racecar

I just got HP Tuners, yes I am stoked. Right away I can see that my LTFT are maxed at +25, but my wideband tells me everything is good, 14.0 cruising and
12.7 WOT. OK it isn't perfect, it moves around and takes some funny ups and downs, something is not right here. The LTFT are +5 around 55-70 MAP at 2500-3500, but at any higher MAP or lower they are 25. With that much LTFT, do I need to increase the numbers in the VE table, or is my injector flow rate really off? I appreciate any help. De-screened stock 99C5 (75mm?) MAF and Throttal Body.

LoWeLL216

iTrader: (1)

Was your IFR table adjusted when you put the new injectors in? That's not a huge increase, but the 99's had the smaller injectors.

racecar

Yes, after the new injectors, I tweaked it several times, that was before I had a wideband, but the 02s were good and the LTFT were good back then. I have made a lot of changes on the VE since then trying to get it to run better below 3000. This tune is close to the stock VE with the first few rows multiplied by 70% 80% 90% etc. No changes above 3200. Now the LTFT are really crazy.

LoWeLL216

iTrader: (1)

How did you adjust your IFR? Did you scale it or use one of the spreadsheets for the new values. From my understanding (my only experience is with my own injector swap to SVO 42lbers) you should input the new IFR table then adjust your VE table to get your fuel trims back inline if they're off. When I used the spreadsheet my fuel trims weren't off too far.

racecar

When I put in the new SVO injectors, I just multiplied the whole table by X percent until the O2s were good and LTFT was 3-4.
Maybe after driving more miles the LTFT went off??? That was a long time ago when I put in the injectors, I have tuned a lot of other things since.

RedHardSupra

iTrader: (1)

you do not tune with IFR. IFR represents the characteristics of your injectors at given fuel pressures. set it to whatever you'll get from the spreadsheet, and if so far you've been using them to tune, your fuel trims will be off, so you'll have to get VE back in line, which is gonna be extra easy and precise with a wideband.

racecar

I see,,, The IFR seemed to be right at one time, so it should still be correct. Even if ALL of the LTFT's are positive now, don't start tampering with the IFR. Just work on the VE table until I get it right. I will get the wideband plugged into HPTuners tomorrow. I was planning to tune my VE in SD mode, but I am so far off, my car won't run in SD now.

ringram

Just use RHS's spreadsheet and do IFR once and do it right. Then work on VE, no point trying to reinvent the wheel, just follow accepted procedures and you will be fine. Buck the trend and not many will be able to help.

See5

iTrader: (53)

Understand that your LTFT below you idle KPA, upper left on MAP will never be right (or matter) as they are decell. But definately input a new clean IFR from RHS and I would then put in a all new stock VE table and get started--

racecar

Thanks for the input guys, it's a nice day here, time to tune it up and go for a run through the country.

Z'mnypit

iTrader: (58)

On a side note, the only time Ive seen my LTFT's be maxed at +25 was when I had a vaccum leak. That may be something to conside. Also what #'s do you have plugged in the IFR table?

RedWS6 00

My LTFT's went to +25 about 3 months back, may not be the same problem as you, but I'll let you know as its something to check.

Well I installed an Intank Walbro fuel pump. I tuned my fuel trims, all was spot on. Had to get my car emmisions checked as it was due for its annual check. Fueling was spot on while up on the ramps. Then on my way home I notice my fuel trims went +25 almost in every cell. Looked at my fuel pressure guage under the hood, dropped from 58psi to 20psi. Got the car home carefully, took out the intank pump (have an access hatch thankfully) the piupe going form the pump to the top of the tank had come loose. So must have had a nice fountain going on in the tank. I corrected the problem and my LTFT's went back in line.

So in my case it was lack of fuel pressure from the tank so the PCM increased the opening times of the injectors by adding to the LTFT's to get more fuel in.

markp03

iTrader: (4)

what do you mean by a vaccum leak? where at?

Z'mnypit

iTrader: (58)

It was sucking air somewhere around the intake. Took it all apart and reinstalled everything carefully, then did a re scan even with out resetting my fuel trims the LTFT's went right back down to around 10 or so...

racecar

Time to get out the fuel pressure gauge for a test, then spray some WD40 on the intake to check for leaks. Do you know of any other way to check for intake or vacuum leaks??
Thanks for the tips guys, those are some good ones.
IFR is from 36.52 to 39.99 is that right for 30 lb SVO?

racecar

Is that the MAP sensor connection in the back of the LS6 intake? I can touch it from the passenger side. It moves up and down, it feels pretty loose in there. Should it be tight. Feels like it's ready to fall out. Oh man, am I going to have to take off the intake??

RedHardSupra

iTrader: (1)

nope, the IFR should start with 34.6

racecar

Hey Red, I'm going to double check on the injector size. Is 34.6 what you calc for 30lb SVO in a C5? Where did you get that number, do you have a calculation sheet somewhere.

RedHardSupra

iTrader: (1)

calculated with the spreadsheet everyone's been already telling you to use. it's in the stickies, on my site, and few other places.

Teutonic Speedracer

iTrader: (20)

I tuned using RHS's IFR spreadsheet, WB02, and AutoVE....and all is good!