Hypothetical Jet Tuner question........

[jstadwater]

Hello to all,

This is my first post here, have a few tuner questions. My name is Mike, I live in Naples, Florida. From what I've read on these pages, you guys seem to know alot about this stuff. I just bought a Jet Dynamic Spectrum Tuner + ELMSCAN5 + PCMSCAN program. The test vehicle is a '96 Suburban 5.7 Vortec 4X4. Let's say, hypothetically, I was able to create a condition that basically allowed all fuel in the combustion chambers to be burned, thus creating an exhaust condition that would send the o2 sensors' voltage signals so far off the charts that the PCM could no longer read them as functional. Let's also say, hypothetically, if I was able to create such a condition, that I would want to be able to use the Jet Tuner to program the PCM in this fuel injected vehicle to allow operation with such a condition present. Does the Jet Tuner have enough functionality to perform this task, or would I need to use a complete stand-alone management system? Another, less favorable and less controlable, option might be to relieve the vehicle of fuel injection altogether and install a carb system in it's place. I would be appreciative if anyone here would post thoughts or ideas on this subject, hypothetically, of course.

Peace,
Mike

[n0dih]

Welcome! You found a great place, may not be the highest traffic here, but the guru's you find here are among the best and most knowledgeable in the world. Some even started the whole shebang of tuning PCMs/ECMs in the aftermarket....

Getting to 100% burn isn't possible, but the factory PCM is bent on maintaining 14.7" in closed loop. You could do pretty much anything you want in open loop (no O2 sensors used for fueling) and dial in what you want. The NB O2's are essentially unit step function, rich or lean, they are stable only at stoichiometric. They swing high or swing low with a very small amount of A/F change over 14.7 (0.45v).

Jet DST is the only program out there (ok, TunerCat OBD2, TunerCat RTOB2, Westers GMT1) are the ONLY programs I am aware of that can tune a 96/97 Vortec 262/305/350/454. Jet DST being the lowest cost, but one of the widest coverage of all tuning tools.

[97K15004WD]

Originally Posted by jstadwater

Let's say, hypothetically, I was able to create a condition that basically allowed all fuel in the combustion chambers to be burned, thus creating an exhaust condition that would send the o2 sensors' voltage signals so far off the charts that the PCM could no longer read them as functional. Let's also say, hypothetically, if I was able to create such a condition, that I would want to be able to use the Jet Tuner to program the PCM in this fuel injected vehicle to allow operation with such a condition present. Does the Jet Tuner have enough functionality to perform this task, or would I need to use a complete stand-alone management system? Mike

Mike:

First, Welcome!

Second, O2 sensors don't look at HC levels; only look for stoch level per PCM programming. Due to federal mandates, the HC levels are already extremely low; therefore burn efficency is already extremely high. The PCM needs the control of the fuel to protect the cats. If the PCM detects overtemp of the cats, it puts more fuel in the system to cool the cats. Running open loop locks you into one geographical area; any changes from the local air pressure where you tuned your vehicle leads to a difference in fueling and hence stoch changes.

There are mechanical factors at play. See this info below:

"There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center. Depending on the chamber design and the burn rate, if one would initiate the spark at its optimum timing (20 degrees BTDC, for example) the burn would progress through the chamber and reach LPP, or peak pressure at 14 degrees after top dead center. LPP is a mechanical factor just as an engine is a mechanical device. The piston can only go up and down so fast. If you peak the pressure too soon or too late in the cycle, you won't have optimum work. Therefore, LPP is always 14 degrees ATDC for any engine.

To improve engine efficency, look at capturing the waste heat. Smokey Yunick tried this with his adiabatic engines back in the first "energy crisis". You old timers, like me, will remember this. You need ceramic engine components (lots of money) and specialized engineering capabilities. Or, use a turbocharger that helps to use the waste heat energy to increase cfm through the engine.

They also made "gas saver" cams back then. Not sure if they still do. Best way to improve combustion chamber issues are to ensure proper quench, multiple spark ignition if necessary, and timing to match LPP. That's it in a nutshell. Good Luck!

[jstadwater]

Thanks guys, for the warm welcome.

Being locked into one geographical area is not really much of a problem, I never go anywhere anyway. If I wanted to play with open loop, is there a site or group of files you guys could direct me to that would aid in getting me started on this adventure? I have found so many different "opinions" online about what o2 sensors ACTUALLY detect, could someone here explain the condition it would take to put the fluctuating o2 signal voltage down in the range of say, -.650V thru +.100V? I may have stumbled onto something here, that my boss won't let me say much about yet, "just in case" he says. Should I mess with trying to program this thing out for the next few months? Or would it be better in my interest to do the Suburban retro-fit available and change it over to a carby? Thanks again for any input, sorry I can't divulge much info at this point, but maybe soon.

Mike....................Naples, Florida

[97K15004WD]

"Being the feds raided the vendor who was making those O2 sims shows EPA feels the reals have an important roll and there is no way you want the PCM wiring for O2s to be in a open circuit state prone to electronic noise.
Other issues since the O2 wiring is special and has a airpath channel you find people hacking the wires length or just adding normal wire to lengthen wires cutting off that colder outside reference air the O2s need to function correctly. "

Messing with the EPA will have you shut down and/or paying big fines. Look up the vendor here, and see what they paid.....

Look up "Caspers" and the resultant court documents.....

[jstadwater]

But................

What if you could fall into the "GREEN" category by eliminating most of the normally present emissions that a vehicle's exhaust puts out? Would that not allow you to be included in the "exempt" category and allow you to legally remove the emission control devices anyway? At this point, I am only looking to change the programmed values that the PCM is used to seeing as normal, to prove or dis-prove that an IC engine can burn much "cleaner" than what is currently thought as "acceptable". I personally, don't agree that it's acceptable. What happens if you go into your garage, shut the doors, crank up your car, and just hang out at your tool bench? YOU DIE!!! In my opinion, the millions of vehicles operating on our highways are kind of turning our planet into a closed garage. I would like to try to make a difference, if I can, and just may be able to if I implement it correctly. I do not intend to remove or otherwise "hack up" the vehicles emission control devices. At least not until such time as when the vehicle can be certified legally to allow such an action. Messing with the EPA is NOT on my "to do list". And yes, gasoline will still be used as the main combustible. Let's face it, the world is what it is today because we CONTINUOUSLY take what exists and make modifications to better our own existence on this planet. The moment we stop doing that, we WILL slowly cease to exist. I'm not, at all, trying to open up a can of worms or anything. Just trying to figure out the best direction to go to begin my testing, that's all. Any thoughts and suggestions, good or bad, are welcome.

Peace to all.......................................Mike

[n0dih]

Going with closed loop, likely you can't do what you want, but open loop, you can do what you are looking for.

So if you were to try to start over, say ditch all the emissions devices, and try to go for trying to do it yourself and see how you fair. Could you? Maybe. Jim Fueling has done wonders with making a very very efficient head for the Big Block Chevy with awesome compression. HP wasn't phenomenol, but when you look at the tiny valves and that he got very good mpg with it, who cared? Jim was the key engineering contracted by Ford for the 3V Ford heads until he died. (And from what I heard, Ford screwed his him on much of that development too). Jim had a ton of patents.

Smokey and his adiabatic engine. I forget who did a 30 mpg 350 Chevy in the early 80's that was in Hot Rod/Car Craft. None great powerhouses (remember, it takes fuel to make power), but many have done excellent efficiency.

So could it be done with emissions? Sure, probably. It has been said Emissions is Easy, MPG is Easy. BOTH at the same time is hard.

So as long as you are willing to forgo the large hp goals, likely you can do well. The EPA or your local smog test may not agree with you if they plug into the PCM to talk. But if they sniff the tailpipe, it isn't hard to do a reasonable emissions friendly engine.

I'll see if I can find the guy who did a 455 Pontiac, ran low 11's in a 67-68 Firebird and passed 1986 California tailpipe emissions. Of course he failed the visual test, but he did it. He knows emissions, he was a lead guy at CARB in California....

He used a special high overlap cam to help keep NOx down, he had AIR system check valves in the head collectors that allowed in some fresh air without leaking it out, he had a Holley carb (I think a Dominator no less), he did have Cats on there too. But he ran low 11's.... But technically it was a fail for CA emissions...

[jstadwater]

Thank you nOdih for that informative post. HP is not what I intend to achieve, clean exhaust and MPGs are what I'm after. I may need a less cumbersome test vehicle though, the Suburban weighs in at 7,200 lbs. Maybe starting with a four cylinder vehicle would make the task a little easier due to smaller scale for a prototype. I will do my best to stay below radar so I don't get SUPPRESSED before accomplishing my goal. Someone once told me, "If you keep on doing what you've been doing, you'll keep on getting what you've been getting". Well, I want more! Time to make it happen, instead of waiting for someone else to do it!

Later...................................Mike

[n0dih]

I wanna see the reverse, ultimate mpg, emissions be darned.... If I was to build a purpose built engine, emissions forgotten, and focus solely on mpg for an intended application, what could be done?

Say a Suburban (I have a 99 K2500 454, 5600 lbs shipping weight, K1500's are 5300 lbs shipping wieght), nice, big and not aero. Ok, can I make it do 20 mpg highway?

[jstadwater]

If my theories and preliminary tests are accurate, and I can figure out the right way to impliment to an existing engine without having to re-design the entire engine, I think 20 MPG is a VERY VERY low figure! BTW, nice Trans Am as your icon picture, '79 right? I built one for little brother before I moved to Florida, loved that car! I figure it got about 10 MPG, 6 on the highway and 4 in town..........that makes 10 right!! I intend to start setting up some further testing platforms tomorrow, called on a couple friends to help. It may be a bit before I post again, depending on how things go, but I will get back soon.

Later.....................................Mike