I got my TNT F1 wet kit all hooked up and ready to go. I want to wait to spray it until I can monitor the A/F ratio. Is AutoTap at least as good as an autometer gauge to monitor A/F? I can set it up to have a warning come on if it goes lean right? I don't want to waste money on a gauge if AutoTap can do as good and watch KR, timing, etc.

On a similar note, I was reading up on AutoTap and saw something about EFILive (LS1 specific). Should I get this instead of AutoTap? I think it is faster and only $20.00 more???

This is on a 2002 z28 A4

 

AutoTap will give you a numerical readout on the O2 sensors. An A/F gauge will just give you a LCD that moves a few notches to the rich side, with no numerical info. Since they both rely on the stock, narrow-band O2 sensors, niether of them is very accurate. It can not be emphasized strongly enough - a stock, narrow-band O2 sensor is NOT accurate at anything other than within the range of about 14.6-14.8:1. That's what they are designed for, and that's all they can measure accurately. At the 12:1 or richer you want for N2O use, they are VERY innacurate. A large change in A/F ratio only produces a tiny change in mV output at that point. The change in mV's for a change in operating temperature is larger than the change from A/F ratio. In my opinion, you should NOT rely on the stock O2 sensors. Get it set up on a wide-band, and check the plugs constantly.

As far as the "EFILive" version of AutoTap, that is a program that allows the PCM program tables to be altered ("programmed") as long as the system is attached to the stock PCM. As soon as you disconnect the system, the PCM will revert to the stock program. And as you noted, it is for the LS1 only.

 

Thanks. I have heard before that the o2 sensors are inaccurate but they are good enough to tell you if your car goes way lean right? For example if the fuel solenoid did not open, you would see that you are way lean and could shut down. Does AutoTap respond quick enough that you would have a chance to save your motor?

I also just found an A/F shutoff switch. Does anyone have this: http://www.speedshop.org/store/Scrip...?idproduct=37. While I'm sure its not good enough to tune off of, it seems like it offers protection from going very lean.

How much should a wide band dyno pull cost me? I know it is the best way to check but I'm 19 and paying for college and my budget is so slim that it is unbeliveable.

Thanks for the help
Dustin

 

You can typically get 3 dyno pulls for about $75... they might charge you a little extra if you want them to log with a wide-band.

Do not rely on anthing that uses the stock O2 sensors... damage will occur as soon as you go "slightly" lean. It's not a matter of going "way" lean.. its too late by that point. You protect against a fuel solenoid that doesn't open by using a fuel pressure safety switch. No fuel pressure, no nitrous flow.

A lot of this depends on how much you are spraying... you might survive a mishap on a 75-shot, but not with a 200-shot.

 

Listen to Fred, Listen to Fred, Listen to Fred...

Rich Krause

 

Thanks for the help so far guys. I think for ~$75 I will get it dynoed to make sure that the A/F ratio is good. I don't see any reason that it should be off since my car is relatively stock, and if the jetting is right, there should be no problem.

I'm not too worried about the A/F ratio being wrong always, I am more worried about something failing and causing a lean condition.

I didn't get a fpss because of things I heard about surging and them being unreliable. I think I might have misunderstood how they work. You said they can help if your fuel noid doesn't open right? How is this? I thought they checked to see for pressure before the noid.

So is the A/F safety switch a complete waste of money since it uses the stock O2 sensor?

Sorry I have so many questions, but no one that I know has any clue about this. This is a big help.

Right now I think it sounds like I should forget trying to monitor O2's while driving, and spend my money on a dyno pull and a FPSS.

Thanks again,
Dustin

 

You can put the FPSS after the fuel solenoid. Arm system, hit the switch, fuel solenoid opens and pressurizes line to nozzle, circuit complete, so the nitrous solenoid opens.

I recently saw an advertisement for an A/F switch that mounts in the intake manifold. Made by an outfit in Whitehouse Station, NJ. I need to find out more about it, but it appears to mount a sensor of some sort in the intake. Obviously only for wet systems.

 

Awesome. I had no idea you could hook it up like that. (The directions w/ TNT weren't that good). That sounds like exactly what I want. Thanks for all of the help. Hopefully I will have it ready to go soon.

Thanks again
Dustin

 

i think an automteter gauge should be fine....tell us how it goes

 

I'm new...but that sounds really cool if it works...tell us how it goes

 

ttt