ram-it

I have been looking at my buddies car which basically has a big cam in it and headers. His Predator showed the LT's at 25 at idle. I plugged the HPT in and sure enough they were. I tweaked the VE tables some and it helped but we are still at 14 at idle, -1.6 at cruise and 0 at WOT. Nothing I can do will get the idle down. Any suggestions would be appreciated.

ram-it

To clarify I only tweaked the 400-1200 VE columns since its an idle problem. We ran the car a couple of times and it is real strong through out the RPM range to 7k.

Black02SS

iTrader: (36)

I had the same problem and it turned out to be a vacum leak. Fixed it and all was good. Are his IAC counts at 0 for idle by chance?

ram-it

I cannot find that readout on HPT. Where is it? He has AutoTap if that has it. I can ask him to go check. For my own info what would IAC being 0 at idle tell me?

Black02SS

iTrader: (36)

Idle Air Control Position is what it is. If it is in fact 0 at idle, I would suspect a leak of some sort. If you check it with autotap, I "believe" there are 2 PIDs for it. One works and one doesn't (I use efilve).

Billiumss

iTrader: (11)

I'm going to guess it smells really rich at idle when warmed up?

The bigger the cam the more your idle Ltrims will go positive.

It has to do with the duration and lsa, your O2s are picking up some of the intake charge.

P Mack

iTrader: (6)

Right, oxygen sensors don't actually measure fue/air ratio, they measure the concentration of oxygen in the exhaust. If you have both unburned fuel and air, the oxygen sensor will see the air and ignore the fuel, and it will think you're running lean. Then your ltrims will go up.

ram-it

Yes, there was a rich smell of fuel in the exhaust when it was warmed up or started warm. That disipated with the lowering of the VE table. So based on the size of this cam it sounds quiet possible to have positive LT's at idle which is okay so long as they go negative at cruise and 0 at WOT. Would that be a fair assessment?

baddogz28

iTrader: (6)

HC02SS, my car's trimming 25 at idle too- I have never had to find a vac leak, how do I go about doing that?

snake_charmer

I am in the same boat with LTFT's at 25 at idle after new cam/fast intake install.

moehorsepower

iTrader: (3)

We installed a fast intake on an 02 and I had tuned the car prior to the intake.after the swap the fast cause a very lean condition,hence the horsepower gain. You will have to adjust your IFR and PE for WOT..