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  #1  
Old April 30th, 2018, 17:56
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alexgalexg alexgalexg is offline
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Problems after 12 hole injection upgrade

98 XJ 4.0
Today I upgraded to 12 hole fuel injection from ksuspension. When running it runs great! Foot to the floor and your head is pulled back, idle is lower and runs much smoother. But having some issues.
Late start
Runs suspiciously quiet for a flowmaster exhaust
Seems to be consuming more fuel than it should
Does not pass readiness test (pic supplied below)
It's important to note that I did not reset the ECU because in my experience it takes many hours for it to actually reset after pulling the battery cables. I simple let the engine adapt.

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Old May 1st, 2018, 03:13
RCP Phx RCP Phx is offline
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Re: Problems after 12 hole injection upgrade

Need more info on the injectors, but late starts are usually from losing pressure in the system. As far as using more fuel, what are your long/short fuel trims?
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Old May 1st, 2018, 05:42
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alexgalexg alexgalexg is offline
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Re: Problems after 12 hole injection upgrade

Quote:
Originally Posted by RCP Phx View Post
Need more info on the injectors, but late starts are usually from losing pressure in the system. As far as using more fuel, what are your long/short fuel trims?
Injectors are 12 hole fuel injectors from ksuspension. Major performance upgrade. There was no leak prior to the upgrade and I ha e checked the I injectors to find no leak now. I left the battery disconnected overnight and will also perform the reset with the headlights in a minute here after reconnecting the battery before work

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Old May 1st, 2018, 08:12
RCP Phx RCP Phx is offline
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Re: Problems after 12 hole injection upgrade

I was referring to - "X" lbs/hr @ "Y" psi . Have you put a pressure gauge on it to see if it's "bleeding" down after you shut it off?
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Old May 1st, 2018, 08:34
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Problems after 12 hole injection upgrade

My pressure gauge leaks. I know it has proper 49psi pressure when running. Also after letting the computer reset overnight I started it this morning and it fired right up. However it still seems to be using a lot of fuel

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Old May 1st, 2018, 08:43
RCP Phx RCP Phx is offline
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Re: Problems after 12 hole injection upgrade

What are your fuel trims?
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Old May 1st, 2018, 09:18
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Re: Problems after 12 hole injection upgrade

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What are your fuel trims?
Unfortunately I am at work until 8pm. I will update tomorrow with fuel trims

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Old May 1st, 2018, 11:13
trippled trippled is offline
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Re: Problems after 12 hole injection upgrade

What are you basing your fuel consumption off of?
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Old May 1st, 2018, 12:34
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lazyxj lazyxj is offline
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Re: Problems after 12 hole injection upgrade

Your scanner shows the evaporative system and O2 heater tests have not passed.
Neither is dependent on the injectors.

I have tried different injectors in several stock XJs.
IMO, most of the improvement people feel is the result of clean injectors, with a good spray pattern, compared to the old, dirty injectors they replace.
The factory supplied injectors are the right size for a stock engine.

It would be interesting to do side by side dyno comparisons between new, stock injectors and the newer injectors, with more holes.

Larry
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Old May 1st, 2018, 17:52
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Problems after 12 hole injection upgrade

Basing my fuel consumption off the gauge which has been accurate every day. Tomorrow I have a day off I will deal with fuel trims and look at timing. I have a light miss as well so something is up. I suspect that it's a bad connection between the injector and the connector but I'm working on that.

So far problems aside I have noticed the engine runs smoother, quieter and has a lot more power

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Old May 1st, 2018, 19:28
Heavyopp Heavyopp is offline
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Re: Problems after 12 hole injection upgrade

What kind of gas mileage are you getting?

My XJ is pretty disappointing mileage wise -- best I've done is just under 14 MPG around town

I have upgraded injectors -- from a Ford Mustang, don't know the number at the moment -- 2000 cherokee


XR3E-A4B New Multi Port Injector CM4956 Set (6) for 99-01 Ford Mustang 3.8L. These are the injectors I used.

Last edited by Heavyopp; May 1st, 2018 at 19:35.
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Old May 2nd, 2018, 05:33
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sinat01 sinat01 is offline
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Re: Problems after 12 hole injection upgrade

If you cant figure it out, shoot raffi at Ksuspension an email. he will help ya figure it out
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Old May 2nd, 2018, 08:04
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Problems after 12 hole injection upgrade

I talked to him. Hes sending me a new set of injectors. In the meantime I'm going to make sure that something's not wrong on my end. I'll update shortly with fuel trims. I'm pretty sure it's the injectors though... didn't have a miss prior to installing them

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Old May 2nd, 2018, 08:06
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Re: Problems after 12 hole injection upgrade

Quote:
Originally Posted by Heavyopp View Post
What kind of gas mileage are you getting?

My XJ is pretty disappointing mileage wise -- best I've done is just under 14 MPG around town

I have upgraded injectors -- from a Ford Mustang, don't know the number at the moment -- 2000 cherokee


XR3E-A4B New Multi Port Injector CM4956 Set (6) for 99-01 Ford Mustang 3.8L. These are the injectors I used.
Cant say for sure what my mileage. But I can literally watch the needle move since I put these in. My commute is 10 mins and the needle drops half a notch each way. Used an entire notch yesterday...

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Old May 2nd, 2018, 09:06
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Problems after 12 hole injection upgrade

Fuel trims
https://youtu.be/S8smQtBR1_4

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