mastacox

I've got a quick question for you Dale-

I know the AFRSC has a map of values in it, are the map's values AFR values (E.G. 12.5:1) or percentage values like in the FTC (E.G. 9.5)? The description on URD's website almost makes it sound like you are able to put AFR values into it (but they could be over-simplifying things...)

mt_goat

Percentage, I thought you had one of them yourself.

mastacox

Now Dale, you know my 4Runner has a narrow-band oxygen sensor and as such I use the oxygen sensor clamp built-in to my FTC1-E...

We've gone over it only eleventy-billion times

mt_goat

Oh yeah, I think I'm getting oldtimers.

Speedy

It's the ECU not fighting you part that I'm most interested in, I understand the principle of how it works. It basically tells the ECU you're at 14.7:1 and you put in values to make the actual AFR what YOU want it to be.

What year 3.4L motor are you running it on? I assume from the product's description that your motor uses a WB O2 sensor for the ECUs AFR readings?

I'd LOVE to be able to have a 13:1 in low boost (1-2 psi) then go to 12.5 at 3-4 psi, then 11.5-11.8 above 4 psi.

How many miles do you have on the unit ?

mt_goat

It's a 5VZFE from a 2001 Taco, I only have about 800 miles on it so far. (yes, it has a WB for the front O2 sensor)

Speedy

Cool. Keep me posted on the results. I've heard it takes about 1000 miles for the ECU to start making adjustments to get back to 14.7:1.

Speedy

Well, I got the truck back. The guy did an awesome job on fixing the studs. He removed all three stock studs (which he said were grade 5 or 6 and break way too easy) and replaced all of them with one size larger grade 8 hardware (looks like a bolt and nut/washer combo). The work looks really good and he said I shouldn't have anymore problems with breaking them as it was now stronger than stock.

mt_goat

Humm....well since my last ECU reset all it has done is get better. The guys I've seen that have to reset the ECU to keep the closed loop ratio right are just running an FTC and didn't have the A/F sensor Cal.

Here's some more info about it:
http://www.customtacos.com/forum/showthread.php?t=51193

Speedy

Thanks. I'll do some reading up on this tomorrow and post back any ideas I have.

My confidence is slowly coming back after this $300 exhaust stud issue. That's still burning me a little.

midiwall

I can feel a difference in about 300-400 miles. I've actually wired a momentary pushbutton into the ECU constant power lead so that I can reset the ECU from inside the truck instead of having to pull the fuse.

Speedy

Why did you need an AFR Calibrator? Your truck being a 96 should just have the regular narrow band O2 sensor that is supposed to be more easily fooled??

And do you have an AFR gauge to actually see the AFR changing from what you have set it to in closed loop?

midiwall

The phenomena of the ECU pushing back against faking is common. In my case it's pushing back against thee SMT5.


Yeup.

Speedy

Man that's so weird. You'd think if you're telling the ECU it's getting a 14.7:1 signal, that would be the end of it. You could then set it to whatever you want. So you're setting your AFR to what value, and what value is it 300-400 miles later?

A local tuning shop said Toyotas are notoriously hard to tune because of this very reason. He said the factory ECUs are stubborn.

Here's a thread from TTORA where a guy had issue with the AFR calibrator:
http://www.ttora.com/forum/showthrea...AFR+Calibrator

The tuning shop ended up removing it to get the engine tuned. They ended up setting him to 14.7:1 in closed loop, meaning even under boost he's 14.7:1. You guys know how much research I've done, and I haven't found anyone successfully get anything but 14.7:1 long term in closed loop. Hopefully being forced into 14.7:1 in closed loop boost is not too detrimental to engine longevity.

midiwall

I thought you and I had gone through this, but I may be confusing you with someone else.

The short form is that I have had HORRIBLE results from the SplitSecond spoofing boxes, specifically the ESC1. I've been pretty vocal in public regarding how I feel about them and the "leading supplier of SplitSecond products in the Toyota truck community".

I alluded to it in a previous post here in your thread, but I was asked in a PM to retract the statement. Drop me an email or PM if you'd like details.


In my case, I can put the AFR pretty much anywhere I want until the ECU catches up. Say I add fuel to get it to 13:1 or so under moderate power. 400 miles later it'll be sitting at 14.7:1. I covered this general phenomena about a year ago here:

https://www.yotatech.com/forums/f2/got-s-c-piggyback-wanna-try-something-77040/

note: This is _without_ using anything to attempt to fake out the O2/AFR signal. See above for my feelings on the spoof boxes.

Speedy

What do you mean?

I'm getting kind of lost here. Either it's OK to run 14.7:1 in closed loop or it's not. If it's not, then what's the point of doing a SC to begin with if this value pretty much can't be changed? If it is, then you just live with slightly reduced power in closed loop, and tune for open loop to be 11.5 or so.

Seems like that other thread you referenced started suggesting that tuning Open loop affected closed loop? That confuses me as I thought once you were in open loop the ECU no longer monitored AFR.

midiwall

We're walking a line here between black boxes that are sold for the purpose of affecting closed loop A/FR, and then the reality of them working or not.

If you intercept the MAF signal, you can create a state where you can create a rich mixture. _In my experience_ this is a temporary change, because the ECU will continue to try to push that mixture back to Stoich (14.7:1). From that other thread, it looks like other folks have seen this happen as well - and some have not. It's VERY evident on my truck.

To combat the ECU doing that, the theory is that you fake the ECU into thinking that the engine is already running at 14.7:1 so that it won't adjust the mixture. This is the marketed purpose of the ESC1 and other boxes. And this is also where I (and a few others) have different feelings between "marketed hope" and "reality".

My statement that you quoted is in reference to my NOT running the ESC1 (or equivalent) but I _am_ running the SMT5 which is hooked up to allow me to adjust fuel deliver by modifying the MAF signal.


Hmm... I'll have to go through the thread again, (unless you can point me to what I said), but if I said something like that then I had it backwards...

You want to tune Closed Loop in order to create a smooth transition in terms of fuel flow on the way to Open Loop.

There are a number of ways to force more fuel at open loop, and "we all" know that we're aiming for something pretty rich, 12:1 or so. If you come up onto the point of open loop with a Stoich fuel mixture, and then all-of-a-sudden you start dumping fuel, the engine will stumble while the timing gets advanced to keep up. In order to combat that, "it would be nice" to be able to tune in closed loop so as to make the transition more gradual.


Now, there is inevitably some crossover between Open Loop and Closed Loop around the fringe area of the tuning tables. There are only so many slots, and they're not very granular. As such, you can easily find a cell in the table where, depending on other things going on, you could be in Open Loop _OR_ Closed Loop. In that case, you'd want to tune the cell for Open Loop.

Speedy

Ok, now I'm back on track. So if there is no real way to modify closed loop AFRs, what is one to do? Do we just live with some stumbling going from closed to open loop? I presume the 14.7:1 in closed loop under boost is "ok" from a motor stand point? With Nissan Xterras and Chevy Cobalts coming with SCs from the factory, I would think they run at 14.7:1 all the time as well.

Finally...you had some engine issue a while back. Was that due to a lack of fuel mods, or did you have fuel mods and STILL experience the cracked head? Any ideas what caused that?

midiwall

Other people have had different results with the spoof boxes. "YMMV"


Generally, Stoich is considered "lean" under boost. Remember what that number is, its the point of maximum burn efficiency in a gasoline engine (the number is different for diesel or propane).

http://en.wikipedia.org/wiki/Stoichiometric
http://www.taftan.com/thermodynamics/COMBUST.HTM


I DID have fuel mods running... Our best guess is that I may have been running TOO rich AND being able to actually burn the mixture, thus creating excessive heat in the cylinders, which lead to the burnt valve.

We never really looked at trying to tie the cracked head in with the high temps - the crack could have been there for quite some time.

Speedy

Thanks for all the info. I'll have to keep digging on this. I've got 75% of the system setting in my guest bedroom now (SC, trans gauge, boost gauge, plastic to fab up my gauge mount, LC-1). I'm now waiting on my custom Nordskog AFR gauge to go with the LC-1. I plan on building my gauge mount out of some of the plastic and installing the gauges above the single DIN Pioneer head unit.

The last thing I have to figure out and order is the fuel upgrade and whatever piggybacks I'm going to use.

After my exhaust bung debacle I'm taking a week off from this thing.

I'm pretty sure I can install the SC, but I may see if there's anyway I can have it done at a local dealership, and "help" with the install so I can learn how it's done (and shoot a few pictures). There's a pretty good dealer here that's done some of these, but they charge $530 for the install (ouch). Might be worth it for the 18 month remaining power train warranty though.