VAFM restriction. real or imagined?

InternetRoadkill · 07-22-2008, 08:09 AM

Has anyone actually put a vacuum gauge on the on the intake plenum and measured the manifold vacuum at WOT during acceleration to see if the intake system really is as restrictive as folklore believes? I'm really curious about this. I would do it, but my vacuum gauge is kaput.

The reason I'm asking is that it looks like it would be possible to fit a modern high-flow MAF to our 22REs and remove the VAFM without having to change the EFI system out. But if the VAFM isn't the problem that everyone thinks it is, there's no point pursuing it.

Flash319 · 07-22-2008, 12:07 PM

2 valves per cylinder is the problem, not the intake. Even if the intake is causing a bit of a problem, you are not going to get much by fixing it if any. 22RE's flow like poop. They are truck engines after all.

4Crawler · 07-22-2008, 12:10 PM

My vacuum gauge easily drops to 0" Hg under wide open throttle acceleration. I do have a 3mm over bored throttle body.

X-Tool Pimp · 07-23-2008, 09:13 PM

MOD EDIT: (Lysmachia) BANNED!

Swansen · 07-24-2008, 05:55 AM

Quote:

Originally Posted by Flash319

22RE's flow like poop. They are truck engines after all.

HAHAHAHA, thats good time, but yeah, the VAFM inlet is about the size of a pencil, and i don't really care, you just can't pull that much air through that like one square inch area.

ozziesironmanoffroad · 07-24-2008, 07:19 AM

just put a supra afm on it, it will open it up. remember its a truck engine, i dont care what you do to it, its not gonna be anywhere near a ferarri

Flash319 · 07-24-2008, 05:47 PM

Toyota Engineers are not stupid like GM and Ford. I would trust that the intake is designed properly for the engine. Unless you modify something (bore size, turbo ect) I think you are pis$ing into the wind.....

you know what happens when you do that don't you? Don't ask me how I know.......

InternetRoadkill · 07-24-2008, 08:55 PM

The VAFM was borderline obsolete when it was introduced. It's a klunky solution to metering air into an engine. I don't know of any modern EFI system that still uses one.

The fun part is that I found my old MCU development tools and I still have a couple of prototyping units laying around looking for something to do, so the converter part is covered. I just need to write a program for it and make a wiring harness.

I also dug up a spare VAFM I had and hooked it to my shop vac. Surprise! The shop vac can pull it to near 80% open which means I can calibrate the MAF to the VAFM using the shop vac instead of trying to do it on a vehicle.

corax · 07-25-2008, 03:01 PM

if you are going to do all that work, you could just run a HKS VPC (Vane Pressure Converter). It's programmable and converts to a Speed Density System - no VAFM, no MAF. They're not made by HKS anymore, so you'd have to find one used.

abecedarian · 07-25-2008, 03:13 PM

and besides, I'd be more worried about that plastic, behind-the-radiator crossover tube than the AFM

Swansen · 07-25-2008, 04:37 PM

Quote:

Originally Posted by abecedarian

and besides, I'd be more worried about that plastic, behind-the-radiator crossover tube than the AFM

little random?? just sayin

abecedarian · 07-25-2008, 04:44 PM

Quote:

Originally Posted by Swansen

little random?? just sayin

that's me- random. just when everyone is going in one direction, I fork off and go another.

Swansen · 07-25-2008, 04:49 PM

Quote:

Originally Posted by abecedarian

that's me- random. just when everyone is going in one direction, I fork off and go another.

yes, i think that is apparent

InternetRoadkill · 07-25-2008, 04:52 PM

You guys have no sense of adventure or curiosity. No guts, no glory.

FWIW, I already have the code for the converter half written. The only thing I'm really missing now is to take a trip to the junkyard and pick up a used MAF and its pigtail. Total expenses so far: $0.00. Can't go wrong with that.

To be honest, I don't really care if it does anything magical or not. It's just an excuse to play with the FI to see what happens.

abecedarian · 07-25-2008, 05:30 PM

Conversion from AFM sensors to MAF and MAP sensors has already been done. There actually is little to no reason to do so since the more accurate sensors offer little advantage over the factory afm sensor other than for accomodating turbo/supercharging applications up to the capabilities of the ECU, for which the AFM can already suffice. Above which, an aftermarket fuel management solution has usually already been implemented.

Swansen · 07-25-2008, 05:44 PM

Quote:

Originally Posted by abecedarian

Above which, an aftermarket fuel management solution has usually already been implemented.

Yeah, and are completely ridiculous, seriously.

Targetnut · 07-25-2008, 06:39 PM

first you need to understand that the stock head only flows about 130cfm.

Even then you'll likely find some pressure drop, and it might even go 1"hg (13.5"H2O/1/2psi) or so which will reduce peak power some, but really It's likely not to make a difference you can feel.

Now if you port the head, go with a bigger cam, and bump up the compression, You'll be increasing the flow potential and that restriction will create a bigger pressure drop and be more of a factor.

I was thinking about using a MAF, but electrically they work very different from an AFM and it was just looking to complicated. But I'm no electronic guru either.

Now I'm working on a Megasquirt. this will use a MAP sensor and eliminate any measurement device in the intake tract

abecedarian · 07-25-2008, 07:31 PM

Quote:

Originally Posted by Swansen

Yeah, and are completely ridiculous, seriously.

how so, if I may ask?

Swansen · 07-26-2008, 07:12 AM

I'm not exactly sure about what you were thinking, but these are not exactly options.

http://www.yotatech.com/f116/mass-ai...sensor-115962/

http://www.yotatech.com/f116/maf-bypass-106148/

InternetRoadkill · 07-27-2008, 01:58 PM

Woot! Controller board for the converting MAF signals to VAFM signals is working nicely. Just need to scrounge a MAF from the junkyard and cross calibrate the two.

abecedarian · 07-27-2008, 02:12 PM

Quote:

Originally Posted by Swansen

I'm not exactly sure about what you were thinking, but these are no

07-22-2008, 08:09 AM	#1 (permalink)
InternetRoadkill Registered User Join Date: Jan 2006 Location: San Antonio, Texas Posts: 789	VAFM restriction. real or imagined? Has anyone actually put a vacuum gauge on the on the intake plenum and measured the manifold vacuum at WOT during acceleration to see if the intake system really is as restrictive as folklore believes? I'm really curious about this. I would do it, but my vacuum gauge is kaput. The reason I'm asking is that it looks like it would be possible to fit a modern high-flow MAF to our 22REs and remove the VAFM without having to change the EFI system out. But if the VAFM isn't the problem that everyone thinks it is, there's no point pursuing it.

07-22-2008, 12:07 PM	#2 (permalink)
Flash319 Registered User Join Date: Feb 2006 Location: Barrie, Ontario CANADA Posts: 825	2 valves per cylinder is the problem, not the intake. Even if the intake is causing a bit of a problem, you are not going to get much by fixing it if any. 22RE's flow like poop. They are truck engines after all. __________________ 89 Extra cab, 22RE not pretty but it gets me there. 420,000 km 95 VW Diesel Extra Cab Toyota, not done yet(edit: DONE!!!)..... http://www.yotatech.com/f116/vw-diesel-build-up-135203/ 92 Runner, Bone stock 415,000km WANTED: Rust free 89-95 extra cab any condition

07-22-2008, 12:10 PM	#3 (permalink)
4Crawler Contributing Member Join Date: Jun 2002 Location: SF Bay Area, CA Posts: 5,751	My vacuum gauge easily drops to 0" Hg under wide open throttle acceleration. I do have a 3mm over bored throttle body. __________________ 1985 Toyota 4Runner SR-5, 22REC engine, dual t-cases, 4.88 gears, dual ARBs, 33x10.50 BFGs. r.c.brown@ieee.org TruckEditor@tlca.org Project: 4Crawler 4Crawler OffRoad Gettin'Off 4WD Club

07-23-2008, 09:13 PM	#4 (permalink)
X-Tool Pimp Banned Join Date: May 2008 Location: So Cal Posts: 59	MOD EDIT: (Lysmachia) BANNED! Last edited by Lysmachia : 07-23-2008 at 09:32 PM.

07-24-2008, 07:19 AM	#6 (permalink)
ozziesironmanoffroad Contributing Member Join Date: Sep 2007 Location: Spring Valley, CA Posts: 3,513	just put a supra afm on it, it will open it up. remember its a truck engine, i dont care what you do to it, its not gonna be anywhere near a ferarri __________________ 1988 Toyota P/U 4x4 22RE 258,000 miles on original motor pioneer CD deck 31x10.50x15 BFG A/T BAJA 100W lights on prerunner bumper KC Daylighters 100W rancho rs5000 MUD IS A VALID PAINT JOB! If not living life to the fullest, why live it? you just hung a vacancy sign on your ass, and my foot's looking for a room my trucks official buildup thread

07-24-2008, 05:47 PM	#7 (permalink)
Flash319 Registered User Join Date: Feb 2006 Location: Barrie, Ontario CANADA Posts: 825	Toyota Engineers are not stupid like GM and Ford. I would trust that the intake is designed properly for the engine. Unless you modify something (bore size, turbo ect) I think you are pis$ing into the wind..... you know what happens when you do that don't you? Don't ask me how I know....... __________________ 89 Extra cab, 22RE not pretty but it gets me there. 420,000 km 95 VW Diesel Extra Cab Toyota, not done yet(edit: DONE!!!)..... http://www.yotatech.com/f116/vw-diesel-build-up-135203/ 92 Runner, Bone stock 415,000km WANTED: Rust free 89-95 extra cab any condition Last edited by Flash319 : 07-24-2008 at 05:50 PM.

07-24-2008, 08:55 PM	#8 (permalink)
InternetRoadkill Registered User Join Date: Jan 2006 Location: San Antonio, Texas Posts: 789	The VAFM was borderline obsolete when it was introduced. It's a klunky solution to metering air into an engine. I don't know of any modern EFI system that still uses one. The fun part is that I found my old MCU development tools and I still have a couple of prototyping units laying around looking for something to do, so the converter part is covered. I just need to write a program for it and make a wiring harness. I also dug up a spare VAFM I had and hooked it to my shop vac. Surprise! The shop vac can pull it to near 80% open which means I can calibrate the MAF to the VAFM using the shop vac instead of trying to do it on a vehicle.

07-25-2008, 03:01 PM	#9 (permalink)
corax Registered User Join Date: Aug 2007 Location: So Cal - near Valencia Posts: 206	if you are going to do all that work, you could just run a HKS VPC (Vane Pressure Converter). It's programmable and converts to a Speed Density System - no VAFM, no MAF. They're not made by HKS anymore, so you'd have to find one used. __________________ '88 4runner SR5 - 3.0 7MGE eng swap - Marlin HD W56 - 4.56 V6 Thirds - '82 Toyota Celica Supra LSD up front - 32"x11.5" BFG AT KO's - NWMP Aux Gas Tank - home fab front and rear bumpers - Hannemann fenders "Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond

07-25-2008, 04:52 PM	#14 (permalink)
InternetRoadkill Registered User Join Date: Jan 2006 Location: San Antonio, Texas Posts: 789	You guys have no sense of adventure or curiosity. No guts, no glory. FWIW, I already have the code for the converter half written. The only thing I'm really missing now is to take a trip to the junkyard and pick up a used MAF and its pigtail. Total expenses so far: $0.00. Can't go wrong with that. To be honest, I don't really care if it does anything magical or not. It's just an excuse to play with the FI to see what happens.

07-25-2008, 06:39 PM	#17 (permalink)
Targetnut Registered User Join Date: Jul 2005 Location: Manassas, VA Posts: 514	first you need to understand that the stock head only flows about 130cfm. Even then you'll likely find some pressure drop, and it might even go 1"hg (13.5"H2O/1/2psi) or so which will reduce peak power some, but really It's likely not to make a difference you can feel. Now if you port the head, go with a bigger cam, and bump up the compression, You'll be increasing the flow potential and that restriction will create a bigger pressure drop and be more of a factor. I was thinking about using a MAF, but electrically they work very different from an AFM and it was just looking to complicated. But I'm no electronic guru either. Now I'm working on a Megasquirt. this will use a MAP sensor and eliminate any measurement device in the intake tract __________________ Targetnut don't talk about it, just do it! Precision Import Service '93 2WD 22RE, Ported w/os valves, custom intake manifold, crane cam, 295cc injctrs, Supra AFM, Supra fuel pump, adj fuel pres reg, 70mm throttle, LCE header, V6 Taco cat, 14lb flywheel, Kevlar clutch, W58 and short shifter, 4.10 gears w/Truetrac, drop spindles and blocks, 245/50-16 Yokos on 16x8 wheels, 4WD fenders, bumper, and valence, skinned tailgate

07-26-2008, 07:12 AM	#19 (permalink)
Swansen Registered User Join Date: Jan 2007 Location: Michigan Posts: 254	I'm not exactly sure about what you were thinking, but these are not exactly options. http://www.yotatech.com/f116/mass-ai...sensor-115962/ http://www.yotatech.com/f116/maf-bypass-106148/

07-27-2008, 01:58 PM	#20 (permalink)
InternetRoadkill Registered User Join Date: Jan 2006 Location: San Antonio, Texas Posts: 789	Woot! Controller board for the converting MAF signals to VAFM signals is working nicely. Just need to scrounge a MAF from the junkyard and cross calibrate the two.