CAMMED/SUPERCHARGED 1LE CAMARO IDLE ISSUE. Negative timing ruining all the fun.

Hey guys, I have another 1le tuning issue. It's procharged, did the bottom end and cammed it. It runs okay but the timing is still negative and it sounds like butt. I have a scan from the same tune in MAF and VE mode. Runs about the same. What should I try next. Adding a bunch to the maf or play with the vvt a bit more. The torque numbers at idle are pretty low already. These 1le Camaros are really touchy with the timing. In stock form I believe they sit at 0-1 degree


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Do you have user defined parameters? Has anything stupid been done like little holes put into the throttle plate?

I should also note that the problem is on the map side of your torque model. High kpa needs to match the air side. Use the VE table change from OE to balance them out.

Throttle body is stock. No holes or anything. When you say use the VE table change from OE to balance them out. Are you saying I should bring down the area in the map torque model that I adjusted in the Ve table? Kind of match it up and make the same changes?

The fueling looks like everything is inline. I could let the ve tune idle a bit longer and the fuel trims tend to zero out.

The map side of the torque model from what I've seen so far is the only side of the model that the "offset" apply's to. Most people just lower the airmass side, but I've had this cause more problems than anything as this was how I initially did it years ago as well - maybe I was just doing it wrong?

The offset I'm talking about is the percentage shift that you made to the MAF and the VE models during dialing them in. I've actually got another member on here right now making a tool that will hopefully do all of the math to get things close, but will require heavily on the VE being ENTIRELY dialed in correctly for it to work.

If you look at these screenshots you'll see delivered torque is the same both vertically and horizontally in the attached torque model pics. I've already made a change to bring torque back up in these vs what was in the log but the offset is still there. I don't have this perfected yet and it still requires other torque controlling tables to be right, but you should be able to get the gist. This one idles around 50kpa, so with yours being 80 it's going to require a lot more re-working.

As stated the torque model in these pics already had 10 added to each to get the torque back toward positive so with that being said in the attached the 41 lb/ft offset is illustrated by the -28 lb/ft delivered value vs the torque model tables +13 value (again gong by numbers for the log before I changed the torque model numbers). This offset comes from dialing in the VE from the original tables with the factory settings. The MAF's 8% offset I'm ignoring in this case, but you can see it's present with different values there too. Thinking about it though, that might need to be included into the tool - don't know yet till it's tested....

Anyway, you dial it in using delivered to get it all close then you put the offset back into it to balance it back out. What I've been doing to get them really close anyway.....

How are you setting up those histograms?

This is for 0 spark and 15 degree cam position [14.161] > -5 and [14.161] < 5 and [2172.161] > 11 and [2172.161] < 18 (translates to spark greater than -5 and spark less than 5 and cam greater than 11 degrees and cam less than 18 degrees)

You have to do the same for all the spark and cam points - pita. I go up through 15 degrees because most performance cams still using variable cam movement will be up around 11ish degrees. I dial in cam movement in the VVE and torque models. Set map up with map kpa as the axis and cylinder airmass with the correct units up as the other axis. Then of course rpm. Log delivered torque in lb/ft - I have my editor set up to display it in lb/ft in the tables. You can also tighten up the splits more if you want, but the +/- 5 is close to what it's looking at.

Just got the rough draft of the tool sent to me, so I'll see how it calculates out for the offset tonight if I get a chance. Delivered will usually get the airmass side close enough on it's own. The map side is what I've always had problems with due to the offset caused by dialing in the VE tables.