I've done no serious mods to my rig and treat her fairly well.
Lately I'm getting the CEL light on and it will go out after a couple of starts. Sometimes it won't start on the first try after a quick shut down but ~10 min and a couple of tries and it fires over and runs like a top. Also a couple of times my tach would flatline, this is while normal driving on a highway. The engine shows no difference and everything else is running fine. then after a few minutes the tach pops back up to the ~2k and stays right for weeks.
The code it shows is for the crank sensor and when it won't start I notice the LP doesn't run after cranking.
If the CPS is shot then how does it run at all? Seems to me that if the sensor isn't showing any revs (tach flat) then the IP wouldn't know when to fire and the engine should just stop.

I have a suspect but I wonder if anyone else has experienced it. My ignition lock is worn to the point I can pull the key out even when it's running. I wonder if there is something else in the switch that is in the injection timing circuit that is loose making intermittent open faults.

Any thoughts?

 

The key doesn't go into the switch. It goes into the tumbler.
It's not uncommon for a CPS to slowly die. Change it unless all your trips are an easy walk home when it finally quits all together.

 

Thanks
I do have the sensor on the list for the first nice weekend because I'm too old for cold and wet on my back in the driveway

I just wonder why the tach would go dead without effecting the engine running. Seems like they should be directly related.

 

Cold in Va Beach?
I've spent 9 hours at -11 without wind chill replacing a VP-44 in my driveway. I'm only 61.

 

IIRC the 99 has both a crank and a cam sensor. Perhaps it is one or the other that is going out. On my 01 it only has the cam sensor, no crank sensor, when it was going out sometimes my tach would get all funky yet the truck ran fine and at other times the tach would get funky and the engine would run funky as well.

 

Yeah I know I'm a wimp but I gave both shoulders to search and rescue so cold damp cement gives me days of pain. I would and have done it if I had to but until it reaches critical I'll wait until a nice 70 degree sunny day.

maybe I'm older and wiser, maybe I'm older and lazier...but for **** sure I am getting older and that beats the other option

 

CRANKSHAFT POSITION SENSOR (CKP)

REMOVAL

The CKP is located on the left/rear side of engine block near the starter motor Crankshaft Position Sensor (CKP) Location
. 1.Disconnect both negative battery cables at both batteries.
2.Remove starter motor. Refer to Starter.
3.Disconnect electrical connector at CKP Crankshaft Position Sensor (CKP) Location
4.Remove CKP mounting bolt and hold down bracket Crankshaft Position Sensor (CKP) Location
5.Pull CKP from engine block with a slight twisting action.
6.Discard old CKP o-ring CKP Removal/Installation

INSTALLATION
1.Install new o-ring to CKP. Apply clean engine oil to o-ring.
2.Clean area around CKP mounting hole.
3.To prevent tearing o-ring, install CKP into engine block using a twisting action.
4.Position hold down bracket and install mounting bolt.
5.Tighten bolt to 24 N·m (18 ft. lbs.) torque.
6.Install starter motor. Refer to Starter.
7.Connect both negative battery cables at both batteries.
Good Luck