I know. It needs to be said in every thread he posts on though, otherwise some poor newb might do something terrible to his new engine.

 

If you can find just one place where I have posted any procedure or otherwise that might have someone doing something negative to their car or engine, I will fix it.

What I suggested above was an appropriate method that can be applied to ANY Stand alone ECU. it was not and was never EVER suggested that it was specifically with respect to a stock pcm. This thread is including ALL Speed Density ecu. Therefore my applied principle is good for any people reading this who do not have an OEM ecu, of which there are plenty!

2. It will work just fine with a stock PCM. Last time I checked, if something works correctly, that is the same as being correct. If you are using EFI and I am using a carburetor, I am wrong because the method I chose is slightly less fuel efficient?

3. the post was more about WHY and WHAT not necessarily meant to be a how-to. The end user establishes their own method for implementing the fuel in the manner I discussed after reviewing the capability of their own computer/ECU. What I provide was an example of how to with any ecu, as some are quite the bare-bones essentials (mega squirt sometimes, and power FC for example)

 

Oh my god, stop. All of your posts in this thread need to be deleted. And this post too. Then you need to step back and ask yourself, "why am I posting this crap when every time I say something everyone tells me I'm wrong?"

 

Its not everyone. Its just one person. and they have no proof, no reason, no theory, not even a suggestion as to why I am wrong. Nor are they providing any details or significant background; I have 15 years of tuning experience, many cars/thread/forums/ active results and all of them are professional, want me to link them one after the other? It goes back at least 10-12 years and a hundred cars or more perhaps. And this happens all the time, there is always somebody (1 person) who jumps in and says "you are wrong" without any reason or proof of why. I always provide reasons and proof; all of my posts are lengthy because of that exact reason. Like this one.

FWIW i found a better way than a gallon of text to show for this FAQ what I mean, and I will provide a picture (1000 words in a picture) soon and they can delete all the garbage and leave the picture which will perfectly explain the procedure I am trying to describe here.

 

Bottom line, all this theory, fact or proof if any leads to what? Engine longevity, cleaner emissions, more power? I think none of the above..Who cares when you lift the A/F dips into a slightly lean condition, again for how long, a millisecond? what does this all prove, ok now your lean dip is instead of 15.1 its now 13.8, your cylinder wall wetting is now this and now that. If all this gives you the satisfaction of attaining a certain goal for yourself, then thats fine, but to this forum, I dont think it helps many if any one trying to tune their own vehicles..

 

It is an engine longevity problem/question. It depends on the ECU you are using, and the kind of firing (batch/seq). Overall, batch fire and long runner engines tend to not suffer from this issue as much, it is the seq. EFI setups with inadequate injector phasing that will benefit the most from this small change. Alot of ECU have many unexplored or un-adjusted functions when their users/tuners are unfamiliar with the advanced fine tuning topics; an entire FAQ could be dedicated just to trigger wheel/phasing IMO. My little method posted above will help eliminate alot of the tip-in lean misfire/potential knock which can result with engine damage under the right conditions when these other parameters are not setup properly, and often they are not, and the user has no idea because the engine seems to run normal. No, you will not feel the difference at 3500rpm between 15:1 and 13.8:1 worth of fuel at 8.8" of Hg in the intake manifold when transitioning to 2.4" Hg, but the engine will if the last injection event for the lower pressure was sent to the valve after it was already closing. The engine will take a big gulp of air and still have the fuel duty from the previous cycle, a lean misfire if you are lucky. The problem exacerbates when the driver is on and off the throttle alot but not fully into fuel cut regions, 2% to 8% of throttle position at higher rpm/vacuum situations, especially on a long cruise on a hot sunny day, and especially when the Accel enrichment has not been fine tuned well. The wideband isn't going to catch the --.-- from those cylinders and instead will only report an average, so when the base map/transition looks tuned it can actually be extremely lean and then extremely rich, while the wideband reports the median and everything looks ok. Except the driver might notice a stumble at lower rpms of course (despite seeing the wideband go rich), a common problem with poor phasing but not an engine longevity issue at those speeds.

Plus it gives us a healthy margin for error in speed density tuning where a tiny, negligible amount of fuel (less than 1ms for sure) in high vacuum regions will help compensate for fluctuating temperatures elsewhere. In Florida I tend to avoid pulling fuel for higher IAT in turbo cars; the factory is trying to save fuel, while we are trying to save the engine.

Here is a random fuel map from search internet images. Notice how generally you see this red, super lean portion in the high vacuum region. It typically saves fuel, causes harmless misfires, and precedes the fuel cut. However in engines with modifications, it can become a detrimental setting, if the user is slightly on the pedal (remember some engines have larger throttle bodies which move a large portion of air per a very small movement of the blade) the A/F will be lean, and as the user tips into the throttle the A/F becomes even leaner despite the accel enrichment, Which is often too little or non-existant when the throttle is moving very slowly (the sensitivity and age/year/mileage of the TPS sensor and it's computer/wiring are factors which determine sensitivity as well as electrical noise) in other words, sometimes the TPS or should i say dTPS (rate of change of TPS) does nothing when the user is tipping into the throttle on some engines (especially 1990's and early 2000's) and as the user steps down slightly the pressure drop can be significant, the A/F starting off lean, becomes leaner as the compression increases (VE goes up when you step down more on the throttle) and this can generate a series of engine knock before compensation from new fuel values, and steady state conditions are allowed to come back.



Now with the new setting, you tip into the throttle at 5000 or 6000rpm and instead of being met with a 16:1 or worse, you get a nice 13.something. Remember this 5k rpm, the last place you want a 16:1 I dont care what the vacuum of the engine is, you better keep that cylinder wet if this is a high performance turbo engine making 180hp/liter or so because conditions can change rapidly with very little throttle movement at those engine speeds.

 

,
Using your numbers ( rounded )
for MAP sensor 1261-5136
Linear 200
offset 8.
Is there benefit to shifting, or adjusting the OFFSET term so as to make local atmospheric pressure exactly match KeyOn MAP sensor reading ?
.
Done once, this should allow accurate MAP readings, and indivually calibrate for the installed MAP sensor... Am I thinking correctly ?

 

Should this really be a sticky thread? It's basically 2 clowns arguing.
I was hoping to see something about Speed Density tuning in this.

 

Yeah, I agree. There's very little sticky material here.

Also, you want your low load MAP zones to be rich... big cam cars buck and surge much less when you pull timing and add fuel...