ive found some more threads of p1391 after these individuals changed sensors. another test ide like to try is getting a spare cap and cutting a hole in the #1 plug, then setting the motor to TDC and checking the position of the rotor in relation to the #1 terminal.


with this scenario if it proves to be off, does this mean the camshaft from the rebuild is something altered from OEM, or is this suggestive of a timing chain that has slack?


again here we seem to fall back on needing a reading from an O scope to determine cam/crank sync...........................ugh this of all jeep codes is by far the most........

 

was this worthwhile to check or a waste of time?

 

is there any reason aligator clips cant be attached to the 2ch probes?

 

Nope! Use anything you want as long as you can get good contact. I use alligator clips with T-pins cause they can get deeply into connectors without damaging anything.

One of those probes has an attenuator but that can be accounted for in the software.

 

Ok, just trying not to buy more than I need to. I can say more than likely I'll never use a scope again.

 

yes, measure runout with a dial gauge...because it should be very easy to do...if the flexplate has any warp in it, that could cause the issue.

In my view it is a long shot, but the OP has exhausted the suggested FSM guidelines I suspect

also wondering if the timing chain & gears might have wear...if this is combined with a misfire (which slows the crank on each miss) that could cause the code

 

ok well i tried this dial guage thing. but i dont think it was very accurate, its pretty much impossible to get a a straight line to the gauge as it doesnt fit in that area at all.

pending the set up I sunk the gauge to 20 so i could see it and while cranking the flex plate around a few times it would be anywhere from 20-30.

again not having a good angle on it at all im not so trusting in what ever this reading ment, i tried a few set ups and nothing gets around the exhaust.

 

I would try sitting the base plate onto something metal placed on the ground, so the pointer should be able to reach in an touch the surface at no more than 45 degrees

that is how I use them to check the diff gears for excessive play

 

this was not an easy task as the dial does not fit well within this area. Best case this is 45* and I tried this four times. the magnetic base was fixed under the jeep and the elbow was resting on the driveshaft, this thing was secured very well. I could not get the camera to focus but it should illustrate the full range of motion that the dial showed. i took this just above the welds of the teeth (the smooth area) on the plate.

 

if your runout is in the order of 10-20 thou, that would probably rule out warped, damaged flexplate...probably better than replacing it

It would appear that in order to progress any further, you would have to obtain an oscilliscope, and check the sync that way.

Cant think of what else to suggest

 

well thats good news I suppose, onto the scope we go.

ill order up the hantek6022be and well see what we can find.


out of curiousity is the run out on the plate from the bolts torqued to the crank and converter or is that just how its machined?

 

got the scope in the mail, i might as well be looking at an alien. ive down loaded the provided software. Is there anything else to do for set up other than the scopes settings?

 

Drivers too?

 

Drivers installed, been fiddling with the horizontal/vertical inputs. it would seem now that I need to adjust the attenuation of the probes?
Ive got those sorted out, easy enough. Im just fiddling with the probes on the scope ground/out and i started toying with the trigger. it seems you can only adjust the trigger on one channel at a time?