1991 Q45 Where do I go from here? FI Issues

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silverqfortyfive
Posts: 15
Joined: Thu May 21, 2009 5:52 pm

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Great car when its running.

Got a set of eight used tested good from the site classifieds.

Was really cold last time I replaced the injectors and rushed neglecting to replace the o-rings.

Went about six months okay then with outside temp changes noticed fuel spilling.

Took the upper intake plenum off no biggie but now half of the injectors test bad one completely gone.

Tested the knock sensors looks like one is completely out.

Car has sit in the driveway for two years and I am missing it.

So what is the best way to go on replacing the injectors with something what will last.

I know this is a common problem.

Located in Camby, a couple miles SW of Indianapolis, IN.

Thanks.



Modified by silverqfortyfive at 9:52 AM 4/2/2010
Modified by silverqfortyfive at 9:53 AM 4/2/2010


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Infinitiguy19
Posts: 7787
Joined: Sat Dec 22, 2007 4:58 pm
Car: 1993 Infiniti Q45 188580 Miles
1994 Infiniti Q45a 240000 Miles

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ALWAY REPLACE THE O-RINGS!!!

What do the used injectors OHM at?

Where was the fuel spilling from?

How much do you want to invest in the car?

Does the fuel system hold pressure for more than 10 min?

You can replace EVERYTHING under there from $2K or do it the cheaper (riskier) way.

Q45tech
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Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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Define something that will last? I have 4 new oem installed that have lasted 22 months.

silverqfortyfive
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Joined: Thu May 21, 2009 5:52 pm

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Q45tech wrote:Define something that will last? I have 4 new oem installed that have lasted 22 months.
i am thinking like 120k miles

is there a budget way to convert to the '95 injectors

are these going to be better?

read a lot of threads but it is hard to tell what is opinion from fact

Thanks

Q45tech
Moderator
Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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Fuel injectors fail from exposure to E10 whether they are 90-93 or 94-96.

Nothing to be gained by changing design as long as you purchase brand new units.

With 20 year old cars you must get use to spending $2200-2500 per year [or do it your self labor]................that's just $200 per month in payments

Failure to spend $40-$50k in repairs since brand new means so very much is worn slap out. [multiple times].

We have a few 90-92 waiting for the owners to save enough for injector replacement same with transmissions. Those $3,000 hits are never saved for.

qship96
Posts: 6624
Joined: Sun Nov 24, 2002 11:31 am
Car: 1996 Q45

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Fuel injectors fail from being subject to high under plenum heat loads over time......the cheap plastic bodies develop cracks.....then the fuel attacks them......ethanol is not the cause of the problem, heat is.....and the lack of proper heat MANAGEMENT........ kind of like the cheap plastic used for the knock sensors......heat eventually causes the plastic to become brittle and crack....poor engineering by nissan

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Infinitiguy19
Posts: 7787
Joined: Sat Dec 22, 2007 4:58 pm
Car: 1993 Infiniti Q45 188580 Miles
1994 Infiniti Q45a 240000 Miles

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Q45tech wrote:We have a few 90-92 waiting for the owners to save enough for injector replacement same with transmissions. Those $3,000 hits are never saved for.
Why isn't it 1990-1993?
qship96 wrote:Fuel injectors fail from being subject to high under plenum heat loads over time......the cheap plastic bodies develop cracks.....then the fuel attacks them......ethanol is not the cause of the problem, heat is.....and the lack of proper heat MANAGEMENT........ kind of like the cheap plastic used for the knock sensors......heat eventually causes the plastic to become brittle and crack....poor engineering by nissan
I think Nissan had to strike a balance between long lasting and failing due to over heating, For Knock Sensors not sure about Fuel Injectors.

Q45tech
Moderator
Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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1993 is so rare because so few sold very short model year, kinda like the 1996................people waited until 94 and 97 came out.

1991 and 1994 were peak sales years.

silverqfortyfive
Posts: 15
Joined: Thu May 21, 2009 5:52 pm

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so i will just get the '95 injectors used, tested okay, rail and harness found for $120

do i have to splice the harness in?

something about grommets?

thanks

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Infinitiguy19
Posts: 7787
Joined: Sat Dec 22, 2007 4:58 pm
Car: 1993 Infiniti Q45 188580 Miles
1994 Infiniti Q45a 240000 Miles

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Search Wes's posts!

silverqfortyfive
Posts: 15
Joined: Thu May 21, 2009 5:52 pm

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Paul Wall wrote:Search Wes's posts!
got it

zerothread?id=399119

searched "Q45 Forum / Cima Forum" & "Infiniti Online Mechanic" forums

for "injector or injectors" post body keyword

for even more

"Replace the lower spacers (stand-offs) that go between the runners and the fuel rail with two washers per bolt. That holds the updated rail into the runner port gaskets a little tighter." -Q451990
Modified by silverqfortyfive at 9:55 AM 4/2/2010


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