[2rods]

I recently bought an LM1 wideband and tried it out. First of all my fuel system is as follows: 255in tank pump and 255 in-line, 38ib injectors, aeromotive FP reg, and stock rails and lines. My FP is set to 36 psi vac off and the AF is 10.5-10.6 all the way through the rpm band until about 5000 rpm where it goes up to about 11.9-12.5. I'm running an s-trim with stock pullies and see 11psi of boost. Shouldn't my AF be 11.5-11.8 all the way through the rpm range under boost to run the best? It seems that in order to do that I would have to drop the FP down to under 30 vac off which doesn't seem right at all. Could something else be wrong here. Hopefully someone here has a similar combo to mine so I can find out what FP it should be to have a better tune. Oh, and one more thing I noticed that doesn't seem normal, my 02 sensors are very white. I'm not sure if that means anything, but I know they used to be a brownish color without the supercharger on it.
Thanks

 

[2rods]

I'd also like to ask about FP spiking with boost. I know that the aeromotive FP regulators are boost sensitive, but my FP stays where it spikes to and doesn't rise at all under boost, is it supposed to rise with boost?

 

[Dac]

ALL fuel pressure regulators are "Boost Sensitive".. That includes the stock regulator. They just will go up 1:1 under boost.

 

[94BLOWNCOBRA]

Looks to me your running out of injector. Your also at the point where your going to have to upgrade your fuel system.. If your fuel pressure dosnt rise with the boost it just jumps to where you set it with the vacuum line off than right there its telling you your not getting enough fuel!!!
Also you MAF has a great effect on the fuel curve. SC calibrations are richer than the NA ones..

 

[2rods]

Well I'm running a C&L 76mm MAF. I've also got an 80mm C&L MAF that I will put in today to see if it changes anything, and 42 ib injectors if that doesn't work. Has anyone used a lightning 80mm mass air before, I know it just needs to be re-wired, but it should work correct?
Thanks

 

[Racer LX]

Hi 2rods,

I run the 80mm C&L with 42's, they work well together. If you have 42's already, I'd say just put them in now and be done with it. I'd also up your base FP setting to 39#'s with the vacuum line off (basically the stock setting). You'll get better fuel atomization when they fire, and probably have better idle and low speed drivability.

BTW, if your FP is just spiking and not rising with boost, then that's a problem, and why your A/F ratio is going lean up top. Check the voltage to your pumps, and make sure they are both in good shape. A 255 intank and 255 external set up should be able to support 11#'s of S-trim boost.

Hope this helps,
Jim

 

[2rods]

I've had the 42's in with the 80mm C&L and 42 (green) tube. I had FP set to 36 vac off and it was still super rich under boost (10.5-10.8) It seems like I'm just getting way too much fuel. The main question here is, is it ok to keep taking FP out until I get it in the 11.5-11.8 range? If I go really low won't I get incorrect fuel atomization?

 

[2rods]

So how low have some of you with 42's run for FP. Im sure theres lots of people on here with a similar setup.
Thanks

 

[2rods]

ttt

 

[Racer LX]

Problem with taking out FP to get your 10.5-10.8 in the 11.5-11.8 range is that in the upper RPM range, your 11.5-11.8 will probably now be 12.5-12.8, and you'll be worse off than you already are when your head gaskets go bye-bye. You need to address the lack of fuel up top.

If the FP isn't rising as it should up top, something's wrong. Have you watch your FP guage when you're on it in high gear? Does it not only not rise, but does it drop too? Is the voltage in the car ok? Is the fuel filter dirty?

 

[2rods]

fp doesnt't drop at all and voltage is fine. Ive got two 255 high pressure pumps, so that shouldn't be the problem.

 

[Racer LX]

Well, if the pumps are moving enough fuel, and the injector size is ok, then I'd look at the mass air meter. Maybe it's maxing out and not able to signal the ECU that you need more fuel up top. Not knocking the C&L meter (I have one too), but they rely on the stock electronics from your old meter being used in their meter body with a new signal tube. Throw a supercharger in the mix, and now you're way far away from stock. Lots of folks use them with a blower with no problem (like myself), but others have issues. Try to borrow another meter (Pro M if possible) cal'd for your injector size if you can, and see what that does for your A/F ratios.

If you are unable to do that, then I'd say the only other option you have is to run a small FMU to give you the fuel you want up top. With 42's you probably shouldnt need an FMU and this would be kind of a band aid, but it would at least allow you to get on the car and not worry about it being too lean.

 

[2MUCHSPRAY]

Has anyone used a lightning 80mm mass air before, I know it just needs to be re-wired, but it should work correct?
Thanks

Im running a 90mm maf from a 02 lighting, works fine for me!!!!!!

 

[jcm3]

What are you using to tune? The wideband allows you to see what the air is, but not tune with it, right? I'm not very familiar with it.

You will be able to tune the air/fuel at different rpm's with a custom chip or another tuning method like a TwEECer, or something similar. That should help you get the air/fuel more where you want it at the lower rpms. I have my fp set to around 42 with the vacuum line off.

I had a similar problem with my air/fuel rising from about 5500 up. We troubleshot everything, watched the fuel pressure, checked the MAF voltages, etc. and it turns out I just needed larger injectors, as I was running 36's at the time. I making around 435 at the wheels at the time, and I would think you are making more than that now.

You may just need larger injectors, but I'm not sure at what point the fuel rails will be a bottleneck.