dec010974

iTrader: (1)

does anyone run thier lsx swap with both front & rear o2 sensors? if this done, can you get a better tune? also, can you increase mpg & performance? the reason for asking, i want to increase my performance results. i swapped a 5.3/4l60e in to 87 c10 with 3.73 posi with no other mods. the combo gets 17 mph. it has no tune. i want the best of every world. ideas appreciated.

Nova 404

iTrader: (5)

Rear 02s are an OBDII thing so the ECM can check CAT converter operation.They will have no effect on tune or economy

72ssguy

I am assuming you have, and are utilizing, the stock 5.3 harness and computer. Right? IMO the tune would depend on the skill level of the person executing the tune. Having 4 o2 sensors will provide the engine and tuner with more feeedback as to the effectiveness of their tune and probably allow the computer to make better adjustments as you drive. Also, I don't see any difference in the gains you can realize in your rig versus somebody with a latemodel truck that gets a performance tune for their dd.

gofastwclass

iTrader: (2)

You are incorrect 72ss. As stated by Nova 404, the rear O2's are simply a check to see if the cats are working properly and have zero effect on the tune if taken out of the program. The PCM uses their signal to compare against the front set to ensure air quality and other things OEM's worry about.

Dec010974 is your 17MPG city or highway? I get around 17 city in my Thunderbird with 3.23 gears and never have a tank that doesn't have at least one full throttle run.

The best way to get economy is make sure all the little mechanical things with the vehicle are up to par like spark plugs, wires, tire pressure, the brakes aren't dragging, all the engine's accessories are working properly, etc. Excessively large wheels, bad alignments, slipping transmissions, steep gears, tall tires and low tire pressure all kill fuel economy as do (some) damaged body panels, poor driving habits, poorly routed exhaust and bad engine combinations. If everything above is in order, the tune would be the last thing I would check and adjust. Adjusting the tune would take a lot of data logging with a wideband O2 sensor and a smart tuner riding with you. A mail-order tune will get you running, but a local tune is the only way to get all the details right.

dec010974

iTrader: (1)

thank you all for your responses. Gofastwclass, my 17 mpg were highway stats, with a 3.73 posi, 3800 lb. truck, standard 15 inch rim, 275-65-15 tire (new tires/alignment) good clean paint. So basically im back to square 1. Is it safe to say my gains in mpg or ft. lbs/hp will come from the tune? i also wanted to add my ls6 cam and springs. Gofastwclass, i just want to make my lsx swap peppy with with good mpg. I came from the Gen 1 400sbc/400th club and im not going back. 5.3/4L60E rule.

hookemdevils22

iTrader: (12)

considering a 2001 silverado 1500 2WD 5.3L was rated at an EPA estimated 15/18 city/highway mpg with better aerodynamics (albeit 250 lbs heavier), you're not doing terribly bad. I think the LS6 cam/springs with supporting dyno tune is an excellent idea, and you shouldn't expect much (if any) mpg hit going that route. But I wouldn't pay to have it tuned otherwise.

dec010974

iTrader: (1)

being realistic, gofastwclass;hookemdevils22; anyone else can chime in; so how can i get the best of both worlds? i know the tune will play a major partin this quest. also im sure someone has accomplished or tried this feat. ive seen on youtube, a c10 with alot of money spent(mast motorsports), with a L92/6l90e with 525 hp that gets 23 mpg on tha highway. honestly im a torque man especially in heavy vehilces. the 6.0(lq4/lQ9)are very thirsty, so thats the wrong direction for me. like i said i want the best of both worlds. did i tell i didnt want to spend a kings ransom to accomplish this. thanks again ls1tech fam.