Too Lean....!!!!!

[chovis38]

So, my car is running lean all of the time, and I am looking into getting and Apexi AFC II, or a wideband o2 kit. What are the positives and negatives of each? I personally think that I should get an AFC rather than an o2 kit. I am just looking to adjust my air fuel ratio, which both of these will do; but they also have many other functions as well. Which one should I get considering the mods I have:


- Big 16G

- Warlboro Fuel Pump

- Injectors on the way (650cc)

- Electronic Boost controller

- Gauges:
+ Air Fuel ratio gauge
+ Boost gauge
+Egt gauge

- Turbo Timer

- Ported Exhaust Manifold

- Greddy FMIC

- Intake

- 3" Catback Exhaust

Any feedback would be great!!!

 

[miden]

So, my car is running lean all of the time, and I am looking into getting and Apexi AFC II, or a wideband o2 kit. What are the positives and negatives of each? I personally think that I should get an AFC rather than an o2 kit. I am just looking to adjust my air fuel ratio, which both of these will do; but they also have many other functions as well.

AFCII and a wideband o2 do different things. An AFC allows you you adjust your fuel delivery and a wbo2 just monitors your a/f mix in a meaningful way (most run from 0-5v), unlike the blinky lightshows of narrowband o2 sensors (the stock o2 sensors are high slew rate. They read either lean or rich. That's why your a/f gauge jumps around so much...).

What boost level are you running? Do you have a afpr? Depending on which walbro pump you have you might be overrunning the stock fpr. You can't accurately control your fuel curves if you don't know what your base fuel pressure is which you don't because you don't have a fuel pressure gauge. (At least you don't have it listed...)

If I were you I would:

1.) Get an afpr with a fuel pressure gauge. Set your fp correctly.
2.) Get a datalogger of some type. This will let you know about how lean or rich you're running and if/how much you're knocking. It will also tell you how your timing is doing. (If you're running lean you're knocking and the ecu will pull timing & you'll lose power...)
3.) Get an AFCII. Now that you know that your fuel system is running at the right pressure and you've got an idea what the engine is doing you can turn up the boost safely and tune with the datalogger & the AFCII.
4.) Get the wbo2 to know exactly how lean/rich you're running.

Good luck and I'm sure others will correct any errors I have made...

-M

 

[kpt4321]

How do you know you are lean?

 

[98spydert]

No you ARE overrunning the fuel pressure regulator.

What are you using to compensate for those 650s?

 

[chovis38]

I orded a FPR the other day that comes with a fuel pressure gauge, so that's on the way too. I know I'm running lean because, like posted above, the air fuel ratio gauge usually jumps around all of the time. Well, my just stays down in the lean area all of the time, and it doesn't go into stoich, or rich at all, ever. Before I put the bigger turbo on along with the fuel pump, under WOT, the gauge would read rich, and upon letting off the gas, and would drop down through stoich into lean, and then the signal would fade until more thottle was applied. How much do dataloggers go for, and how are they installed? And once I get the FPR, how will I know how to set my fuel pressure correctly? What do you mean "compensate for those 650cc's"? What should i do to compensate? Oh and by the way, I am usually running 8-9 psi of boost under normal driving, but when I am in a racing situation, I bump it up to 17-18 psi. The gauge reads lean all of the time, no matter what boost is set. Thanks for all of the help guys!!!

 

[miden]

Ok. So good start w/fpr. There's another thread around here that fully explains how to set your fp. I can't remember how to do it right off the top of my head, so I'll deffer to that thread...

I'm not sure I'd trust a af gauge. I've got one, mostly to satisfy the ricer in me. Mine seems to work somewhat differently. Mine runs rich in open loop mode, then bounces back & forth when I'm in closed loop mode. That's really all they're good for. And pehaps impressing girls...

As for dataloggers, there's a bunch of freeware out there. Mostly they run on the Palm 3.5 OS, some on laptops. The major expence is the cable that attaches to the ODBII port. Again, there is a current thread, so look for that. Once you have this, it can tell you what your o2 voltages are as a function of throttle & rpm, get knock sums, fuel trims, tons of stuff.

As for compensating for 650's, 650's flow more fuel than 450's. 45% more, I believe. So running at the same PF and the same injector puslewidth, you're getting 45% more fuel. Plus your fuel pump has likely overrun the stock FPR, so you might be getting even more. (base fp is higher, so at a given pw, you get more fuel...) An AFC will allow you to adjust the amount of fuel added.

If I had to guess, I'd say you're running rich. While running rich is better than lean, too rich can cause knock too and damage your pistons.

Have you noticed a change in your gas mileage? If you're running rich under 9-10 lbs. of boost your mileage will drop. You also mention that you have a egt gauge. How has that changed? If you're truely running lean your egts will jump, if you're rich it will drop.

Again, good luck...

-M

 

[mad_trbo]

According to all VFAQ's i have seen you want to start with a base Fuel pressure reading of 37 psi with a 1g and 43 with a 2g.

This is the reading you should have with the vacum disconnected from the AFPR. Once disconnected you will basically adjust until you have one of the aforementioned on the guage.

 

[CanadianTSi]

The Simple solution would be to turn the boost down until you have the appropriate fuel mods

 

[chovis38]

Well, no matter what the boost is set at, it's lean no matter what. And as far as my EGT and mileage..... the egt is still the same as it was, and so is my mileage. Thanks for all of the help guys...... when I get the 650's and the FPR, I will set the FPR accordingly, and if that doesn't help out the situation at all, I wil opt for the A/F controller. Then, maybe for kicks, a datalogger too. Again, thanks for all of the help.

 

[CanadianTSi]

If your EGT's are normal then your not running lean...you can't rely on a narrowband o2 to tell you your A/F Ratio..

Atleast get a logger so you can see whats really going on.

 

[lowridin2g]

theres only 2 possibilities for you here.

1: your o2 sensor is dead

2: you hooked up your gauge to the o2 sensor HEATER and not the actual o2 sensor.

 

[chovis38]

What do you mean my o2 sensor is dead? When I hooked it up, it worked fine, but after I put my big 16G on and my fuel pump on, then it started reading lean. I suppose I can't really rely on it, however, it isn't reacting the same as it did before, which is cause for concern. Just to be sure, there are 4 wires for the o2 sensor, a blue, white, and 2 blacks. What wires from the gauge are wired into the o2 wires? I will check, but I'm pretty sure that it's wired properly...... I'm still waiting for the damn FPR and injectors!!!!

 

[1fast97gsx]

theres a white wire up by the ecu for the O2 sensor. Wh not just tap into that? It was 72 or 76 or something like that I forget. It's already inside the cabin of the car ... no way you can confuse it with the wrong wire, and it's easy to get to.