I know ive only got a 2.5, but help me out people...

I am getting a Misfire, pulling up Code P1391, it Randomly misfires, and at times will run Perfectly fine, My brother says its a Ground, but i see all of my grounds secured, 2.5 engine is bored .060 over (new pistons/rings)

Engine has about 300 miles so far

My Compression is as follows (Ran 3 Times), I just learned i need to do it again (I only took plugs out)

Cyl 1: 140 140 140
Cyl 2: 125 130 135
Cyl 3: 125 120 120
Cyl 4: 125 125 125

i managed to find a 2.5 in a yard and pulled the Dizzy and the crank sensor, i swapped out the dizzy and its still doin the same thing, i havent changed out the crank sensor just yet

i believe my injectors are dirty as well, i managed to get a connector from the 2.5 in the yard, so ill be opening and cleaning the injectors soon

 

You pulled the distributor? You likely messed up the fuel sync and it'll need to be reset.

 

dont mean to sound like a n00b, but what exactly are you talking about, never heard of this so i dont have any knowledge of what "Fuel Sync" is, i do have a 2.5L 4 cylinder engine, if you could please enlighten me on this subject, id greatly appreciate it

 

Basically fuel sync is when the injectors open in regard to cam position. The injectors don't spray fuel all the time, just at a specific moment.

When you turn the distributor you change the fuel sync, not the ignition timing. The ignition timing is primarily controlled by the crank position sensor.

You could have a fuel related misfire.

 

And it is a beyond royal pain to re-set it....you might have it easier with half as many holes...would also make it be further off I'd imagine, feeding the misfire. You can be within +/-4 degrees and still be able to run without a code, I believe. Otherwise you'll get misfire or fuel sync codes.

 

so how do i re-sync, and how would i know how many degrees im at, i understand moving the crank to 0 degrees and the distributor rotor pointing at #1, This i am not understanding VVV


"Now look straight down over the top of the rotor
and you will see the button centor is behind the
line on the pickup plat marked cyl

center the rotor over the line and you will be
right near 0 turning the dist counterclockwise
will move towards + side line the edge of the
rotor button with the line and you will be around
+2 to 3 and you will notice the diff in how your
truck runs."

Aaaand If i swapped out distributors and its still doing it, wouldnt that eliminate this as a possible cause?


"The injector sync can only be changed by rotating
the dist nothing else will change that.

You should move that to the + side

Turn the engine over untill the TDC mark is lined
up with the 0 on the tab and the rotor is pointing
to the #1 wire on the cap.

Now look straight down over the top of the rotor
and you will see the button centor is behind the
line on the pickup plat marked cyl

center the rotor over the line and you will be
right near 0 turning the dist counterclockwise
will move towards + side line the edge of the
rotor button with the line and you will be around
+2 to 3 and you will notice the diff in how your
truck runs.

when rotating the motor only go clockwise do not
back up if you over shoot. and push lightly
counterclockwise on the rotor to remove any play
with your finger than set."

 

Swapping out distributors will not fix it. If anything, it will aggravate the situation. You know the fuel sync is off.

A dealer can do it easily with the DRB (scan tool). You can probably "ballpark it" by turning the distributor.

 

Im sure i just fixed the problem... and i will make note of how i did it in my thread, this morning i read every line in the ignition system section of the FSM, totally understood what you said about the position of the distributor, SO i was reading about a plastic pin thats in place on NEW distributors, So i found a Zip tie, stuck it in the hole, zipped it up, secured it in place, kept turning the oil pump until i got it perfectly on time, and i cranked her up and she runs much much much better, im sure i solved my issue, thank you for noting this issue

 

Thanks for the tip on the pin. I was not aware of that.

 

So i believe one of my lifters is ticking

P1391 has dissapeared and P0420 has appeared



have any suggestion on how to be sure my rings are settling in correctly? i believe i had p0420 pop up once before, the AZ employee that scanned it says its for a vacuum leak, ive known this code to be for a bad cat, but why would this code show now and not earlier?