3-FE VAF Meter Woes: Lesson learned the hard way (1 Viewer)

[spdwaver]

This thread is dedicated to VAF sensor illogic.

I decided today that I would look into cleaning the AFM (aka, MAF, VAF) sensor to see if this would help gain a little power.

**I will update this thread with proper terminology once I retrieve my FSM from the Cruiser, more than likely tomorrow. Anyone who wishes to add diagrams or pictures, please feel free to post.**

Well, I have never messed with this before, and just like anything else, I briefly skimmed the FSM to gain an understanding of what I was looking for; then I began to take everything apart from the air cleaner.

In so doing, I unscrewed the sensor plug (DO NOT EVER DO THIS) - and out came all of the various connectors from the housing's PC board when I gave it a tug. Now, I know that there are many knowledgeable here who would cringe at the thought of being so reckless, but I was not paying much attention, which is reminiscent of my whole day today. :whoops:

I attempted to simply put the plug receptacle back into place, plugging in the exposed leads, but the engine would not start. I unplugged the unit altogether, then it started; but it quickly died, so then I knew it had something to do with the plug.

To get to the point, I was stuck wondering what to do since I pretty much ruined a perfectly good running engine:

Option 1: Park it and check the classifieds for a replacement housing.

Option 2: I am not going any where, so may as well remove the sealant on the cover and attempt to figure it all out.

Being who I am, I went with option 2.

First, I removed the housing from the truck and brought it to the work bench.

I cut away the rubber sealant from the plastic housing, being careful (for the first time tonight) not to puncture the thin plastic cover. I used a screwdriver to remove the sealant so that the chances of cutting were reduced.

Next, I removed the plastic cover and took a look inside. There were three blade connectors on the plug receptacle that were in alignment with where the female end of the wires would eventually meet. I made note of this for reassembly.

I saw that I had pulled three other posts from the PC board during the initial removal: these needed to be soldered back into place.

I soldered the three posts back onto the PC board, then re-attached all of the connectors, replaced the plastic cover; then I used a silicon sealant to make it water-tight. I allowed this to dry, then assembled it back onto the air intake.

I plugged the sensor cable back in and turned the ignition key:

It started right up!

I am breathing a sigh of relief right now, but I will not know fully how this "tune up" worked out until I drive it to work tomorrow.


I will keep you all updated as testing progresses.

 

[spdwaver]

Here is an FSM scan (thanks semlin) of where I went wrong.

 

[jonheld]

Sean,

There have been several threads here about folks trying to adjust the air flow meter (AFM) spring to change the logic being sent to the ECU. IIRC this was in conjunction with advancing the timing.

Some have had good results, others have had to purchase a new AFM. If you find that you "screwed the pooch" on your AFM you can pick up a used unit from Cruiserparts.net. Any 3FE (FJ62-FJ80) unit will work. I have an untested one from an FJ62 that was pulled off at a boneyard. You are welcome to it if needed.

 

[spdwaver]

Sean,

There have been several threads here about folks trying to adjust the air flow meter (AFM) spring to change the logic being sent to the ECU. IIRC this was in conjunction with advancing the timing.

Some have had good results, others have had to purchase a new AFM. If you find that you "screwed the pooch" on your AFM you can pick up a used unit from Cruiserparts.net. Any 3FE (FJ62-FJ80) unit will work. I have an untested one from an FJ62 that was pulled off at a boneyard. You are welcome to it if needed.

Jon,

Now that I have been into it, I am not so shy about going back in and doing some more damage in an effort to make a performance modification - if in so doing there is an advantage.

If you are inclined to send a unit my way, I would be more than happy to give it a shot. Only this time, I will take a lot of detailed pics with descriptions to match.

 

[spdwaver]

UPDATE:

After driving to work this morning, I did not notice much of a difference in power, so this "mod" is not worth attempting yourself.

The only difference in performance, which is slightly less than optimal (whatever that may be) may be attributed to the computer re-programming, if that is even the case.

In detail, the normal cruising speed of ~40 mph does not hold very well at a slight incline; but then again, it never has. I always find myself having to hit the accelerator to cause it to down shift; in other words, I always have to give it a lot of pedal. But, it does fairly well when in the ~2800 - 3000 rpm range, just not much performance below that.

 

[Fergie]

I feel your pain!

I bought a used, but good AFM as a back-up after buying a used one from Specter to get me going again.

For around $130, you can send your damaged AFM to SIA electrconics and they will rebuild it like new.

 

[spdwaver]

After driving it home from work today, I noticed that not everything is right; this could be the ECU or a damaged AFM. Either way, I will know after a few days, I suppose.

How long does it take for the computer to "re-learn" anyway?

 

[gotmud]

Sean, you're in good company!

 

[spdwaver]

Sean, you're in good company!

Are you referring to Mud in general, 3FE ownership, or the fact that I was able to botch such a simple procedure?

 

[cool breeze]

i did the same thing last week searching for my not starting problem. only difference being it was done 800 miles away on the side of the interstate I thought it was all boogered up so i called c-dan and got a discount price of ~$650, not something you want to break just because you are curious...lesson learned.

Are 1fz and 3fe vaf's the same?

 

[Lka1988]

Here is an FSM scan (thanks semlin) of where I went wrong.

Welcome to the club! It's a very misleading connection, I'll give ya that. I did the same thing a few years ago...

You'll find there's a lot of guys who have done this same thing, you're not alone

 

[spdwaver]

Welcome to the club! It's a very misleading connection, I'll give ya that. I did the same thing a few years ago...

You'll find there's a lot of guys who have done this same thing, you're not alone

That's pretty surprising and comforting, actually.

Now that I am aware of that thin metal retaining clip, I will not make that mistake again.

Now, geting back to what I wanted to do in the first place, which caused all this: Is the AFM to the 3FE what a MAF is to a 1FZ-FE engine? I am trying to clean it; in the FSM the only thing I see that has the term "Air Flow" is the Air Flow Meter - have I already found what I am looking for?

For the life of me, I can not make the distinction; I am looking for a thin wire inside an intake tube, whereas I do not find one on this engine - not even in the FSM.

Forgive me if this should be rudimentary knowledge, but I need to ask.

 

[Lka1988]

The AFM is to the 3FE as the MAF is to the 1FZFE.

Big difference in design, though, obviously. The AFM uses a flapper door inside the intake tube, which is attached to an arm inside the plastic-sealed box on top. That arm has a contact on it which slides along a thin metal strip on the PCB. The flapper door opens according to how much air is being sucked into the engine, which moves the arm with it along the contact, which sends a signal to the ECU.

IIRC.

The MAF uses a heated wire setup. Which I am totally unfamiliar with.

 

[spdwaver]

The AFM is to the 3FE as the MAF is to the 1FZFE.

Big difference in design, though, obviously. The AFM uses a flapper door inside the intake tube, which is attached to an arm inside the plastic-sealed box on top. That arm has a contact on it which slides along a thin metal strip on the PCB. The flapper door opens according to how much air is being sucked into the engine, which moves the arm with it along the contact, which sends a signal to the ECU.

IIRC.

The MAF uses a heated wire setup. Which I am totally unfamiliar with.

By design, then, it could be said that the "sealed" design of the sensor's PC board is better in wet conditions only, correct? That is, except for the temperature sensor which is external.

Since I now know what the inside of one of these looks like, it no longer is a mystery to me (I should have taken pics of it). Mine was clean, FWIW.

 

[spdwaver]

Sean,

There have been several threads here about folks trying to adjust the air flow meter (AFM) spring to change the logic being sent to the ECU. IIRC this was in conjunction with advancing the timing.

Some have had good results, others have had to purchase a new AFM. If you find that you "screwed the pooch" on your AFM you can pick up a used unit from Cruiserparts.net. Any 3FE (FJ62-FJ80) unit will work. I have an untested one from an FJ62 that was pulled off at a boneyard. You are welcome to it if needed.

Well, I think that is exactly what happened. When I put it all back together, everything looked really clean and in order; but I guess visual confirmation is not everything.

Here is what I have noticed: Before I made this awesome modification, I had zero issues when accelerating after the engine is not fully warmed up. Now, it sputters, lacks power, and it even back-fired tonight when I laid into it slightly, although it was almost fully warmed up. Kinda reminds me of a carburated engine that is not fully warmed up, like my old 40 did with the SBC.

So, I guess I really did mess it up. Lesson learned (until next time, of course).

 

[JerseyCruiser]

This thread is dedicated to VAF sensor illogic.

I decided today that I would look into cleaning the AFM (aka, MAF, VAF) sensor to see if this would help gain a little power.

**I will update this thread with proper terminology once I retrieve my FSM from the Cruiser, more than likely tomorrow. Anyone who wishes to add diagrams or pictures, please feel free to post.**

Well, I have never messed with this before, and just like anything else, I briefly skimmed the FSM to gain an understanding of what I was looking for; then I began to take everything apart from the air cleaner.

In so doing, I unscrewed the sensor plug (DO NOT EVER DO THIS) - and out came all of the various connectors from the housing's PC board when I gave it a tug. Now, I know that there are many knowledgeable here who would cringe at the thought of being so reckless, but I was not paying much attention, which is reminiscent of my whole day today. :whoops:

I attempted to simply put the plug receptacle back into place, plugging in the exposed leads, but the engine would not start. I unplugged the unit altogether, then it started; but it quickly died, so then I knew it had something to do with the plug.

To get to the point, I was stuck wondering what to do since I pretty much ruined a perfectly good running engine:

Option 1: Park it and check the classifieds for a replacement housing.

Option 2: I am not going any where, so may as well remove the sealant on the cover and attempt to figure it all out.

Being who I am, I went with option 2.

First, I removed the housing from the truck and brought it to the work bench.

I cut away the rubber sealant from the plastic housing, being careful (for the first time tonight) not to puncture the thin plastic cover. I used a screwdriver to remove the sealant so that the chances of cutting were reduced.

Next, I removed the plastic cover and took a look inside. There were three blade connectors on the plug receptacle that were in alignment with where the female end of the wires would eventually meet. I made note of this for reassembly.

I saw that I had pulled three other posts from the PC board during the initial removal: these needed to be soldered back into place.

I soldered the three posts back onto the PC board, then re-attached all of the connectors, replaced the plastic cover; then I used a silicon sealant to make it water-tight. I allowed this to dry, then assembled it back onto the air intake.

I plugged the sensor cable back in and turned the ignition key:

It started right up!

I am breathing a sigh of relief right now, but I will not know fully how this "tune up" worked out until I drive it to work tomorrow.


I will keep you all updated as testing progresses.

HA HA! I did the same thing to mine trying to clean it. Then S**T a brick when I found out its around $700. to replace but was able to resolder, and reseal it. It was me being too ambitious and getting into something I knew nothing about.

 

[spdwaver]

HA HA! I did the same thing to mine trying to clean it. Then S**T a brick when I found out its around $700. to replace but was able to resolder, and reseal it. It was me being too ambitious and getting into something I knew nothing about.

Yeah, that about sums up my 'logic' for getting into it as well; thinking I was on the right track.

Again, lesson learned (until next time).

 

[spdwaver]

One more thing: I got approximately 7-8 MPG from a full tank.

Is this normal for stock gearing and 33's?

 

[Lka1988]

One more thing: I got approximately 7-8 MPG from a full tank.

Is this normal for stock gearing and 33's?

Depends how you drive. If you drive like me, then yes it's normal.

 

[spdwaver]

Depends how you drive. If you drive like me, then yes it's normal.

I read somewhere that you keep the pedal mashed down almost all the time: well, I have come to find out that this is a necessity.