H/C/I 02 Trans-Am tune

[Tang]

Hello All,

After lurking for some time, I think I'm ready to start working on a tune for my ride.It's a 2002 Trans-Am WS6. It was modded way back in 2002, and the tune was done at the same time. I say tune very lightly, as it doesn't look like much was done. There are the obvious changes, but the only real things I see are to the High/Low Octane spark tables. The car put down a respectable 419rwhp, and the air/fuel readings at the bottom of the dyno graph appear to look decent.

I've attached the current tune and a log I just did to see how things looked. Let me know what you think! Here is a list of my mods:

TR227 cam
GTP Stage 2 241 heads
Kooks 1 3/4 headers w/ offroad y-pipe
Stock MAF with screen
Ported stock throttle body
SLP lid

[JasonS5555]

It really looks like they just tuned a bit for WOT. I would look at the stickies at the top of the Gen 3 forum for some tips on tuning the VE, MAF, and idle. That should help the driveability a lot. Your LTFT are all rich and I'm sure that will cause some inconsistent fueling at WOT in the real world.

http://www.hptuners.com/forum/showth...o-and-how-to-s

HTH,
Jason

[Tang]

Thanks Jason, that's what I figured. The car starts, idles, and drives surprisingly well considering the lack of changes made. I get some surge/bucking at low speeds when the rpm is sub 2000, but that's it.

[JasonS5555]

I think that's because you're not maxing out any of the LFTF so the PCM is able to compensate for the most part. But it will be closer to ideal if you tune the three areas listed above.

[Tang]

I noticed a difference between my left and right ltft's, is that anything to worry about? I've read that anything below a 10% difference is OK.

[nkautz]

Set your wot spark to 27 , you have detonation. I would also set the power enrich eq ratio to 1.2 across the board.

[Tang]

Thanks nkautz, I'll make those changes. I think I made the PE change in a tune I just set up to properly log for the VE correction. I may have used 1.24 or 1.25 though. I'll better research the difference there. I've read some doing 1.14, but that may be for cars with a power adder.

**Added**

After reading up on that again I had it backwards. Wouldn't 1.2 bring my AFR down to the low 12's at WOT? Would it be safe to do 1.13 to get me closer to 12.9?

[nkautz]

1.2 for PE is a safe starting point. Set it , do a couple pulls , if you don't see any KR then lean it out to 12.3. Highest I'd go is 12.5 until you really have an grasp on tuning. You want to find the right balance of spark and AFR to get max power without detonation. That's how you tune WOT. Much safer on a dyno though.

[Tang]

1.2 for PE is a safe starting point. Set it , do a couple pulls , if you don't see any KR then lean it out to 12.3. Highest I'd go is 12.5 until you really have an grasp on tuning. You want to find the right balance of spark and AFR to get max power without detonation. That's how you tune WOT. Much safer on a dyno though.

Ok, fair enough. Thanks for the clarification.

I only purchased the standard HPT suite thinking I'd get it tuned by a professional, and just have the program for small changes on occasion and to log, but now I'm hooked HAHA! I may have to look into upgrading it and getting a wideband. I'll stay away from attempting any WOT tuning until then.

[nkautz]

You can wire a wideband with standard hptuners if you feel like getting creative. You can hook it up to your a/c pressure wires or your egr wires. Or any wires from the pcm that use a 0-5v range. https://www.google.com/search?hl=en&...m+widebband+ac

[Tang]

You can wire a wideband with standard hptuners if you feel like getting creative. You can hook it up to your a/c pressure wires or your egr wires. Or any wires from the pcm that use a 0-5v range. https://www.google.com/search?hl=en&...m+widebband+ac

Great tip! May have to do that, thanks!