Here are some resources for those of you interested in knowing the truth about the LS tuning platform. I would say you should take a look before allowing any doubting Toms on here telling you what I said isnt true.

HPtuners website. Join and search for common topics such as what I posted:
http://www.hptuners.com/forum/index.php

C5 section tuning info fro term explanations. Takae a look at LTFT's:
http://www.c5forum.com/diy/ltft.php

Why you have a CEL:
http://www.magma.ca/~johnhunt/fbody/ls1_tune.html#trims

Here is the section you need:

Long Term Fuel Trim Description

The long term fuel trim (FT) is a matrix of cells arranged by RPM and MAP. Each cell of the long term FT is a register like the short term FT. As the engine operating conditions change, the PCM will switch from cell to cell to determine what long term FT factor to use in the base pulse width equation.

While in any given cell, the PCM also monitors the short term FT. If the short term FT is far enough from 0 percent, the PCM will change the long term FT value. Once the long term FT value is changed, it should force the short term FT back toward 0 percent. If the mixture is still not correct (as judged by the PCM), the short term FT will continue to have a large deviation from the ideal 0 percent. In this case, the long term FT value will continue to change until the short term FT becomes balanced. Both the short term FT and long term FT have limits, which vary by calibration. If the mixture is off enough so that long term FT reaches the limit of its control and still cannot correct the condition, the short term FT would also go to its limit of control in the same direction. If the mixture is still not corrected by both short term FT and long term FT at their extreme values, a FT DTC will likely result. When the PCM determines that the long term FT is out of the operating range, the following DTCs will set:

DTC P0171 FT System Lean Bank 1
DTC P0172 FT System Rich Bank 1
DTC P0174 FT System Lean Bank 2
DTC P0175 FT System Rich Bank 2

Under the conditions of power enrichment, the PCM sets the short term FT to 0 percent and freezes it there until power enrichment is no longer in effect. This is done so the Closed Loop factor and the long term FT will not try to correct for the commanded richness of power enrichment.

The ability of the PCM to increase or decrease long term fuel trim adjustments is +/- 25% in either direction (23% and 13% for 01's and up). It will set a diagnostic code. At that point, you are forced to look at your system and either remedy it by go back to where you were, or tuning your system, and/or adding larger injectors, etc.

The one area not agreed with by most tuner platform developers isthat the car adds fuel in PE mode in addition to the commanded a/f by calculating the amount lean it was in closed loop. Those that scan with a wideband as I do not e the car is way richer if there are positive LTFT's than if they were non-positive including zero.

 

Not necessary. We believe you Spinmonster.

 

I would not disagree with SpinMonster who has been giving nothing but great information and services.

SpinMonster, is there any advantage to removing the restrictive MAF screen? Is there any hp gains by the removal? I have a ported and polished TB with Vararam.

 

I finished up my header install yesterday evening, started the car, no leaks, no engine lights sweet success! Given it was pouring last night, left it on the jacks, give it the once over in the AM & test it out.

Started it, gave it the once over, still checked out, so off the stands & off I went. When I started the car off the jacks, bam, CEL! So much for sweet success. Took it out for a 20 miles run half city streets half highway. Engine light still on. Gave a quick once over from what I could see, nothing noteable. Parked it & started cleaning up garage.

When I started it put it away, no CEL, again, sweet success! Took for a short spirited run, very impressed w/ sound & sotps improvement, also noticed more tire spin, i.e. HP?

Finally, started it once more 30 min later, no CEL! Awesome, & honestly the car has never felt stronger, maybe its the cool temp, & just the sound, I would swear to marked improvement.

Next, FAST install, modified by Spin (awesome job thank you very much) then off for a cam & tune. I am very curious what the impact of the FAST will be. When installed, the mods. will be as follows:

Vararam w/ spacer
1-3/4 Kooks 3" x-pipe
3" back to 2-1/2 Flowmaster connect
Flowmaster 17427
Fast 90 (mild self port)

Anyone have a guess where I'll be rwhp, pre-tune?

 

It is likely that you will have intermittent CEL's since the car did it once already. As I said earlier in this thread, its in degrees of lean. You car is likely at 20-22% lean on the long term fuel trends and peaking at times at +24% triggering the codes for lean running.

A tune will end it forever.

 

388 fully tuned and 372rwhp untuned. Let me know how I did with a guess.

 

As Mr SpinMonster quoted, due to the change in the volume and velocity of air now entering the intake manifold the pcm does not recognize this new higher flow, and then throws a code, you live in NY, give Chuck coW a call or pm him in this forum he will get you dialed right in, Happy New Year.

 

I noticed when I pulled the plugs doing the header install they looked as if the car has been running lean already, probably from the Vararam, so based on the detailed info in the posts the headers no doubt put it over the lean side. Should I be concerned driving the car lean enough to trip the CEL. After I install the Fast I was planning to drive it to have the cam & tune which is not local, 200 plus miles. An other question, or advice actually. Should I bother installing the Fast intake given I am getting a cam swap?

 

Here's what I do in my shop.....

Log your LTFT's by MAF HTZ. Basically, you need to make a LTFT table that reflects the same MAF Htz columns of your MAF calibration.

Then log the fuel trims. on a good ride trying to hit as many cells as possible.

The way it works..... If at 3600 Htz, you're reporting a LTFT of 15, then make a positive adjustment to that cell of the MAF table by only about 50% or so of the actual LTFT (or AFR Error). Do this for all areas of the LTFT table you created until you have roughly positive 5 in your fuel trims from the bottom of the table to about 7,500 htz. Try to get the 7,500-12,000 fuel trims to 0 (zero).

This will make the car run the best it can run without getting too scientific.

REMEMBER: If you're gonna get a "check engine" light for the LTFT's, it will usually occur when a particular cell goes above positive 20. DO NOT DISABLE THE LTFT CODE! It's important.

Sometimes when installing a high quality (HIGH FLOW) intake system like the VARARAM, it's not likely you'll get a light, but every car and system is different. Porting the TB will make it worse, so will headers and the like.

For those of you out there that are not MAXX EFFORT with your vehicles....Do yourself a favor and leave the MAF SCREEN in place.

Likely, SPIN and other tuners will have different opinions on this, but...This basic approach will make your car run great and not give you any problems.

For anyone who has a light on or just wants the VARARAM-MOBLIE you're driving to be the best that it can be.....

PLEASE SEE MY MAIL ORDER TUNING THREADS ON THIS FORUM.

It's NEW YEARS! And I'm OUTA HERE!
Chuck CoW

 

Well thank you so much everyone for your help especially spin monster, I live in northport, but i work in west babylon so I'm not far from u. Im doing the headers tommarow and I cant wait to see what I get out of them. as far as the CEL goes I'm goin to get the car tuned at RAMP corvette where I bought the car from, the guy their told me he will use the LS1 edit to tune the car, they do the "rampage" tuning their he told me off a bone stock vette he can get another 20hp just buy a tune? Ive heard good things about them so I'm gonna give it a shot. Is it bad to drive my car being that its so lean it threw up a CEL? and also will the headers/cats/x-pipe/mufflers make it worse? should I be careful?

 

I drove my car 4 hrs that way with the CEL on when getting my 1st tune at a shop in NJ. You won't have any problems, just don't drive aggressive and keep the rpms down.

 

My CEL came on about 2 weeks after my AR header and tune work was done.

I'm going back to my tuner this weekend to get the CEL removed.

 

Well I installed the headers today, I went with the dynatech system w/ cats and xpipe. Very pleased with how easy is was just time consuming. I had the batt disconnected for the process and I hooked everything baxck up when i was done and the CEL was gone(knock on wood) I dorve the car all over and no prob. The car is nasty now big dif in power I can't wait for the tune! anyone have any idea what I should expect from the tune as far as power?

07 Z51 vert
vararam intake w/ spacer
dynatech headers/cats/xpipe
borla sport cat back
and it will be tuned with an LS1 edit

 

I gained 17hp just with the AR header install on my 06 a6, then after the tune 30hp and 24 ft lbs.

 

It isnt running lean, it runs stoic-14.7:1. Thats the purpose of a closed loop system with O2 sensors. If it sometimes peaks outside the range it gives you a code for lean. The lean long term fuel trends make you run rich at wide open throttle because it dumps more fuel after measuring the lean cndition at closed loop to protect the engine.

Tuning gets the LTFT's to be non positve near zero which is the same 14.7 it always is but it wont dump more fuel than commanded in WoT.

The cam's breathing requirements would be helped by the FAST manifold. You will be fine driving to get the cam installed. The manifold typically makes you 3% leaner on the LTFT's. It snt that much worse.

 

Hopefully Brad does the tune for you. He is a very intelligent guy and went away to the C6 schooling that requires you to assemble a C6 top to bottom.

Too bad about LS1 edit though. What do they charge?

 

Ok so today I drove the car all over again, no CEL, I drove it to the dealer for the tune and some other little bs with no CEL. Literally as I was pulling in BAM! CEL I was actually kind of happy it cam on b/c i wanna make sure when i get it back it doesn't come back on. They explained to me their tune consists of fuel trends,recalibration of the MAF, 1-4 shift eliminator, higher rev limiter, tourque curves, lower fan activation temps, and some other stuff, He said that i should be able to get an additional 20-25 hp with the tune, all togethr with my mods I should be around 400rwhp? i dunno if thats the case but w/e. They charge 399$ for a tune however when i bought the car they were doing a special where u get 1000$ in accessories/parts/service for free. So I figured what the hell. Anyways spin monster if they do a sh*t job and u can tune it then hey lets do it!

 

Since they use LS2edit it will likely be locked after the tune.

Mine was free and you could have saved the money. You went where you felt comfy.

 

well thanx neways for ur help spin. today i found out that the CEL i had gotten when i was pulling in was something with one of the o2 sensors, not the MAF. They said something along the lines that on the new exhaust the o2 sensor sits at a dif depth in the bung? which cause the CEL? dont make much sense to me but i was assured ill never see that code again.

 

My CEL just went away today for some reason. I had a CEL about 10 days after my AR headers and tune, now 6 weeks later it's gone.