jnybbad

How come my WOT o2's vary so much between runs. I took some Auto Tap logs to send to Nelson . He had me do one WOT run from a stop, a second from 20mph and a third from 50 mph. On my WOT run from a stop my o2's averaged 929. on my 20mph WOT run my o2's averaged 952, and on the 50mph WOT run they averaged 935. I saw as high as 977 on my o2's on the 20 mph WOT run.

Which numbers should I be looking at for tuning? My truck just feels sluggish during WOT under 5 psi boost. Nelson has been playing with the timing but its still sluggish. He has my timing at 19 deg but its running at 15 to 16 deg under conditions. My intakes never get above 125 deg and I have no KR. Could I use more timing??

F8L Z71

I think I was running 16deg of timing with just the IC and no methanol at 13psi. I am now running a tiny bit of meth with the IC at 12-13psi and 18deg of timing. We used 20deg before and the truck ran like a raped ape! But I backed it down to be safer on the street.

You might wanna just pay the money to have it dyno tuned. *shrug*

jnybbad

I had it dyno'ed at a local shop in Suisun but they used a dynojet dyno so it didnt load the motor enough to get full boost. Im going to take it to synergy next week and have them look at it. Do you know of any dyno shops around our area that use a mustang dyno or one that loads the engine?

On a second note, why is my timing 15-16 deg if he is setting it at 19? How adjust for this. I was told that the timing is being pulled because of IAT's. My IAT's look good so could I modify the amount of timing that gets pulled?

StupidFast

Make sure your fuel trims stay in the negatives. If the fuel trims are positive before WOT the PCM will add more fuel to compensate for the "lean" condition. This will make your A/F ratio vary greatly.
Also, it would be alot better to buy a wideband for tuning. The stock O2s are very accurate around 14.7 but as the ratio goes richer or leaner, it becomes a less reliable reading.
Hope this helps. I am NOT a professional tuner, I just play alittle.

StupidFast

Your IAT may be moving around because of the IATvsMAP table. The hotter the air gets the more timing is pulled.

F8L Z71

I believe I read in the FI seciton that the IATs can only pull soo much timing. It's actually not very much. You may also be getting partial KR too. Not enough to show up while scanning but will show up when you put it in Excel. My T/A used to do that.

Like stated above. The PCM takes time to figure out what it's next move is. So when you first hit WOT it is calibrating itself off parameters it saw a few moments ago so it is essentially always playing catch up. That's why going really lean is very dangerous because the computer takes too long to correct.

I've never seen any fast LS1 comes out of Lance's shop so I don't know his ability to tune a turbo'd LS1. Rick can definately help you out. He has the wideband o2s and the datalogging equiptment to get you a great street tune and you can always roll over to ATP in Fremont to dynotune the truck if needed. The can load the dyno so you get full boost AND they know a ton about turbos since they specialize in turbocharged VW, Audi, and Mitsubishi. Rick uses their dyno to tune his cars sometimes. They won't tune the truck for you though. You need to talk to Rick and he can tell ya what needs to be done. He is a great guy. Just be upfront about what you want out of the truck and he can make it happen. He likes to tune for safety though so don't expect the best peak #s. In our opinion what good is an extra 20rwhp if you can't keep the pistons from melting?. LOL

jnybbad

Thanks for the info. Ill call Rick and go from there.

Black Blown 02

Actually, IAT's can pull a TON of timing. In my stock 02 file, 125 deg IAT will pull 11.2 degrees of timing out. It will pull more as the temp rises above that.

marc_w

I don't think it's recommended to pay attention to 02's when running boost... They need that fat mixture and even us N/A guys have a hard time trusting them.

Here is my stock IAT table for reference... You can see that it doesn't take much to start pulling timing.

F8L Z71

Damn, then the guy that said it doesn't must have been smokin then. Good to know