lex afm, apexi neo, 440 inj. will this work

[Kai]

If you add the Lexus AFM without increasing the fuel injector size, you're shovelling in 25% more air without the corresponding match for fuelling. TCCS expects 440cc injectors, and its regular AFM. The lexus trick works with 550cc injectors because the AFM housing is 25% larger (550cc = 440cc + 25%). If you increase fuelling without air, you run rich, and get bore wash. You increase air intake without increasing fuel, you run lean and run the risk of turning your combuston chamber into a plasma cutter. Doesn't matter how much you trim it out on a piggyback, you're STILL GOING TO BE RUNNING LEAN.

Whats the point of telling you people how things should be done, explaining WHY and the pitfalls of it, if you insist on half-assing it because you somehow magically 'know better'?

DO IT PROPERLY OR DON'T DO IT.

 

[Poodles]

If the boost remains relatively the same, the addition of ONLY a Lexus AFM will do no harm at all. The ECU has enough capability to correct for the "strange" air sensor data its getting. May also lower fuel cut to compensate, since it modifies the open loop mapping by what learned values its recorded in closed loop, though I have not personally experimented.

As with any mod, always remember to reset the ECU before running it.

Boost doesn't matter, though it will complicate the issue. The ECU does NOT have the ability to correct for 25% more air, and won't lower fuel cut. You'll run lean, period, end of story.

SAFC MIGHT be able to tune with it, but adding that much fuel is seriously going to fuckup the timing tables and cause loss of power in the best case, and major engine damage on the worst case.


You haven't done this yourself, I have put my car on an inspection dyno with and without a lexus AFM and it was VERY lean with the lexus AFM alone. This wasn't even at open throttle! Unless you have a way to physically increase fuel (more fuel pressure/flow, larger injectors) you're going to damage something. Toyota tuned these cars rich, but not THAT rich.

You're wrong, and you haven't do it yourself. Disinformation in the tech section is not tolerated.

 

[SideWinderGX]

You say that like you've read it on the interweb, no doubt written by an "expert".

I've tried, tested, and logged all of what I just described, myself. Might want to check yourself before spreading hearsay over tested fact.

OK, post it up.

 

[mkIIIman089]

Unfortunately the reference material had died with the old forum, so its no longer available. (yea, yea "That's convenient!"... well that's the truth.)

The gist of my finding was that is was JUST within the ECU's correction ability (Show me the documentation that it's limit is in fact less than the magical 25%, please) with no other fuel mods to bring AFRs back to normal. With the bone stock fuel system obviously closed loop was 14.7:1, and open loop peak was about 10.1:1. With the ECU reset and the Lex AFM installed, it was at worst an average of .1:1 leaner and open loop peak moved to 10.3-10.5. Hardly plasma torch.

 

[Poodles]

Unfortunately the reference material had died with the old forum, so its no longer available. (yea, yea "That's convenient!"... well that's the truth.)

The gist of my finding was that is was JUST within the ECU's correction ability (Show me the documentation that it's limit is in fact less than the magical 25%, please) with no other fuel mods to bring AFRs back to normal. With the bone stock fuel system obviously closed loop was 14.7:1, and open loop peak was about 10.1:1. With the ECU reset and the Lex AFM installed, it was at worst an average of .1:1 leaner and open loop peak moved to 10.3-10.5. Hardly plasma torch.

On the ragged edge of what the ECU can tune for isn't remotely safe, and it's a hell of a lot leaner than that.

 

[mkIIIman089]

Mind you that was at sea level, so few places in the world will have a worse outcome than that. Its on the edge of what the ECU can do to keep the AFRs BONE STOCK, which many consider vastly too rich anyway. Not implying that this is an AFR tuning method, simply that it isn't harmful, and likely won't net any benefit that the Lex AFM mod is done for anyway.

If you experienced different you either didn't reset the ECU's learned value, or you didn't give it enough time to recalibrate after the reset.

 

[Poodles]

So running dangerously lean for 50 miles is safe? Do not post again.

 

[Supracentral]

Folks,

I've got a few comments to add to this and I'll ask that all of you tone it down a notch. This doesn't have to get personal and if you're unhappy with the moderation of any section of this site, contact an admin.

As for the topic at hand, let's make a few things perfectly clear.

#1 - it is possible to run a stock fuel system with a Lexus AFM. I did it personally a decade plus ago. It's dangerous, your tune has to be 100% perfect and if anything goes wrong, you're probably looking at a set of melted valves or worse. At the very least throw a big fuel pump in the tank...

#2 - Today there are an incredible number of fuel computer options, injectors are incredibly cheap (what you guys are paying for a set we used to pay for one injector back in the 90's...) and you're pretty much an idiot (IMO) for even bothering with something like this.

Simply put, it's primitive, there are better ways of going about it with a larger margin of safety without breaking the bank. To me, that makes it a stupid way to achieve your goals, but it is possible.

Again, let's tone down the hostility folks.

DO IT PROPERLY OR DON'T DO IT.

Adhering to that philosophy will save you a lot of grief.

 

[mkIIIman089]

OK, to ensure there isn't some misunderstanding, my setup is: Lex AFM, 3 bar base FP, Walbro 255 (The HP one), professionally cleaned 440s, as well as an SAFC 2 with a tuning scheme I developed on my own. Plus more than enough monitoring equipment onboard to be able to check almost any important value at a glance.

I don't think there is any benefit to running solely a Lex AFM and no other mods, I don't think its a risky endeavor either since a relatively healthy EFI system has enough capability to increase inj duty cycle per AFM Hz output to bring AFRs back to the stock values, and in all likelihood reduce the power cut to a lower AFM Hz output as a result. Thats all I'm saying.

 

[Supracentral]

3 bar base FP, Walbro 255 (The HP one), professionally cleaned 440s

Ok, now a 3 bar base FP isn't stock. (Stock base fuel pressure is 33 to 40 psi at idle with the hose disconnected. With the hose connected it should be in the 23 to 30 psi range.) Injectors are rated at a specific pressure. Your 440's are likely acting like 490's at this point. The downsize to running a high base is:

1. More wear on the injectors
2. More wear on the pump (remember pressure is a measure of resistance to flow)
3. Spray patterns go to crap (potential driveablilty, fuel pooling and/or emissions issues)

One of the things about fuel pump failures is that they often flow weak before they stop flowing at all. Generally you don't see it at open flow, but flow under pressure. This is part of that margin for error I was talking about earlier. If you get a fuel pump falloff and you're relying on that 43.5 psi base and you might find out the hard way how lean a Lexus on 440's can go.

Provided you're aware of all of this, have fun with it. Personally I wouldn't go down this road (nor would I recommend anyone else does) but if it works for you, it works for you.

 

[SideWinderGX]

Unfortunately the reference material had died with the old forum, so its no longer available. (yea, yea "That's convenient!"... well that's the truth.)

The gist of my finding was that is was JUST within the ECU's correction ability (Show me the documentation that it's limit is in fact less than the magical 25%, please) with no other fuel mods to bring AFRs back to normal. With the bone stock fuel system obviously closed loop was 14.7:1, and open loop peak was about 10.1:1. With the ECU reset and the Lex AFM installed, it was at worst an average of .1:1 leaner and open loop peak moved to 10.3-10.5. Hardly plasma torch.

Good to know, I'll take your word for it that the data existed.

I can't prove with concrete evidence it is less than 25% because the only proof I have is Supracentral's post here: http://www.supramania.com/forums/showthread.php?t=39856

Of course, that is before the o2 sensor correction, so maybe the 25% claim is valid. It still is on the ragged edge though.

 

[Supracentral]

Good to know, I'll take your word for it that the data existed.

I can't prove with concrete evidence it is less than 25% because the only proof I have is Supracentral's post here: http://www.supramania.com/forums/showthread.php?t=39856

Of course, that is before the o2 sensor correction, so maybe the 25% claim is valid. It still is on the ragged edge though.

Actually it's 20% --- but that's "close" since we all know the 7M ECU's run pig rich. So the variance just makes the car run "a little leaner" which isn't really all that much of a problem.

However, understand that since you are at the absolute limit of adjustment, there's no margin for error. On a stock car with a stock AFM, a small vacuum leak can be compensated for by the ECU. On a stock car with a Lexus AFM, there is no adjustment left in the system. If you develop a small leak, you're going to run lean. That is a problem.

This is why I say it's possible but not smart. 0% margin for error is not a good position to put yourself in.

 

[lowtaco]

Ive kicked the idea around of using a Lex AFM with stock injectors, SAFC, stock CT @ 10psi and wide band. Reason why, because I am running rich as a mofo under WOT 10.5-11.0 and this was with the SAFC pulling 20% fuel through the RPMS. At stock settings I was getting a 10.0 @ WOT prolly richer then that my AEM I dont think will read lower. But I myself would rather be on the safe side and get a new set of 550's over the tired stock 440's.