Hmmm, thought I got 550s... think I have 650s

[DCsGST]

So I ordered some 550s a few months ago, but the more tuning I do I've noticed the settings are way off. My low settings are -18% across the board (except at 800 and 1500 where I had to richen it up to hold an idle because of the cams) My high settings are -23% and my datalogs still show .94-.96V. I can't seem to get .92V dialed in.

I'm also running a 190 FP and a Big28 Killa at 18-19 PSI. Is this normal for 550's or did I happen to luck out and get some 650/660's???

 

[tigerstalon]

Assuming you went from 450's to 550's, it sounds like you have 550's. Simple math says that the 550's are roughly 20% larger, so your settings should be around 20% different. 650's would be closer to 40% or so.

 

[DCsGST]

OK cool, I just wanted to make sure.

 

[kpt4321]

Don't tune with O2 voltage. Use timing and fuel trims.

 

[DCsGST]

My timing is smooth with 16° at 6800. I didn't know 2G's could use fuel trims to tune from. Would I use STFT or LTFT?

 

[kpt4321]

Both.

You want the sum of the trims to be around 0%.

In reality, the total trim is not the sum but the product, but the sum will be close enough, and you'll always be fine tuning anyway.

 

[Blk_99gst]

I didn't know 2G's could use fuel trims to tune from. Would I use STFT or LTFT?

STFT and LTFT are only used for Low safc settings. They don't affect WOT tuning/High safc settings. For the high safc settings, use timing advance, and maybe o2 voltage, but don't put much trust into o2 voltage. Or get a wideband too for the high settings.

 

[DCsGST]

That's what I thought. 1Gs get a little more info from a datalogger then we do (2G). I wish I had a wideband, but don't we all.

 

[ClipseT96]

I bought 750cc injectors and while tuning we kept wondering why the fuel was so hard to tune. We did a flow test on the injectors and they are 990cc. They are kinda a pita right now but when i'm done w/ break in period and start to hit boost its going to help out a lot. Big injectors suck for gas mileage and the price of gas today. Price to pay to go fast.