Stupid Engine Issues

[Baseshakers]

The heep is throwing codes again. It started with PO340 (camshaft position sensor circuit malfunction) then once cleared it later threw PO344 (camshaft position sensor intermittent)

The symptom is a lurching/bucking and sometimes stalling, and it can be hard to restart. Happens right when it throws the code.

I can floor the engine and bring it up to redline and it's fine, but when it does buck and throw a code it happens at about 3000 rpm at moderate load. So no correlation to high rpms or load that I can tell so far.

Rebuilt engine has less than 1500 miles on it, so I'd be shocked if it's something internal.

So far I've fully charged the battery (low voltage supposedly can cause it), swapped the camshaft sensor with a spare I had laying around and inspected the wiring harness for nicks/cuts for both the camshaft and crankshaft sensor.

One forum suggestion is that it could be a bad cat. There was a ton of heat on that side when I blew the PS line at F&F and the PS reservoir was roasting. How would I tell? Wouldn't it throw a different code since I have the tri-cat setup with 4 O2 sensors?

Are there any good test points for confirming the wiring harness is ok?

Any other suggestions? Thanks everyone!

[MDSRACING398]

Mine would do this if missed a shift screwing around or revved it to high climbing something. It was around 3000 rpms and it would throw it into limp mode. Ended up being not just the cam sensor but the whole distributor like unit. I forget what they call it. Not sure if you replaced it when put motor back together. If you pull the front 02 sensor you can usually tell if clogged, the pressure will push out the o2 hole, usually at idle it will come out but not with pressure if that makes any sense. Also if there clogged at night they will be nice and orange.

[Modeler]

OPDA is the assembly Mark is thinking of. It still functions as a kind of timing system. Could be in need of replacement or just not timed correctly. Bring the engine to TDC on compression stroke and check that the marker holes are aligned.

[Frank]

All the internals are new Ryan . Theres no issue in there . It has run flawless till now ? I gotta believe its something to do with that circuit . If the CPS cant count or whatever it does and send a signal to the ECU , it will and can shut the whole system down. Id first suggest riding with the scanner in place while driving . If yours has live time it will monitor actual functions as they happen. You will be able to see just whats going on. How bout the guy you use for inspection ? Hes a repair shop ? He would have the scanner , take him for a ride . Most guys will charge an Hr labor or in hopes of fixin it , wave it. Good luck Bud. FjR68

[Baseshakers]

Update: OPDA was maybe 1/8" off of TDC (which shouldn't matter) but I centered it anyway.
OPDA was replaced with a Crown Automotive maybe 20k miles ago, pre engine rebuild. The Crown was recommended as a replacement for the problematic stock unit.
I've tried this with both the stock sensor in the Crown OPDA and the Crown sensor in the Crown OPDA, hasn't made a difference.
Pics below of the cam and gear; they are fine.



Quite a bit of exhaust flow (and a ton of noise) came out the top O2 sensor holes at both idle and at ~1500 rpm. Both mini cats were ~850 degrees after a 20 min drive.

Today the engine quit completely while cruising at ~2500 rpm with the throttle at maybe 1/4. Took about 5 turns of the key before it restarted, but it did restart once I gave it some gas and ran ok. Same PO340 code for the camshaft sensor.

Franky, my scanner only reads codes and readiness and can't live scan.

[Kurt]

Jus a thought...
Maybe do a continuity test on each of the camshaft sensor wires between the sensor connector and the connector to the ECU.
Hook up your meter and then manipulate the harness and see if you have solid continuity or an intermittent.

[MDSRACING398]

Recheck your grounds too

[Baseshakers]

So I had to go spend $140 at the stealership to get the PCM reprogrammed but so far it's solved the issue. Of course it was a TSB so nothing I could have done about it. http://www.wkjeeps.com/misc/LX/TSB_300C ... 801509.pdf

I've only driven the heep to work three days since the PCM flash but it used to throw the code every time I drove it. Crossing my fingers that's it...

[BlackNBlue-ISH]

You have to pay for tsb repairs at the stealership? I've got one I need them to do. How long did it take em to reprogram the pcm?

[Baseshakers]

Yep, they said if it was a recall they would pay but TSBs are on me. Took about 1.5 hrs to reprogram.

[Frank]

Glad they were able to fix it . With all the electronics today , I wont tell you of my fear converting Mona to EFI ! She "WAS" a simple girl . FjR68

[Frank]

That looked like quite a process . It would seam to me that it would be covered as they had an issue with a dealer only serviceable item. For as little as the dist was off , Id bet you feel a difference . Did the same thing with Dans Ranger. We installed a pair of modified heads and a high lift cam with specially made push rods to my specs. (for Clearance) I had marked his dist and it didnt run all that much better but you could hear the cam lope. Bought a set of tools that would zero the dist and crank and what a difference on the bottom end and mid range. It has to be spot on for the ECU to work within the range it was flashed for. Overall , I now have special tools for a 4.0 V-6 Ranger motor which has gone through 14 changes in its years of service. Soooo , hows it running for you ??????????????????? FjR68