CPS (Crank Postion Sensor) Connector

Has anybody here had a bad\loose CPS connector and what were your engine symptoms like. My engine has a little misfire at idle when it warms up. Could this be caused from this and how due you test it?

The typical symptoms for a bad CPS is intermittent engine cutouts or just plain refusing to start when cranking over. Usually the tach will immediately drop to zero if this happens or won't budge when cranking. I've never seen it described as a misfire - that sounds different.

My CPS is good I'am taking about a bad connection in the connector. You are talking about a completly failed CPS which I do not have.

A CPS is what the PCM uses to monitor misfires, it measures differences in cranksfatf speed and when it detects a drop in rpm for that cylinder, the pcm assumes the cylinder misfired, a poor connection would most likely cause your engine not to run at all, not intermittent misfires.

kemarsh said:

My CPS is good I'am taking about a bad connection in the connector. You are talking about a completly failed CPS which I do not have.

Click to expand...

The symptoms are the same. Often people reporting the problem are able to unplug and replug the connector and the engine cutout problem goes away. I suspect most of the CPS problems are in fact a wiring or connector problem as there really isn't much to go wrong with the sensor itself. It's really just a coil of wire around a center magnetic core.

It might also be worth checking the wiring itself - sometimes it slips and ends up resting against the exhaust manifold.

Still, when I've had that happen, I'd not call it "misfiring" - more like "cutting out entirely." It can be easily repaired with any convenient twin-lead (I actually used a section of 18/2 electrical cord last time!) and just tie it up out of the way of the exhaust manifold.

What year is your XJ? If it's 1991 and up, it should be OBD-compliant, and having a MIL can be instructive. If it's 1990-back, we'll have to troubleshoot...

5-90

This is what I found from another thread I know that a bad connection can due funky things and cause things to intermediatly work and not completly fail, thats why I believe this to be true. This is why I'am asking if anybody else has had this problem.

Re: idles good cold, not warm
Good points from Eagle. I would like to add a couple additional thoughts. My experience w. my 89 has shown that 90% of the time it is the cps or its connector. Just the other day it would randomly run bad and miss at idle and on throttle but only when warmed up fully (consistently only at warmup never when cold a few times each day for a couple of days). I discod the cps connector and looked inside and one of the female connectors was stetched open more than the other. Since the cps only generates less than one volt on the Renix system the connector is critical. I rebuilt the connector and the problem went away (been 2 wks now). This is the second time I have had to rebuild this connector in the last couple of yrs. Note the female side of the connector is on the wire harness side and does not get changed w. a cps replacement. The heat from the engine and vibration caused the slightly loose connector to expand and make the connection worse. Not sure its your problem but just another thing to look into. Good Luck. Greg

I'll not argue with you - but my experience with CPS problems (I've had a few...) has resulted in the engine fully cutting out - either totally (when the connection doesn't get made again) or temporarily (when the connection comes loose and comes back.)

You still haven't answered my question - what year? It would help with diagnostics, because the systems changed drastically for 1991, and somewhat for 1996...

5-90

92 HO