Base AFR with FMU

[david-b]

Hey all;
So I've been turbo for awhile and been working on getting her tuned better. When WOT, my afr is reading on average around 12.0-12.5afr which is way too lean.

I'm using stock injectors, 12:1 FMU, SAFC and 255fp. Now I know this is a basic setup and a SFMU is best and blah blah... but my question is... with this setup and the AFC zeroed out, where should my AFR be sitting at? I heard it's supposed to be sitting around 10afr. I know other people here have very similar setups, so please help.

 

[rstare]

Unfortunatley a fmu offers no tuning what-so-ever. A safc can control your out of boost fuel but other then that its not a very useful on the 420a.
Your at 12:1-12.5:1 AFR under full boost (8psi?)?
With a 12:1 fmu I would say honestly thats pretty good. 11:1-11.5:1 would be ideal but for what you have I would say your sitting pretty good.
Sfmu is the best? Not quite....
MSnS. With PnP soon. Thats the best.

 

[david-b]

Unfortunatley a fmu offers no tuning what-so-ever. A safc can control your out of boost fuel but other then that its not a very useful on the 420a.
Your at 12:1-12.5:1 AFR under full boost (8psi?)?
With a 12:1 fmu I would say honestly thats pretty good. 11:1-11.5:1 would be ideal but for what you have I would say your sitting pretty good.
Sfmu is the best? Not quite....
MSnS. With PnP soon. Thats the best.

Well I know MS and all that is the best... but I was talking for my setup right now.

Full boost (according to gauge) is about 6.5psi. Not sure why that is so low neither. May be mis-calibrated gauge.

12s just seem way too lean to me. When I was N/A we dyno tuned for 12.5.

 

[rstare]

Like I said 11:1 to 11.5:1 is where you want to be idealy. But you have no real way of tuning it, so I dont know what you expect to do.
I was saying 12:1 is pretty good for using a fmu.

 

[totaleclipse_05]

Did you get your fuel pump new?

And you said your boost gauge might be off?

 

[david-b]

Did you get your fuel pump new?

And you said your boost gauge might be off?

Fuel pump is brand new.
Boost gauge is a GlowShift. When car is off and needle at 0, it's a little below 0 in vacuum. All the other boost gauges I've seen sit right at 0 when off. That's why I think it may be off a little.

 

[bagged420a]

your guage might be right, what is your actuator spring rated?

 

[david-b]

your guage might be right, what is your actuator spring rated?

7.25psi

 

[Shadow98]

Do you have a MBC? If not you have a pressure drop at your IC, but that completely normal as long as it's not more ~2-3 PSI.