The problem I am having is that I have a seriously lean idle. The o2 is reading 15-100mv at idle. What are the steps for tuning this back to around 450mv?

I have the injector constant set at 24lb. Is this wrong for ford injectors?

 

What mask/xdf, bin and program are you using?

Engine modifications?

 

$6e mask and I am using bin ANYX. 24lb ford injectors.

Mods - SLP CAI / SLP Runners / Ported Accel Base / Ported Upper / BBK Pullies / Edelbrock Catback / 24lb Injectors / No cat

 

That question depends a lot on your Maf output.

I have run 5 different mafs on the same car (24# ford injectors and 50# of Fuel pressure) and have seen this observation and these results.

All the Mafs read different values both at low air flow and at high, idle air flow may or may not be consistent as to the wot amount.

I classified them as to their wot grs/sec air flow which seemed to repeat with some consistency.

Az 183
stk 187
stk 205
Reb 232
CB 255

The lower air flow mafs would lean the mixture and only require a 22#-24# injector constant.

The 232 is running well with a 30.5 injector constant.

The other observation is that even though the O2 is lean the "engine" is running rich. You can watch the IBPW and just under 2 ms is the best idle.

There is an offset for idle to cruise, 158 blm at idle and a 129 blm at cruise. This offset is very consistent, if the idle is at 128 blm, then the cruise is at 100 blm. I am going to either adjust the O2 swings and/or the lower Maf tables to level this out.

So depending on the Maf calibration, the maf will make a big difference in what injector constant is "correct" I ran the 187 maf with a stock bua chip for almost a year, it was a little rich but got over 20 mpg at cruise. Idle was rich and ran the 158 blm.

Even though my cam is a low duration 206/212 @ .050 with a 110 lsa,
there is enough overlap to fool the O2 into reading the "wrong" O2 amount at idle. This is with stock intake, Chip, exhaust manifolds, and true dual exhaust (no cat or egr).

 

The O2 sensor could be cooling down too much at idle. Are you using stock exhaust manifolds? Also the sensor could just be faulty. Another thing to think about is that some injectors are rated at different fuel pressures.
just something to think about.

 

Brand new o2 sensor running on stock manifolds. Whats weird is that my BLM and INT are at 128, but the o2 sensor registers super lean at around 40-50mv. I have no idea what to do. I hooked up my autoprom and emulated and dataloged at the same time and I tried all different injector constants and the only thing that seemed to help was setting the single fire size to 19. Then the mv would wildly fluctuate. I feel as though I am trying to capture the wind with my very limited knowledge.

 

How does the car drive with injector constant set at 19 ? What color are those 24# injectors ? It sounds to me that your injectors were rated at a higher fuel preasure than you are running. I always stay away from ford stuff J/K it had to be said.

 

Why stay away from the ford injectors I always heard they were good

 

The injectors are light blue.

The car drives good with the injectors set at 20.

 

J/K stands for just kidding, Ford injectors are fine and in a lot of cases made by the same company as GM injectors. I just like to bash on ford guys for fun, though I have alot of friends that love fords.

 

Good I have ford 30lbs

 

Looking through tunerpro I found this "Closed Loop Rich/Lean threshold vs Airflow". I noticed that there is no spot for under 8gm/sec, would this mean that anything under 8 gm/sec is not controlled or metered?

If it is metered, I don't understand why the o2 mv are so lean. Maybe someone can chime in and explain or link an article that explains how idle fuel ratio is calculated and controled.

 

I have used 3 different heated O2 and of course the single wire, no difference.

The injectors and fuel pressure are always the same.

I can switch from the Arap 6E tune back to stock 32 or 32B by just installing the lower reading maf and the factory memcal.

 

When the O2 sensor swing points are outside of the range in the bin (699 mv and 199 mv) the ECM goes into open loop and sets the blm and int to 128.

The O2 is suppose to fluctuate wildly, (it is a switch), depending on the gain settings and time delay. The ECM goes higher "richer" till the upper swing point is crossed then leaner "lower" till the lower is crossed. On my car the O2 mv at 123 blm to 133 blm peak at 850 mv and valley at 200 mv. If you graph, it I looks like this, and is a very normal O2 output at 128 blm in closed loop.

 

what do the plugs look like?

 

You have to understand that the O2 measurement is "at the sensor" not "in the cylinder chamber". Any fuel air mix not burnt in the cylinder can be burnt in the exhaust manifold and change the true AFR, or just pass by the O2. Since the sensor is a "O2 sensor only", it will read the Oxygen and not the fuel, giving a false lean reading (false AFR).

The more overlap cam you have (lumpy idle), the more this is an issue.

 

WIth 220+ duration flat tappet cams I gave up on getting the idle MV to behave. I got nearly flat zero idling unless I made the mixture so rich the car didn't run right. The O2 swing limits didn't help because I was so far out of the range

 

do you have more than a stock cam? there is no detail about your cam in this thread, so it could be as said above if the duration is high enough.

I also see you have SLP runners, when I first put my engine together, I had a small vacuum leak becuase the runners got hung up on a machined lip on the lower base, since the runners were larger than the stock ones. I had to take them back off and sand down the one edge on a slight taper so it missed the lip on the manifold. i beleive it was near the pcv valve/cold start area, where everything is very tight. if you have a leak, this will register false air (not metered through the maf) and cause a lean condition.

 

to my knowledge the car has the stock cam.

 

To add some updated info

With a new Maf in this mix, it fell in at 215 grs/sec at wot max rpm.

The injector constant had to be lowered to 25# to bring the BLM's at cruise back to 128.

Increasing the middle Maf table values in table #1 15%, lowered the idle BLM's to 128 from 158.

So you can see that the difference in Maf output airflow makes a big difference in the Injector constants and BLM's.

Remember this was with the same everything but only changing the Maf and injector constant in the bin.