So when I purchased this car for my Son it had a knock upon startup
I've always assumed it could be bearings or the timing chain tensioner most likely
One day it died on my Son & now it's only firing on 3 cylinders, cylinder 4 doesn't fire
I've replaced plugs, coils, injectors cam & crank sensors & intake manifold gasket
I brought a used ecm that did nothing & couldn't even be flashed I was told
I have a new timing chain kit as well as rod & main bearings which I don't think is the issue but the price wasn't too bad so I bit the bullet
I forget the codes that came up bc it's been a few months but they all revolved around the work I did
I'll get her back this weekend to mess with it once again but I really think my chain jumped or so
Any input would be greatly appreciated & if there are any Nissan Tech's in South Jersey please hit me up lol
Car only has 83,000 miles
2004 Nissan Sentra 2.5S
Thanks All

Ok so I just did the compression test & the numbers were all low but all around the same
110-110-105-110
I did the noid test but only on cylinders 1 & 4
1 lit up & 4 did not
Also plug 4 is clean while the other 3 show carbon so where do I go next lol
I'm glad this was super easy these two jobs

I found a thread that said if all 4 cylinders read low the timing is off. Can anyone confirm this? Thanks again!

louielace69 wrote: ↑

Sun Apr 17, 2022 3:33 pm

I found a thread that said if all 4 cylinders read low the timing is off. Can anyone confirm this? Thanks again!

That's generally correct.

So since having this car at that shop since 5/6, I finally got a call back that it is the timing chain tensioner that went bad (duh) & also my #4 injector is not firing lol
He basically had to repeat to me a few months later what I initially told him?
If I have to get an ECU flashed for my ride that's cool so long as my timing has been replaced?
Who knows, maybe getting it back in timing will also get the ECU to recognize everything is synched correctly
I've come to the realization that absolutely no one wants to work on the 2.5 Nissan motors & always come up with excuses as to why it's something else
Gee Wiz!?!

louielace69 wrote: ↑

Mon Aug 01, 2022 6:20 pm

Who knows, maybe getting it back in timing will also get the ECU to recognize everything is synched correctly
I've come to the realization that absolutely no one wants to work on the 2.5 Nissan motors & always come up with excuses as to why it's something else
Gee Wiz!?!

Everybody likes working on the QR25, just not in a Sentra because it's a similar situation to the VQ35 Altimas, five pounds of s#!t crammed into a three pound bag. Doing anything under the timing cover is a minor PITA on an Altima or Rogue, but on a Sentra it's nightmarish.

It's actually pretty unusual for a single injector-driver in the ECM to fail unless the injector coil shorts out. That's unlikely, the vast majority of injectors fail either open-circuit or mechanically. Short-circuit failure is pretty rare, so chances are all you have is a bum injector and not a bad ECU.

Thanks VStar650CL, I'll keep y'all posted as I hope to get the car back later this week to someone who will hopefully, finally attempt the job

Ok, I finally got my ride back. Still isn't running right but I'm going to take care of her.
New issue she has now is no power to the fuel pump relay, the other wires are getting juice just not this one. Black/yellow wire by my left foot & starter signal fuse isn't lighting up either.
Can the fuel pump be going bad or might it be something else?
At crankup since she doesn't start the pump is not hissing but after a few cranks you can here where it hisses afterwards
Again thanks for your time & knowledge Everyone

When you key-on without starting, the pump only runs for a second and a half to prime and then shuts down. The ECM only turns it on continuously during cranking or running. When you check pressure or check the relay, you need to be aware of that. Generally the first priming shot will bring the pressure right up to the rated 51 psi, if it doesn't then you probably have a weak pump.

could be the fuel regulator,

outThere wrote: ↑

Mon Dec 12, 2022 7:09 pm

could be the fuel regulator,

Still means a pump if so. The regulator is integral on the QR's, not external like the QG's.

Ok, so I finally got the balls to start this timing job.
I watched Ericthecarguy on YouTube & also skim my trusty Haynes or Chilton manual
So far I removed the valve cover, serpentine belt, alternator, ac compressor, power steering pump, both oil pans, 2 of the 3 motor mounts & exhaust.
I still have the passenger side mount, the timing cover & the water pump.
I did loosen up the big crank bolt so I'm good there.
I'm going to use black gasket maker for everything but wanted to ask for any advice in case I forget something
I will be cleaning off the mating surfaces with my drill & some gasket removal type attachments
I've never done a timing job because I've always felt intimidated but I think I'm gonna be just fine here.
Thanks for any advice in advance Everyone
Peace!

If the black stuff is regular RTV of any sort, you'll probably be sorry. Standard RTV won't stand up. Permatex Ultra Black is probably okay, but Permatex Ultra Gray is the equivalent of Nissan gray death and is really the right stuff.

BTW, you don't need to rely solely on aftermarket SM's unless you want to. Nico has the complete factory FSM for your ride. The QR25 section starts on EM-81, the timing chain R&R starts on EM-121:
https://www.nicoclub.com/service-manual ... 2%2Fem.pdf

Thanks VStar650CL
I am actually going to use Aisen gray stuff specifically for Japanese rides & I appreciate the warning for the black
Thanks for the heads up on the FSM as well
I'll be skimming through that tonite

Can I post pic's right from my phone?
Crankshaft is at tdc with bottom dot on orange link & top marks are as close as can be
Up top the intake cam is lined up with one yellow link & the same on the exhaust side notch on link
I haven't removed the balance shaft tensioner cover yet but I know there's another color link down there
I just want to make sure I can pop that off & continue with removing my 2 chains lol
I'm a scared 1st timer here with timing anything but I'm almost at the finish line
Also I want to replaced all the rubber o-rings on the old pump/front timing cover & there are no grooves to sit them in.What can I use to hold/stick them in place?
Again thanks for any help support & knowledge Guys & Gals

How to upload pictures on NICOclub: Using IMGUR Pictures can also be added as an attachment.

So as I was trying to take the exhaust camshaft wheel off to replace it, the cam turned to the left but did not go around
I'm hoping I didn't F anything up
Anyways I put everything back to TDC, installed the new chains & tensioners & will continue once I get 4 missing bolts for the oil pump/timing cover from the dealer by Wednesday
I will keep you all posted
Thanks Everyone

Ok so everything is back together but I forgot to mark my coils so I don't remember which ones are 2-4
Two of them are kinda taped together & one is by itself
I assume the wires going in the coil packs are colored differently
Also before I took it to the last mechanic she was firing on 3 cylinders & then I got it back & she would crank but not fire up. Now I got the same issue,crank but she won't turn over
I'm gonna pull the coils to see if they're shooting spark & also run a test light in my fuse box but what else should I possibly check?
Fuel pump is new as well
Thanks again everyone
The finish line is very close

The trigger wire on COP's is always a different color on each coil, the other two will be the same on all four. On your ride:
#1 - Brown
#2 - Purple
#3 - Blue/White
#4 - Gray/Red

You can find the wiring diagrams here starting on EC-566:
https://www.nicoclub.com/service-manual ... 4%2Fec.pdf

Thanks VStar650CL