Sean Buick 76
I'm Awesome
So how many guys are running on the original 02 sensors at 200,000+ miles?
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Lol....this guy!!!! At 330 000km!!! On the to do list in the near future.So how many guys are running on the original 02 sensors at 200,000+ miles?
Many I would guess. Nobody thinks to replace them until they go bad entirely. The two parts that have done the most for performance in my tired ol truck motor have been the O2 and ECT sensor. Both worked but not optimally.So how many guys are running on the original 02 sensors at 200,000+ miles?
I can tell you that is not correct at all provided it is a stock engine and stock ECM or PCM calibration. The open loop air/fuel ratio lockup table will still command a 14.7:1 air/fuel mixture when the engine reaches ~150F and the fueling is still reasonably close. Some of the TBI and Vortecs even came from the factory without 02 sensors at all. I have owned an Innovative LM1 with dual widebands for years, when I tune these trucks in person, I pull the front narrowbands out, slip the widebands in, clear the long term fuel trims and tune the VE table and MAF table in open loop. It will throw codes for lack of 02 activity, but it does not signifigantly change the air/fuel ratio.Without the 02 sensor the engine runs off a default air fuel and timing trim which is super rich and will burn 30-40% more fuel.
I will take your word for it but I am surprised. How does the computer keep the engine at 14.7ish without the input from the 02 sensors?I can tell you that is not correct at all provided it is a stock engine and stock ECM or PCM calibration. The open loop air/fuel ratio lockup table will still command a 14.7:1 air/fuel mixture when the engine reaches ~150F and the fueling is still reasonably close. Some of the TBI and Vortecs even came from the factory without 02 sensors at all. I have owned an Innovative LM1 with dual widebands for years, when I tune these trucks in person, I pull the front narrowbands out, slip the widebands in, clear the long term fuel trims and tune the VE table and MAF table in open loop. It will throw codes for lack of 02 activity, but it does not signifigantly change the air/fuel ratio.
I think what he's saying is, the VE table was developed to achieve 14.7 AFR as long as the conditions are optimal like, elevation, temperature, vacuum leaks (to a certain extent), etc. But, if they vary at all, it doesn't have the feedback from the O2 sensor to correct the VE settings. GM did not set the table to run rich when in open loop, it's as close as they can get it, not a target of running rich.I will take your word for it but I am surprised. How does the computer keep the engine at 14.7ish without the input from the 02 sensors?
If the truck is all factory (intake and exhaust) The MAF and VE tables are based around that. So if its stock, you can remove the Oxygen Sesnors and the goes back into Open Loop which is VE and MAF without any fueling corrections.I will take your word for it but I am surprised. How does the computer keep the engine at 14.7ish without the input from the 02 sensors?
Back when I had 33s, 3.42s and no lift I was getting 13-14 mpg. If I remember right I lost about 1-2 mpgs going from a 285 A/T tire to a 12.50 M/T tire for what it's worth. This was all tank average at the pump but more highway than city most of the time.
...The dual exhaust and big (heavy) wheels aren't helping either, taxing the engine every time you take off from a stop.
If you're gonna go LS go 6.0,better torque.So the 305 is underpowered for the work we are asking it to do. I agree that if this motor gets tired or gives us issues we can easily put a 350 in, or I have read about many putting the next generation 5.3 in with some modifications to wiring and computer system.
Your truck is 4WD so you would want to change the gears in the front too.What does it take to put different gears in the rear? You get a donor rear axle and attach drive shaft and rear suspension to it? Foolish question but if the gear ratio is 3.73 then that is too 'tall' meaning not enough torque and the engine works harder to get it going? I thought higher gears meant lower rpms at higher speeds and better mpg (like adding a overdrive to a 3 speed) But then if we are using fuel trying to get the heavy truck going at low speeds then we need a smaller gear, like a 3.4?