Nice write up.
Is there no advantage for the UZ AFM on a 7M-GE? (ie N/A)
I have had many people PM me asking why and how the 1UZ AFM works on a 7M in combination with 550cc injectors and an SAFC. Whilst there are many sources on the net that state that it does work, none of them really explain WHY it works. So for those 7M, AFM and SAFC novices, heres a (hopefully) simple explanation of why things work as they do;
The reason the 1UZ AFM is used is long and complicated, but here goes
The sensor in the 1UZ AFM is identical to that used in the 7M AFM, but the diameter of the throat of the 1UZ AFM is bigger. The bigger the throat, the slower a greater amount of air moves past the sensor (like sucking air through a straw, and then through a vacuum cleaner pipe. the air through the straw moves faster but there's less of it.) An AFM reports air velocity to the ECU, and based on what the ECU knows about it's AFM (throat size) it fuels accordingly. Obviously when using a 1UZ AFM the throat of the AFM is bigger, therefore it takes more air rushing past the sensor to make the ECU think it's getting the same amount of air it would get from the smaller throated 7M AFM.
The result? Because youre introducing more air to gain the same velocity reading you can have higher boost (more air) before boost cut kicks in (around a 25% rise, as the thoat of a 1UZ AFM is around 25% bigger). However, you also get 25% less fuel, which can lead to overly lean fueling conditions, as the ECU is fuelling for 25% less air than it's actually getting.
Now, the reason you would use 550cc injectors and an SAFC is simple. An SAFC (like a 1UZ AFM) also lies to the ECU. The SAFC interupts the AFM signal to the ECU, telling the ECU it's getting more or less air than it is, depending on how the SAFC is tuned. So if you have an unsafe/too lean tune by using the 1UZ AFM alone, you can add fuel back in by using the SAFC. However, when you add more fuel back in with the SAFC, you are undoing the work done by the 1UZ AFM (as the SAFC is now telling the ECU that the engine is getting less air than the AFM is reporting to make the ECU supply more fuel), and your boost cut lowers again. The solution? Add bigger injectors! The ECU doesnt know that the injectors are bigger, therefore it pulses them open for the same amount of time,delivering more fuel. The SAFC can now be used to take fuel out again, raising boost cut again. So now the ECU thinks it is getting less air than it is, and supplying less fuel than it is. The SAFC is able to control this balance to a safe level
So, in simplest terms for the dumbasses;
7M + Stock AFM, ecu and injectors = 11psi boost cut
7M + 1UZ AFM, stock ecu and injectors = ~16psi boost cut, but possibly over-lean fuelling
7M + 1UZ AFM, SAFC and stock injectors = safer tune, but around about 14psi boost cut due to fuelling change through SAFC (if properly tuned to correct AFRs)
7M + 1UZ AFM, SAFC and 550cc injectors = safe fuel tune, boost cut around 20psi due to SAFC being able to remove over fuelling caused by 550cc injectors
HOWEVER..... Once you get over 15psi on a CT26 (if you can) timing becomes an issue, something the SAFC or stock ECU cannot contol. If you want big power from a 7M, you are now entering aftermarket standalone ECU territory, but that's a story for another day kiddies....
Last edited by whatthe?; 14-04-2007 at 12:20 AM. Reason: typos farkin
Project megap00 - Gave up and sold up. Money tree died
Nice write up.
Is there no advantage for the UZ AFM on a 7M-GE? (ie N/A)
Originally Posted by skiddz
Will a 7M HG survive more than 11psi?
Friends
ed_jza80 has not made any friends yet
1UZ AFM is Karmaan Vortex, 7MGE is flap, they are not compatible.
Just to clarify something further, when you use the 1UZ AFM, you reuse the 7MGTE AFM electronic box. You do not use the 1UZ box.
Peewee
1985 MZ12 Soarer - 1UZ Powered
2013 86 GTS
You can use either, it's the same sensorOriginally Posted by CrUZida
Project megap00 - Gave up and sold up. Money tree died
dam man you have a lot of patience to write up that.
good work!!!
Matty
Same loom plugs as well? I was under the impression that you had to reuse the 7m-gte electronics(hence my answer in another thread about this).Originally Posted by whatthe?
Oh, and as a bit more extra information. There is a small bypass area in the AFM that can be adjusted by making up a screw. This allows some fine tuning of the amount of air going through the AFM. Most people don't bother though seeing as the S-AFC will allow them to make any adjustment that is necessary. I think if you use the screw and set it properly you don't actually need to use the S-AFC.
+rep for explaining it nicely!
EDIT: Spelling and stuff I forgot.
Plug is definitely the same, but I wasn't aware that the electronics were identical.
Peewee
1985 MZ12 Soarer - 1UZ Powered
2013 86 GTS
Yep, identical. Same part number printed on the top of both as well
Project megap00 - Gave up and sold up. Money tree died
Good write up, but i think one or two point (AFAIK) need clarifying.
The 1UZ AFM tricks the ECU, not by allowing more air at a slower velocity, it allows extra air that (via the bypass chamber) that the ECU does not know about. The ECu makes its initial fuel calculation based on the signal from the AFM, when it reaches a predetermined voltage, fuel cut (nasty!!) and this is around the 9-11PSI mark, depending on who you ask.
Meanwhile we have snuck extra air in that the ECU does not know about, how do we use this to make more power? The second stage of fuel calculation (or the fine tuning adjustment) occurs via a signal from the oxygen sensor, this does not have any ability to trigger a fuel cut.
Hence the extra air gets in via the by-pass, the first stage of fuel calculation does not trigger the fuel cut, and the O2 sensor makes the fine tuning to get the mix write.
This is summarised (as well and briefly as i can remember) from a guy in Canadia (land of the flip top head!!) Supra Sonic I think and his website has a very detailed article on this that explains the Toyota Fuel system calculation much better than i have.
No sur3e how identical the electronics are but i believe it is a straight swap so might as well do it.
I think the reason for larger injectors is that about 15-16psi you are starting to run the stocko's at close to 90 or % duty so it is more of a safety thing. And yeah the SAFC helps ensure you have a nice safe fuel tune.
Cheers all.
Jim
I currently have a 1UZ AFM and am on the look out for 550cc injectors, hint hint anyone???
They call them fingers.... but i've never seen them fing!!!!
Originally Posted by Supra-Jim
Obviously you havent tried to fit the 1UZ AFM, when you do you'll realise how much bigger it is than the stock one (it takes quite a bit of persuasion to get it into the concertina)
The reason for using 550cc injectors is not that the stock ones top out at 14-15 psi, it's that using the 1UZ AFM makes the car run leaner than it otherwise would and adding fuel back in via the SAFC lowers the boost cut back to just about stock. When you put bigger injectors in you can now use the SAFC to remove fuel, and this raises the boost cut again
Project megap00 - Gave up and sold up. Money tree died
Except in the MS13x, where the 7MGE has a Karmann Vortex doover.Originally Posted by CrUZida
so why not just buy the new map ecu2 that way you dont need any maf at all and you can tune the ass off it while also having some control over timing as well,sure its about $800 but if you buy a lexus maf$100-$150 apexi safc $350-$450 only to still not really be able to control advances in timing all of sudden it seems pretty good value.
yes ?no?feedback or experiences with useing one would be great.hope im not off topic,shoot me if i am.
spaces, commas, full stops, and use of the "enter" key are all overrated apparently?
my eyes have just been raped.
Elmo.
also-
7mgte + 550ccs + real good CAI + 1uz afm + SAFC = leaning out way to much at 4000-5000rpm.
7mgte + 550ccs + real good CAI + 7mgte afm + SAFC = boost cut at around 13.5-14psi...
just thought i'd add my own experiences nice writeup matt
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