Q45 Injector ?

[1qckser]

I know that the 94 and up injectors have four squirting holes compared to one on the 90-93 injectors, can the newer style be used on the older motors, my understanding is that you will possibly gain some throttle response in the lower rpms, Thanks in advance.

[Q45tech]

Whether the heads/lower runner was redesigned to fit the injector pattern or the injector to fit the runner design is not know.

The engineers explained to me that the purpose was to solve a fuel puddling [recondensing from vapor] on a section of cold [cooler from fuel evaporation] wall inside the head.

Whether they had to change the software to match the injector is unknown. Probably!

Injectors have dead time and slope and shut off bounce. there is a time lag between the instant application of voltage, when the pintle begins to move up and the rate of change of the pintle position till it is fully open. Based on mass flow the rule of thumb is 66% of the expected flow during the opening time segment.The non standard flow period varies from injector type to injector type. The first 1.3-1.5 milliseconds. At idle the total time is 2.2 millisecs..........66% is non standard flow. [confirms that they used the rule of thumb].

The battery voltage is critical as the slope changes and the total ramp up time. The ecu monitors battery voltage and corrects the open time............especially important at cranking and beyond till alternator replenishes the amount in the first few seconds......the battery may drop to 9-10 volts in a cold crank.

You can see this clearly by seeing the current waveform on the injector fuse line..........you can see the current start to flow, the ramp up, a little squiggle when the pintle moves off its seat [0.6-0.7 millisecs], and the final current which is faily level until the shut off, when it drops to zero, then there is a bounce when the back emf collapses and the pintle spring unloads its energy.

http://www.asashop.org/autoinc/dec2000/mech.htm

By observing the current peak and ramp up and pintle opening point at the fuse you can see all 8 injectors simultaneously and compare the averages.

A 35 #[370cc/min] flows [34psi/43.4psi=.78341 squareroot=0.8851 x 370= 327.5 cc/min or 5.4581 cc per second or 0.0054581 cc per millisecond.

At cruise the O2/ecu would fix errors, WOT and acceleration probably wouldn't matter as everything is super rich.

We would have to compare 2 Q [perfect 90 and perfect 94] at exactly the same rpm /coolant temp/idle fuel pressure ----side to side and read with the Consult, the injector open time at idle to determine if they made software changes.

See why the power balance is so accurate in determing injector health.

A 0.1 millisec at 2.2 millisecs is about a 6% flow change, at WOT high rpm it [the same 0.1 millisecond] is 1%.

The ecu sets injector opening time at idle by rpm....[tries to maintain a certain rpm]....once everything is warmed up.

If you have the time and energy probably a good experiment to see what if anything happens with 94 injectors on a 90-93. I WOULDN'T do the converse using 90-93 injectors on a 94-96.

Obd2 [1996 Q and later] would be much more sensitive to type of injectors.

Obd2 reads the fuel temperature to correct for viscosity changes in fuel and flow rate thru the injector........very very fine tuned system.

[1qckser]

Do you think I would have to put the notch in my runnres to accomadate the newer injectors such as the 94 has? The Nissan engineers did somethin similar with the SE-R except they change the whole intake design and head design to stop the puddling in the bottom of the manifold, they went from a highport head to a low port head or visa versa, the injectors also change in the same fashion the Qs did, we have actually used the newer injectors on the older motor with no problems, however I think it might not work on the Q, either way ill give it a try. As usual thanks for the great info.

[John Nordling]

I've been thinking about replacing the old style injectors in my 90Q with the newer ones. What happened when you tried it? Has anyone else tried this in the meantime?

I am trying to get away from the repeating injector problem I hear about and was going to replace four injectors anyway. Thanks in advance.........John

[maxnix]

Since the head design is optimized for the specific type of injector used, I would think it would be wisest to maintain the OEM specified injector for each type of head.

[DougQ45]

The electrical connector at the injector body is different for a 90 than a 94. I had both cars at one time and speak from first hand experience. Maybe you could replace the entire harness with a second gen (94) but then you would have to do all 8. Maybe prudent to just keep the earlier style??

[911/Q45]

If this was a viable option, I think Infiniti would have dropped the early design injectors and superceded them with the newer version to simplify their parts inventory.

[Q451990]

That's true... except I don't know how they'd handle the different harness issue. Even Nissan wouldn't be heartless enough to say you have to replace all eight and the harness, would they?

Heath

[911/Q45]

Let's give them the benefit of the doubt and say they made the connectors different to keep you from putting the wrong injector in.

[squeefoo]

I found brand new Bosch injectors for $130 ea. I wonder if they are resistant to RFG, does anyone know offhand? For $1K its tempting, just to avoid wondering if that occasional wiggle is another injector going. -Squee

[911/Q45]

I think Joe sells OEM for less than that.

[DAEDALUS]

$142 and change last time I bought one a couple years ago.

[squeefoo]

But the ACTUAL question remains ; Are they proven RFG resistant? I have an 89 Cherokee w/ 148k no injector issues (ever), RFG all its life, occasional rail flush. Can I expect that out of a new set of injectors for my Q45? Peace of mind is what I ask. Will $1040.00 U.S. get that for me? -Squee

[Q45tech]

In the South Q injectors just don't fail. But the only warranty you'll get is 12k/12months..............you buy the gasoline not Nissan.

It's not the RFG per se, it is refinery short cuts and mistakes.

Saw multiple articles a few years back about serious blending/transport pipeline problems in WS and MN [every brand has multiple failures].

If you do spend the money change your fuel filter every 6 months and use isopropyl alcohol every month to misculize the water in the fuel tank.

The injectors [90-93] were probably made last in 1992 and have been sitting for 10 years.

The design life of all components is 100k [other than engine internals].

You never know when they will change the RFG formula.

[shadedoc]

Yes, it is correct they are different. Different electrical connector, different spray nozzel, and different depth. Hope this helps someone