Jeep Strokers

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.

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)

That sucks, but seemed like the obvious answer. At least you got it fingered out quickly!!

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.

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)

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).

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)

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.

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.

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.

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

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