04Z06vette

69 Chevelle. 04 LS1 from GTO with Magnuson supercharger. My mechanic has been trying to tune with wideband O2 sensor and HP tuner SW. We did data captures for almost 200 miles so far. Car starts and idles okay but when its under load, it sputters a lot before it finally revs up. No codes are thrown. Looking at misfire data, he says the driver side is acting 'funny'. It cycles between lean and rich under load. Passenger side shows a good curve. He says the fuel mixtures and enrichment tables look good and he sees minuscule differences between bank 1 and bank 2 tune data. I cleaned all fuel injectors again, swapped in new plugs and wires with no change. Looking for some coils to swap next. Any other suggestions? The engine was supposedly low miles (~25k) and the supercharger has even less mileage on it.

Project GatTagO

iTrader: (7)

Make sure you don't have any exhaust leaks, especially ahead of the O2 sensors.

Andrew

04Z06vette

thanks

CattleAc

iTrader: (7)

Maybe just swap the ones you have side to side, and see if the problem moves with them...

04Z06vette

tried swapping coils side to side with no changes. still misfires on driver side. tuner is grasping at straws now, but suggested a leak down test. so today's question is which cylinders are paired at TDC so I only have to turn over the engine a few times. And whats the easiest way to be sure it is TDC or BDC when all the valves should be closed without taking off rocker covers to see valves

G Atsma

Check all connections and grounds.

04Z06vette

would that only cause a problem under load? idle and easy throttle are running very smooth

G Atsma

The more current demanded, the more likely to malfunction. But it can happen any time.

aknovaman

iTrader: (7)

Find a person that can actually troubleshoot the issue and not your current tuner. Throwing $$$ an issue only shows incompetence. Where are you located?

Explain " he says the driver side is acting 'funny'. I" and "he sees minuscule differences between bank 1 and bank 2 tune data. "

04Z06vette

east of Dallas about 30 miles

04Z06vette

he was showing me all sorts of stuff in HP tuners graphs on a tiny laptop screen that i couldn't see so I don't remember what signals he was trying to say were acting strange. I don't know anything about tuning so I don't know what to call the data he was showing. it was table of numbers that I think were for how much fuel at each RPM and throttle setting. they were very close between right and left bank. He said that is a normal amount of deviation.

04Z06vette

solution - 2 o the injectors were same part number but different brand. must have had different flow rates. once I got all the same brand, it cleared the issues