Jump to content

Injector options for the 2.5 TBI?


Recommended Posts

I need to replace the injector on my '86 2.5 TBI. After looking around, I've found my options are $80 for a reman unit from the injector shop in town or $200 for a new unit from NAPA. The parts dept. at the Jeep dealer lists the OEM unit as discontinued.

 

I've read how the MPI guys can use Ford injectors to get a boost in performance. Is there a similar mod for the TBI? An injector from some other vehicle that will fit and give a little better flow & spray pattern? (and maybe even be cheaper/more available?)

Link to comment
Share on other sites

Your options are pretty limited from what I have been able to find out. They are discontinued from Jeep and there doesn't seem to be a lot of options in the aftermarket either. If you have found solution options...make your choice and get it done :cheers:

Link to comment
Share on other sites

I recently used Witch Hunter Performance out of Washington state. They clean and service injectors for $18 ea. After the cleaning, my 01 XJ MPG wen't up and it starts just as quick the day I bought it new. I'd highly recommend this service to anyone. :thumbsup:

 

http://www.witchhunter.com/

The unit we are talking about here is a 2.5L TBI, not MPI.

 

:dunno: Why would you spend that kind of money to clean injectors when you can upgrade to the Ford Motorsport injectors for the same money? ;)

Link to comment
Share on other sites

Hey guys - thanks for the tips ... especially the link over to 4bangerjp.com - lots of good info over there. Especially in this thread: http://4bangerjp.com/forums/index.php?topic=3563.0

 

I had to jump through a few hoops (the supplier sent the wrong part twice, and then sent an empty box before finally getting it right.) but I eventually got a replacement injector.

 

Just to let you know what I found out through research and talking with the guy at the parts store:

- The Jeep TBI's are identical in fit, size & appearance to the standard GM-style TBI's from the 80's-early '90's. But they are a unique flow rate, and therefore don't cross-reference to any GM applications

- The flow rate for the 2.5 Jeep injector is just in between the GM Injectors for the 4.3 V6 and the 5.0 V8. (according to test results the poster at 4bangerjp.com got, the Jeep is 48lbs, while the GM 4.3 V6 is 47lbs, and the GM 5.0 V8 is 50lbs)

 

Of course, the big difference is that GM injectors are a dime-a-dozen at junkyards, in stock at most parts stores, and GM ones can cost significantly less simply because of better availability and bigger market.

 

I had to go ahead and get my truck running quickly, so I just dropped in the Jeep injector. But I think for my next project, I'm going to fab up a TB spacer, swap in a GM 5.0 Injector, and see if that combo gives any slight boost in performance.

Link to comment
Share on other sites

If you're running too rich, it will also wash the oil off your cylinder walls and mix gasoline into the oil, causing increased wear.

 

You could use the smaller one (47 pounds), and maybe gain a bit of economy. But if it makes your engine run too lean, that's not good either.

Link to comment
Share on other sites

Hey guys - thanks for the tips ... especially the link over to 4bangerjp.com - lots of good info over there. Especially in this thread: http://4bangerjp.com/forums/index.php?topic=3563.0

 

I had to jump through a few hoops (the supplier sent the wrong part twice, and then sent an empty box before finally getting it right.) but I eventually got a replacement injector.

 

Just to let you know what I found out through research and talking with the guy at the parts store:

- The Jeep TBI's are identical in fit, size & appearance to the standard GM-style TBI's from the 80's-early '90's. But they are a unique flow rate, and therefore don't cross-reference to any GM applications

- The flow rate for the 2.5 Jeep injector is just in between the GM Injectors for the 4.3 V6 and the 5.0 V8. (according to test results the poster at 4bangerjp.com got, the Jeep is 48lbs, while the GM 4.3 V6 is 47lbs, and the GM 5.0 V8 is 50lbs)

 

Of course, the big difference is that GM injectors are a dime-a-dozen at junkyards, in stock at most parts stores, and GM ones can cost significantly less simply because of better availability and bigger market.

 

I had to go ahead and get my truck running quickly, so I just dropped in the Jeep injector. But I think for my next project, I'm going to fab up a TB spacer, swap in a GM 5.0 Injector, and see if that combo gives any slight boost in performance.

 

The 2.5 TBI also used the same MAP sensor as the GMs. You could try the larger GM injector and fine tune it with an adjustable MAP voltage adjuster.

Link to comment
Share on other sites

shouldnt the O2 sensor decect that it is above or below 14.7a/f ratio and adjust accordingly?

 

Yes, it should in closed loop mode if it's working right along with the engine control module (if the 2.5L TBI engine has an engine controller). But an adj. MAP can help the lean or richen the A/F ratio under WOT conditions and in open loop mode when the engine is first started. Under these conditions the O2 sensor is ignored. :D

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...