Running lean with cams

[sk8freak8989]

Ok so i put in some 264/272 cams and now all of a sudden the car is running very lean at idle. I have dsmlink and I have been trying to get it to run right but i have had no luck. The weird thing it is doing is O2 sensor is not cycling like it should or sometimes not at all, but the car is still in closed loop. Before the cams the O2 sensor was cycling fine. I have checked base timing and also fixed all boost leaks. Does anyone have any idea what it could be wrong?

Thanks

I just drove around while logging and i noticed that the o2 sensor looks normal while driving. Could this be a bad o2 sensor?

Here is a log of idle and cruise. The o2 sensor voltage is very rough at idle and looks normal while driving. when it is started when cold the o2 sensor voltage is around 0 but the car is in closed loop. As you can see in the log i have raised the deadtime a lot just to get the afr to 14.7 while idling, but the fueltrims are still very high.

 

[Mrdocprofessor]

it could be bad o2 or another problem with the electrical check your grounds to see if there tight and check altenator and batt voltage at idle hope this helps

 

[sk8freak8989]

I thought the o2 was bad so i replaced it and then a couple days later the alternator died so thats new to. It still does the same thing though.

 

[kthackst]

Your airflow looks low. Your grams per rev should be .26-28. Try doing the MAF adjust tool and see if that helps.

 

[Black-Out]

Ok so i put in some 264/272 cams and now all of a sudden the car is running very lean at idle. I have dsmlink and I have been trying to get it to run right but i have had no luck. The weird thing it is I just drove around while logging and i noticed that the o2 sensor looks normal while driving. Could this be a bad o2 sensor?

The key - or at least what I'm seeing here is self explanetory found right there in the first line of your description of the issue. You've installed a different set of camshafts with more lift and duration which changes the V.E. right from the time the car starts till red line. It doesn't suprize me in the least that your running lean at idle. You'll just have to increase your fueling to smooth things out. If your 0/2 was reading correctly before I highly doubt that you have a faulty sensor now just from changing cams. Rather I'd say you have an 0/2 sensor thats telling you you're flowing alot more air at idle......especially if its reading correctly while your driving down the road when the computer is going to throw more fuel into the motor to match load demand. Idle maps generally don't require much attention to fueling as most modern cars will idle with mixtures as lean as 17:1 (or at least what I've seen from personal experiance)

Try this- add alittle fuel to the map at idle and see if your readings normalize and check the engines behavior. If the engine smooths out a little or the engine becomes a little quieter you were indeed running lean and needed the fuel to compensate for flow increase from the cams.....
William-