When to replace injectors

So I am a weekend tinkerer with my Jeep and love replacing parts. I have a 2000 with 120,000 miles 4.0 classic.
Jeep is excellently maintained and I never have any problems. Should I go ahead and replace my injectors or just wait until I have problems?

Will I see MPG increase with a 19lb injector over stock?

Any recommended injectors?

I see a lot of people on here talking about replacing their injectors, but not when it should be done.

As always you guys are awesome, thanks for all the help.

Unless you are getting really crappy mileage....if it ain't broke don't fix it.
Get a better exhaust and CAI instead.

Run a can of BG44K through the gas and the injectors will work like new.

I have ~183K on my injectors, having done nothing more than replace the O rings during a manifold swap, and ran a can of BG44K through it a year or two ago.

old_man said:

Run a can of BG44K through the gas and the injectors will work like new.

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Excellent advice. Add a can to a full tank of gas and run that tank almost completely out. You'll begin to feel the difference in under 100 miles.

Agreed.

Unless you have the multi-part RENIX ones that are known for springing a leak and producing a car-be-que, just leave em until they cause you problems, periodically run some injector cleaner treatment.

kastein said:

Agreed.

Unless you have the multi-part RENIX ones that are known for springing a leak and producing a car-be-que, just leave em until they cause you problems, periodically run some injector cleaner treatment.

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Yessiree. Good plan. The Renix injectors could leak at a crimp and spray raw gas on your exhaust manifold. Not good.

Just repainted my 87 and don't want it to burn to the ground:laugh:

What injectors do you recommend?

87XJ/4.0/AW4/NP231/D30/D44 4.56

Thanks!

www.precisionautoinjectors.com. Price is for a set of 6.

smiley said:

So I am a weekend tinkerer with my Jeep and love replacing parts. I have a 2000 with 120,000 miles 4.0 classic.
Jeep is excellently maintained and I never have any problems. Should I go ahead and replace my injectors or just wait until I have problems?

Will I see MPG increase with a 19lb injector over stock?

Any recommended injectors?

I see a lot of people on here talking about replacing their injectors, but not when it should be done.

As always you guys are awesome, thanks for all the help.

Click to expand...

The Ford 19lb injectors will not work in your 2000 XJ as the connectors are completely different. Also the 2000 XJ runs 22.5 lb/hr at 49psi while the Ford injectors are 19 lb/hr at 39psi. The 2000 XJ injectors flow at 234cc while the Ford injectors flow 210cc. The Fords are just not a good option for the newer XJs. They are a nice upgrade for the older Renix XJs and early HO XJs running at 39psi. For your XJ find a Dodge Neon or anything Mopar from 1998 and on with the 2.0L DOHC motor and use those injectors. These have the newer connectors but have the specs as their older year cousins that alot of XJ guys pick up to run in their 49psi XJs, these have a part number 0280155703. I helped my cousin pick up the newer style for his 99 and the part numbers were the same except for the last 3 digits I believe they had a part number of 0280155784 but don't hold me to that.

I can confirm that the 19lb Ford injectors are no good in the 49psi XJs as I installed them in my 97 and they did not give me any of the performance improvements that I was expecting. The idle is the same, gas mileage got worse, and power feels a little less. The only upgrade was it starts just a little bit easier since the injectors have four holes and atomize the fuel better for an better burn. I fully cleaned these injectors and replaced all the filters and o-rings also so they are in great shape.

Go for the later Neon's for the upgrade but if you only have 120,000 on the clock and maintain it well with regular use of fuel cleaner then your injectors should be in good shape and shouldn't NEED replacing.

A good indicator of partially clogged injectors is to check the long term fuel trim via the OBD port. If its a high + then you have a good chance you could use new injectors... its also a good indication of other problems.