I think, I over thought, and now no longer think I know

[BlueDragon]

OK,

My LTFTs are high I get that, They are in the 14s to 25s. Now I need to run a logging run, set up to log LTFT, got that! I expect to see high numbers. I think if I have to add 25 to the VE table to bring down the LTFT is sounds kind of high? thats one question.

I do VE first then MAF. Let's say I get the trims to zero with VE what do I do with MAF or do I even need to do MAF?

I attached my scan file. This is a normal running scan and not set up for VE tune.but they appear to be switching.

Car runs great but rich. the o2 voltages are higher than in the past.

Do I just do a VE tune and live with the high numbers in the VE table?

Take a look at this scan file and give me your suggestions.

[jimmypop13]

Add 25? You mean multiply by 25%?

[WS6FirebirdTA00]

Need to know your mods.

[BlueDragon]

Mods are LG log tubes with 3"cats and pipes, LS6 intake, Halltech MAF mods, screen removed and cleaned up. RPM Tranny, with 2400 stall converter. 3:42 gearset. Dewitts radiator, B&M Tranny cooler, Phadt coil overs with Hotchkiss sway bars, Baer brakes.

The rear O2s were removed. LG recommends moving the rear O2s to the front position so I did. They say because of the header the rears operate are more accurate in the front position. (can't confirm) I have sims in the rear position but I also shut them off in the PCM.

[WS6FirebirdTA00]

Your VE does not look high...

Are you disabling the MAF and tuning with a WB (and resetting your fuel trims)?

[BlueDragon]

Don't have a wide band yet, and no that run I posted was a first test run after replacing head gaskets, intake gaskets and new injector O rings. This configuration has tranny changes, gear changes, stock MAF tables, rear O2s shut off.

Really? it does not look that high? I thought the LTFTs should be in the zero range not up around 25, or am I thinking something else? The STFTs look right or close to right (not perfect).

I set up a config to run VE this weekend, but if you think VE is ok?? Maybe I should just do a MAF calib.

[WS6FirebirdTA00]

You have to disable the MAF to tune the VE. Was the 25% with the MAF still enabled? Was that part throttle out of PE or in PE?

[BlueDragon]

MAF was enabled, and I think part throttle was out of PE but can't confirm.
That run was with the setup that I was planning to run with just to see where it fell.

I guess my main concern was in pulling down the LTFTs. It has always run on the rich side since new.

Looking things over everything looks fairly good except for the high LTFTs and a little more black on the tail pipes than Iwould like to see.

[WS6FirebirdTA00]

To tune the VE you MUST disable the MAF and your MUST filter by non-PE with the NB sensors.

Please search/read the help files.

[BlueDragon]

Yes, I know that, the scan I sent was a straight out of the box run with a street config. I have to use the method with the MAF connected as the C5s have the IAT sensor in the MAF. I have a config set up and ready to run this weekend for MAF and VE. The tune Config has the PE enable kicked up to 75Kpg. to stay out of PE. I realize without wide band, I have to make do with whats available. I plan on ordering a wide band soon.

I am not a full time tuner, just one car and limited time to work on it. Heck it took me four weeks just to rebuild the top end after a blown head gasket.

I guess my question now is based on your earlier observations do I need to run VE or just do a straight MAF, or should I always do both?

Where my thinking gets me in trouble is and I could be totally wrong, but doesn't one affect the other. Which is why you should run VE first? But if VE is ok, than maybe MAF only and go back if necessary as these are never one shot deals.

[WS6FirebirdTA00]

Tune the VE by disabling the MAF and then go back and re-enable the MAF and tune it. VE will affect the MAF. You don't know if the VE is OK until you disable the MAF with the fail frequency and see what it does.

[BlueDragon]

Tune the VE by disabling the MAF and then go back and re-enable the MAF and tune it. VE will affect the MAF. You don't know if the VE is OK until you disable the MAF with the fail frequency and see what it does.

Ding! ha, you just answered my question! I will be doing some tune scans this weekend. I planned on doing scans with the MAF disabled.

In one of the starter threads they said to just set the PE enable high, I did not see anything about using MAF fail Freq. which is a good way and ensures the MAF is out of the picture. What is a good number to set the fail freq too? I guess the number would be zero simulating a dead MAF?

[WS6FirebirdTA00]

zero

[BlueDragon]

Well, Well, started dialing in the VE this weekend, MAF disable worked great, stayed out of PE mode. Kept the MAF connected due to IAT and rant the PE Kpg up to 75. I only have two concerns:

1. I have an RPM automatic and it seemed to shift harder, I did not change the shift properties? Could be caused by the MAF disable.

2. The corrections to the VE table to get the LTFTs in line seem high, but they are comming into line. Could be those rear O2s I am running in the front position, they are known to cause high LTFTs.

Could not wrap it up this weekend, so we will see next weekend. How do you guys hit the high RPM cells? Fourth is out of the question as we can't break the sound barrier.Third still puts me in the 120 range , second does not hit the load cells as she winds up pretty quickly.

Once I get through this and the MAF tune, will be good to go.

It seems to me that this will be something that to maintain perfection it will take constant tweeking!

[WS6FirebirdTA00]

Yes, you have to disable the max line pressure code when the MAF fails.

If you want perfection, no way it is going to happen with the fuel trims. If you want to fix #2 and make sure it is right, you need a WB.

[BlueDragon]

thanks,

Hum, did a lot of reading and seemed to miss the disable max line pressure code thingy, good to know, I thought it would be something like that.

Yup on the wide band been doing some research, lots of LC-1s out there. There is a really nice write up over on the Corvette forum on running it through a spare port on the ECM straight to HP tuners. Got to get the bung welded in. Problem around here is finding somebody to do it right, I am pretty fussy. I don't know if I want something with a meter or guage to see AFR all the time or one where I need to hook up a scanner.

I am a weekender right now, and not driving it every day.

I am happy with the results so far.

I basically set up a test VE config. file, then I copy the changes to a street run test file and finally to the file that I plan on using long term. This way if I have any concerns about potential problems, or hickups I catch them before they become bigger problems.

[WS6FirebirdTA00]

I would recommend the NGK AFX WB, I have an extreme dislike for the LC1.

[BlueDragon]

The AFX was my other choice.

NGK AFX it is then, I read good things about it, and I can still wire it into the ECM to get it to talk to HPtuner without extra wires. I can have the monitor under the dash, wish they had it with a blue display I am going to finish the tune I am working on and see where I wind up.