96 timing issue possibly

[chevyCowboy]

when I started my truck this morning it started normally and then within half a second. seemed like the timing changed and it was running almost like it had a knock. didn't have time to mess with it right away so when I got home from work I hooked up the computer and these are the codes that I got. there was a bunch

I cleared the codes and fired the truck up. everything seems to be fine now. not sure which one I should look at. first. I went to the live data metering and all the timing stuff looks right. the TDC offset is a little far if I remember right. it's like -1.94 or something is the desired

I have been having a issue with this truck doing A weird surge but it does. it. super randomly and it could be weeks in between times it does it. I was guessing it is something to do with the injection pump being worn, when I add tranny fluid to the fuel it seems to do it less.


The other day it did it and then started running similar to what it did this. I shut the truck off And restarted it and it was fine after that.

anyone have any thoughts on this? thanks

 

[dbrannon79]

I would start by cleaning your grounds for the PCM. look at the passenger side head on the intake near the trans dipstick tube. there should be three wires on eyelets bolted to a stud. make sure those have a good connection. also check the ground strap from the frame to the block along with the ground cable from the batteries to the body and block. to me it sounds like it's pulling a ground where ever it can due to a bad connection. could also be weak batteries and or a starter pulling too much to crank giving you low voltage during cranking.

start there and eliminate the easy stuff first.

 

[ak diesel driver]

TDCO is high should be a code for -2.02

 

[chevyCowboy]

TDCO is high should be a code for -2.02

I did a re learn and got -1.06 best I could get

 

[MrMarty51]

I did a re learn and got -1.06 best I could get

If You want higher the top of the injection pump needs to be rotated to the left, drivers, side of the vehicle.
Then do another relearn.

 

[Big T]

That Crankshaft Position Sensor (CPS) could be the root cause of your problems. They are cheap and relatively easy to replace.

 

[Will L.]

Do the alternating unplug/plug test with it and the optic sensor.

 

[chevyCowboy]

well it happend again the other day while I was dumping a load of trees and was able to get the computer hooked up while it was running badly.

here's the codes I got

second is what the timing looked like I'm guessing my issue has something to do with it showing 0 for the actual injection pump timing

third is after I cleared the codes and it went back to running normal

 

[ak diesel driver]

I'd do the CPS and OS tests

 

[ak diesel driver]

Just thinking the test may not work if the issue is intermittent

 

[Will L.]

The way to figure it out is just disconnect the optic and leave it that way for a couple days worth of driving. When it acts up again if it does same thing but still runs then it aint the cps. If the engine dies or won’t start, then its the cps

 

[chevyCowboy]

The way to figure it out is just disconnect the optic and leave it that way for a couple days worth of driving. When it acts up again if it does same thing but still runs then it aint the cps. If the engine dies or won’t start, then its the cps

I wasn't aware that it would run with our the optic sensor plugged in

 

[chevyCowboy]

If You want higher the top of the injection pump needs to be rotated to the left, drivers, side of the vehicle.
Then do another relearn.

it's odd to me that it was at -2.02 and I did a re learn and can't get it any higher I did get -1.14 the other night

 

[Will L.]

The optic sensor and the cps work in conjunction with each other to smooth everything out.
With one or the other good, it will be a hard start but will start & run. Doesn’t run great.
But if you unplug one and the other is still in and it never starts or stops running- that shows the one plugged in is toast.

 

[ak diesel driver]

So to be clear unplug the cps and try to start it. I will take alot of extended cranking. When it starts it should run smoothly with no hiccups of any kind. It will be running in limp mode so power will be down. If after that checks out unplug the OS and repeat. If it won't start or has any hiccups then there's an issue with the sensor or wiring that's not unplugged.

 

[MrMarty51]

When you unplug one and run the test, plug it back in before unplugging the other one.
Just to clarify the poorcedure.

 

[chevyCowboy]

So to be clear unplug the cps and try to start it. I will take alot of extended cranking. When it starts it should run smoothly with no hiccups of any kind. It will be running in limp mode so power will be down. If after that checks out unplug the OS and repeat. If it won't start or has any hiccups then there's an issue with the sensor or wiring that's not unplugged.

I first unplugged the CPS and it took a while to crank but did start and ran fine. I got the first set of codes and the timing was at zero and 8.4

then I unplugged the optic sensor after plugging the CPS back in and it started but had a couple hiccups and then ran smoothly and I got these codes and these numbers for the timing


so if I'm understanding your instructions right, it sounds like my crankshaft position sensor is bad. is that correct?

 

[dbrannon79]

Looks like the CPS is bad or has a bad wire. lots of times oil gets on the wires and starts to break down the insulation causing issues . cheap insurance is to replace that sensor, but iirc you will have to do a TDC offset relearn once it's replaced.