Near stock '01 LS1 with negative LTFT's, please help

[Jason B]

I have a problem with my LTFT's NEVER going positive, and I'm trying to figure out why. I've read here, other LS1 sites, google, and found nothing that helps.
LTFT's average 0 to -14
STFT's I have seen swing from +5 to -43
At WOT they all do go to 0
It seems to run ok but the mileage isn't the best and the dead O2's I have plugging the post cat o2 bungs are sooty black.
It's been running about 1200 miles and the only problem I had when I first got it running was a dip to 400rpm in idle when coming to a stop. I fixed that by changing some numbers in the idle cracker table.
I just don't think a near stock car should be that far off, can someone please offer some ideas on why these numbers are so far off?

Here are details on the car.
It's a 2001 Z28 that I bought as a roller. It has an A4 trans.
I bought a 2001 LS1 for it with 83,000 miles, it was already wired. I cleaned it and inspected everything. The VCM is out of a 2002 T/A.
It's 100% stock except for a Lid, Gutted cats, TB bumpstop mod, TR55 plugs, AIR delete, And the car had a Racetronics fuel pump and wiring harness when I got it so I left it in. It puts out around 60-62 psi at the rail.
When I got it running I did 3 seafoam treatments.
The VCM had a custom tune so I did an entire re-write using the hpt file taken from my '02 SS. The only tuning done is deleted codes, TM, WOT AFR, misc transmission.

[WS6FirebirdTA00]

logs and tunes are worth their weight in gold. From the large STFT values, sounds like a bad o2 could be an issue or an issue with the MAF.

[Jason B]

Heres the tune and two run files.

[Jason B]

logs and tunes are worth their weight in gold. From the large STFT values, sounds like a bad o2 could be an issue or an issue with the MAF.

Do you think anything of the fuel pressure?
I've been told it's the fuel pressure, and also told it's not the fuel pressure.
And I've been told I need to scale my IFR table, someone else said scale the VE and MAF table.
I'm thinking more along the lines of there being a problem so I'm not willing to jump into changing the tune to cover it up. Mainly because it close to stock.
This is a first on the MAF and O2's.

[WS6FirebirdTA00]

whats wrong with the fuel pressure, that is normal for these cars. If you have stock injectors, then that is fine as well.

[Jason B]

whats wrong with the fuel pressure, that is normal for these cars. If you have stock injectors, then that is fine as well.

This is whats wrong with the fuel pressure.

Welp...here's the problem. The PCM has no way of monitoring or knowing what your fuel pressure is. You are above the base 58 psi operating pressure, and are seeing the reasonable effects of that.

Adjusting your IFR table is the correct way to go here...you just need to make sure it shows the right flow rate based on 61-64 psi (you'll have to pick a value in there) instead of the stock 58 psi.

Racetronix, in this case, is wrong...any difference in fuel pressure from stock can't be monitored, and will cause you to run rich. It's just how the system works...and Racetronix pumps installed with the stock, in-tank regulator are known to cause a pressure increase at the rails.

you're fine, nothings gonna blow up and spill gas everywhere and catch on fire

+1. My car has 68lbs of fuel pressure at the rails.

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.

have the ve and maf tables been tuned yet?

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.

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

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

More fuel pressure + No retune = Worse mileage
At least check your fuel pressure at the rail and adjust your IFR table accordingly. If all you have done is put in the Racetronix pump, then I bet your fuel pressure is close to 62-63psi at the rail at idle.

If you are running stock injectors and fuel pressure regulator there is nothing to tune for. Make sure your FPR is in good working order...

"z28_theantirice" is correct if you haven't changed the FR or the FPR the pressure and volume is increased to the rail but past the rail everything still the same per inj. pulse and psi.

I installed a Racetronix kit and gained Mpg's by 3-5 with a new tune!

I guess it's time to shut the computer off and consider the internet and forums useless. WTF am I supposed to do with all this conflicting info?
Any ideas?

[WS6FirebirdTA00]

yes, you can rescale the IRF to reflect those rail pressures. That is not going to cause an issue of -43% fueling though, maybe 3-5%.

[Frost]

Really, what is the problem here? I mean.... did you think something was wrong based on the way the car was running BEFORE you saw the trim values? No.

The sky is, in fact, not falling. Adjust your IFR to reflect your actual rail pressure as said in this post. Or don't... except for being a bit rich at WOT, you won't notice it at all driving around.

It's not going to hurt anything, and you aren't going to even feel it while driving around, so try not to let it upset you so much. Fuel trim correction is a basic part of tuning.

[Frost]

I mean it could be worse; they could be positive.

[Jason B]

Really, what is the problem here? I mean.... did you think something was wrong based on the way the car was running BEFORE you saw the trim values? No.

The sky is, in fact, not falling. Adjust your IFR to reflect your actual rail pressure as said in this post. Or don't... except for being a bit rich at WOT, you won't notice it at all driving around.

It's not going to hurt anything, and you aren't going to even feel it while driving around, so try not to let it upset you so much. Fuel trim correction is a basic part of tuning.

I'm just looking for a straight answer, something like what you said.

Like I said I bought this car as a roller and bought the engine and VCM seperate so when I got it running naturally I did a running scan to see if everything looked ok and thought the LTFT's looked a bit odd for it being near stock. (I do have an '02 SS and nothing seems odd when running a scan on it.)

So if I want to bring the ltft's closer to zero do I scale the IFR numbers smaller or larger?
I would think smaller but I've been told to make them bigger.
Thanks for the reply.

[WS6FirebirdTA00]

DO NOT SCALE THE IFR TO FIX THE PROBLEM

use the calculators at the beginning of this forum in the stickies to calculate the correct flow rate. They will get larger, leaning the car out, but only slightly.

[Jason B]

DO NOT SCALE THE IFR TO FIX THE PROBLEM

use the calculators at the beginning of this forum in the stickies to calculate the correct flow rate. They will get larger, leaning the car out, but only slightly.

So does this mean you think I have a problem?
It seems you think theres nothing wrong, yet you give advice to fix a problem but won't give me any clues as to what the problem may be.
It looks like no one downloaded the june 3rd tune, in that one the stft's went to -43 is that normal? I don't think it's normal.

[WS6FirebirdTA00]

I did not see you post that tune up. It looks like something caused the o2 sensors to just rail rich. The thing is the first time it happened was at constant throttle and the second was when you let off. If you had a WB in there, we would know for sure if it was a real fueling problem or an o2 problem.

I was just saying that IF you rescale the IFR, do it with only the actual values you have. Yes it will help, but no that is not going to cause -40% fuel to be pulled.

[Jason B]

Well i think I'll get some new O2's, it couldn't hurt.
And I'll work on a wideband, I had a LM-1 for 8 months, it failed and was repaired under warranty three times. That was a $350 wideband I ended up selling for $150 so that kind of left a bad taste in my mouth as far as that goes.

It's a little inconvenient when you plan a whole day to tune a OBD1 truck and burn chips etc only to have your wideband fail 5 minutes into it. But thats another story.
Thanks for your help.

[JasonB]

I found my old user name and password-trying to get rid of the newbie persona.

I messed around with the Fuel System Status pid which shows OL/CL.
I found that while in CL and running steady it slips into OL decel when it hits -43 on the STFT. So I guess thats normal.
I'd like to be able to verify this with a wideband but I got rid of the one I had.
I'm assuming this is normal to see -43 in OL decel?