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Author Topic: Is the SAFC or similar compatible with the 22RTE?  (Read 12330 times)
Turbo4Runner
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« on: December 04, 2007, 08:24:54 PM »

Has anyone ever used an HKS SAFC on a 22RTE? I have used them on other turbo cars and coupled with larger injectors you can squeeze a fair amount of additional, tunable 'headroom' into the system.

My experience with them comes from 90-94 Mitsubishi Eclipse/Eagle Talon (DOHC 2.0 turbo). When turning up the boost on the factory ECU fuel cut was an issue exactly like it is on our trucks.

Using larger injectors and an SAFC allowed you to 'trick' the ECU into thinking there was less air flow coming in. Essentially if you used injectors that are 15% larger then stock, you could remove about 15% of the signal and it would allow you 15% more tuning room. (Numbers are approximate, but I have always used it as a starting place).

This is certainly no replacement for a full stand alone unit as the SAFC doesn't allow you to adjust things like your injector dead time, timing and the maps are some what limited (hi and low throttle maps and a configurable amount as the switch point). which means you are limited to a percentage over stock (30% is about the max in my experience, but the experience is not from a 22RTE). However its very easy to install and fairly easy to tune.

I know they support flapper style MAF's, and they can be had for around $200 from eBay. I had considered using that prior to installing MegaSquirt.

For my application MegaSquirt is a far better solution but if I was planning on staying closer to stock I think an SAFC would be worth a shot.

Any other experiences?
« Last Edit: May 15, 2008, 06:00:09 PM by mosk » Logged

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« Reply #1 on: December 04, 2007, 10:54:56 PM »

The issue with virtually all of the piggy back systems is that the 22RTE uses a very non-standard voltage for its AFM signal. Most modern EFI systems use sensor voltages in the 0V-5V range. The 22RTE uses an AFM voltage of 2.5V to ~9.0V. These two voltage ranges are not compatible.

Once, long ago, I tried to use a product (made by Link systems of New Zealand) that eliminated the AFM and replaced it with a user-programmable MAP sensor. Unfortunately, this product operated in the 0V-5V range, and it proved to be *absolutely impossible* to get this thing to work right with the stock ECU. We tried all sorts of things, including building a small op-amp to step up the output voltage, but the gap between this device and the stock AFM signal requirement was just too weird to bridge. As a side note, this product had one of the most painful user interfaces I have ever encountered -- and I've worked in the software industry since 1995, so that's saying a lot. DO NOT WANT!

So while I have not specifically tried a SAFC, I don't have much confidence that it will work.

AFAIK, there are only three devices that will work as piggyback signal modifiers to the stock AFM voltage. They are:

1. The HKS PFC F-CON. HKS made a 22RTE-specific version of this little box, with a 22RTE ECU wiring harness and specific 22RTE chip. This unit had a single potentiometer that could be tweaked for additional fuel enrichment. You could add a fuel cut defender, and also an HKS GCC (graphic control commander?) that acted like a graphic equalizer and took that one potentiometer and divided the signal into 5 or 6 "bands" of adjustment, I believe by RPM. These are now long discontinued but still turn up from time to time on eBay.

2. The Split Second ARC2. In stock form, this device has modifies AFM signals in the range of 0V to 8V, but i believe Tim Rodda at TCR/Toyotaperformance.com had Split Second make a special version for use with the 22RE/RTE that works in the appropriate range for our vehicles. See Split Second or toyotaperformance.com for more info.

3. The Perfect Power SMT6 (NOT the newer SMT7). This is a loved/hated little box that purports to allow you to do all sorts of wonderful things, including modify AFM signal voltages in a range from 0V to 10V, and gives you a generous 128 cell table to do it in, which is a generous amount of resolution. It also has a second table that allows you to control an additional injector. Unfortunately, the device has a "meh" reputation for quality control, and is reputed to have some power issues, shutting off unexpectedly, etc. The newer SMT7 addresses these and other issues, but it operates in the more standard 0V-6V range, IIRC -- well, it's either 0V-5V or 0V-6V, but certainly NOT the necessary 9V.

Anyway, AFAIK, those are the only three devices that will work with the first generation 22RE/RTE EFI system.

-Jeff
« Last Edit: December 05, 2007, 12:38:41 AM by mosk » Logged

Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
Turbo4Runner
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« Reply #2 on: December 04, 2007, 11:25:58 PM »

Oh right.. I forgot about the 'unique' voltage range on these mafs. The SAFC only supports 0-5v maf signals... I wonder why Toyota decided to use such an odd voltage range?

My truck had the SMT6 in it when I purchased it, and I couldn't get rid of it fast enough. For the money and complexity of the SMT6 you might as well go with MegaSquirt. Especially with all of Darin's documentation..  Grin
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sno4rnr
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« Reply #3 on: February 16, 2010, 07:21:18 PM »

I know this post is suuuuper old ( but I just saw it as I am a newb ) but has anywone ever tried a AEM FIC ? its fairly new and I have used it on a couple other vehicles, it has an onboard 3 Bar map sensor and can directly drive the injectors so you dont need to trick signals in order to get your output fuel wise and can even spoof signals to the ecu.

Just a thought, I have a spare one laying around and am contemplating trying it.

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« Reply #4 on: February 16, 2010, 08:28:16 PM »

Hi,

This is the FAQ section of the site, so "old" doesn't mean "irrelevant"; these threads are here because they are still relevant. Also, this vehicle was made in 1986 and 1987, and that requires some perspective: When this powerplant was new, Ronald Reagan was president, the Soviet Union was still a nation, the Berlin Wall had not yet fallen, and Microsoft had not yet released Windows 3.0. There is very little that is "new" about this motor.

History aside, this is the most important part of this topic:

Quote

The issue with virtually all of the piggy back systems is that the 22RTE uses a very non-standard voltage for its AFM signal. Most modern EFI systems use sensor voltages in the 0V-5V range. The 22RTE uses an AFM voltage of 2.5V to ~9.0V. These two voltage ranges are not compatible.


Unless the AEM FIC supports a 2.5V to ~9V AFM signal voltage it won't work. Period.

I took a quick look at AEM's specs for the FIC, and this is what they list:


F/IC Specs
Processor: Dual 16bit 32mips processors.
Logger:
   Internal: 64 KB, 10ms max sample rate,
   PC: 10ms fixed sample rate.
Pressure: 2psia - 40psia +/-.5psia resolution .1psia
MAF: 0vdc - 6vdc Input, 0vdc 6vdc Output, overload protected
Power: 8-15vdc
Log switch: GND to activate
VTEC: High-side driver, 6 amps max, overload protected
Injectors: 1.7 amps max, overload protected
O2 : 0vdc - 4.95vdc
Size: 5.5"L x 4.6"W x 1.4"H


So based on that, no, this won't work. Too bad, it sounds like a nice interface.

-Jeff
« Last Edit: February 16, 2010, 08:58:46 PM by mosk » Logged

Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
sno4rnr
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« Reply #5 on: February 16, 2010, 10:09:58 PM »

Understood,

However it is possible to leave the factory AFM in there and since it is a piggyback the factory ecu is happy, and you can drive the injectors directly off the FIC using the on board 3 bar map ( IE no need to modify the AFM signal at all ).

just a thought, maybe ill try it out and see what happens. My thought process is I dont care what the ecu tells the injectors to do if it isnt actually connected to them, and I can drive all my fueling straight from the piggyback.

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mosk
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« Reply #6 on: February 16, 2010, 10:33:42 PM »

If you are going to do that, why keep the factory ECU at all? Why not just run a MegaSquirt or other standalone ECU?
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Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
sno4rnr
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« Reply #7 on: February 16, 2010, 11:15:55 PM »

Good question, but I have a couple reasons:

I dont really want to run a megasquirt as I have tuned a few and they are always a little "buggy" ( I tune alot of EFI, from remapping OEM systems to full standalones like haltech's motec's aem's FAST etc )
I have 3 other cars on full standalones and if I do it to this one I really honestly think the wife will kill me  Wink

and I live in california which means every 2 years I gotta go back to stock for smog, so with a piggyback that allows me to tune for more boost etc then I can pull it and put in the jumper harness for smog reasons, and I also get some of the corrections for timing based on temp and knock control etc.

for me personally I just want the ability to fine tune for a little more boost / added IC ( possibly will swap over to a garrett 28r since I have one ) so the need for a full standalone really isnt there.

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mosk
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« Reply #8 on: February 16, 2010, 11:28:16 PM »

Oh, OK. With three standalones and MS experience, it sounds like you know more than I do, lol  Grin (though I do run a FAST standalone on mine, so I'm not completely ignorant...)

The funky AFM signal voltage really makes it hard to run any aftermarket gear at all.

So are you considering using an AEM F/IC to drive additional injector(s) under boost, or to drive the primary/only injectors? Would your F/IC control timing as well?

Sorry, I'm sort of scratching my head to understand how the F/IC will function as a piggyback in this scenario since it can't interface with the stock ECU.

BTW, I, too, am in CA and know all too well about CA's smog rules.  Roll Eyes
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Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
sno4rnr
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« Reply #9 on: February 25, 2010, 02:53:44 AM »

Well now that I have spoken with the guys at AEM, you can add this to the list of things that wont work. It would seem that unless I built a circuit to put the voltage into something the FIC can use as well as pass through to the oem ecu what it wants to see its a no go, and honestly thats more than I want to try to do . SOO it seems I will be on the megasquirt track now , seems there is a decent support for this one and w p&p I may as well give it a go as I KNOW I cant leave this thing stock lol.

thanks for the help.

btw, how are you getting your truck through smog w the fast setup? I am wondering if I can "hide" everything well enough I can sneak it through without having to undo everything.
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« Reply #10 on: February 25, 2010, 04:15:23 AM »

Well now that I have spoken with the guys at AEM, you can add this to the list of things that wont work. It would seem that unless I built a circuit to put the voltage into something the FIC can use as well as pass through to the oem ecu what it wants to see its a no go, and honestly thats more than I want to try to do . SOO it seems I will be on the megasquirt track now , seems there is a decent support for this one and w p&p I may as well give it a go as I KNOW I cant leave this thing stock lol.

thanks for the help.

OK, well, I sort of assumed that would be the case, but now we know.

Quote
btw, how are you getting your truck through smog w the fast setup? I am wondering if I can "hide" everything well enough I can sneak it through without having to undo everything.

I'm not, and it's not currently smogged -- no joy here  Cry My truck is parked in my driveway until I come up with a solution. Unfortunately, inspiration hasn't struck yet, plus I have a life to live, so the truck is going to have to wait a while longer. I hope to get back to it at some point, but I have too many other irons in the fire at the moment. If it were a simple problem to solve, I would have solved it simply, but so far a simple solution is eluding me.

According to Ron (ronmar on this forum), the MS PnP electronics can be swapped back and forth with the stock ECU in about 5 minutes, plus maybe swapping some sensors under the hood. My FAST system, on the other hand, has its own wiring harness and GM sensors, so I can't move things back and forth without a lot of work. But the electronics are really the least of it: I basically built a race motor that runs on pump gas, so it's not really not smoggable without removing almost everything that's been bolted to the block; live and learn, lol. if I had it to do over I might have chosen a different vehicle/motor/level of commitment, lol. As it is, I have a full life with a wife, kids, work and lots of other stuff going on, and this truck has already received waaaaaay too much of my attention, so it's just going to need to wait its turn.

-Jeff
« Last Edit: February 25, 2010, 03:41:03 PM by mosk » Logged

Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
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