Haha its all good

I actually have a nice pair of black fuzzy dice I was going to put up! on carbureted cars fuzzy dice are usually worth about 25 extra hp by themselves,on a fuel injected engine they've gotta be worth at least 30-35hp gain haha.

I'm just probably going to go with headers, the throttle body boring and maybe the 1.7 roller rockers & computer tuner and call the mods good, the truck has a set of ***** the way it is, anything else is just frosting on the cake for me. I did a brake stand yesterday morning about 60 feet long of posi marks and when I made the corner around the stop sign at half throttle roasting the tires I floored it and it started to just melt those tires and swing the *** end the other way haha. I think some of the people on youtube trying to do brake stands with these use too much brake lol.

Definitely suprised at how easy it is for my '97 Ram, to break em loose with a blown plenum gasket & misfire, my sisters 2000 Ram 1500 I had to put a '97 360 in (after her husband couldn't read the dip stick to see how low oil was and toasted the original motor main bearing... wtf?) couldn't even do a brake stand, though it wasn't properly fuel synced when I tried and always threw a #8 misfire code, unfortunately I'll have to pull that motor out & rebuild it, the guy who sold her that motor was a sack of $hit and sold her a motor with an oil pickup full of permatex and that engine guess what? blew a rod bearing! it was lucky to be sucking oil through anything bigger than a Taco Bell straw.

My phone camera sucks but you can see my posi marks go around the corner too if you look close (and no the Neon didn't do them, didn't want to be seen taking pics of my marks in the truck I did them with lol), the tires on my truck kinda suck they don't leave very black marks, right side faded out a bit but did roast too lol I'm going to make a proper video of my truck roasting soon instead of my lame phone taking a pic of the after effects.

 

for a little extra juice pull your air intake temp sensor, i mounted mine on the passenger side next to the ac line on that litttle shelf with holes in it, just extended the harness, what it does is tricks the engine to think its cold so its going to dump more fuel to compensate, and ill tell you i noticed a little difference pulling my trailer

 

Doesn't that hurt your mpgs? I was thinking about doing this for when I pull my boat, but I'm already only getting around 8 mpg towing and don't want to get less!

 

... but only when the PCM is in open loop mode. At all other times the pre-cat oxygen sensor output determines the fuel/air mix.

 

I personally would think the pre cat O2 would always use/sample the IAT all the time and work in conjunction to get the best air/fuel ratio for different climates. Proof of this, is that when your IAT $hits the bed, your truck runs like crap even after warm up & driving long trips. Besides closed loop mode is itself a default operating procedure the PCM uses until warm up is achieved, meaning that some sensors are ignored until warm up, never heard of them being ignored after warm up. For examples some cars have closed loop modes that even ignore the o2 sensor readings itself until warm up!...basically meaning it doesn't care what the air/fuel ratio is its just going to dump a pre-determined amount of fuel in even though a leaner mixture could suffice for most starting conditions above 20 degrees.

My Neon for instance has the richest smelling raw fuel exhaust you'll ever smell until warm up, my truck also smells a little raw until warm up then its normal. Another thing that also ignores o2 sensor & map sensor input is the condition of Wide Open Throttle, then the PCM decides what to do.

 

Open loop mode ignores the oxygen sensors, closed loop never does. It's the inclusion of the oxygen sensor signal in the feedback system that defines closed loop mode: sensor consulted equals closed loop; sensor ignored equals open loop.

During closed loop operation, the injector pulse width is determined by the PCM in reliance upon the oxygen sensor output signal; the MAP, IAT, CTS, TPS, and engine speed are factored into the ignition timing calculation. There is absolutely no need to consult anything other than the O2 sensor to determine injector pulse widths during closed loop operation, as the oxygen sensors provide the most accurate and reliable indication of fuel/air ratio.

During open loop modes, the oxygen sensors are ignored for a variety of reasons. During warm up the sensors are not hot enough to provide reliable feedback; during rapid throttle opening, hard acceleration and WOT the oxygen sensors' slow reaction times render them unusable (and if relied upon would likely cause temporary but destructive lean conditions); and during rapid closed-throttle deceleration the injectors are shut off so the oxygen sensor outputs are meaningless anyway.

MAP feedback is used in all operating modes, but is factored into injector pulse width calculation only during open loop modes. It is never completely ignored.

 

Thats what I was wondering, theres lot of conflicting information going around the net about what the pcm does at certain times under certain running conditions, but I suppose your post makes a lot of sense in the way it would take information needed to run.

 

How is this affecting fuel economy?

 

Open Loop: PCM is running off of pre-programmed tables for fuel, and ignition.

Closed Loop: PCM pays attention to the O2 sensor for fuel.

Closed loop is better for fuel economy, that was the whole idea behind O2 sensors in the first place. Ideally, you always want to be in closed loop.

To get in to closed loop, engine coolant needs to be 108* or higher, and O2 has to report as Ready. O2 only takes about two minutes or so to heat up, as they are.... heated..... (not like the old, unheated fellers, that were warmed by exhaust flow....)

PCM will drop out of closed loop, even if all other parameters are met, at large throttle openings. (greater than 50% or so...)

As O2 sensors age, the start to respond slower. (get lazy) That will beat up your fuel economy as well. They can also fail in various states, and the PCM may, or may not.. figure it out..... in which case, fuel economy will just suck.....

 

Excellent post!

To be honest with you I had always been lead to believe closed loop was the startup procedure the pcm uses...glad you straightened that out and explained in detail, it makes a whole lot more sense now.