Uh..... STFT's going mad.

[IDRIVEAG8GT]

So, you guys tell me your opinions here because this is driving me up the wall.

Basically, this is another issue with my truck where my STFT's at idle are freaking out. I.E.(Bank 1, -2.3, Bank 2, +14.1%) now get this though, at part throttle and WOT both banks are perfectly well behaved. Only at idle is this issue present.

Engine is a 415 LS3, port/polish LS3 heads, Kenne Bell 3.6 supercharger, decent sized 236/245 cam on a 114, and ID1000 injectors.

I've recently changed plugs, inspected gaskets, changed plug wires, changed O2 sensors, and it's still going nuts.

Is this the cause of the design of the intake manifold or do I need to pull the supercharger and rails off to clean the injectors?

Kinda lost here because nothing in the tune could allow it to do this, and the worst part is that the Wideband confirms that the O2's are responding correctly.

Any thoughts?

Thanks guys.

[edcmat-l1]

I've seen the exact same scenario with different PD blowers. Didn't waste much time getting caught up in it. They ran good right off idle, and the fuel trim split at idle didn't seem to affect idle quality too much.

[DSteck]

I see the same thing with PD blowers, most notably Kenne Bell. I ignore it. I don't have a reason for it. Doesn't matter if you're in SD, MAF, or hybrid. At that little airflow, I can't imagine how effed the distribution is. I'd bet cylinder to cylinder deviation looks like hell.

[vette_c6]

drive your car and hold it in 2500 RPM while driving and see if you still have this issue

your camshaft isnt small ,, and it could lead to some issue with sensor


i am not the expert guy in here
but doing that might help u ,,,
and the best thing is to share us the scanning file ( if you dont mind )

[383_Stroker]

And i thought it was just our truck

We're not that far out, but it idles about 5 steps apart (-2, +3 or something similar)

[IDRIVEAG8GT]

Thanks guys, I imagine that this problem is accentuated by the cam at idle as well as stated above.

Driving at 2,500 rpm both banks are perfect. ST's follow each other around and Long Terms are typically around -2.3.

Funny thing though, I just did a KB Camaro a few days ago (granted with a smaller cam) and there was only a 5% variance between banks

Thanks again everyone.

[vette_c6]

Thanks guys, I imagine that this problem is accentuated by the cam at idle as well as stated above.

Driving at 2,500 rpm both banks are perfect. ST's follow each other around and Long Terms are typically around -2.3.

Funny thing though, I just did a KB a few days ago (granted with a smaller cam) and there was only a 5% variance between banks

Thanks again everyone.

good luck

keep us update if you have any problem

[MikeOD]

I'm running into this without a blower...wideband and narrowbands agree (I usually can't make them agree so well...I was shocked) everywhere...at idle the car just goes lean and gets a positive trim.

[BigDaddyCool]

Amazing, hopefully someone will come up with a solution on this thread as I have the same issue. Only since fitting an otr

[IDRIVEAG8GT]

I actually made a P.I.D in the scanner that takes the average of the Short Term Readings and spits out a percentage to be applied to the MAF table. I.E. one bank idles at -5 and the other +5. That's about as close as I've got it.

Doing an air model test I see where a big problem to the Kenne Bell Superchargers is. The bypass tube/primary air feed to the engine bends the air to the hard left and down, which accounts for. In vacuum situations like at idle cylinders 2,4,6,8 all get a big dose of air, while 1,3,5,7 starve.

Simple intake design causes this

[DSteck]

Uhhhhh. You do know that logging the STFT sensor already averages them, right?

[MikeOD]

Amazing, hopefully someone will come up with a solution on this thread as I have the same issue. Only since fitting an otr

I just removed my shitty OTR intake and went with a much more conventional Halltech setup.

[IDRIVEAG8GT]

Uhhhhh. You do know that logging the STFT sensor already averages them, right?

Yeah, I think you misinterpreted what I said. The P.I.D/scan table I created averages the SPLIT between the two sensors and returns a value that I multiply the MAF table with so that the two read evenly at a given load, versus manifold pressure.

It provided the best results and idle quality.

[DSteck]

The sensor HPT has programmed will make a Bank 1 of -3 and Bank 2 of +5 read +1. I don't understand what you're doing differently.

[IDRIVEAG8GT]

The sensor HPT has programmed will make a Bank 1 of -3 and Bank 2 of +5 read +1. I don't understand what you're doing differently.

Huh? I had to set it up manually for each different axis on the MAF tables I use it with. It turns each percentage difference into a decimal to be added straight to the MAF.

Maybe I didn't get that sensor in my VCM Scanner since I had to create all my stuff from scratch.

I had to make two for dual MAF table applications as well.

[DSteck]

I guess you don't use paste special - multiply by %.

[BigDaddyCool]

....

[BigDaddyCool]

I have more of a valid question.......... to do with fuel trims.

Nuting it out and tuning maf is a pain........... I went from the stock airbox to a OTR, can I just maybe flog a 2012 Corvette MAF table and chuck it into mine? seems to be OTR..... so then I'd only have to fine tune it.

[IDRIVEAG8GT]

I guess you don't use paste special - multiply by %.

Yeah, no I don't. I guess it just boils down to how we use our computers. Whatever though, it gets the job done.

[DSteck]

Work smarter, not harder!