slowjoe99

iTrader: (7)

Long post I know but please help me out

I recently swapped my heads (ported ls6), cam (MS3), intake (LS6), and stall converter (3500). after all this the car was tuned with HP tuners. My tune was done in two sessions a couple weeks apart. During the first tune the oxygen sensors weren't working some of the time and the tuner told me that I should replace them before the tune is finished up. I forgot and when it was time for the second part of the tune they were not working at all... Now I have replaced both O2 sensors and the idle still isn't that good and the car still bucks when the torque converter locks up (over 45 with low throttle). Half of the time it's not so bad and the other half its kinda hostle. And when the motor is cold (first start up of the day) it takes about 30 seconds for the idle to even out. it usually goes up and down between 500 and 1200 rpm's. I was told that since the O2's weren't working when the car was tuned I might be able to get a little more power and drivability out of it with a retune. Is this true or should I let it go? I want to full potential and no more bucking

macca_779

Obviously your tuner did not use a WB O2 Sensor to tune your car as the stuffed O2 sensors wouldn't mean squat if that was the case. Subsequently without even valid NB O2 sensors on board your fuelling is totally up the ****. The symptoms you mention sound very familiar as I've seen it many times by lazy tuners. The idle hunting is probably caused by to rich a mixture and the bucking at part throttle because its lean. Hell if its tuned Open Loop Speed Density or even more the case if its tune Open Loop MAF you wont even need the O2 sensors as all fuelling calculations will be accurate and the O2 sensors will have nothing left to trim.. Hence they will be redundant.

redtail2426

iTrader: (10)

you will probably always have a little bucking with an ms3.I still dont think there is a cure for cams that size.but good luck anyway

shoemike

iTrader: (25)

your "bucking" could be from your desired airflow table needing adjustment.

macca_779

There is a cure dude.. Its called TPS fuelling.

redtail2426

iTrader: (10)

Even with tps fueling,its hard to completely rid a car of bucking,at least with a 6 speed.I have fixed bucking with a 6 speed to a point where its hardly noticable,but not completely gone.I can see with an auto it would be much easier to fix bucking.

slowjoe99

iTrader: (7)

whats the best kind of tune for a car like mine?

BLK02WS6

iTrader: (2)

The proper way to tune is to put the car in open loop (factory O2 sensors offline) and use a wideband. Then when the tune is completely done, you put the factory O2 sensors back on. If the car is not trimming properly (LTFTs) at that point, you have one of a couple problems - faulty O2 sensors, an air leak on the intake side of the MAF, or air leaks in the exhaust upstream of the O2 sensors. A good tuner should know this and be able to point you in the right direction if the car is not fueling properly in closed loop...

slowjoe99

iTrader: (7)

Should I ask the tuner to use a wideband O2?

Bird

iTrader: (25)

If he's NOT using one, maybe you should look for a different tuner.....


Bird

slowjoe99

iTrader: (7)

any other helping info??