Need fuel up top!

[s10xtremist]

First let me say that I am planning a LS-series swap relatively soon, so I am not interested in investing alot of money into my 4.3. I do want to try to get the most out of my current setup. I went to the track for my first time a few weeks ago and my best timeslip of 3 runs read as follows:

R/T....368
60'.....2.210
330'...6.422
1/8....9.852
MPH...71.00
1000'..12.883
1/4.....15.455
MPH....87.75

I gained 16mph from the 1/8 to the 1/4. It even felt like my truck died the last half of the run. I know my 60' is a little slow as well. According to my dyno and AFR graphs, I'm running too lean for boost. I am considering getting an FMU. Is this a good idea and how would I install this on my particular truck? Do I need to do anything with the stock FPR inside the intake? What other options do I have?

[Sparky2263]

Your 1/8 mile speed should be 80% of your 1/4 and the ET should be about 2/3's.

71 / .8 = 88.75
9.852 / .66 = 14.92

The reason our ET's generally don't work out well is the V6. It just can't overcome the wind resistance our trucks have and skews the formula. But, you're pretty darn close on speed.

Easiest way to knock off ET and not waste money on the engine is a high-stall converter. It'll get those 2.2 60' times down around 2 flat and drop your ET .3-.5

Yes, that much. Just make sure you have the tires hooking.

[s10xtremist]

I must be spinning my hides off. I'm almost convinced I should be at least in the high 14's as my truck sits now. I'll put on some softer tires and try different launching RPM's next time.

[mrmidnight]

My 1/8 times weren't too bad in the 2.2 I had, not as good as yours, work on that RT as well, you'll be able to do it brother. I do recommend the stall converter as well, a change in the oil helps too, when I raced I put in 4 quarts of 5w30 and a thing of Lucas. Worked wonders, and kept pressure up

[ZR1-S10]

I still recommend the FMU. Show them the chart of your air/fuel ratio, I don't think anybody here has seen it, just the guys at mys10.net.

[Sparky2263]

Show them the chart of your air/fuel ratio.


Yes, please.

[s10xtremist]

I'll get it up this weekend!

[s10xtremist]

Here it is. Is it possible to get more fuel by having my program adjusted, or is my injector maxed out just trying to keep it below 15:1? I know you can't accurately tell without seeing how the program is written. But, does anyone know from their knowledge of the CPI? I may be able to get my programmer recalibrated for just the cost of shipping, but if it's not going to help much then I'll get the FMU. Or maybe I should just get the FMU and be done with it.

[Sparky2263]

You actually have CMFI, not CPI. But, the fuel pressure regulator still sees the boost and raises fuel pressure accordingly. It's just not enough above 4000 rpm's.

First, I'd make sure the fuel pump is keeping up and the regulator actually increasing fuel pressure via a fuel pressure gauge. I'd never have a power adder w/o a gauge anyway. Too much to lose.

If fuel delivery pans out okay, I'd just program in the extra fuel. Rat can tell you more about that.

[rat]

Holy smokes, that is way lean, i know my truck i run at 12.6:1. Power Noticably drops off leaner, or richer than that. With boost i might run even a little richer(with your blower, with my blower a lot richer).

Did the dyno also datalog your obd2 data? It all depends on what the current duty cycle on the injectors is right now as to weather or not you can richen that up or not with a tune. A good datalogger can tell you this. It needs to have the enhanced parameters. A tech 2 should have this data, or autotap, or if you are 2001+ there are a bunch of good scanners for your computer.

I would not run wot running that lean, unless you hate your engine. That is a good way to screw up pistons.

Also, a wideband may not be a bad investment.


Now, i would not spend a whole lot on it if you are planning on swaping the engine. Deffinately do as Sparky suggests, and check that fuel pressure. Make sure the fuel pump is keeping up. And, you might pull the upper manifold, and raise the base fuel pressure a little bit. Your part throttle will be rich, your computer should be able to lean it out. With the end result a richer wot mix.

Annother thing i will mention. Is a maf translator. I haven't looked into this particular one in depth, i don't know if you can do non linear scaleing with the cheep one, but it is only $100, and it would allow you to tell the comptuer more air is coming in, so it will fatten up the pulse width.
http://www.zzperformance.com/grand_prix/products1.php?id=172

If you can get your tune recalibrated then you should just do that, they can do the same thing(annother reason why i am not a fan of mail in tunes, they have no idea how your truck is going to run with given modifications). If i paid to have someone tune my truck, and this was the result i would be very angry, assuming the tune is to blame.

Annother Thing that would be interesting to know is how the air fuel ratio is in different gears. If the maf table is adjusted for proper air fuel ratio's in a given gear, and the VE table is off, then you will have different air fuel ratios in different gears.

Remember with any fueling changes you should really have a wideband(i mention this twice, because i think it is that important).

You aren't running a granneteli maf, or a descreened maf are you? Have you cleaned it lately if you have a k&n? All of these things will make your truck run lean.


Edit, afr wise, generaly what you are looking for is rich up to peak torque, then you can lean it out a tad going up to your peak horsepower. Remember if you run too lean, and you have to pull timing due to knock your power will suffer.