odd idle at startup ( 90 XJ)

I am trying to figure out the latest gremlin on the daughters 90 XJ:confused1
when I first start it in the am , sometimes it will only start on a few cyls so I turn it off and try again . I get the same thing , when I try it the third time walah it runs perfect. It only does this on ocasion and usualy first thing in the am I have replaced everything on this jeep except for the dist cam sensor . it literaly has everything new from the fuel pump to the plugs .

any ideas on what it might be? I know it's not a lot to go on ,I am Just hopeing someone else has had and solved this issue.

The dist cam sensor does synchronize the fuel injectors...I would try indexing the distributor and see if that helps it. Line the crank pulley to 12* BTDC and line up the distributor rotor so that it points directly at the no.1 cylinder post on the cap.

cabz said:

I am trying to figure out the latest gremlin on the daughters 90 XJ:confused1
when I first start it in the am , sometimes it will only start on a few cyls so I turn it off and try again . I get the same thing , when I try it the third time walah it runs perfect. It only does this on ocasion and usualy first thing in the am I have replaced everything on this jeep except for the dist cam sensor . it literaly has everything new from the fuel pump to the plugs .

any ideas on what it might be? I know it's not a lot to go on ,I am Just hopeing someone else has had and solved this issue.

Click to expand...

How about the IAT, Intake Air Temperature sensor, when mine drifted it worked fine once it warmed up, but took forever to get it started in the morning, on a cold start. Also the IAC, Idle Air Controller valve or its wiring could be hanging up until the ignition switch is cycled once or twice.

I've seen that for a few reasons. Moisture in the distributor, high voltage will arch until the condensation evaporates. Wipe out the distributor with a dry cloth, one place WD-40 seems to help more than hurt.
Carbon arching in the cap, there is often a coating of carbon dust in the cap, wear from the rotor contact and other oxidation.
Weak spark, low battery voltage is always possible, check your battery voltage before startup (above 13 volts is often good). Turning on your headlights and seeing how bad they dim (during cranking) can be helpful in troubleshooting a tired battery, a starter sucking too many amps or even poor connections.
Weak spark happens, sometimes it's corrosion in the input voltage to the coil and module, through the connectors (corrosion), or line (voltage) loss from moisture in the connectors. Have you checked the connection between the coil and the module (you have to separate the coil from the module to look)? I've had a lot of trouble with this, I often get my motor wet or muddy.
Compare the battery voltage to the voltage at the test point on the coil, with the key on. You might ne surprised at how much voltage is lost in the harness and at the connectors.
A random miss at idle can be the coil to cap wire, Renix seems to be some sensitive to the proper ohm value for this wire. Too much or too little resistance seems to cause some random missing at idle.
Re check all of your plug wires, the connection hasn't moved up in the boot. Do an ohm test. During cranking the available voltage goes way down, excessive resistance in a plug cable can cause an odd path to ground, usually at the boot. Once the high voltage finds an odd path to ground it has a tendency to repeat (carbon tracks).