Went and picked up my moms 04 Navigator this afternoon. She hasn't been able to drive it because she says it has the "hiccups".

I took the scan tool up there assuming it would have the SES light on and a DTC or two, but it didn't.

During the 63 mile drive from her house to mine torque pro recorded a total of 6487 misfires. Still no check engine light, no individual misfire codes...... no codes at all.

Can/will a bad injector(s) create a misfire that the crank sensor can't see? Can a weak fuel pump cause this? I'm not sure where to start on this one. One thing I don't want to do is start shotgunning parts at it.

Anybody been here before?

 

Start w/ fuel filter and PC valve and good visual inspection?

 

You need to look at the individual cylinder misfire counts in the Mode $06 data for situations where you have a "mild" or intermittent misfire situation.

The PCM will only set a MIL and corresponding DTC(s) when the rate of misfires exceeds a preset threshold.

 

Hopefully in the 4 months since he posted this it’s fixed.