What are others doing when their VAF’s go bad? ‘94 FZJ80

mudgudgeon

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Sporadic rough idle at low rpm's. Will be idling nicely at an intersection or red light and then slowly begin not breathing well. Will get to a point where it almost dies. I've gotten into the habit of sliding into neutral and giving it a bit of gas to keep the idle a bit higher. I've changed my O2's, my spark plugs, my distributer and wires. Replaced the fuel filter and fuel pressure regulator. Troubleshot the EGR and fuel pump relay.
I cleaned the Mass Airflow Meter, which wasn't very dirty, and it ran perfect for 3 days with no CEL. I finally took it to the local Toyota dealership and they pointed at the mass air flow per the readings off of the multimeter master computer. I try to do as much as I can myself on my land cruiser. I've owned it for over 20 yrs and currently sitting at around 340,000 mi.
Sounds like it could also be a vacuum leak.
You said you redid PCV and grommet?

Vacuum hose is cheap as chips. Change all the vac hoses
Also change oil filter cap o-ring
 
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When I bought my LC, I had really high cold startup RPM, then intermittent low idle and stalling once warm.

In my case, with ~254k miles, the O2 sensors were bad, the EGR modulator had failed at some point and allowed carbon into the intake manifold passages, my IAC valve port was full of carbon, bad EGR solenoid, and it had various vacuum leaks even though most of the hoses looked good.

With only 145k miles, maybe you don't have most of those problems. But it's still an old rig, and the rubber has seen a lot of heat cycle, so if I were you I'd replace all the vacuum hoses. Since you have to pull the upper intake to reach several of them, you'll be able to inspect it, check that the passages are clear, and test the solenoids under there.
 
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Have to agree I'd exhaust every other possible avenue first. Idle Control Sensor? Align the throttle cable and throttle position sensor?
 

FMC80

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After rereading, it's probably not the VAF. I agree with you guys, I think there needs to be more troubleshooting. I wonder if the techs at Toyota are full of it when they claimed the VAF was indeed bad.
 
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Have to agree I'd exhaust every other possible avenue first. Idle Control Sensor? Align the throttle cable and throttle position sensor?
My challenge is I feel I have looked at or changed out a majority of what would cause the issues I'm having. Why can't it be the VAF? Does it have a lifetime guarantee? I understand it more than likely shouldn't fail and a long list of contributors exist. But from the 6-12 months of reading, research, and wrenching I've done and if it looks, acts, and sounds like a duck, why can't it be the VAF? When I was in high school I drove a truck my Grampa had owned. A 1979 Mazda Rotary pickup that my cousin rolled. One day the engine stopped on me and I couldn't get it to turnover. My brother pointed out it had an engine fuse and to check it. Changed out the engine fuse and ran perfectly. What a great day that was.
 

JunkCrzr89

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I wonder if the techs at Toyota are full of it when they claimed the VAF was indeed bad.
From my experience, most Toy techs no longer have any idea what they’re doing with a vehicle that’s >15 years old. Occasionally they’ll have an old timer on staff who knows, but it’s rare.
 

FMC80

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My challenge is I feel I have looked at or changed out a majority of what would cause the issues I'm having. Why can't it be the VAF? Does it have a lifetime guarantee? I understand it more than likely shouldn't fail and a long list of contributors exist. But from the 6-12 months of reading, research, and wrenching I've done and if it looks, acts, and sounds like a duck, why can't it be the VAF? When I was in high school I drove a truck my Grampa had owned. A 1979 Mazda Rotary pickup that my cousin rolled. One day the engine stopped on me and I couldn't get it to turnover. My brother pointed out it had an engine fuse and to check it. Changed out the engine fuse and ran perfectly. What a great day that was.
Again, over the course of this troubleshooting journey, have you verified it yourself?
 
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From my experience, most Toy techs no longer have any idea what they’re doing with a vehicle that’s >15 years old. Occasionally they’ll have an old timer on staff who knows, but it’s rare.
I agree. Once my VAF is returned from NAPA and its trip around the US, I'll be able to better troubleshoot some of the above suggestions I may have overlooked. My throttle cable isn't in the best shape but I don't believe it would cause the issues I'm having. You never do know. I need to find new friends. None of my friends know how to do squat. Working on an issue alone can get old.
 

FMC80

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So you actually have your VAF to Napa. Hope you took 5min to validate what Toyota told you before giving it to them.

How much are they charging you?
 
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Borrow someone's working VAF from another 93-94. That will tell you if your VAF is indeed the problem. Otherwise, double check your throttle cable adjustment according to the FSM.
 
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I not trying be disrespectful and not a 5-banana expert. After going down the same road, just basing my advice on the fact that finding a working replacement VAF is a wildcard at best so it's the last thing I'd focus on after trying ALL else. I hope you get squared away. :)
 

mudgudgeon

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My challenge is I feel I have looked at or changed out a majority of what would cause the issues I'm having. Why can't it be the VAF? Does it have a lifetime guarantee? I understand it more than likely shouldn't fail and a long list of contributors exist. But from the 6-12 months of reading, research, and wrenching I've done and if it looks, acts, and sounds like a duck, why can't it be the VAF? When I was in high school I drove a truck my Grampa had owned. A 1979 Mazda Rotary pickup that my cousin rolled. One day the engine stopped on me and I couldn't get it to turnover. My brother pointed out it had an engine fuse and to check it. Changed out the engine fuse and ran perfectly. What a great day that was.

No- one is saying it's absolutely not the VAF.
just suggesting other possible contributors that may solve your problem for less cost

Example, eeplacing vacuum lines is maybe $20-50 for hoses, and a few hours work.

Vs $100's for VAF repair
 
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No- one is saying it's absolutely not the VAF.
just suggesting other possible contributors that may solve your problem for less cost

Example, eeplacing vacuum lines is maybe $20-50 for hoses, and a few hours work.

Vs $100's for VAF repair
Sounds good... the vacuum lines were 1st on my list and replaced all a while back.
I got the VAF back from NAPA yesterday. Quick recap... NAPA has VAF rebuild on the website - https://www.napaonline.com/en/p/NECXTP420097
7-10 days they send off for rebuild. 40 days later nothing done due to local store not filling out correct paperwork. I may try another Napa location as they wanted to send off to a local place here in TX. Will try to find out if it's a 3rd party. So I've put the VAF back in and happy to drive the rig again. Same issues so will look at troubleshooting a few other areas this evening and weekend. Will research and look at checking fuel injectors and also testing the VAF myself with multimeter as suggested.
 

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