9000th01ss

iTrader: (10)

2001 Z28, A4. Stock 83,000 miles. SLP lid, AIR delete, gutted cats, TR55 plugs, bumpstop mod. Codes deleted with HPTuners. TB cleaned, engine has been seafoamed. It has a Racetronics pump and wiring kit and puts out 64 psi at the rail.

The problem is the long term fuel trims NEVER go positive, they average -8 to -11 and often dip to -14. The short term trims are up and down -8 to +8, but they have dipped down off the scale at times. -24

It seems to run ok but the dead o2's that plug the rear holes are black, mileage is around 16 city. No codes.

I've cleaned and tried 3 MAF's on it and they don't help.

I did take the MAF off my other car and it was better, LTFT's only went to -8 and maybe +2
STFT's went up and down between +5 and -5.

Any idea what the problem could be?

9000th01ss

iTrader: (10)

Could anyone that reads this at least tell me why no one knows anything or wants to tell me anything?

crewchef

iTrader: (6)

Have you done any actual tuning or just logged what it's doing? With higher fuel pressure the injectors are probably putting out more fuel than what's being commanded. I've never dealt w/ higher fuel pressure on stock injectors but assume you might have to scale the IFR table w/ new values. VE and MAF tables are the other basic starting points.

mcfarlnd

iTrader: (15)

have the ve and maf tables been tuned yet?

9000th01ss

iTrader: (10)

The engine tuning is all stock. There are a few threads in the fueling section that say if your fuel pressure is higher it still gets regulated before it gets to the injectors. Thats what has me confused. I've spent several hours reading on this site and searching google. I've even asked here before an no one has a clue. I can't even find that thread now.
Even racetronics at one time said it would be fine with no tuning.
I did try putting the VE tables way lean once and the trims will go positive.

So is that the answer, since the fuel pressure is higher to scale down the VE and maf tables, I've been told the IFR needs to be change and I've been told it doesn't. It seems to me it would be the only thing needed.
But I'll try anything at this point.

9000th01ss

iTrader: (10)

This has me confused https://ls1tech.com/forums/fueling-injection/930266-worse-gas-mileage-after-racetronix-fuel-system.html
In fact just about every topic on this site when searching just stops "open ended"--not having an answer and no one reposting what if anything they did to correct a problem.

69LT1Bird

iTrader: (1)

What are you using to regulate the fuel pressure? I am not sure why you would want to run that much fuel pressure on stock injectors and a basically stock engine. Set the pressure to 58psi and see what it does. Do the basics things first. Remember Air, Fuel, Spark.

9000th01ss

iTrader: (10)

It's stock. I bought the car without an engine. It had a racetronics pump and wiring kit so I left it. The engine is 100% stock except whats listed above.

I was going to put a stock pump in it but racetronics said that would be a stupid idea, basically acting like I was a dumbass. So I left it.

Stock regulator, there is no fuel pressure adjustment.
They said their pump is an excellent upgrade to even a stock engine so removing it is pointless. And no tuning is needed.

One guy here also said to see if the vacuum hose is connected to my FPR. Well it's the stock LS1 regulator.

69LT1Bird

iTrader: (1)

The 2001 Camaro has the fuel pressure regulator in the tank as part of the stock pump and sending unit. How do you have the Racetronics pump plumbed? You could install a corvette style fuel filter/regulator in place of the stock filter.

9000th01ss

iTrader: (10)

I didn't install the pump but since it had the harness I dropped the tank to see if it had the pump. It's installed in place of the stock pump. How is it plumbed? it just replaces the stock pump.

I'm really not going to retrofit anything into this, if the problem is high fuel pressure I'll just put a factory pump in it.

The question is about negative fuel trims though. The manufacturer of the pump said it would be fine with a stock engine/stock tune, several people on here said 64 psi won't cause any problems.

So I'm trying to figure out what to do about the negative fuel trims. If everyone said 64psi is too high then I'd address that issue.
So far it's two people saying it's too high and several saying it's not.

69LT1Bird

iTrader: (1)

The pressure should be that big of a deal, did you change the IFR table in HP Tuners to match the stock injector to 64 psi pressure? You may want to do that, than the injector pulse width should be closer which should help.

I think you have 24lb injectors stock, correct? If so, here is what the numbers look like for 64psi.
Injector Flow (lb/hr) 25.21127971 25.35371501 25.49535458 25.6362116 25.77629891 25.91562899 26.05421398 26.19206571 26.32919571 26.46561518 26.60133506 26.73636601 26.8707184 27.00440238 27.13742781 27.26980433 27.40154135

9000th01ss

iTrader: (10)

Thats the IFR vs kPa VAC table? This is what I've been running, it's stock.
28.70851 28.89453 29.08055 29.26656 29.45258 29.57659 29.76260 29.94862 30.13464 30.25865 30.44466 30.63068 30.81670 30.94071 31.12672 31.31274 31.43675

I'll paste your numbers into my tune and see, should I see a difference pretty quick or does it take so many driving cycles?
I'm not sure of the injector size but they are stock and have the same part number as the ones on my '02.

I really appreciate this, thanks. I'll post back when I run it enough to get some readings.

69LT1Bird

iTrader: (1)

Use these. Your stock injectors are 28 lb.
Injector Flow (lb/hr) 29.41315966 29.57933418 29.74458034 29.90891354 30.07234873 30.23490049 30.39658298 30.55741 30.71739499 30.87655104 31.0348909 31.19242701 31.34917147 31.50513611 31.66033244 31.81477172 31.96846491

9000th01ss

iTrader: (10)

I'll try those. Bigger numbers make it run more lean?
Do you have any links to figuring this out, I've read some before about the formula.
This way I can read up and understand rather than keep bugging you.
Thanks.