First serious Scan, Where should I start?

[BlueDragon]

Greetings,

I finally got the time to get some serious scans with my mods.
This is a 98 C5 rag top A4 with a 2:73 rear end. Mods include, LG long tubes with 3" random techs and X pipe into a Corsa Indy system. Modified MAF (removed screen, Halltech ends, removed un-necessary plastic) Halltech snorkle (early style) 176 high flow thermo. LS6 intake manifold. No changes to the computer yet. Plugs are Iridiums and been in a while, MSD wires. Running the rear O2s in the headers, used sims in the rear position (per LG instructions).

I was impressed with the SOP of the first run, I rolled in easy up to 35 MPH as she will fry the tires at anything less, still got moderate wheel spin, but not enough to trip the TC. Flat footed it and manual shifted at 5900, traction control came on as she tried to bust them loose again! Not bad. I think it could do better.

Reading the charts here is my first impression.

1. LFTs are high at 18 - 19.5 at WOT
2. INJs duty cycle seems high in mid-high 17ms even an 18 (these are the larger INJs offered in 98.)
3. MAP seems low and drifty running 98 to 101
4. MAF seems to be working right.
5. Fuel Trim cell is a constant 22 ? don't know what this means?

I do have a run where she threw some KRs, but I believe that they are false. As sometimes they happen and sometimes not, so I got to go looking for something hitting or rattling, AC was on so it could be that.

Thank you in advance. I think if I can get the LTFs lined up she should be pretty close. All in all for a 98 with 125K miles and a 2:73 she is strong!
Below is the spread sheet form this run.

Can I get some expert opnion on what you think? And where I should start. Where would you start?

For the run below, I reset the Fuel trims then drove for 50 to 70 miles and then did several lead up runs then the one below.

[Dellz06]

Hi,

There's a good sticky post at the top with tons of good information.

That being said, it looks as though your LTFT's are +20ish. I would attempt to get them between 0 and -4. This involves disabling your MAF and adding to your VE table.

John.

[BlueDragon]

Yes, I am looking at those. Need to get a wideband setup. to go through the process.

I am still pretty much a newbe so making sure I understand everything before I tear into it.

Looking at the INJ pulse width she seems to be taking a bunch of fuel as is. tail pipes show just a hint of black, and she is pulling hard.

Like I said, on the 1st to second shift, she will bust the tires loose. How many C5s with a A4 and 2:73 and stock converter will do that? Granted they are run craps but with the 2:73 she shifts out of first at 60 MPH. I don't mean she squeaks them, she actually busts them loose.

Having said that I want to be careful and not go backward. The high LTFTs mean she is adding fuel. Think I will pull the plugs and take a reading first.

[Dellz06]

With 15 points extra fuel at WOT and the stock PE table, your AFR could be in the 10's. If you like the SOTP now, you'll love it when you get the AFR in the 12.5 ~ 13.0 range.



John.

[BlueDragon]

Oh, no doubt ;D I think I am going to take it to a tuner that has done it before. I am not really confident on the entire process yet. The guy I am thinking of has done a number of cars with HP tune and has a dyno with a wide band set up. after I go through the process with him, I should be good on my own after that. I think I need to upgrade the tires.

How do I know when the INJs are maxed out?

Jer

[Dellz06]

That's a good question and I'm not sure of the answer. I'd search on "duty cycle" to find the answer. Somewhere in the 80% to 90% range. Found a calculator that says 18@6000rpm = 90% [20@6000rpm = 100%]

One thing I do remember hearing is that you're probably not gonna max out your injectors with the mods you listed (intake and exhaust).

John.

[Dellz06]

One other thing that came to mind as I hit "post" is that you might max them out running as rich as you are, but if you lean up to the right place you'll have injectors to spare.

John.

[Dellz06]

What does this mean:

"Running the rear O2s in the headers, used sims in the rear position (per LG instructions)."

You removed the front O2s altogether?

John.

[BlueDragon]

yea, I don't know what it is about this car, but over the years it has just run like gang busters. The base line Dyno was 320 RWHP, bone stock with the A4 and 2:73 rear. Remember this is a 98 and supposed to be 345 FW.
Three autocross championships later and mods and she is hitting 350 RWHP which is great. Some of the tuners looked at it and said it must be a Wed. car ;D In the 4600 to 4900 RPM range in third gear she is pulling really hard and the INJ values are in the mid to high 17s and the LTFTs are 18 and 19.5 Soooooo to knock them down to zero or close it stand to reason that I need to increase the INJ width. The banks looked fairly balanced. both INJ and LTFTs.

I got this car in Dec. of 97. So it was really early in the 98 build cycle. One tuner I talked to thought that it might have been a quality control car, that was taken off the line and tested and tweeked, they do a few of them every now and then. Right from the factory, the manual and lower rear end optioned cars have not been able to touch it. I modded the intake in two stages halltech first, then as soon as they came out I added the LS6 intake manifold. Same for the headers first I ran the B&B shorty's, X pipe and Corsa Indy last year I stepped up to the LG Long tubes and 3" Random Tech cats system. The car has responded very positive every time! I think it was very rich from the factory, and with the mods making it leaner, now with the LG's I think it went over.

I just read an article about adjusting the LTFTs with the MAF table, and the IFR table. This article was written by a guy using LS1 edit, but the results were the same. Because my MAF is modified, it stand to reason that I should recalibrate it, and then go after the IFRs to touch it up. Wha~cha~ tink?

Looks like there is more than one way to skin this cat.

Jer

[BlueDragon]

What does this mean:

"Running the rear O2s in the headers, used sims in the rear position (per LG instructions)."

You removed the front O2s altogether?

John.

With the Lg Long tubes you take the rear 02s and put them in the headers, and then put 02 simulators in the plugs for the rear 02s. The long tubes don't hold the heat that the stock system does, and some guys throw 02 codes, and this eliminates that. LG makes the adapter plugs and sends them with the headers. LG = Lou Gillotti (sp)

The Rear 02s have a lower temp range on them.

[Dellz06]

Ok, I could be wrong about this --

The front O2's work to determine your LTFT's and the back O2's are used to determine whether the cats have failed. If you removed your front O2's, you ought to be throwing a code or something right?

I thought that when you used O2 sims in the rear that you left the front O2's in place and tossed the rears...

John.

[BlueDragon]

Ok, I could be wrong about this --

The front O2's work to determine your LTFT's and the back O2's are used to determine whether the cats have failed. If you removed your front O2's, you ought to be throwing a code or something right?

I thought that when you used O2 sims in the rear that you left the front O2's in place and tossed the rears...

John.

LOL! I am not explaining this very well! OK, let's start here. You take the rear 02s out and install them in place of the fronts. You use a provided adapter and plug them into where the old fronts plugged in. So you now have the rear 02s in the front position. Now you just plug the sims into the old rear connectors.

So now the rear 02s are now mounted where the fronts were and functioning as the fronts and there are no rear's!

[Dellz06]

LOL -- that makes sense. I get confused easily. I ate paint chips as a kid.



John.

[luv2spd]

From the looks of things you could stand to add some timing. 21.5 deg isn't much....try to get that up to 25-28 or so.

[BlueDragon]

Hum, good point, glad you brought that up.

[luv2spd]

Hum, good point, glad you brought that up.

any updates on this??

[BlueDragon]

Welp,

After reading a whole bunch of stuff and being a newbe at this game, I think I am going to start out really simple. This weekend I plan on Rescaling my MAF table. One thing I did was to rework my MAF, I took out the screen, have Halltech polished ends and hogged out the un-necessary plastic so essentially I have just the bars and wires. I think I am going to scale up by 10% across the table and see where it takes the LTFTs.

Hell if I don't like that I can always go back to stock. I am not going to get into any really heavy stuff yet as I have a couple more mods that will affect the tune.

At 125K My 28lb. stock FIs are probably tired at the top end they are running about 80% (18ms) so I am going to go to some SCO 30lb'ers, and with all the autocrossing and High revs, the valve springs are also pretty tired, so I think I am going to put in some crane 1.8 rockers with new springs and pushrods. Pluse a fuel filter and check the fuel pressure.

So for now I will use the MAF table to fatten it up till I get the other stuff done!

At 125K I am impressed with the lower end, compression perfect and no lower end noise! Just the traditional valve train clatter from the headers and high milage.

[Dellz06]

Rescaling the MAF by 10% is a pretty good idea IMO.

My LTFT's were in the +20's and I rescaled by 10% -- got them pretty close. If you're keeping the MAF and looking for quick-n-dirty, this is a pretty good choice.



John.

[Dellz06]

Hey BlueDragon,

If you do another run with your MAF rescaled, it would be great to see the logs -- I would predict that the duty cycle would be lower, the question is by how much.

Thanks,

John.

[BlueDragon]

Will Dew! should have something to post by Sunday night~~I hope!