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  #1  
Old May 5th, 2020, 18:23
Ramcharger3 Ramcharger3 is offline
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Running rich and back firing after swapping injectors

So I have talked to multiple people on reddit and looked all over Google and I cant figure out what my problem is. I have a 1990 xj, 4.0 with the ax15 and yesterday I decided to swap in my new 4 hole injectors from k suspension. Installation went pretty smooth and had zero leaks but when I started it it ran very rough and didn't clear up. There's black smoke coming out of the exhaust and it seems like it's running very rich but all the injectors/cylinders seem to be firing. I disconnected each injector and could hear it start to misfire everytime and cleared back up when I put it back on so I'm pretty positive the injectors are working. I double checked the map and pcv vacuum lines because I had to disconnect those but they both looked good, checked the iac, tps, and iat because I disconnected those but they were all in place. Tried resetting the ecu 2 more times but that didn't help. A guy on reddit suggested a injector being stuck open so I took the rail off with the injectors still attached but none of them leaked so I dont think it's that. I thought maybe the ECU just needs time to relearn these new injectors but I've let it idle for a long time, taken it on like 3 drives and it's only gotten worse. The last drive it started back firing out of the exhaust and big plumes of black smoke started coming out of the exhaust and died at every stop. I already tossed the original injectors so I cant try putting those back in and I really dont know what else to do. I read that the map and iat can effect fuel trims but I dont know how I would've messed those up just unplugging them and they seem kinda expensive to just replace on a whim. If anyone has any suggestions the would be really really cool.
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Old May 5th, 2020, 18:31
RCP Phx RCP Phx is offline
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Re: Running rich and back firing after swapping injectors

First reason I can think of is K fabs rep for this exact thing, do some searching!
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Old May 5th, 2020, 18:47
Ramcharger3 Ramcharger3 is offline
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Re: Running rich and back firing after swapping injectors

I saw a few similar posts, did I get the wrong injectors or are they all just junk? Some people had individual Injectors that sucked but I cant seem to pinpoint it to any specific injector. I tried contacting him earlier but how do I know if I get a replacement set they won't do the same thing?
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Old May 5th, 2020, 21:17
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lazyxj lazyxj is offline
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Re: Running rich and back firing after swapping injectors

Quote:
Originally Posted by Ramcharger3 View Post
seem kinda expensive to just replace on a whim. If anyone has any suggestions the would be really really cool.
Unless your Jeep was running the same way before you replaced the injectors, you got a bad set of them.
I assume they are an aftermarket rebuild from a company no one has ever heard of before. I would guess one or more of the injectors is flowing way too much fuel, the cause of the black smoke, they certainly are not flow-matched.
How about telling us that injectors you choose and what the problem was before you changed them.
The stock injectors work fine for the application and have the capacity to satisfy the needs of any modification you make to the stock block.
The 'big' difference between the single hole, two and four-hole injectors is mostly a myth, most that report incredible differences in performance probably had dirty injectors in the first place
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Last edited by lazyxj; May 5th, 2020 at 21:34.
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Old May 6th, 2020, 03:55
Ramcharger3 Ramcharger3 is offline
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Re: Running rich and back firing after swapping injectors

Quote:
Originally Posted by RCP Phx View Post
First reason I can think of is K fabs rep for this exact thing, do some searching!
Quote:
Originally Posted by lazyxj View Post
Unless your Jeep was running the same way before you replaced the injectors, you got a bad set of them.
I assume they are an aftermarket rebuild from a company no one has ever heard of before. I would guess one or more of the injectors is flowing way too much fuel, the cause of the black smoke, they certainly are not flow-matched.
How about telling us that injectors you choose and what the problem was before you changed them.
The stock injectors work fine for the application and have the capacity to satisfy the needs of any modification you make to the stock block.
The 'big' difference between the single hole, two and four-hole injectors is mostly a myth, most that report incredible differences in performance probably had dirty injectors in the first place
They were replaced with the "remanufactured Bosch injectors" from K Suspension. They should match my jeep perfectly and for over $100 I would expect them to work better than they do.
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Old May 6th, 2020, 04:07
Ramcharger3 Ramcharger3 is offline
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Re: Running rich and back firing after swapping injectors

Quote:
Originally Posted by lazyxj View Post
How about telling us that injectors you choose and what the problem was before you changed them.
The stock injectors work fine for the application and have the capacity to satisfy the needs of any modification you make to the stock block.
The 'big' difference between the single hole, two and four-hole injectors is mostly a myth, most that report incredible differences in performance probably had dirty injectors in the first place
And I wasnt really having problems before, the idle wasnt the smoothest and I was only getting 200 miles a tank though so that is what I kinda hoped to fix. Other than that it ran good, as soon as I got these injectors in, it will barely idle at all and runs extremely rich. Also sorry for the double reply this is my first post here and I'm still trying to figure it out.
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Old May 6th, 2020, 07:11
RCP Phx RCP Phx is offline
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Re: Running rich and back firing after swapping injectors

Here's the only 2 companies I buy injectors from......injectors are all they do!
https://precisionautoinjectors.com/
https://fuelinjectorconnection.com/
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Old May 6th, 2020, 07:47
Ramcharger3 Ramcharger3 is offline
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Re: Running rich and back firing after swapping injectors

Quote:
Originally Posted by RCP Phx View Post
Here's the only 2 companies I buy injectors from......injectors are all they do!
https://precisionautoinjectors.com/
https://fuelinjectorconnection.com/
If I'm able to get my money back I'll check em out! That's why I went with ksuspension because I didn't wanna cheap out but I guess these were just cheap injectors as well..
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  #9  
Old May 6th, 2020, 17:56
Peteinpeb Peteinpeb is offline
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Re: Running rich and back firing after swapping injectors

Call or email Raffi at K suspension. He gets back to you quick. I bought some and had 3 of the 6 pintle caps cracked, and chipped. I was worried I would have to send the injectors back. I just removed them and installed and injectors worked fine. They are remanufactured so buyer beware. I am sure he can send you a new one, or set. While quality control might not be the best, he does do a great customer service job and will help you troubleshoot. Mine were one of the best mods I have ever made.
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  #10  
Old May 8th, 2020, 12:59
cwyman6 cwyman6 is offline
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Re: Running rich and back firing after swapping injectors

Make sure to run the volvo injectors. The neon injectors are to much for the renix system. Renix go to open loop slot more than nonrenix. Mine did the same thing
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