99 Maxima P0303 Fuel Injector Replacement
02-12-2018, 12:11 AM
#1
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Join Date: Feb 2018
Posts: 38
99 Maxima P0303 Fuel Injector Replacement
Hi!
New here - amateur at-home mechanic with some successful repairs under my belt.
Had a CEL and white exhaust coming out of a 99 Maxima (3.0 engine) - also smells like fuel and clearly running rough. Put the OBD on it and got a P0303. Tried swapping coils - misfire stayed on cylinder 3. Spark plugs were pretty old so I changed all 6. No change - still misfire on cylinder 3. The #3 coil electrical adapter/harness looked a little funky so I replaced that, too - no change.
Figured next place to check would be fuel injector. Why it had to be #3 god only knows - the only one that's completely hidden under the UIM....
Anyway, I got that off and on the outside the #3 injector looks okay. Ohmmeter gives me about 10.7 ohms (same on the other injectors) - so that seems fine (right?).
What I can see is that the #3 opening going down into the cylinders (not sure what that opening is called - one of openings the UIM covers up - the openings you gotta be careful not to drop a bolt into!) looks strikingly different from the other 5. The other 5 are pretty black and gunky whereas #3 looks bare and even a bit rusty (I attached some pics). The opening I am referring to is right beneath the (suspected) bad injector in the pictures - #3.
I'm suspecting maybe a bad O-ring or faulty/leaky injector - I'd like to take it out BUT (here is why I am posting here) - I totally spaced on draining the fuel rails before I got knee deep in this whole project....
Everything related to or touching the UIM is all hanging off disconnected - can anyone tell me if there is a safe way for me to drain/depressurize the fuel rail and remove the injector at this stage? If I have to put some things back together I will, of course, but man I'd really like to avoid that, if possible!
Thanks in advance for your help!
New here - amateur at-home mechanic with some successful repairs under my belt.
Had a CEL and white exhaust coming out of a 99 Maxima (3.0 engine) - also smells like fuel and clearly running rough. Put the OBD on it and got a P0303. Tried swapping coils - misfire stayed on cylinder 3. Spark plugs were pretty old so I changed all 6. No change - still misfire on cylinder 3. The #3 coil electrical adapter/harness looked a little funky so I replaced that, too - no change.
Figured next place to check would be fuel injector. Why it had to be #3 god only knows - the only one that's completely hidden under the UIM....
Anyway, I got that off and on the outside the #3 injector looks okay. Ohmmeter gives me about 10.7 ohms (same on the other injectors) - so that seems fine (right?).
What I can see is that the #3 opening going down into the cylinders (not sure what that opening is called - one of openings the UIM covers up - the openings you gotta be careful not to drop a bolt into!) looks strikingly different from the other 5. The other 5 are pretty black and gunky whereas #3 looks bare and even a bit rusty (I attached some pics). The opening I am referring to is right beneath the (suspected) bad injector in the pictures - #3.
I'm suspecting maybe a bad O-ring or faulty/leaky injector - I'd like to take it out BUT (here is why I am posting here) - I totally spaced on draining the fuel rails before I got knee deep in this whole project....
Everything related to or touching the UIM is all hanging off disconnected - can anyone tell me if there is a safe way for me to drain/depressurize the fuel rail and remove the injector at this stage? If I have to put some things back together I will, of course, but man I'd really like to avoid that, if possible!
Thanks in advance for your help!
02-12-2018, 03:16 PM
#2
Senior Member
Join Date: Mar 2010
Posts: 373
While you're back there, you might as well replace all three rear fuel injectors, and get the Hillman screws if you don't already have them. And replace the valve cover gaskets and clean out the EGR tube while you're under there.
Just because it looks OK doesn't mean it is. The issue can be from a bad seal, or some other non-electrical component of the injector gone wrong that would cause a problem but still give you the correct resistance on a ohmmeter.
Honestly, I wouldn't even worry about draining/depressurizing it. I actually forgot to do this when I replaced an injector. At least it was #4, in the front, so I didn't have to take the engine apart!
But you should still be able to simply pull the fuel pump fuse and (attempt to) start the car. Of course it won't start, but let it crank a few times.
Just because it looks OK doesn't mean it is. The issue can be from a bad seal, or some other non-electrical component of the injector gone wrong that would cause a problem but still give you the correct resistance on a ohmmeter.
Honestly, I wouldn't even worry about draining/depressurizing it. I actually forgot to do this when I replaced an injector. At least it was #4, in the front, so I didn't have to take the engine apart!
But you should still be able to simply pull the fuel pump fuse and (attempt to) start the car. Of course it won't start, but let it crank a few times.
02-12-2018, 04:34 PM
#3
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Join Date: Feb 2018
Posts: 38
While you're back there, you might as well replace all three rear fuel injectors, and get the Hillman screws if you don't already have them. And replace the valve cover gaskets and clean out the EGR tube while you're under there.
Just because it looks OK doesn't mean it is. The issue can be from a bad seal, or some other non-electrical component of the injector gone wrong that would cause a problem but still give you the correct resistance on a ohmmeter.
Honestly, I wouldn't even worry about draining/depressurizing it. I actually forgot to do this when I replaced an injector. At least it was #4, in the front, so I didn't have to take the engine apart!
But you should still be able to simply pull the fuel pump fuse and (attempt to) start the car. Of course it won't start, but let it crank a few times.
Just because it looks OK doesn't mean it is. The issue can be from a bad seal, or some other non-electrical component of the injector gone wrong that would cause a problem but still give you the correct resistance on a ohmmeter.
Honestly, I wouldn't even worry about draining/depressurizing it. I actually forgot to do this when I replaced an injector. At least it was #4, in the front, so I didn't have to take the engine apart!
But you should still be able to simply pull the fuel pump fuse and (attempt to) start the car. Of course it won't start, but let it crank a few times.
Valve cover gaskets - you mean the intake plenum gasket? Or the big rear valve cover gasket? Or both?
I'll get to the EGR tube once I sort the injectors - good thinking! Same as above: may as well!
So if I just let it crank a few times with the fuse pulled that should more or less do the trick? And should not have any awful side effects given the car is half disassembled?
Thanks!!
02-12-2018, 05:50 PM
#4
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Join Date: Mar 2010
Posts: 373
Yes, you will need new screws for fastening the injectors in place, as almost all of Nissan's original screws strip too easily. The Hillman screws I'm talking about are these
The best injectors to get are one of these:
Bosch 62027
Hitachi FIJ0023
Beck/Arnley 158-0861
(all three are the actual OE injectors)
Also, the O-rings are sold separately. Get Beck/Arnley 158-0957. Each package of O-rings covers one injector, so you will need to buy three of them.
Yes, I mean both the big rear valve cover gasket *and* the intake plenum gasket. The best brands to get are wither Beck/Arnley, Mahle, or Victor Reinz. They are the actual OEM gaskets.
Correct. Just let it crank a few times with the fuse pulled should do the trick. The engine being disassembled shouldn't have any side effects since the car won't actually start anyway (engine won't be getting any fuel)
And even if you don't do it at all, there won't be too much fuel spilling out of injector #3 since the injector is no good anyway.
You might also consider replacing the fuel filter if you depressurize the fuel system. Get Bosch part #71650
The best injectors to get are one of these:
Bosch 62027
Hitachi FIJ0023
Beck/Arnley 158-0861
(all three are the actual OE injectors)
Also, the O-rings are sold separately. Get Beck/Arnley 158-0957. Each package of O-rings covers one injector, so you will need to buy three of them.
Yes, I mean both the big rear valve cover gasket *and* the intake plenum gasket. The best brands to get are wither Beck/Arnley, Mahle, or Victor Reinz. They are the actual OEM gaskets.
Correct. Just let it crank a few times with the fuse pulled should do the trick. The engine being disassembled shouldn't have any side effects since the car won't actually start anyway (engine won't be getting any fuel)
And even if you don't do it at all, there won't be too much fuel spilling out of injector #3 since the injector is no good anyway.
You might also consider replacing the fuel filter if you depressurize the fuel system. Get Bosch part #71650
Last edited by maximaxi; 02-12-2018 at 05:53 PM.
02-13-2018, 12:51 PM
#6
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Join Date: Oct 2012
Location: Portland, Oregon
Posts: 2,979
As others have said, replace all 3 rear injectors.
Do the other while you are in there anyway things as well. Otherwise you will do everything again a 2nd or 3rd time.
in fact, if one injector starts leaking, the others will too. I would replace all 6 injectors. Rebuilt ones are fine.
02-14-2018, 09:03 PM
#7
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Join Date: May 2012
Location: Long Island
Posts: 1,564
As far as removing injector screws and having to replace them or strip them, it would help if you had the RIGHT screwdriver.
Japanese Philips screws are different and they use JIS screwdrivers (different that what Americans use). You would not believe how much better they marry to the screws used in our Maximas.
Buy yourself one of these and show up prepared if you're serious about working on your own car:
Japanese Philips screws are different and they use JIS screwdrivers (different that what Americans use). You would not believe how much better they marry to the screws used in our Maximas.
Buy yourself one of these and show up prepared if you're serious about working on your own car:
02-14-2018, 09:09 PM
#8
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Thread Starter
Join Date: Feb 2018
Posts: 38
As far as removing injector screws and having to replace them or strip them, it would help if you had the RIGHT screwdriver.
Japanese Philips screws are different and they use JIS screwdrivers (different that what Americans use). You would not believe how much better they marry to the screws used in our Maximas.
Buy yourself one of these and show up prepared if you're serious about working on your own car:
Amazon
Japanese Philips screws are different and they use JIS screwdrivers (different that what Americans use). You would not believe how much better they marry to the screws used in our Maximas.
Buy yourself one of these and show up prepared if you're serious about working on your own car:
Amazon
any other words of wisdom regarding
1) removing fuel injectors/putting new ones in (should I dip them in fuel?)
2) good gasket sealant/glue - just plain old RTV silicone? do i need to use any sealant on the plenum gasket?
3) worth it to clean the EGR tube or get a new one?
thanks everyone!
02-14-2018, 09:26 PM
#9
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Join Date: May 2012
Location: Long Island
Posts: 1,564
Lube the new O-Rings like a greased pig and insert gingerly. If they move out of their place, way too much gas dumps.
Most clean their EGR tubes. Assuming they aren't corroding. Mine corroded through (perfed) and sounded like the exhaust manifold was cracked. If it's solid, cleaning it is fine. If it's thinning, go new.
I'll let the guys that have opened this up multiple times address the handling of gaskets and anything else used to reseal everything right.
Most clean their EGR tubes. Assuming they aren't corroding. Mine corroded through (perfed) and sounded like the exhaust manifold was cracked. If it's solid, cleaning it is fine. If it's thinning, go new.
I'll let the guys that have opened this up multiple times address the handling of gaskets and anything else used to reseal everything right.
02-25-2018, 10:40 PM
#10
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Join Date: Feb 2018
Posts: 38
alright - i think we're almost there - but not out of the woods yet!
replaced rear 3 injectors - no problems
replaced intake plenum gasket - old one was pretty dry and brittle
replaced fuel filter - no problems
replaced PCV valve (whoops - broke it when disassembling UIM)
rear valve cover gasket actually looked relatively new - it was the blue kind - still fairly rubbery and sealed quite well - did not replace that nor the rear spark plug seals - they seemed fine, too
cleaned EGR tube (externally - did not take it off - it did not look too bad - had some gunk around the opening but not clogged)
replaced valve cover to valve cover breather hose - old one was super cracked and hard
when putting back in the #3 ignition coil, the one of the poor, soft old screws broke - now half of it is left sticking in there - i tried my damndest to get it out but no luck - its screwed on with the rear screw and seems pretty snug, though
first time i turned car on, it was not getting a misfire, but i got a P0505 and a P1320 and the exhaust was pretty plume-y - although not nearly as bad as it was before
checked some connections and saw that a hose that i had re-hooked to the UIM was not on as well as it should have been - adjusted that - also realized i had not tightened the big airbox hose around where it hooks to the UIM quite snug enough - tightened that
ran the car again and it seemed to be getting better - checked that cylinder 3 was firing (unhooked coil-pack) and it was!! that was a good feeling -
now it seems to be idling fine (no visible exhaust) but i took it for a spin and:
1) it seemed to heat up kind of quickly - temp gauge only got to about 45% but i was only driving the car for about 10 minutes...
2) after the short drive the exhaust started to look a bit funky again - not nearly as bad as it was but not great
there is no CEL coming on - and the car feels fine (although maybe a bit shaky? hard to tell now that i am being super paranoid)
im wondering: should i replace the front 3 injectors? i only did the rear 3 so far -
....hmmm
replaced rear 3 injectors - no problems
replaced intake plenum gasket - old one was pretty dry and brittle
replaced fuel filter - no problems
replaced PCV valve (whoops - broke it when disassembling UIM)
rear valve cover gasket actually looked relatively new - it was the blue kind - still fairly rubbery and sealed quite well - did not replace that nor the rear spark plug seals - they seemed fine, too
cleaned EGR tube (externally - did not take it off - it did not look too bad - had some gunk around the opening but not clogged)
replaced valve cover to valve cover breather hose - old one was super cracked and hard
when putting back in the #3 ignition coil, the one of the poor, soft old screws broke - now half of it is left sticking in there - i tried my damndest to get it out but no luck - its screwed on with the rear screw and seems pretty snug, though
first time i turned car on, it was not getting a misfire, but i got a P0505 and a P1320 and the exhaust was pretty plume-y - although not nearly as bad as it was before
checked some connections and saw that a hose that i had re-hooked to the UIM was not on as well as it should have been - adjusted that - also realized i had not tightened the big airbox hose around where it hooks to the UIM quite snug enough - tightened that
ran the car again and it seemed to be getting better - checked that cylinder 3 was firing (unhooked coil-pack) and it was!! that was a good feeling -
now it seems to be idling fine (no visible exhaust) but i took it for a spin and:
1) it seemed to heat up kind of quickly - temp gauge only got to about 45% but i was only driving the car for about 10 minutes...
2) after the short drive the exhaust started to look a bit funky again - not nearly as bad as it was but not great
there is no CEL coming on - and the car feels fine (although maybe a bit shaky? hard to tell now that i am being super paranoid)
im wondering: should i replace the front 3 injectors? i only did the rear 3 so far -
....hmmm
02-25-2018, 11:36 PM
#11
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Join Date: Oct 2012
Location: Portland, Oregon
Posts: 2,979
alright - i think we're almost there - but not out of the woods yet!
replaced rear 3 injectors - no problems
replaced intake plenum gasket - old one was pretty dry and brittle
replaced fuel filter - no problems
replaced PCV valve (whoops - broke it when disassembling UIM)
rear valve cover gasket actually looked relatively new - it was the blue kind - still fairly rubbery and sealed quite well - did not replace that nor the rear spark plug seals - they seemed fine, too
cleaned EGR tube (externally - did not take it off - it did not look too bad - had some gunk around the opening but not clogged)
replaced valve cover to valve cover breather hose - old one was super cracked and hard
when putting back in the #3 ignition coil, the one of the poor, soft old screws broke - now half of it is left sticking in there - i tried my damndest to get it out but no luck - its screwed on with the rear screw and seems pretty snug, though
first time i turned car on, it was not getting a misfire, but i got a P0505 and a P1320 and the exhaust was pretty plume-y - although not nearly as bad as it was before
checked some connections and saw that a hose that i had re-hooked to the UIM was not on as well as it should have been - adjusted that - also realized i had not tightened the big airbox hose around where it hooks to the UIM quite snug enough - tightened that
ran the car again and it seemed to be getting better - checked that cylinder 3 was firing (unhooked coil-pack) and it was!! that was a good feeling -
now it seems to be idling fine (no visible exhaust) but i took it for a spin and:
1) it seemed to heat up kind of quickly - temp gauge only got to about 45% but i was only driving the car for about 10 minutes...
2) after the short drive the exhaust started to look a bit funky again - not nearly as bad as it was but not great
there is no CEL coming on - and the car feels fine (although maybe a bit shaky? hard to tell now that i am being super paranoid)
im wondering: should i replace the front 3 injectors? i only did the rear 3 so far -
....hmmm
replaced rear 3 injectors - no problems
replaced intake plenum gasket - old one was pretty dry and brittle
replaced fuel filter - no problems
replaced PCV valve (whoops - broke it when disassembling UIM)
rear valve cover gasket actually looked relatively new - it was the blue kind - still fairly rubbery and sealed quite well - did not replace that nor the rear spark plug seals - they seemed fine, too
cleaned EGR tube (externally - did not take it off - it did not look too bad - had some gunk around the opening but not clogged)
replaced valve cover to valve cover breather hose - old one was super cracked and hard
when putting back in the #3 ignition coil, the one of the poor, soft old screws broke - now half of it is left sticking in there - i tried my damndest to get it out but no luck - its screwed on with the rear screw and seems pretty snug, though
first time i turned car on, it was not getting a misfire, but i got a P0505 and a P1320 and the exhaust was pretty plume-y - although not nearly as bad as it was before
checked some connections and saw that a hose that i had re-hooked to the UIM was not on as well as it should have been - adjusted that - also realized i had not tightened the big airbox hose around where it hooks to the UIM quite snug enough - tightened that
ran the car again and it seemed to be getting better - checked that cylinder 3 was firing (unhooked coil-pack) and it was!! that was a good feeling -
now it seems to be idling fine (no visible exhaust) but i took it for a spin and:
1) it seemed to heat up kind of quickly - temp gauge only got to about 45% but i was only driving the car for about 10 minutes...
2) after the short drive the exhaust started to look a bit funky again - not nearly as bad as it was but not great
there is no CEL coming on - and the car feels fine (although maybe a bit shaky? hard to tell now that i am being super paranoid)
im wondering: should i replace the front 3 injectors? i only did the rear 3 so far -
....hmmm
03-07-2018, 10:21 PM
#14
Junior Member
Thread Starter
Join Date: Feb 2018
Posts: 38
alright -
replaced front 3 injectors. car seems to be running OK but:
1) CEL came on with a P0134 (o2 sensor)
2) still seems to heat up kind of fast, but then stays steady with the temp gauge right below the middle
3) a faint smell of burnt gas - but no suspicious exhaust or anything
cleaned the bad spots - cleaned where the injectors go in and around intake plenum - i did replace the plenum gasket, but the rear valve cover gasket was in good shape and i didnt want to mess with it.
i cleaned the MAF sensor (the careful way, dont worry!) - the air filter looked not so good so i will replace that -
any troubleshooting thoughts/tips?
replaced front 3 injectors. car seems to be running OK but:
1) CEL came on with a P0134 (o2 sensor)
2) still seems to heat up kind of fast, but then stays steady with the temp gauge right below the middle
3) a faint smell of burnt gas - but no suspicious exhaust or anything
i haven't seen a vq that dirty except in a junkyard max. really need to clean that motor off and make sure all the gaskets are replaced before you put it back together.
i cleaned the MAF sensor (the careful way, dont worry!) - the air filter looked not so good so i will replace that -
any troubleshooting thoughts/tips?
03-08-2018, 05:48 AM
#15
should've done the valve cover gasket since you were in there. run some premium gas through her, that'll help clean out any carbon deposits left over in the cylyliders, and check the maf boot, could be torn and leaking air on you.
Last edited by max ride 41; 03-08-2018 at 05:51 AM.
03-13-2018, 02:09 PM
#16
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Join Date: Feb 2018
Posts: 38
cleaned air box - replaced air filter -
MAF boot looks OK -
ran some premium gas and did some highway driving -
car seems to be running pretty good now - exhaust is clean, no smell - engine sounds good -
but
1) P0134 - 02 sensor 1 bank 1 no activity keeps coming on
2) still a little concerned about how the heat gauge goes up quickly - it does not exceed 45% but does get there kind of quickly -
any thoughts on diagnosing the P0134 at this point?
MAF boot looks OK -
ran some premium gas and did some highway driving -
car seems to be running pretty good now - exhaust is clean, no smell - engine sounds good -
but
1) P0134 - 02 sensor 1 bank 1 no activity keeps coming on
2) still a little concerned about how the heat gauge goes up quickly - it does not exceed 45% but does get there kind of quickly -
any thoughts on diagnosing the P0134 at this point?
03-14-2018, 11:25 PM
#17
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Thread Starter
Join Date: Feb 2018
Posts: 38
I'm going to change that O2 sensor -
like I said, car seems to be running fine but that P0134 keeps coming back - don't wanna fry the catalytic converter and I'm guessing while the car was misfiring and spewing all kinds of dirty fuel it may have clogged/shorted/broke the sensor -
I live in Nevada but the car was purchased in California - I've read about some different sensor specs depending on emissions requirements in different states - can anyone clarify this for me so I get the right part?
like I said, car seems to be running fine but that P0134 keeps coming back - don't wanna fry the catalytic converter and I'm guessing while the car was misfiring and spewing all kinds of dirty fuel it may have clogged/shorted/broke the sensor -
I live in Nevada but the car was purchased in California - I've read about some different sensor specs depending on emissions requirements in different states - can anyone clarify this for me so I get the right part?
03-15-2018, 09:21 AM
#18
When ordering parts, it's best to use sites like Courtesyparts.com that ask for you VIN. This will ensure you order the right part for your particular Maxima.
03-15-2018, 09:29 AM
#19
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Thread Starter
Join Date: Feb 2018
Posts: 38
Emission requirements are different state to state, but the O2 sensor part# is the same (for the primary 3 O2 sensors). No such thing as different sensor specs. You may be referring to a CA spec Maxima, which require a 4th O2 sensor and additional/different emission equipment.
any recommendations for which sensor to get? seems to be quite a range -
03-15-2018, 06:16 PM
#20
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Thread Starter
Join Date: Feb 2018
Posts: 38
k got a denso -
last question:
the sensor in question (bank 1 sensor 1) is the one located near the passenger side wheel - the electric harness has 3 leads and goes up to right on top of the UIM by the #1 ignition coil - correct?
last question:
the sensor in question (bank 1 sensor 1) is the one located near the passenger side wheel - the electric harness has 3 leads and goes up to right on top of the UIM by the #1 ignition coil - correct?
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