When should the fuel injectors be replaced?

MoonShadowTJ

MoonShadowTJ

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I’ve been fighting the number three cylinder misfire once the TJ heats up and is restarted. I’m adding the fuel rail and injector insulation package soon, so I was wondering if a 2001 TJ with 80,000 miles on it would need replacement fuel injectors. And then there is the extreme spread in the cost of new fuel injectors. Amazon has a set of six for about $70, summit racing has injectors for $70 apiece. That’s quite a spread. I would love your thoughts.
 
I upgraded to Bosch 4 hole injectors in my '02 around 80k miles. Was having a #2 injector circuit issue but it ended up being in the wiring harness. Don't know if it changed much, maybe a little better acceleration. Theoretically it atomizes the fuel better.
Where the wiring harness wraps around the back of the engine is where I was getting the short. On the back right stud.
 
Pantera99 said:
I upgraded to Bosch 4 hole injectors in my '02 around 80k miles. Was having a #2 injector circuit issue but it ended up being in the wiring harness. Don't know if it changed much, maybe a little better acceleration. Theoretically it atomizes the fuel better.
Where the wiring harness wraps around the back of the engine is where I was getting the short. On the back right stud.
Click to expand...

Years ago I replaced the fuel injectors on my '98 XJ 4.0L and went from the 1 hole to the 4 hole injectors from Five O Motorsports. Living in CA at the time dealing with the SMOG checks; I did notice that my emissions went down noticeably (clean injectors and better atomization), the MPG went up 2 mpg and the throttle response was noticeably better.
Shortly after purchasing my '01 TJ 4.0L I installed a set of 12 hole injectors. Never had a SMOG check on the Jeep so I have no documentation on whether it affected the emissions (suspect there was a change), but the gas mileage did improve by 2 mpg and there was a little difference in throttle response.
With so many companies going out of business and many companies still in business are having difficulty with materials; so I wouldn't know who to recommend although I would stay away from Amazon as a source of fuel injectors.
 
MoonShadowTJ said:
I’ve been fighting the number three cylinder misfire once the TJ heats up and is restarted. I’m adding the fuel rail and injector insulation package soon, so I was wondering if a 2001 TJ with 80,000 miles on it would need replacement fuel injectors. And then there is the extreme spread in the cost of new fuel injectors. Amazon has a set of six for about $70, summit racing has injectors for $70 apiece. That’s quite a spread. I would love your thoughts.
Click to expand...
Your injectors should still be 100% fine, I would not replace them yet. Do the fuel rail and injector insulation install and see what happens. Personally I'd just wrap the #3 injector as I did for the #3 misfire and it completely cured it. This part on Amazon is the correct part per the TSB the factory issued for the #3 misfire, it's held on by a zip-tie. https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

This is mine after installing that insulator wrap...

Fuel Injecdtor Insulation .jpg
 
With a meter, measure the resistance of the injectors. They should all be within a few Ohms of each other. If not the outliers are going bad.

I'd run some fuel injector cleaner through them at your mileage.

Just say no to Chinese fuel injectors on ebay, amazon.

If you need injectors, either go back with OEM, which should be Siemens/Deka, or get the Bosch 4 or 12 holes that have been rebuilt.

I put the 4 hole Bosch rebuilts from K Suspension in my 06 at around 250K. I found a deal on brand new Siemens OEMs for my 92 and put them in it at around 275K.
 
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Jerry Bransford said:
Your injectors should still be 100% fine, I would not replace them yet. Do the fuel rail and injector insulation install and see what happens. Personally I'd just wrap the #3 injector as I did for the #3 misfire and it completely cured it. This part on Amazon is the correct part per the TSB the factory issued for the #3 misfire, it's held on by a zip-tie. https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

This is mine after installing that insulator wrap...

View attachment 366286
Click to expand...

I have purchased the #3 insulator as you recommended, along with the Design Engineering Heat Shield Fuel Rail insulation as my factory insulation was junk.

So I have pulled the Fuel Rail & injectors out and every one of the sockets were oily. The small injector areas were clean but from the bottom o-ring was quite oily. The head elsewhere was clean. I did have the Valve cover gasket replaced about a year ago And I recently replaced the plugs and they were all dry. Here’s a photo.

F470EB71-456F-4085-9B59-22A7C26B9754.jpeg
 
JKP said:
Just say no to Chinese fuel injectors on ebay, amazon.
Click to expand...

Echoing this. Another poster here went with unknown-quality injectors and was chasing down a rich condition because the injectors were dumping in way more fuel than the computer could compensate for. Good injectors aren't cheap, cheap injectors are definitely not good. I would trust cleaned injectors from a junkyard before I'd trust Amazon-sourced injectors.

Injectors are not really wear items; they'll eventually fail, sure, but there's not a mileage limit where they suddenly stop working.
 
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You may have a local company that will clean/test your injectors. A place in Mesa did a good job for my wife's MKZ. Ohms were only way off on one of them but two were actually bad.
 
IOwnCalculus said:
Echoing this. Another poster here went with unknown-quality injectors and was chasing down a rich condition because the injectors were dumping in way more fuel than the computer could compensate for. Good injectors aren't cheap, cheap injectors are definitely not good. I would trust cleaned injectors from a junkyard before I'd trust Amazon-sourced injectors.

Injectors are not really wear items; they'll eventually fail, sure, but there's not a mileage limit where they suddenly stop working.
Click to expand...
Pantera99 said:
You may have a local company that will clean/test your injectors. A place in Mesa did a good job for my wife's MKZ. Ohms were only way off on one of them but two were actually bad.
Click to expand...

Great info!
 
MoonShadowTJ said:
I’ve been fighting the number three cylinder misfire once the TJ heats up and is restarted. I’m adding the fuel rail and injector insulation package soon, so I was wondering if a 2001 TJ with 80,000 miles on it would need replacement fuel injectors. And then there is the extreme spread in the cost of new fuel injectors. Amazon has a set of six for about $70, summit racing has injectors for $70 apiece. That’s quite a spread. I would love your thoughts.
Click to expand...

I have the same issue!! Intermittent misfire on cylinder 3! WHERE do you get the "insulation package??"I went to my local Jeep off road and they looked at me like I was lost...Please help me!! racerray@yahoo.com
 
i have the Design Engineering kit on my 2006 LJ and it worked/fit fine.

The Design Engineering website also says '97 - '04 but it works. Here is an image directly from their website and my installation looks identical. I see no reason why an 05/06 would be different.

Screenshot 2024-09-12 at 11.35.12 PM.png
 

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