ?

Test the fuel pressure. Test the Throttle Position Sensor. Have the battery Load Tested inside a test machine. The EGR and any vacuum leaks are not likely suspects.

Perform basic trouble shooting of the start and charge systems. Remove, inspect, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush until clean and shiny the cable/wire ends and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Yes, but keep in mind that many critical sensors share the same crappy ground.

From Tip 1:
"The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff."