1991 FJ80 3FE AFM issues. (2 Viewers)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Jun 28, 2025
Threads
2
Messages
9
Location
TEXAS
I recently purchased a "new" remanufactured AFM after discovering the one on my Land Cruiser was not the correct AFM. However, when I plug in the "new" AFM, the Check engine light does not illuminate anymore, and it will not start now. If I plug the old one back in, the check engine light appears, and it starts. This is actually the second "new" AFM that I have purchased. I thought the first one I purchased may have been damaged internally through shipping, but the second one is doing the same thing. I'm currently in the process of replacing basic LC maintenance issues, for example, the fusible links that I have read about on the forums, and ran across this issue. I have also read and gone through the no CEL-No start diagnostic sheet, and everything seems to check out, so any help is helpful. Thank you.
 
How did you discover it was "not the right one"? It sounds like the one currently in there is working fine. Maybe I'm not getting the whole picture, but it kinda sounds like a case of, "if it ain't broke, fix it 'til it is". What issue are you having that you suspect the AFM is an issue?
 
Has not been running right at all. Rough idle, bogs down, etc. Aside from that had a large gap where AFM bolts up to the air box lid. The bracket with the one 10 mm that has the two holes wouldn’t line up at all and the diameter size of the hole was MUCH smaller then the size of the “new” correct one.
 
Has not been running right at all. Rough idle, bogs down, etc. Aside from that had a large gap where AFM bolts up to the air box lid. The bracket with the one 10 mm that has the two holes wouldn’t line up at all and the diameter size of the hole was MUCH smaller then the size of the “new” correct one.
The "large gap" is what's causing it to not run correctly. Any unmetered air entering the system will cause these issues. The top end of the 3FE wants to be air tight.
If the CHECK ENGINE light does not illuminate with the key in the ON/RUN position before cranking the starter, this engine will not run. Don't even bother cranking it.
Please see the documents linked below for more information.

 
Last edited:
Since you have posted @jonheld I have gone through the 3fe diagnostic cheat sheet like 3 times making sure I have not missed anything and I have all 12v where I need it even checked the grounds making sure they are good. So when I go to plug in my “new” correct AFM the check engine light still does not illuminate now I know on the cheat sheet it says with the AFM unplugged if it illuminates it could be the internals of the AFM but this is the second correct afm that I am using. Now If I go plug in the incorrect AFM check engine light turns on and it will fires right up but obviously runs like crap.
 
Since you have posted @jonheld I have gone through the 3fe diagnostic cheat sheet like 3 times making sure I have not missed anything and I have all 12v where I need it even checked the grounds making sure they are good. So when I go to plug in my “new” correct AFM the check engine light still does not illuminate now I know on the cheat sheet it says with the AFM unplugged if it illuminates it could be the internals of the AFM but this is the second correct afm that I am using. Now If I go plug in the incorrect AFM check engine light turns on and it will fires right up but obviously runs like crap.
Obviously the correct AFM is working. As for CEL, there could be a numerous reasons, i think you have other issues that are unresolved. Pull the code and see...
 
Obviously the correct AFM is working. As for CEL, there could be a numerous reasons, i think you have other issues that are unresolved. Pull the code and see...
I do not believe it is the correct AFM though because of the rough idle, bogging down and not sealing correctly. For example the intake tube is way to big for the diameter of the afm opening I have to crank down on the hose clamp on the intake tube just to get a tight seal and I know that’s not correct. The thing is the LC only reads the incorrect afm and not the proper one. I will go through the diagnostic sheet again to make sure that it isn’t another underlying issue.
 

Users who are viewing this thread

Back
Top Bottom