Apexi' NEO tuning/general tuning advice

[mattmk3]

Hey guys looking for some NEO tuning/general tuning assistance.

I've seen some very knowledgeable tuning help from members such as Cre, but I don't see much activity when i search for tuning stuff relevant to AFC's.

In this thread, There's some good help, but nothing on idle.
http://www.toyota-supra.info/forums/...xus-afm-2.html

I've been doing some research on tuning this little Neo, but I'm stuck at how to tune the idle a/f with the NEO or afpr or that adjustment screw on the lex afm. Currently I'm on the stock afm with the 550's and i've pulled fuel but i'd like to put my lex afm in and boost 14-15lbs and be more efficient instead of wasting these injectors.

Any tips on tuning my idle a/f? It's my only set back currently.

Let me know what other info you need, I can supply all.

[cre]

What specifically is your issue with the idle? Do you have a wideband installed? Is the ECU running in a forced, full time open loop mode (I don't recommend it with the Toyota TCCS systems)? Leave the bypass screw on the AFM alone, you don't need to use it in conjunction with the NEO.

Unless the ECU is put into a constant open loop mode (can be accomplished via a few different methods) the ECU will work to adjust the idle AFR on its own just as it does during low to medium load engine operation. This is closed loop mode. The only time you can manually affect the AFR without the ECU fighting you is when it's operating in open loop mode. Open loop mode is engaged when the engine is first warming up, throttle is at 70% or higher (I think it's about 70%), or there is a fault with certain components such as the O2 sensor... These are your tuning windows. Any tuning of the idle AFR will need to be done when the engine is in open loop mode. Tuning should be done to keep the cold idle AFR at about 13:1. Don't try to stray from the ECU's normal operation when it comes to tuning idle, cold operation and closed loop operation... just tune it so the ECU doesn't have to work it's ass off and so the two systems will play nice with each other.

[mattmk3]

Originally Posted by cre

What specifically is your issue with the idle? Do you have a wideband installed? Is the ECU running in a forced, full time open loop mode (I don't recommend it with the Toyota TCCS systems)? Leave the bypass screw on the AFM alone, you don't need to use it in conjunction with the NEO.

Unless the ECU is put into a constant open loop mode (can be accomplished via a few different methods) the ECU will work to adjust the idle AFR on its own just as it does during low to medium load engine operation. This is closed loop mode. The only time you can manually affect the AFR without the ECU fighting you is when it's operating in open loop mode. Open loop mode is engaged when the engine is first warming up, throttle is at 70% or higher (I think it's about 70%), or there is a fault with certain components such as the O2 sensor... These are your tuning windows. Any tuning of the idle AFR will need to be done when the engine is in open loop mode. Tuning should be done to keep the cold idle AFR at about 13:1. Don't try to stray from the ECU's normal operation when it comes to tuning idle, cold operation and closed loop operation... just tune it so the ECU doesn't have to work it's ass off and so the two systems will play nice with each other.

Well that makes a lot of sense! Thanks for clearing that up. How long do you suppose it takes the ECU to learn a new idle when i put the Lex afm in? And the proper reset for the ecu is pulling the ecu fuse from the fuse box under the hood for a minute or so correct?

As for the adjustment screw on the lex afm, what's a good position to put it in? (because it's not where it is stock, I already screwed around with it a while ago and i'm back at it so i don't remember where it was originally)

Thanks!

[cre]

It doesn't take the ECU long to adjust and learn any offsets as long as everything is already reasonably close to where it should be. The ECU can only adjust things so much, if factors are way off it's not going to get better and just start running well on its own.

Yes, just pull the EFI fuse for 30 seconds or so is all I've ever needed.

As for the bypass screw, It doesn't matter much. You'll be tuning around it with the fuel controller anyway. Just set it close to where you think it was and then worry about tuning with the NEO. The bypass airway screw is essentially just a primitive tuning device.

[mattmk3]

Now 1 more thing. I'm at it right now and I installed it and reset the ECU and I cannot get it to idle in a safe a/f range. It's off my AEM wideband... What am I doing wrong? I'm going to head out and warm it up so it is using the o2 to adjust idle a/f (correct?) because I think that's the problem, so we'll see how that goes. It's just annoying how many times I've swapped this lex afm in and out since i bought the damn thing. Searching high and low for a step by step installing it but it's all just word of mouth and random tips here and there. Simple thing to do I get that, but I do not want to run lean and do damage, i'm always super paranoid. No clue how some people just toss it in and just drive WITHOUT a wideband! Crazy.

[mattmk3]

Reset ECU while HOT, figuring it needed to be warmed up to use the o2 to adjust idle, but it did not matter, Idle is still OVER 18a/f. Went out for a drive with fuel pressure at 30 which i believe is too low, it was because i backed it off for the 550cc injectors with no lex maf, but then:

-Came back quick, readjusted that. Will STILL not idle at 15a/f like it did with the stock afm.

-Adjusted fuel pressure to 38psi no vacuum. No change, still over 18a/f off the scale.

-Adjusted the Lex afm screw all the way closed. Slight change in idle a/f.

-At cruise, it sits at 17-17.9 a/f
-At a slight incline, it sits 16.2 a/f
-I did not want to boost it but if i stepped into it a bit, it would gradually go through 15-12 a/f but i never actually got into good boost, too nervous, i feel like it's running LEAN and i'm frying things.

Or maybe that's normal and i'm just used to 550's with no lex afm? Is what i'm seeing normal? It feels good, but that's feel... AEM wideband is in the red most of the time and it just seems bad...

I'm getting super frustrated with this and I'm going to snap. What the hell am I doing wrong?