Help on understanding fuel injector wiring

[jonseyq45]

Just installed complete injector, rail, and harness out of an 94 in my 90. I have two injectors showing open ( no resistance). May be bad injector or harness. Where I need help is in understanding what the two wires at the injector top connector go to. Ground, power,ECU. I want to eliminate them as problem areas.

As always, thanks in advance.

Jonsey....

[Haitian_King]

Just installed complete injector, rail, and harness out of an 94 in my 90. I have two injectors showing open ( no resistance). May be bad injector or harness. Where I need help is in understanding what the two wires at the injector top connector go to. Ground, power,ECU. I want to eliminate them as problem areas.

As always, thanks in advance.

Jonsey....

How'd that go? Was it hard? I've been considering just doing the 94+ rail to replace the older (side-feed?) injectors.

[jonseyq45]

Went well.....had 17 year old young son fresh out of Auto Tech do it. Jump in the deep end. Had him repeat the mantra "one thing at a time,,,one thing at a time" Tore a couple of gaskets, replaced a couple of bad hoses but other wise painless. Now have two dead cylinders where I had one before (different cyls). I think I am having a harnes issue more than an injector problem

[Q45tech]

The injectors are all connected to 12+ and the other terminal goes to ecu where a transistor grounds it to energize.

Didn't you test the rail [injectors] before installtion.

I wish you luck, recently we have seen as many 94-96 injector failures as 90-93.......................4 different 94-95 Q in past 2 weeks..

One had 3 different failures in 3 weeks.

They all looked rusted from water on tip and screen.

[jonseyq45]

You caught me breaking the #1 rule, install known good part. While at work I had young son doing the work. But like it always seems to happen, try to short cut and it winds up bitting you in the butt. I down loaded all the harness tests and will do these before removing the plenum again. I used to do this for a living but I guess I'm human and not a "Tech God"(self-parody) after all.

Thanks for the quick response,

Jonsey
Modified by jonseyq45 at 4:04 PM 6/19/2008

[elwesso]

Like tech said the 8 terminals on the harness on the back passenger side of the motor are all grounds that go to the ECU.

How'd that go? Was it hard? I've been considering just doing the 94+ rail to replace the older (side-feed?) injectors.

More accurate description would be pintle (early) vs rotary disc. id be interested to see if they actually changed more of the internal construction.

I remember reading an article on the Z forum (it might have been posted here) that NISMO has acknowledged the ethanol related failures that their 555cc and larger injectors are seeing, and have made design corrections. im not sure if Nissan has done the same (doubtful)

[Q45tech]

I posted this in another forum as an answer to how to test injectors for pintle lift:"You will find a fuse for injectors, replace with a wire loop and use an amplified current probe to view the current ramp up of each injector on a digital oscilloscope.When the pintle lifts open you will see a ~ in the current graph [/] and can compare the real open time in milliseconds with the ecu commanded time.

See this graph:http://www.picotech.com/auto/a...s.jpgh ... /a....html

Note that during the first 0.8>1.0 milliseconds of on time zero fuel flows until pintle opens.

At idle the open pulse is 1.2ms yet fuel flows only 0.4 at max yet at WOT high rpm 10ms less 0.8 is 9.2 ms of fuel...............23x difference [9.2/0.4]

The point is view all injector current ramps simultaneously and look for any unusal shapes."

[maxnix]

I wonder if the rotary disc is not faster than the single pintle design?

[Q45tech]

Easy to test with the method provided.................all solenoids have the same distinct signature ~. When the center core moves no matter what the core is attached to a pintle or a disk.

You must measure voltage at the injector since the voltage varies and so does the dead time from crank to idle ac.on-off, other alternator loads. ECU self adjust it's timing based on injector voltage:12v - 1030 uSec13v - 870 uSec14v - 760 uSecOnly critical at idle as cruise is O2 corrected and WOT like 2.5% at max from 12-14volts.

The 12+ wire is bigger until just before the injector harness, then splits into 2 smaller wires to HALVE the voltage drop in injector harness [4 injectors are feed 12+ in parallel].

At high rpms and WOT the 1 amp peak injectors are at 55% duty cycle so they appear to draw 0.55 x8 x 1 ampere peak or 4.4 amperes.

For scientists the above is not 100% accurate as some tiny amount of gasoline will flow BEFORE the pintle [or disk] is 100% open depending on the viscosity and psi of fuel..............again only important at idle*http://www.yawpower.com/inject....html

* the Power Balance Test shows how the tiny variances can affect rpm. When you use BG44k and see differences some of it is from tiny air flow changes [cleaner intake valves] and tiny gasoline flow changes [cleaner injectors].

Brand newindividual injectors are only 3-5% accurate vs published flow and this nonlinearity varies with voltage, duty cycle and fuel viscosity.

Why professional racers trim [adjust open time] each injector individually in their search for every HP.

[qship96]

You must have been using the old. original formula BG44k, as the current product has been void of any powerful ingrediants .....they took ALL the PEA detergents out of it.....now just way over-priced can of snakeoil like most other additives/elixirs sold by auto stores and repair centers to make a quick buck.

[Q45tech]

Duh obviously smart organic chemistry educated people bought it by the multiple 24 can cases wholesale and have the [7 personal units of] old stock on hand in home garage.

Same with old Japanese made oil, air and fuel filters.

Yep what happened when they started cable TV ads............old formula too strong for the public.

If the BG jobber drops by every week at 3 stores you learn in advance whats happening cause they want to sell old product out first.

Speaking of BG our old salesman jumped their ship after 12 years and into selling high risk mortgages in 2007. The vapors got to him!

[qship96]

Interesting how you continue to promote BG44k here on the boards, and never mentioned how the product has changed until prodded several times.....by the way, the change took place over 3 years ago .

Redline SI-1 and Techron remain PEA based products, and are a better product at a much less cost for those wanting something in return for their $$$