Driving issue leads to the question; since OEM replacements are discontinued, who has purchased and is running an aftermarket AFM?

the t3d

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I've never cleaned or ever replaced mine, but when I think about having a spare one to have as a known working back-up, the aftermarket AFMs seem to be less of a risky purchase than a "good working" used one you can't return from someone online. This one has a 3 year warranty and is an OEM replacement for the part number of the original.
https://www.ebay.com/itm/22204-42011-Mass-Air-Flow-Meter-For-Toyota-Supra-Lexus-LS400-SC300-SC400-91-95/402464972791

So I'm just curious if anyone has run one of these and if they have had any issues with them?

***main reasoning for considering this is my Supra just started this dramatic idle increasing out of nowhere. My previous post of about IACV changing when tapping on it was fixed when I replaced that whole harness and connector. The car ran better than it ever had. I let it sit for a couple hours, went to start it up, and then the idle just started climbing to like 2-2500rpm. I blipped the throttle and then it died. Started it back up. Wasn't as bad but noticeable, so I drove it. Then every time I came a stop the rpm started surging from like 1500-2500. I decided to just park it until I got some time.

I have a code 51, but feel like this code has never left. I recently tested the TPS and checked out. I used all the proper feeler gauges to per TSRM to calibrate it. I don't have AC in the car, it's a 5spd swap no neutral safety switch and the throttle linkage is holding it open. I'm going to jumper IDL and E2 on the harness to hopefully rule out the TPS. I've never replaced the TPS before, so I wouldn't surprised if that was the issue, but I do know there's never been a time I can remember that code has not been there when checking. Question though: The online TSRM has this written note about "Throttle clearance when at stop screw ~0.0015"-0.002", is it saying to set it to this instead of what the TSRM says to be 0.00"???

Non-TPS related, I've unplugged the IACV while the issue was happening leading to no change whatsoever and I've swapped that out with a known good replacement with no improvement either. I have never cleaned or replaced the AFM and know as I improve other performance-affecting components and wiring, I'm revealing the next weakest links, so this is what leads me to my questions for the AFM replacement. I'm also tempted to just purchase a genuine Toyota TPS to have on-hand as well.
 
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Piratetip

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A BIG FYI on these aftermarket units.
They are something completely different inside from the original design.

They have very clearly converted them to a hotwire style AFM.
How they have done this is anybody's guess, and if they can accurately output the appropriate accurate signal to the ECU? haha...

I wouldn't chance it, it's likely very sketchy signal conversion going on inside.
Visually it's pretty easy to see that it's a very half assed attempt, likely chinese sourced counterfeit design.
I know that sounds stereotypical but I've benchmarked/reversed engineered similar looking cheap as shit electronics that remind me a lot of this.

That being said I would like to tear one down and investigate what the heck they have done to create this thing.
Compare it against the OEM AFM teardown investigation I've already done.

If anyone wants to fund buying one of these aftermarket things I will volunteer tearing it down and showing the results.
I've got an oscilloscope to check the signal output as well.
 
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the t3d

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A BIG FYI on these aftermarket units.
They are something completely different inside from the original design.

They have very clearly converted them to a hotwire style AFM.
How they have done this is anybody's guess, and if they can accurately output the appropriate accurate signal to the ECU? haha...

I wouldn't chance it, it's likely very sketchy signal conversion going on inside.
Visually it's pretty easy to see that it's a very half assed attempt, likely chinese sourced counterfeit design.
I know that sounds stereotypical but I've benchmarked/reversed engineered similar looking cheap as shit electronics that remind me a lot of this.

That being said I would like to tear one down and investigate what the heck they have done to create this thing.
Compare it against the OEM AFM teardown investigation I've already done.

If anyone wants to fund buying one of these aftermarket things I will volunteer tearing it down and showing the results.
I've got an oscilloscope to check the signal output as well.
I would consider splitting the cost or throwing down $25 towards one of these ebay sensors. So what would you say is the worst harm these aftermarket replacements would do? Throw a code? Fry the computer? These ebay purchases always favor the buyer if there are any issues. I sell shit on ebay and I'll usually get burned if they bitch enough. Plus, there is a 1 year Plus warranty on these units. I'm just trying to weigh the risk of buying used stock AFM from someone that you can't return and one that you can return and exchange for the next 3 years. How effective is using the MAF sensor cleaner on our units?
 

Piratetip

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I might consider it, though I will be tearing it down.
So the unit would no longer be functional after I am done with it.

Our MAF is not to be cleaned.

What is wrong with the one you have?

I hear you on eBay, I'm really getting tired of selling on that platform.
 

the t3d

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I might consider it, though I will be tearing it down.
So the unit would no longer be functional after I am done with it.

Our MAF is not to be cleaned.

What is wrong with the one you have?

I hear you on eBay, I'm really getting tired of selling on that platform.
I really didn't think it was, but 33 years old gotta induce some sort of wear and tear I'd imagine. And I am totally fine with you tearing one of those down rendering it unusable in the name of science. As long as you do it before 2021 lol. I'll paypal you the $25 if you're down. Just keep me posted on which one you plan on purchasing so I can mark it on ebay for future reference.

And my issues leading to the AFM questions are here. I copied it from the original post. It's a little long, but I tried to be thorough in my explanation and thought process...

***main reasoning for considering this is my Supra just started this dramatic idle increasing out of nowhere. My previous post of about IACV changing when tapping on it was fixed when I replaced that whole harness and connector. The car ran better than it ever had. I let it sit for a couple hours, went to start it up, and then the idle just started climbing to like 2-2500rpm. I blipped the throttle and then it died. Started it back up. Wasn't as bad but noticeable, so I drove it. Then every time I came a stop the rpm started surging from like 1500-2500. I decided to just park it until I got some time.

I have a code 51, but feel like this code has never left. I recently tested the TPS and checked out. I used all the proper feeler gauges to per TSRM to calibrate it. I don't have AC in the car, it's a 5spd swap no neutral safety switch and the throttle linkage is holding it open. I'm going to jumper IDL and E2 on the harness to hopefully rule out the TPS. I've never replaced the TPS before, so I wouldn't surprised if that was the issue, but I do know there's never been a time I can remember that code has not been there when checking. Question though: The online TSRM has this written note about "Throttle clearance when at stop screw ~0.0015"-0.002", is it saying to set it to this instead of what the TSRM says to be 0.00"???

Non-TPS related, I've unplugged the IACV while the issue was happening leading to no change whatsoever and I've swapped that out with a known good replacement with no improvement either. I have never cleaned or replaced the AFM and know as I improve other performance-affecting components and wiring, I'm revealing the next weakest links, so this is what leads me to my questions for the AFM replacement. I'm also tempted to just purchase a genuine Toyota TPS to have on-hand as well.
 

Piratetip

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Interestingly enough, inside the AFM the is no wear and tear from what I saw.
The unit also has self calibration abilities and something else that's interesting.
I found an old Fuji document stating the AFM also has a strategy built in to compensate if any dust or contaminants get on the mirror.

I'd just pick up another used AFM for $60 and call it a day.

For sake of interest I still want to tear one of these aftermarket units down to have a look.
But I'd highly recommend no one use them on their engine.

@3p141592654
Do you think an AFM would cause this surging?
 

the t3d

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Interestingly enough, inside the AFM the is no wear and tear from what I saw.
The unit also has self calibration abilities and something else that's interesting.
I found an old Fuji document stating the AFM also has a strategy built in to compensate if any dust or contaminants get on the mirror.

I'd just pick up another used AFM for $60 and call it a day.

For sake of interest I still want to tear one of these aftermarket units down to have a look.
But I'd highly recommend no one use them on their engine.

@3p141592654
Do you think an AFM would cause this surging?
Hmm that's interesting to know. Well I'd still be down to contribute to you breaking down one of these to see how dissimilar they really are. It would be amazing if these were one of the parts they start putting back into production.

I've had this code 51 light for what seems like forever, so at the very least I may just purchase a new TPS just to have one on-hand. I'm also replacing the entire harness and connector for the AFM. I've done so for every other drive performance circuit, so I might as well do this one too. It just seemed so weird for it to just instantly develop into a problem after a flawless drive just a couple hours prior.