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2nd Gen Dakota 1997 - 2004 Dakota's

1998 dakota 2.5 Bored .060 over, Trouble Code P1391

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Old 12-16-2013, 05:33 PM
Bigboi407 Bigboi407 is offline
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Default 1998 dakota 2.5 Bored .060 over, Trouble Code P1391

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
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Old 12-16-2013, 06:02 PM
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You pulled the distributor? You likely messed up the fuel sync and it'll need to be reset.
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Old 12-16-2013, 10:25 PM
Bigboi407 Bigboi407 is offline
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Originally Posted by 00DakDan View Post
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
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Old 12-16-2013, 10:33 PM
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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.
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Old 12-16-2013, 10:47 PM
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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.
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Old 12-17-2013, 05:52 AM
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Originally Posted by magnethead View Post
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."



Last edited by Bigboi407; 12-17-2013 at 07:16 AM..
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Old 12-17-2013, 09:14 AM
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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.
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Old 12-17-2013, 10:06 AM
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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
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Old 12-17-2013, 10:21 AM
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Thanks for the tip on the pin. I was not aware of that.
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Old 12-17-2013, 02:29 PM
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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?
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Old 12-17-2013, 04:17 PM
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P0420 is not a vacuum leak. As you thought it's 1/1 catalyst efficiency. You may have a bad catalytic converter.

Some of the faults only appear after so many "trips" which is basically a cycle of the systems. I'm not positive about a '98 but later models used the downstream sensor to check converter efficiency. It may be a slow O2 sensor but your misfire could have also damaged the converter.

On the rings, just drive it normally. Some occasional heavy acceleration and then deceleration is good. You don't really have to do anything drastic to it. I'd suggest a conventional oil for break-in too.

The lifter may be bad or possibly has some dirt in it from the rebuild. See what happens in a few days with it.
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Old 12-17-2013, 05:15 PM
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Quote:
Originally Posted by 00DakDan View Post
P0420 is not a vacuum leak. As you thought it's 1/1 catalyst efficiency. You may have a bad catalytic converter.

Some of the faults only appear after so many "trips" which is basically a cycle of the systems. I'm not positive about a '98 but later models used the downstream sensor to check converter efficiency. It may be a slow O2 sensor but your misfire could have also damaged the converter.

On the rings, just drive it normally. Some occasional heavy acceleration and then deceleration is good. You don't really have to do anything drastic to it. I'd suggest a conventional oil for break-in too.

The lifter may be bad or possibly has some dirt in it from the rebuild. See what happens in a few days with it.
i am 95% positive ive got a dirty injector, truck ran on 3 cylinders for a bit, then ran fine, then back to 3 cylinders
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Old 12-17-2013, 05:23 PM
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Are you sure it's the injector? How noisy is the lifter? If it's collapsing the valve won't open and you'll misfire.
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Old 12-17-2013, 06:48 PM
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Where does this pin/zip tie go? what hole?

On the rings, the most important part is to unhook the breather tube. You want the crankcase slightly pressurized when you seat the rings. We unhook the vacuum system on our motor for every start, then spin it on the starter until the 15psi oil pressure switch activates, then reconnect the vacuum line once the water temp is 150 degrees (which puts crankcase from slightly pressurized to 8 inches of vaccum at idle, and takes oil pressure from 80 to 60 psi). This prevents dry starts, and always makes sure the piston rings are seated by the positive pressure on the combustion side, and not the vacuum on the crankcase side. Also, put the pistons in dry, don't wipe the cylinder walls in oil, as it will prevent the rings from seating.
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Old 12-18-2013, 08:13 AM
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Quote:
Originally Posted by 00DakDan View Post
Are you sure it's the injector? How noisy is the lifter? If it's collapsing the valve won't open and you'll misfire.
the lifter gets pretty damn loud, but i can hear the engine firing on all 4, i can really only notice it running on 3 when im at idle speed... once i accelerate, it smooths out until i let off, and then if i tap the gas pedal 2-3x it may go away for a bit, i stop somewhere, get back in the truck then starts running on 3 when i crank it up, then when i take off and come to a stop it will be running fine, so i think ^ This issue made P1391 WORSE

Click the image to open in full size.

"Factory replacement distributors are equipped with a plastic alignment pin already installed. The pin is located in an access hole on the bottom of the distributor housing Plastic Alignment Pin It is used to temporarily lock the rotor to the cylinder number 1 position during installation. The pin must be removed after installing the distributor"

"If original distributor is to be reinstalled, such as during engine overhaul, the plastic pin will not be available. A 3/16 inch drift pin punch tool may be substituted for plastic pin.
5.Remove camshaft position sensor from distributor housing. Lift straight up.
6.Four different alignment holes are provided on plastic ring, Note that 2.5L and 4.0L engines have different Pin Alignment Holes"
Attached Images
File Type: jpg 0996b43f802097bc.jpg (20.1 KB, 18 views)

Last edited by Bigboi407; 12-18-2013 at 08:27 AM..
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Old 12-18-2013, 10:28 AM
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Next time you hear it running on 3 cylinders, verify it. Pull the plug wire to find out which cylinder.

You could have a bad injector. How are the harnesses, clean and tight?

Have you double checked the rocker arms?
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Old 12-18-2013, 10:39 AM
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Quote:
Originally Posted by 00DakDan View Post
Next time you hear it running on 3 cylinders, verify it. Pull the plug wire to find out which cylinder.

You could have a bad injector. How are the harnesses, clean and tight?

Have you double checked the rocker arms?
P0304 has popped up this morning, Cyl #4 Misfire

Spark is good

Spark plug looks a bit too orange, (no oil though)

im sure my #4 injector is dirty, i bought a harness plug for injectors, now i need to figure out how im going to power them to keep them open while i clean em.

I suspect the#4 injector is dirty, i had them in a bag rolling around for a few weeks, i had intended to get them cleaned, but had to build my engine Quickly

EDIT: i just checked my rockers and they look to be fine

Last edited by Bigboi407; 12-18-2013 at 11:47 AM..
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Old 12-19-2013, 11:55 AM
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I took the #4 injector out, cleaned it with the injector open, it sprayed pretty good... thought i solved the issue, minutes later she starts running on 3 cylinders again, so now im gonna swap the #4 injector with #1 and see what happens

Swapped the injector out to #2 and #4 is still misfiring.............. =/

Last edited by Bigboi407; 12-19-2013 at 01:21 PM..
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Old 12-19-2013, 03:48 PM
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Like dan said, do the old school trick. When the engine is missing, pull the plug wire off the distributor, then plug back in and repeat for each wire. As you drop holes, it should get worse. When you unhook a wire and the motor stays the same...that's the dead hole.
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Old 12-19-2013, 05:21 PM
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Quote:
Originally Posted by magnethead View Post
Like dan said, do the old school trick. When the engine is missing, pull the plug wire off the distributor, then plug back in and repeat for each wire. As you drop holes, it should get worse. When you unhook a wire and the motor stays the same...that's the dead hole.
Did that, and #4 is the problem

Im hoping the lifter is causing the misfire, but because i overheated the engine to hell, im thinkin #4 on the head is damaged, only thing left to do is

Change lifters

Leak down test

theres a 2.5 in my local yard at the moment so i should go pull the head ASAP

Last edited by Bigboi407; 12-19-2013 at 05:57 PM..
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Old 12-19-2013, 05:21 PM
 
 
 
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