Stock ECU air fuel turbo observations at 5 pounds (1 Viewer)

[asuddendeath]

I noted tonight when power breaking to build boost that at around 3 pounds of boost the A/F starts to go from 13.5:1 to 11:1. (around that)
Also seems as soon as it hits 2nd it goes to 10:1 or richer.

What do others see?

Ill find out what 3rd and 4th does at WOT.

 

[audi2nr]

is this a wide open or very close to situation? probably going from closed loop fueling to open loop? at least its going toward rich under boost and not the other way.

 

[asuddendeath]

WOT. I AFM or MAF must read some amount and assume as RMP goes up to increase fuel. But they overdo it so it goes very rich.
Its very true in 2nd gear.

Pic is in 2nd gear maybe 4000-4500RPM

 

[scottryana]

Yep that is the open loop condition that we capitalize on to do a turbo on a stock ECU.

 

[omergin]

i think its part of oem ecus knock prevent protocol.

 

[scottryana]

Not on the US ECU. It is simply Open loop vs closed loop since the stock O2 sensors are simply narrow band.

i think its part of oem ecus knock prevent protocol.

 

[landtank]

Here in the US our ECUs respond to a MAF signal above 3.9v by running rich and pulling timing. The only way for that to happen in a NA truck is for there to be a fault in the system. It looks a lot like limp mode.
You might watch your timing as well to confirm a similarity.

 

[scottryana]

Are you saying a stock NA truck can not run 10:1 without a fault in the system?

Here in the US our ECUs respond to a MAF signal above 3.9v by running rich and pulling timing. The only way for that to happen in a NA truck is for there to be a fault in the system. It looks a lot like limp mode.
You might watch your timing as well to confirm a similarity.

 

[landtank]

Are you saying a stock NA truck can not run 10:1 without a fault in the system?

I'm saying the only time I've seen an AFR of 10.1 is on a boosted system. During my testing a stock system open loop runs at 13 with wide open throttle. Due to where I live that is at sea level and cool temperatures so probably a rather dense air.

 

[scottryana]

That doesn't match my experience on several trucks but good to know.

 

[landtank]

I’d be willing to check it again but my truck is way past the point that it can be easily done.
Now that I think about it, it was running on flat highway in second gear. Maybe increasing the load by pulling a hill would have brought that out.

 

[Heckraiser]

Means you've got room for some more boost!

I was getting around 11.4 with the same setup and a little leaner when I added the intercooler. That's with the 5.8psi spring and reading 5.8psi on the gauge.

 

[jertiffauk]

What's the AFR point you want to stay under? I'm replacing my failed WG actuator and bumping up the boost to 8-10 PSI. Installing gauges to monitor AFR/Boost...

What AFR numbers have you seen at high altitude? ( My truck lives at 7-11K Ft) It would seem like at higher altitude you would have less problems leaning out?

 

[scottryana]

Under boost try and stay under 12.5-12:1 when under moderate boost and a little richer with more boost. @10psi without any control of ignition I would want 11:1.

What's the AFR point you want to stay under? I'm replacing my failed WG actuator and bumping up the boost to 8-10 PSI. Installing gauges to monitor AFR/Boost...

What AFR numbers have you seen at high altitude? ( My truck lives at 7-11K Ft) It would seem like at higher altitude you would have less problems leaning out?

 

[asuddendeath]

Means you've got room for some more boost!

I was getting around 11.4 with the same setup and a little leaner when I added the intercooler. That's with the 5.8psi spring and reading 5.8psi on the gauge.

Waiting on the intercooler. It's been hot around here.

Trust me your turbo system ended up in good hands. I beat the fawk out of it every time I drive.
It is tested and true lol.

 

[asuddendeath]

@scottryana and @landtank

So AC running today mid 80's driving 70MPH under 10-15 pounds of vac I see the A/F meter going all over the place. Rich lean rich lean.

The computer tries to compensate but it is not fast enough.

@landtank Timing is massive. Before I replaced 1 knock sensor and adjusted the timing I pinged like crazy.
I would have to check the timing again, comes to life hard at 2800- 3000 but you know she is there at 2k.

 

[scottryana]

I don't want to get preachy but under load it goes rich lean rich lean? Or it goes rich then you let off the throttle and it goes lean, and so on? The truck only has narrow band O2 sensors. So the ECU attempts when in closed loop (minimal throttle cruising) to keep the AFR between 13.7:1-14.7:1. When you are off the gas, you can see readings as rich as 20+:1 because no fuel is being burnt. All of those things are totally normal.

You need to be concerned for steady state load/boost. Find a hill and maintain boost, driving around town this will be almost impossible. Also the timing is going to retard that is normal.

If your truck is in good repair, and the kit is the same kit I helped Heckraiser design, and you don't **** with it. Everything will be fine. Once you start changing things. You really need a standalone ECU.

 

[asuddendeath]

I don't want to get preachy but under load it goes rich lean rich lean? Or it goes rich then you let off the throttle and it goes lean, and so on? The truck only has narrow band O2 sensors. So the ECU attempts when in closed loop (minimal throttle cruising) to keep the AFR between 13.7:1-14.7:1. When you are off the gas, you can see readings as rich as 20+:1 because no fuel is being burnt. All of those things are totally normal.

You need to be concerned for steady state load/boost. Find a hill and maintain boost, driving around town this will be almost impossible. Also the timing is going to retard that is normal.

If your truck is in good repair, and the kit is the same kit I helped Heckraiser design, and you don't f*** with it. Everything will be fine. Once you start changing things. You really need a standalone ECU.

I'll run a video tomorrow or the next day under stock ECU conditions crusing.

And this is my **** with it pass.

 

[scottryana]

Alright! Well setup the Haltech boost as much as your fuel system will take!

 

[mehbohdi]

Sub'd, I want to see how this goes, because you know boost is addictive. If some is good, more is better. Also would be good to know how smart I have to be to add a stand alone. Does that Haltec control Trans too?< looked it up it doesn't. How will you deal with trans?