Ok. Ill give you guys an idea of my mods.

I have a BNR stage 4. at 7-8 psi only.
550 primaries and 720 seconds with aeromotive FPR.
I have a stock ECU.

Ok we hooked up my bros innovative wideband and the results were a bit a strange.

AT idle im getting 14.0 +- afr's
AT normal driving under 3,000 rpms its hella lean 14.0(this one worries me most- because when im grandma driving slowly picking up speed without even hitting boost [granny driving in vacuum only] and its hella lean. BUT when i get to the destined cruising speed when i barely have to hit the gas it goes to the 11.0+- afr's


AT WOT im getting 10.2 afr's


Can anyone explain why my afr's on partial throttel is so lean?

 

most obvious thing would be a vacuum/boost leak... deleted emissions or no?

 

got anything to control those injectors?

 

Doesn't look like it.... he just says stock ECU.

 

DOOOD, you're supposed to be 14.0 - 14.7 or so at idle and stay in that range until you hit boost. Then you're supposed to get progressively richer. 11.0 -12.0 when over 10psi. These numbers are just a guideline.

If you're cruising speed / RPM is over 3800, those secondaries will come alive and since they are 720's you will go considerably richer than when you had 550's.

Make sure you have a fuel pump, and also make sure that you set the regulator pressure (at idle) without the vacuum line attached to it (Pressure changes when you apply vacuum.)

 

I do have a walbro 255. The only way im controlling fuel is through the FPR.


ANd no i dont have emmisions.

But if boostlee is correct about it staying near the 14.0 afr area in idle and any condition "not in boost" than there is nothing wrong with my car.

I just found it crazy for it to be so lean when im baby driving. I guess it'll get good gas mileage=D

 

it's running exactly how i would expect it to be running with no aftermarket engine management system. it's rich because you have those 720s and you're running low boost

 

What do you see when you floor board it between 2000 and 3500 rpm in third or forth? Just talking about afr under 3500rpm at full tilt. Any gear but first or fifth.

 

14.7 is optimum, any leaner than that is risking detonation, and kills your side seals. When boosting, it should be running richer. Your car is fine; my question is why are you limiting that stage 4 to only 8 psi?

 

^ he still has a stock ECU and small injectors. and 14.7 is just for emissions

 

junito1, I know this is WAY off topic, but by any chance, are you originally from NorCal?

 

Everything sounds reasonable.

This is a good example of when people freak out cause they don't know what they are doing.
Please do your research before getting paranoid on what is bad and what is okay...


-Ted

 

No not from Nor Cal.

Yup only running 7-8 psi because i cant tune timing.

I have the fuel to go 14 psi becaus I tried it already and it stays rich... (pulls like a ****)
But I'm leaving it at 7-8 till i get an EMS.

 

Sounds about right to me....

 

can somebody explain this though? I get the same thing, it will cruise at 14.7, if you let off the throttle, it will drop out of closed loop and get afr in the 13's (which i understand is completely normal), but if you continue to let further off the throttle, it just gets richer and richer (down to 10's) until it finally goes into decel fuel cut. i often get backfires when cruising down hill due to it being so rich

i have an rtek 2.0 and tried to tune it out, but to no avail. it will only make the 13 afr area leaner, and it starts to stumble. still get 10/11's at extremely low throttle either way

 

could be the secondary injectors just dumping too much fuel in, or it could be a TPS problem

 

Typical behaviour of the stock ECU.

I believe (but could be wrong) that it is related to how the ACV is supposed to operate under decel. Combustion is supposed to continue in the exhaust manifold to aid in cat operation.

 

I still think it's the ECU acting like an accelerator pump(like on a carb car), so you don't go lean when you reapply throttle after letting off. In other words keeping it from hesitating each time you let off the pedal then reapply the pedal.