Throttle body & MAFS Cleaning!

[Benjaman]

Just did a cleaning today. The TB had over 1/8" of crud build up. As for the air flow sensor, I could not get a line of sight on the filament, but did drown the unit in CRC Mass air flow cleaner.

So there is a VAST improvement! in overall snappyness. Idle has also improved.

Most cost effective repair yet.

 

[Spook50]

It's amazing how much cleaning out all that gunk can do.

I really wonder if there's any room for flow improvement in the 3FE's MAF. I saw someone developed a higher flow MAF for FZJ80s, and wondered if there was a way one could be done up for a 3FE (and if any benefit would be seen from it in conjunction with a bored out TB).

 

[overhanger]

The 3FE is controlled by an Air Flow Meter - AFM - and not a Mass Air Flow Sensor. There is no filament to see and, unless you have been running air cleaner-less, there should be no dirt build up in the sensor. The throttle body does get gunked up and cleaning it out is always of benefit.

 

[Spook50]

The 3FE is controlled by an Air Flow Meter - AFM - and not a Mass Air Flow Sensor. There is no filament to see and, unless you have been running air cleaner-less, there should be no dirt build up in the sensor. The throttle body does get gunked up and cleaning it out is always of benefit.

I never did understand exactly what the difference between an AFM and an MAF is.

 

[Benjaman]

The 3FE is controlled by an Air Flow Meter - AFM - and not a Mass Air Flow Sensor. There is no filament to see and, unless you have been running air cleaner-less, there should be no dirt build up in the sensor. The throttle body does get gunked up and cleaning it out is always of benefit.

Now it's coming together! Where were you when a spent $7. on the M.A.F.S. Cleaner!!?

And yes! it was very clean.

 

[overhanger]

Spook, take a look at that FSM I sold you and see what the AFM looks like and then check out the many MAF threads in the 80 section, especially those regarding Landtank's modified MAF sensor. It will be most instructional for you. Benjaman, I suggest you buy an FSM for an '89 or '90 Cruiser if you don't already have one. It's a great read!

 

[Benjaman]

Spook, take a look at that FSM I sold you and see what the AFM looks like and then check out the many MAF threads in the 80 section, especially those regarding Landtank's modified MAF sensor. It will be most instructional for you. Benjaman, I suggest you buy an FSM for an '89 or '90 Cruiser if you don't already have one. It's a great read!

I do have a fsm, I bought it for wiring and bearing clearance. I'm new to Fi, as 24 years in my 85 22r is what I'm used to. My bike is Fi, but it never brakes down.

I've read the fsm cover to cover! I just mix up all of the acronyms. like MAF, AFM or TLA!

 

[Moby]

I never did understand exactly what the difference between an AFM and an MAF is.

An AFM uses a spring loaded door to infer how much air is entering the engine (determined by how far the door moves). Ours measure in a 5-0 volt range as opposed to the more common 0-5 volt range. Ours also has a fuel pump relay built in for safety to make sure that the fuel pump doesn't continue to pump fuel if the engine isn't running (in the event of a crash).

A MAF uses a heated wire to infer how much air is entering the engine (determine by how much current is required to keep the wire at a fix temperature).

Speed density uses pressure/vacuum to directly measure the volume of air entering the engine.

The AFM is a Bosch design (or whoever Bosch bought their early EFI designs from). Very common on EFI systems from the '80s, including BMW. Toyota '80s EFI systems are very close to Bosch designs. I believe various bits, if not the majority, are licensed replicas of Bosch designs.

AFMs are the crudest of the measuring devices but are generally very forgiving to engine efficiency changes (such as chaning the cam profile, head porting, exhaust and displacement changes like a 2FE). MAF and speed density excel in different conditions. Gen IV chevy motors use both and rely on them for different engine conditions.

I'm in the middle of a Split Second AFM to MAF conversion right now. This eliminates the inherent air flow restriction of the AFM's door and gives programmatic control over the air flow signal to the ECU.

 

[Spook50]

I'm in the middle of a Split Second AFM to MAF conversion right now. This eliminates the inherent air flow restriction of the AFM's door and gives programmatic control over the air flow signal to the ECU.

Interesting info. So the "higher performance" (for lack of a better way to put it) MAFs are really just bored out and/or profiled for smoother airflow through them?

Any details on your conversion? I'm curious to see what all will be involved and if there's any benefits afterwards.

Have you done any other modifications to your engine that'll benefit from the conversion (or help more in combination with it)?

 

[Moby]

Interesting info. So the "higher performance" (for lack of a better way to put it) MAFs are really just bored out and/or profiled for smoother airflow through them?

The actual measurement process can vary, so there is room for improvement in the resolution, but only to the point that your ECU can make use of. If it only has increments of 1 but your meter can measure .1, well, that may not be of any actual value because the ECU will round up or down to fit into its map.

A larger MAF may or may not help. If there is a pressure drop across the meter there may be benefit in a larger diameter meter. If there is no flow restriction larger probably won't be of any help.

Any details on your conversion? I'm curious to see what all will be involved and if there's any benefits afterwards.

http://www.splitsec.com/technotes/AFM_to_MAF_Conversion.pdf More details here: Tech Notes

I'm not going to be able to finish the conversion until fall. I had to put a new ring/pinion in the rear diff (long story) and now I'm not going to get the conversion and tuning done before leaving on a long trip at the end of this month because I need enough miles to break the gears in before leaving. So I'll pick it up again in Sept. I'll post the results when I'm done.

Have you done any other modifications to your engine that'll benefit from the conversion (or help more in combination with it)?

Yeah, stock has been a distant memory for some time

 

[Spook50]

Yeah, stock has been a distant memory for some time

Now I'm going to have to go back through your build/mod threads and find out what all you've done

Reading the stuff on the AFM to MAF conversion, this sounds like an interesting way to go. A big limit to airflow (and possible source of turbulence) that I see is the sharp right angle turn that the air has to make right after passing through the filter box though.