CPS voltage/resistance??

i did some searching last night... found the thread about voltage and resistance readings of a good crankshaft position sensor.
(125-275ohm, .5-.8VAC) tested out my sensor last night and i had 218ohm and .433vac. is it possible for the sensor to be "sorta bad"?? i'm getting a random no-start condition. most of the time it starts just fine, however sometimes it dosn't. maybe once every couple of weeks it dosn't start. when it does start, it runs great. perfect idle, only a very slight hesitation on hard accelleration. no misfire.

is it possible that the signal is just getting too weak from the sensor so that it dosn't start sometimes???

thanks all

-chris

twoksl2 said:

i did some searching last night... found the thread about voltage and resistance readings of a good crankshaft position sensor.
(125-275ohm, .5-.8VAC) tested out my sensor last night and i had 218ohm and .433vac. is it possible for the sensor to be "sorta bad"?? i'm getting a random no-start condition. most of the time it starts just fine, however sometimes it dosn't. maybe once every couple of weeks it dosn't start. when it does start, it runs great. perfect idle, only a very slight hesitation on hard accelleration. no misfire.

is it possible that the signal is just getting too weak from the sensor so that it dosn't start sometimes???

thanks all

-chris

Click to expand...

I had one with just about the same reading, it wouldn't start when it was hot. I'm guessing the ohms change with the temperature somewhat, though I never did do an ohm test when it was hot and acting up, to prove my theory. One thing I did do to prove my temperature theory, was one day when the old XJ left me stranded, I poored a bottle of water on the CPS to cool it down, XJ started right up.

I'm not sure about the 90, but my 88 has more than one connector between the CPS connector and the ECU. I bypassed the harness, cut the CPS wires 6-8 inches from the firewall and soldered the harness CPS connector on there. There is a kit available to redo the CPS to ECU harness, to make it shorter and more direct. The CPS really doesn't put out much of a signal.

The CPS also has a magnet in there, that does get weak with age.

they can fail many different ways. i have heard of them checking out fine with a dvm and still being bad.

8Mud said:

There is a kit available to redo the CPS to ECU harness, to make it shorter and more direct. .

Click to expand...

do you have any information on that kit??? or even a harness kit for a easonable price???

just as a note, i took the readings right off of the plug for the sensor, i'm not sure if theres more then one or not. the wire disappears into the harness right after the plug connection.

The harness is a little different for the 90, they may have already shortened the CPS harness. Follow the wires from the CPS plug back to the firewall and see if there is another connector between the CPS connector and the ECU. On some models it's a gray connector, 6-8 pin or so.
The kit is PN 83-100-066 for the auto tranny and PN 93-100-063 for the manual.
If your CPS is the slotted type, usually the top bolt hole, make sure it is pushed down as far as it will go on the top bolt hole, before tightening. Or the CPS makes a weak pulse. The washers and stock bolts are also important.
A motor that is slinging oil out of the rear main seal can also have CPS problems. Sometimes cleaning helps, sometimes it doesn't.