93' fzj80 wont idle after new VAF (1 Viewer)

[Darrenkime]

I have a 1993 fzj80 that iv been chasing a low idle issue for awhile. Truck had a code 24 so I decided to test the VAF and failed the continuity test so I ordered a used one off cruiserparts.net.
After installing the new one the truck will start then immediately die unless I hold the gas and rev it past 1k rpm. I decided to test the new one I got and it showed that is was good.

Question is why is the truck dying with the new one and was at least idling ok with the "bad" one? Is there a better way to test them to make sure they're really good?
Any help is appreciated

 

[Desert Dino]

Did you reset the ECU after VAF change ?

Do you have CEL light ON before starting the engine?

Code 24 is a problem at Intake Temp sensor

1994 check engine light.

I just moved to New Hampshire, and it has become Winter. I noticed the check engine light come on and a distinct smell of burning tires, or brakes or something burning. Also the idle has becoming very erratic. I understand there is no simple diagnostic port on a 94. What should I do to begin...

forum.ih8mud.com

I would reset the ECU, run OBD scanner to see live data and hold the RPM by foot on gas or the hand throttle at 1000 RPM let it warm up and start the learning process

 

[Desert Dino]

@Darrenkime What's up with your rig?

 

[LandLocked93]

Perhaps messing with the intake tube (large rubber pipe connecting to the intake plenum) during replacement of the VAF has opened a crack somewhere? Especially if it's vintage.
Do you hear sucking sounds (other than the ones in your head while you're messing with all this lol) when cranking or during the short bursts of life?

 

[sogafarm]

I've got the same code 24 with my original AFM as well, but I had to do some emergency soldering after pulling the plug loose. I have a replacement used one now and no codes. The place you bought your new used AFM may have done some repair work to it that was not done correctly. Check to see if the new one's top seal has been replaced compared to the stock unmolested unit. If it's been opened, then it could have been boogered up by someone. Look up resurrectedautoparts on ebay who is also on mud @Resurrectedauto can rebuild it for you.

 

[Darrenkime]

So I did get the truck running after tinkering with it for a little I unplugged the fuel pump relay and jumped it to see if the fuel pump was running right. Which it did the same thing where it wouldn't idle. Then when I plugged the relay back in I started it and it stayed running and ran just like before I changed the VAF. Still have the code 24 but at least I could drive it.

Then something else came up.
Yesterday I changed out the spark plugs and took it for a drive and it drove fine. Drove it to the gym fine, but when leaving the gym I started it and it started idling and driving REALLY rough. It kept cutting out and when flooring it it would kind of bog down. It kept dying the whole way home. It would always crank over and start for a second and then die then sometimes it would start and I'd be able drive it a few hundred feet but could never get it past 2nd gear. I finally limped it home and shut it off and looked under the hood to make sure I didn't bump anything loose then started it again and it ran fine...

Not sure if these issues are related at all but it almost feels like a fuel pump issue like maybe the fuel pump is dying or the fuel pump relay isn't always working.. I'm gonna drive it around the neighborhood after today and try and get it to run bad again so I can try and troubleshoot it but any insight would be appreciated

 

[Darrenkime]

Intake tube is new BTW and I have disconnected the battery so that the ecu can relearn

 

[Darrenkime]

Got home from work and fired it up and it ran fine got it nice and warm then parked it and had some lunch. Went back out to fire it up and it started running like crap again I noticed it started making a ticking noise that went up with rpm (only when running bad). I put a timing light on each of the spark plug wires and the spark was kind of sporadic, like lots of misses. But then it started to run fine again. I also got a new code 32 - airflow meter signal. This seems to happen after I drive it then let it sit for about an hour then start it again.

I'm gonna just put the old VAF on again and see if its just this new VAF that's causing these issues.

 

[BILT4ME]

Does @landtank new unit work on the 93-94 trucks?

 

[Darrenkime]

Does @landtank new unit work on the 93-94 trucks?

I dont think so. Those are mass air flow sensors.
These are volume air flow meters from what I hear they're very different

 

[Darrenkime]

Put my old VAF in and it has yet to act up, just the same old code 24 and low idle.. I think I will send it out to get rebuilt like sogafarm suggested