Nissan Repair Questions? Ask a Mechanic for Answers ASAP
you need to clean the EGR ports. there is an allen head plug in each intake runner, so there is 4 of them. they are in the intake manifold about an inch or two down the runner from the head. take out each plug and use a small screwdriver or round wire brush to punch through the carbon in the hole.
what is happening is your cyl #4 egr port is open, or slightly open and all the other ones are plugged. this makes all your egr gas go all into one cyl and makes it misfire. I have seen this problem many many times and am confident this should fix your problem.
if you have any further questions on this, please post them here.
if you look in this picture here, this is the approximate location of each plug. this is marked with a red dot.
just a side note, each plug is an 8mm allen head. dont round them off. they are very tight to break loose.
ok. what happens is the carbon builds up and it makes it look like there isn't a hole down in there, i bet you just scrapped away the top layer of the carbon. once you remove each plug, down inside the hole, there should be another hole about 1/4 to 1/2 the size of the bolt hole, if there is not, you need to take a small screwdriver into the center of each hole and push hard to puncture through the carbon. every time I have done this job, the hole was covered up so it doesn't even look like there was a hole there, there is a hole there, it is just filled with carbon. you need to puncture through it by pushing straight down into it...
you should at least clean as many as you can.
when you remove the plug, you are just gaining access to the tube that the egr flows down. at the bottom of the tube, inside each hole, in the center of each hole, there should be another small hole, if not, then it is plugged. then just take a small screwdriver and push straight down into the center of the hole at the very bottom. once you clear the hole, you will now have actually punched through to the intake manifold runner. so a small screwdriver should be able to go about 2 inches down into the hole. once you break through one you going to have one of those AHAH moments.
I hope im explaining this well enough. any more questions?
It would be best if you erased it. but, it will eventually go off after the problem is fixed.
just remember, after you get the plug out, at the very bottom of the opening, there should be a hole. just push through it with a screwdriver. it may be a little tough, but it should go through.
have a great evening.
code p1402 means there is egr flow when there should not be. so now we got the egr system flowing by clearing the ports. the next step is to get the computer back in control of when the egr system is allowed to flow.
since there is egr flow even when the computer says there shouldn't be, this could be due to a stuck open egr valve, or a stuck egr solenoid valve. or you could have the wrong vacuum hose hooked to the egr causing it to flow when it shouldn't.
reach underneath the egr valve and see if it is open, it should open "you will feel it lift" if the vehicle is warmed up and you rev the engine slightly just off idle. if you reach underneath it and push up on the egr bellow, and it is already up, this means it is open. remove the vacuum hose and see if it lowers.
let me know what you feel then we will move on.
I will look for a diagram, but they are not very clear.
the odd thing is, this code is because there is egr flowing when there shouldn't be, not the other way around. also, the symptoms you had before suggested there was flow, but the flow was going all into on cyl. cyl #4. the one that wasn't clogged..
this would suggest the egr valve was stuck open, or you have the wrong vacuum lines hooked up and the egr valve was opening when it shouldn't be.
be back soon, going to look for a vacuum diagram
here is the best diagrams available from the service manual.
well that would explain it then, the EGR valve was sticking...
good luck, and thank you!