M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

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lcolina
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M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by lcolina »

Hi Guys,

I have had the M9593-aa302 for a long time and fuel ratio is usually at idle at between 13.5 and 13.8, and in WOT it can get to 12.X with an AFPR at 50 PSI.

Yesterday, I installed the newer model M9593-LU24A (Brand new) with USCAR connector as a friend who will not use them gave it to me as a gift (lucky bastard)

Both injectors are the same specs except for the connector, nothing else was changed, only injectors and connectors.

Now, when started the Jeep there was a noticeable lean condition (engine failure) at idle (AFR around 17) and I had to increase the AFPR to 60, to be able to get an AFR of around 14.5 at idle. I reset the PCM all night and started my Jeep this morning. It started around 13.5 but while warming up it got to 15.x.

I took the Jeep for a drive, no noticeable problem but AFR keeps around 15.x normal throttle and at WOT it gets to 13.9-14.2 with 10 PSI more than older injectors.I also have the feeling of having less power at WOT, like less explosive than before.

I will take both models to a fuel injector shop to make a comparison in the injector machine tester and will post the results later today.

I dont feel there is one cylinder failing, engine seems quite, just a very unperceptive rough idle.

Any suggestions what can be causing the lean condition?


I can always rollback but it would be painful to change the connectors and soldering again.

My Setup:
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom Forged Bulltear Pistons 0.60 20cc
68231-4 camshaft Compcams
7120 head ported.
Mopar/Victor 0.043" head gasket
99+ Intake, ODB1 system with MAP sensor from ODB2 and OEM Throttle body.
Fuel Pump DW200 255 lph.
OEM YJ 91 PCM and harness.
E3 Spark plugs.
lcolina
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Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by lcolina »

Fill test for both injectors models, same machine, same time:

M9593-AA302 - 55cc
M9593-LU24A - 45cc

10 cc is a big difference in 12 seconds so I guess they are not equivalent as Ford stated (24 lbs) :doh:
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SkylinesSuck
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Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by SkylinesSuck »

That sucks, but seemed like the obvious answer. At least you got it fingered out quickly!!
lcolina
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Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by lcolina »

SkylinesSuck wrote: June 6th, 2018, 5:50 pm That sucks, but seemed like the obvious answer. At least you got it fingered out quickly!!
I agree that sucks, and hopefully forum users will see this info to decide if purchase this newer model.
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Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by Cheromaniac »

lcolina wrote: June 6th, 2018, 4:59 pm Fill test for both injectors models, same machine, same time:

M9593-AA302 - 55cc
M9593-LU24A - 45cc

10 cc is a big difference in 12 seconds so I guess they are not equivalent as Ford stated (24 lbs) :doh:
The M9593-AA302 were rated to flow 24lb/hr of fuel at 39psi (2.7 bar).
The M9593-LU24A are also rated to flow 24lb/hr but evidently at a higher fuel pressure (most likely 58psi or 4.0 Bar).
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
1995 Mustang GT - 4AT - Modded Sold
2006 Mustang GT - 5MT - Modded Midlife Crisis Car :mrgreen:
lcolina
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Vehicle Model: CJ7

Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by lcolina »

Cheromaniac wrote: June 7th, 2018, 3:21 am
lcolina wrote: June 6th, 2018, 4:59 pm Fill test for both injectors models, same machine, same time:

M9593-AA302 - 55cc
M9593-LU24A - 45cc

10 cc is a big difference in 12 seconds so I guess they are not equivalent as Ford stated (24 lbs) :doh:
The M9593-AA302 were rated to flow 24lb/hr of fuel at 39psi (2.7 bar).
The M9593-LU24A are also rated to flow 24lb/hr but evidently at a higher fuel pressure (most likely 58psi or 4.0 Bar).
Dyno, according to this page they are rated to flow 24lb/hr at 39.15 psi:

https://performanceparts.ford.com/part/M-9593-LU24A


I adjusted my pressure to 60 psi and the max I got was 14.5 at idle but at wot no less than 13.5. I will ask ford performance parts an explanation.
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Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by Cheromaniac »

lcolina wrote: June 7th, 2018, 8:58 amDyno, according to this page they are rated to flow 24lb/hr at 39.15 psi:

https://performanceparts.ford.com/part/M-9593-LU24A

I adjusted my pressure to 60 psi and the max I got was 14.5 at idle but at wot no less than 13.5. I will ask ford performance parts an explanation.
As Confucius would say, Sum Ting Wong.
lcolina
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Vehicle Model: CJ7

Re: M9593-aa302 to M9593-LU24A Fuel Injector Change Issue

Post by lcolina »

:lol: :lol: :lol:

It seems that if I want to use theses injectors I will have to go back to the MAP Sensor voltage adjuster option. But I didn't need that with old injectors. :frustrated:

https://performanceparts.ford.com/parts ... -LU24A.pdf

https://performanceparts.ford.com/parts ... -aa302.pdf
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