So I just received my 1991 Q45 and now i'm diagnosing a misfire (I was aware of the misfire when I bought it). After going over it I found that cylinder 3 had a new ignition coil and all the plugs look to have been replaced. I pulled the #3 plug to compare to the other cylinders and sure enough the #3 plug looks super clean while the other plugs on B1 are relatively normal looking.

I then checked with a stethoscope to listen to the injectors and I can hear a distinct clicking from all the injectors, except the #3 injector. So i'm pretty sure the injector is bad.

My question is, i'm looking at trying to buy new injectors and I keep seeing different P#'s or identifiers. I checked Amayama and it shows two P#'s, a 16600-60U00 or a 16600-60U01. Both are the same price and the same description.

Checking rockauto and even my local O'Reillys (just out of curiosity) and they also show different options available but the determining factor is a green dot, orange dot, or yellow dot. I don't see dots, but they're also old and grimy so i'm not sure if they've just worn off or what.

Does anyone have any ideas on what the differences between P#'s/dots mean, or where the dots are supposed to be located for identification? I'm assuming it may have something to do with injector impedance? But its not clarified in the parts catalog or ESM (at least from what I can find).

You can get the OE part number by plugging in your VIN at InfinitiPartsDeal.com, they have the same dbase and diagrams as Nissan/Infiniti DPC. Once you know the correct OE part number, you can easily cross-ref it.

VStar650CL wrote: ↑

Wed Apr 19, 2023 4:31 pm

You can get the OE part number by plugging in your VIN at InfinitiPartsDeal.com, they have the same dbase and diagrams as Nissan/Infiniti DPC. Once you know the correct OE part number, you can easily cross-ref it.

Thanks! Amusingly I have access to Infiniti's parts system and it doesn't specify the color the vehicle is supposed to have. When I put my VIN into the actual Infiniti system it gives me 3 options:

16600-60U00 (no color)
16600-60U01 (Yellow)
16600-60U02 (Green)

When I check that website, it shows to use 16600-60U01, but it also shows that 60U00 and 60U02 are discontinued. So i'm not sure that the website means my vehicle was built with yellow, or if the yellow dot injector is literally the only option available still because the others are discontinued/no longer available (so it displays yellow by default).

It means your vehicle was built with yellow. The beauty of InfinitiPartsDeal and NissanPartsDeal is that they're an online dealer consortium, so all their build data and diagrams come straight from the horse's mouth, Nissan/Infiniti DPC.

So I went to look at an easy to access injector (the #2 injector) and removed the connector and I noticed the housing of the injector is yellow.

I'm thinking that maybe this is what is being referred in the aftermarket catalogs as "yellow/green mark/dot". But its not a mark/dot, its just the color of the injector itself.

Here is a picture of the #2 injector. Maybe if someone has time, they can compare to their Q's (if they are still using stock injectors) to see if we have variations between yellow/green/no color (black maybe?)

https://imgur.com/a/ZJPTjZP (link because I guess I can't insert images)

VStar650CL wrote: ↑

Wed Apr 19, 2023 5:37 pm

It means your vehicle was built with yellow. The beauty of InfinitiPartsDeal and NissanPartsDeal is that they're an online dealer consortium, so all their build data and diagrams come straight from the horse's mouth, Nissan/Infiniti DPC.

As mentioned, I have access to the Infiniti DPC and it doesn't show that specifically. It lists all 3 color options and you're supposed to choose from what matches the vehicle and the injector you pulled out. It doesn't auto select through the Infiniti DPC/EPC. This is straight from the dealer parts system after selecting the injector P#:

https://imgur.com/a/3papKLu

In my case it does appear yellow is correct when checking the injector body. But this might be helpful for others trying to find the same info.

Build data and fit data are two different things. Supersessions fit and sometimes alternate numbers fit too, but the VIN through DPC should give you build data.

The dots are dots, not the color of the housing. Nissan took great pains to flow match the injectors, and used the dot system to match them as sets by category. At this point, everything is so far out of factory spec - it doesn't matter as much.

Have you ohm tested your injectors? That's the usual way of finding a bad one.

Q451990 wrote: ↑

Fri Apr 21, 2023 2:56 pm

The dots are dots, not the color of the housing. Nissan took great pains to flow match the injectors, and used the dot system to match them as sets by category. At this point, everything is so far out of factory spec - it doesn't matter as much.

Have you ohm tested your injectors? That's the usual way of finding a bad one.

Yes, I narrowed it down through 3 tests

1. Listening using stethoscope (no click)
2. Power balance/Cylinder contribution test (unplugged the coil for that cylinder and no rpm drop)
3. Measured resistance and found the injector is OL/Open

So that injector isn't doing anything at all

Just waiting on parts at this point. Ordered some coolant hose stuff since i'll be under the manifold, as well as the knock sensors and various other things relating to tune-up and maintenance.

Ahh cool. It sounds like you have the job figured out pretty well. I haven't tried the stethoscope method, but it sounds like a great idea.

Stethoscopes can be your best friend for all sorts of noises big and small, and it isn't like you need to buy it from med supply for $200. This is my BFF for $6.99:
https://www.harborfreight.com/mechanics ... 63691.html

Its nice to use, since its cheap (can even use a long screwdriver up to your ear) and doesn't require taking anything apart (at least on the VH45 since all the injectors are visible depending on the angle you approach). It can quickly point you in a direction so you aren't fumbling around trying to measure resistance on every injector if you don't need to.

These older injectors have a pretty loud and distinct click when they're working (even with the noise in the rail from the other injectors)

From the research I did when replacing my injectors, the stock size is 370cc, and this is usually designated by the injectors having a purple housing. I did see some that were advertised as being 370cc but had different color housings, but that may have been due to using stock injector photos rather than pics of the actual injectors being sold.

Ryantzer wrote: ↑

Tue Apr 25, 2023 2:50 pm

From the research I did when replacing my injectors, the stock size is 370cc, and this is usually designated by the injectors having a purple housing. I did see some that were advertised as being 370cc but had different color housings, but that may have been due to using stock injector photos rather than pics of the actual injectors being sold.

I think they are all 370cc but potentially the different dots/colors indicating differences in resistances/impedance between injectors. As was noted earlier in the thread, it was Nissan likely trying to match the resistances of a group of injectors so they were all the same, instead of having some injectors with 10 ohms and others with 14 ohms.

At this stage, they are so old, a few ohms variance between injectors is imperceptible to engine operation. I actually ordered a replacement injector from https://www.fiveomotorsport.com/370cc-jecs-300zxtt/ and they don't even ask about the dots. They provide a resistance value in the specifications sheet (12.5 ohms) and the one I received has a purple top.

Currently working on taking off the plenum, so will let everyone know how it goes (probably going to be awhile, still waiting a bunch of other parts to come in that require replacement while i've got the plenum off)

I don't think they were matching resistance. That was very consistent. It was more spray pattern and flow rate.

There's a lot of discussion about the dots, flow matching, and other cool injector stuff in this old thread.

g50-aftermarket-injector-alternative-t347484-30.html

Ah alright thanks for the clarification. I'm not too bothered by it at this point. Just going to replace the clearly open circuit/non-working injector to get it running good enough to make a 40 mile drive where it'll live in a bigger shop space so I can do more in-depth stuff with it.

Eventually I plan on upgrading the entire fuel system, but this is just a stop gap. Admittedly, I am questioning trying to convert to S2 right now since i've got the plenum off... but after just buying the car and ordering a slew of maintenance parts (so many rotted out hoses, why do you have 3 PCV hoses per valve cover Q45?) i'm not really feeling spending money on the S2 rail + S2 injectors at the moment.

One note. When my injectors failed on the first Q, the corresponding spark plug was so badly fouled that it had to be cleaned or replaced to work.

I'm replacing all 8 plugs while i'm in there. Someone else put autolites in trying to fix the misfire and i hate autolites, so i'm replacing with NGK's

Current stuff being replaced:

Injector
Spark plugs
coolant hoses under the plenum
knock sensors
knock sensor connectors (if needed)
thermostat
radiator hoses
fuel pressure regulator (not for any particular reason, its just very rusty/crusty and its easy to access at the moment)
various vacuum hoses
various PCV hoses
sanding/scuffing and repainting PCV lines because some are getting decent corrosion/rust build-up and I want to stop it
cooling fan (cracked)

I might tackle resealing valve covers too.. don't really want to, but now is probably the best time for it. Plus there was small amounts of oil in the spark plug tubes.

Right now i'm mainly just waiting on parts and its been a pain trying to get the plenum gasket. I apparently got the last 4 that infiniti has, so i'm trying to source 4 more. Might just have to go aftermarket for the other 4. Unless people don't have any issues re-using the originals (mine are still fairly flexible, but that probably doesn't mean much).

welp, finally got around to fully removing the fuel rail (because there isn't a way to re-install the "Y" coolant tube in the valley with the fuel rail installed (when using the VH performance silicone hoses anyway, there isn't any flex/bend to prevent smearing the RTV). Decided to check all my injectors and ended up finding 2 more that are OL, and 3 are showing high resistance.

With the 1 new injector and 5 other injectors being NG, I figure I should just replace all of them. The problem is I really don't see any remans available other than whats on rock auto (GB Remanufacturing). I checked AUS injection and they show a remanufactured injector, but its out of stock/discontinued.

Anyone have any dealings with GB remanufacturing injectors or alternate remans that aren't ebay/amazon specials? I'm hesitant because its rockauto and i've had bad luck with their injectors before (not on the Q). I can buy new injectors, but weighing my options for remanufactured to be a little cheaper.

I would call AUS Injection directly to check their stock. They have lots of injectors on-hand and probably just don't have any that are already reman'd and ready to go.

Ryantzer wrote: ↑

Wed May 10, 2023 7:08 am

I would call AUS Injection directly to check their stock. They have lots of injectors on-hand and probably just don't have any that are already reman'd and ready to go.

Thanks, I called them directly and they said they are discontinued but they still had some in stock, so I ordered a set.

The 1 new injector I got came with a small clear packet of lube. Is this just petroleum jelly? In case the remans don't have lube for the o-rings, whats the recommend lubricant so I have enough for all of them?

Any neutral lube should work fine, I've never seen any issues with either Vaseline or white lube. The word of the day is restraint. Whatever you use, don't goop it on there.

Lubing the o-rings is very important, as the design of the fuel rail means a pinched or damaged o-ring can allow fuel to leak into the combustion chamber and potentially hydrolock the engine. Hopefully you've read this previously and are already aware, but make doubly sure that you attach the fuel rail to the fuel system and pressurize it BEFORE you install it on the engine, to make sure there are no leaks.

Ryantzer wrote: ↑

Fri May 12, 2023 5:48 pm

Lubing the o-rings is very important, as the design of the fuel rail means a pinched or damaged o-ring can allow fuel to leak into the combustion chamber and potentially hydrolock the engine. Hopefully you've read this previously and are already aware, but make doubly sure that you attach the fuel rail to the fuel system and pressurize it BEFORE you install it on the engine, to make sure there are no leaks.

Yep, i'm aware and plan to pressurize the rail after installation of the injectors to check for leaks. Thanks for the heads up though.

StitchedQ wrote: ↑

Thu May 04, 2023 10:32 am

I'm replacing all 8 plugs while i'm in there. Someone else put autolites in trying to fix the misfire and i hate autolites, so i'm replacing with NGK's

Current stuff being replaced:

Injector
Spark plugs
coolant hoses under the plenum
knock sensors
knock sensor connectors (if needed)
thermostat
radiator hoses
fuel pressure regulator (not for any particular reason, its just very rusty/crusty and its easy to access at the moment)
various vacuum hoses
various PCV hoses
sanding/scuffing and repainting PCV lines because some are getting decent corrosion/rust build-up and I want to stop it
cooling fan (cracked)

I might tackle resealing valve covers too.. don't really want to, but now is probably the best time for it. Plus there was small amounts of oil in the spark plug tubes.

Right now i'm mainly just waiting on parts and its been a pain trying to get the plenum gasket. I apparently got the last 4 that infiniti has, so i'm trying to source 4 more. Might just have to go aftermarket for the other 4. Unless people don't have any issues re-using the originals (mine are still fairly flexible, but that probably doesn't mean much).

I would use the OE NGK PFR5G11s. They are a double platinum. Some (even me) have used the Iridium at times, but if you do, make sure they are DOUBLE iridium (grounding electrode too).
Last I checked the OE (hitachi?) KS harnesses were "manufacturing stopped", even from amayama. You may consider buying the connectors and fabbing your own harness.
On the plenum donuts I would not hesitate to use aftermarket for those. remember though to keep/re-use your steel inserts regardless.
worst worst case, ornigsandmore.com will have something you can use to get a seal, albeit round cross section vs. square shouldered rings.

3Q Jay wrote: ↑

Sat May 13, 2023 2:26 pm

I would use the OE NGK PFR5G11s. They are a double platinum. Some (even me) have used the Iridium at times, but if you do, make sure they are DOUBLE iridium (grounding electrode too).
Last I checked the OE (hitachi?) KS harnesses were "manufacturing stopped", even from amayama. You may consider buying the connectors and fabbing your own harness.
On the plenum donuts I would not hesitate to use aftermarket for those. remember though to keep/re-use your steel inserts regardless.
worst worst case, ornigsandmore.com will have something you can use to get a seal, albeit round cross section vs. square shouldered rings.

I got new connectors for the knock sensors. I think I got the last 4 plenum gaskets from Infiniti (and new steel inserts, just because). Ended up ordering the intake manifold gasket set from VH performance to get a full set.

My main issue is finding the seals that go inbetween the fuel rail and lower fuel/intake runners. I cannot find those seals anywhere. Amayama has them as discontinued, I even messaged them to see if they maybe had a supersession or aftermarket option and they didn't have any other alternatives.

Someone mentioned using KA24DE injector rail seals, so I got one and they won't work. The size is close (1.2x1.1 diameter, compared to 1.5x1.5 on the Q45) but the inner diameter where the actual injector would sit is too small. Aftermarket doesn't sell them for the Q45, they aren't available through infiniti and amayama doesn't have them. So i feel like I don't have any other option other than cleaning them up and re-using them (they don't look to be in that bad of shape all things considered). Hopefully they'll be fine and I can worry about this later and when later comes, probably means just re-doing the whole fuel rail/fuel system.

I'll take a look at that o-ring website you mentioned to see if they have anything comparable.

StitchedQ wrote: ↑

Sat May 13, 2023 7:20 pm

3Q Jay wrote: ↑

Sat May 13, 2023 2:26 pm

I would use the OE NGK PFR5G11s. They are a double platinum. Some (even me) have used the Iridium at times, but if you do, make sure they are DOUBLE iridium (grounding electrode too).
Last I checked the OE (hitachi?) KS harnesses were "manufacturing stopped", even from amayama. You may consider buying the connectors and fabbing your own harness.
On the plenum donuts I would not hesitate to use aftermarket for those. remember though to keep/re-use your steel inserts regardless.
worst worst case, ornigsandmore.com will have something you can use to get a seal, albeit round cross section vs. square shouldered rings.

My main issue is finding the seals that go inbetween the fuel rail and lower fuel/intake runners. I cannot find those seals anywhere. Amayama has them as discontinued, I even messaged them to see if they maybe had a supersession or aftermarket option and they didn't have any other alternatives.

Someone mentioned using KA24DE injector rail seals, so I got one and they won't work. The size is close (1.2x1.1 diameter, compared to 1.5x1.5 on the Q45) but the inner diameter where the actual injector would sit is too small. Aftermarket doesn't sell them for the Q45, they aren't available through infiniti and amayama doesn't have them. So i feel like I don't have any other option other than cleaning them up and re-using them (they don't look to be in that bad of shape all things considered). Hopefully they'll be fine and I can worry about this later and when later comes, probably means just re-doing the whole fuel rail/fuel system.

If the injector rail to runners seals are not cracked and somewhat pliable I would just clean them and then dress them with a reputable rubber rejuvenant. I have used "einzett" gummi on a lot of rubber with good results.
On mine, I also "flipped over" the rubber seals so that the compression witness marks left by the rail were now seated in the runners, and the "virgin" side was up against the rail.

I've just used Mobil 1 motor oil as lube for the o-rings, and had no issues.

3Q Jay wrote: ↑

Sun May 14, 2023 7:13 am

If the injector rail to runners seals are not cracked and somewhat pliable I would just clean them and then dress them with a reputable rubber rejuvenant. I have used "einzett" gummi on a lot of rubber with good results.
On mine, I also "flipped over" the rubber seals so that the compression witness marks left by the rail were now seated in the runners, and the "virgin" side was up against the rail.

Thanks. Got around to putting the lower intake manifolds/runners back in after finishing up the valve covers and replacing all the hoses in the valley. Turned out the injector rail to runner seals, while crusty, were still very much pliable after removal. So I just soaked them in warm water with soap to wash off the grime and flipped them over like you said. There is some.. corrosion (?) build up on some of the seals, but I think its just superficial and shouldn't interfere with sealing.

Hopefully will get the rail + new injectors in tomorrow. Will prime the rail to confirm no leaks afterwards. There might be a chance I can get her started back up tomorrow, which will be nice.

Picture of where I'm at for now: https://imgur.com/a/WW2U6BE

Edit: The alternator is pretty well covered in old oil from the valve cover leaking. I'm hesitant to blast it with parts cleaner/degreaser just because the grime is so thick and I don't want it getting stuck inside. Any other alternatives or should I just start blasting?