Pop quiz: What flag is enabled in the scanner when in PE mode, open or closed.

I have?

keep up with the personal attacks.


-- Joe

 

Interesting question regarding PE anyway.

The PE mode flag is bit 7 in the ram byte at L0038 in $32 and $32B and L0039 in $6E.

It is not normally present in the serial data, but could be with a simple code change to output this byte in place of something else in the data stream.

I think I've just found something else to modify...cool.

The BLM learn control flag (Bit 1 in the Air Fuel Mode word #2 L0044 may also be useful as a PE indicator). I see it now, the BLM learn enable flag is cleared if the Target AFR is not equal to stoich AFR. If PE results in a non-stoich Target AFR, which is typical, the BLM learn flag will be cleared.

On the contrary, if the PE tables are changed to 0% AFR change, then PE mode won't clear the BLM learn flag.

It is a good indicator of PE mode, but not perfect since open loop will likely command a non-stoich AFR also and have the same effect on the flag. Therefore it could indicate either PE mode "or" open loop. In addition, coolant temp and load also play a role in setting the BLM learn enable flag.

I'll try and compare these flags once I have them both in the serial data, but I have a good understanding now of what to expect.

 

I am not a programmer. But even as unsophisticated as I am in computer code and programming, at least *I* understand the difference between open and closed loop. It is absolutely amazing that you don't.



You have.



I really don't want to take it to a personal level, but you avoid commenting on specific points I've made. It is as if you aren't listening or don't understand the comment. An example is your reply, "I have?" Your question is as in defiance, but with no substance. I made a comment on the idea you presented, in saying, "You have introduced a non sequitur into the discussion, confusing the issue for no good reason, only because it is YOU who doesn't understand.". "I have?" is counterproductive to continued discussion of the subject at hand.

Is it a personal attack to plead with you to stop posting falsehoods and misinformation? I just hate to see people who are trying to learn, be so mislead. I don't know how else to do it. Sorry.

RACE ON!!!

 

After the "tracks" that you laid down in the last thread, I'm blown away that YOU are making accusations toward others about personal attacks. You, yourself took it to about as personal (and inappropriate) a level as I have ever seen on this forum.

You have at least three people here telling you why you were erroneous in your posting about gas laws, reletive to fuel pumping, yet you come across as being Holier than thou. Strange behavior.

 

I have learned to ignore him. (anesthes)

 

Actually, I pointed out a simple point about the pump volume. I was told that was wrong. I then posted charts and references to these pumps. I was again told I was wrong. Fine whatever, believe what you will. Then CFI jumps in with his normal attacks. Your his friend, so you back him up. I'm pretty sure "MK 82" is a returning banned member, so I can see why he would back him up too. It's ok though.

On the other thread you mentioned, I responded to CFI with the same type of posting he is doing - and you are right, that was 100% wrong of me, which is why I edited the posts. (which were then deleted). It was my mistake becoming like him, even if it was temporary and it won't happen again.

-- Joe

 

I'm not 100% on the $32B mask, but on $6E and $8D the closed loop enable flag will remain set. Active 02 feedback will not change BLM/INT,
but whatever the blm/int was prior to entering PE mode will adjust to the injector PW while in PE. I've verrified the closed loop flag on both datamaster, and my snap-on scanner.

In true "open loop" there is zero correction, and the injector pw is calculated based on the main fuel table.

The statements made previously were "At WOT the engine does not use the O2 sensor to correct for air/fuel ratio.", thus implying the car would run rich under "wot". This is not entirely true. As long as the car has entered closed loop, it has learned the fuel trim offsets and will apply those corrections while in PE assuming it was able to correct in closed loop. (within the BLM boundries).

Obviously this went over someones head, because it was easier for them to say "Your stupid! You don't know what closed loop is" rather than read and understand what I was explaining..

-- Joe

 

The closed loop flag can remain active during PE and the appropriate fuel trim will still be applied. Typically the cell 15 blm value for the MAF masks.

I would consider PE within closed loop as a "compensated" form of open loop control, since the long term fuel trim is compensating for a previous rich/lean error in cell 15.

This will accomodate small changes in fuel pressure or injector size. Of course, if you increase it enough to peg the blm at 108, the extra fuel pressure will result in extra enrichment even in closed loop.

This would only really make sense if the MAF was pegged and normal (12.0-12.8ish) PE targets are resulting in a too lean mixture and if it was your only available means of tuning.

Today we have better options with readily available custom tuning.

 

I know it. I'm not trying to create conflicts but they happen everywhere I go. Just ask my wife.

 

The reasons you gave for the actions of liquid gasoline were "gas" (as in the gaseous state of matter) laws, which is a flawed application of those laws. Despite my pointing that out, you stood your ground, and with no more theory, cited the results of tests. I explained those test results. So far that explanation has been ignored. But there is no foul, because as I pointed out, the possibility of diminishing pressure was a moot point for the purposes of the OP's original question.



Is "Active 02 feedback will not change BLM/INT" not the definition of open loop? Closed loop is the ECM altering the pulse width of the injectors based on readings from the O2(s). The O2(s) can't even accurately read the A/F ratios at PE, let alone have the ECM adjust to them.



And in the open loop of PE, in your own words, "Active 02 feedback will not change BLM/INT". Also in the PE ""open loop" there is zero correction". "Active O2 feedback" changing the pulse width to alter the A/F ratio is the essence of "closed loop. The open loop of PE operation also has "zero correction", the same correction as the open loop of an engine not yet warmed up.



First, I never called you or anyone else stupid. If getting caught saying that open loop is closed loop, makes you feel stupid, then, if the shoe fits... That is YOUR reaction to being caught, not something I called you. It did not go over my head, that in the PE mode, the fuel mixture may be based on the last previous feed back from the O2, before entering PE and leaving closed loop. The point is moot. The point is that the pulse widths are NOT changed in PE mode, based on incoming O2 readings. The fact remains that closed loop IS left when WOT is activated and the PE mode invoked. In other words, the ECM does NOT continue to react to O2 readings while in the PE mode. That, of course, makes the PE mode, "open loop". Q.E.D.

RACE ON!!!

 

This issue was already discussed and backed up. It's not worth anymore of my time. If you want to learn about prom tuning, go read some of the stickies @ TGO. I've got more important things to do than argue with you all day Jim.

-- Joe

 

Now there is the easy way out. It HAS been discussed, but it hasn't even been convincingly stated, let alone backed up. In PE, the A/F ratio is NOT being adjusted based on continuous, incoming O2 readings, as is required to be, as is the definition, of closed loop. Yet you refuse to see that the opposite of closed loop is open loop, or do you contend that the ECM is reacting to the unreadable O2? Not only does the ECM revert to ignoring O2 readings, it does so wisely, because the O2 is incapable of sending useful data at proper PE A/F ratios. It doesn't matter how much or how well you know programming, you cannot get production C4 O2s to accurately report the A/F ratios necessary for PE. Your refusal to "argue" is a thinly disguised "Uncle". You have more important things to do than admit you are wrong. Go advance your timing 30° and pick up 100 HP.

RACE ON!!!

 

I refuse to argue it any longer with you because I've already documented it, along with other people, for many many years.
You failed to read my points, you would rather twist it to make it sound like something else - than argue that. You are not helping anyone here.
Thats fine. For a guy with an crossfire C4 and a beat up truck, you seem to think your quite the expert on *everything*. But then again, spending 10 years working a parts counter would probably make you feel that way.

-- Joe

 

I have read your points. They defy fact. When presented with fact, you "refuse: because you have taken an indefensible position. It saves face to say "refuse", rather than say "wrong". You have documented nothing. The only thing you have documented is your refusal to listen. Oh yeah. You have attempted to document, by giving the wrong, inapplicable gas law reasons for the behavior of a liquid, for a fuel pump to decrease in volume as the pressure is increased. Even that was pointless, because the fuel volume wasn't an issue. And you have stated that "The more spark you can run, the more power you can make." All thoughts, ideas, and theories that are seriously flawed.



You certainly seem obsessed with the details of my personal life. Some of your information is surprisingly correct. WHY do you follow my movements so closely? I won't make the obvious speculation. I don't think I'm an expert on anything, but a few facts and a little knowledge has rubbed off on me.

RACE ON!!!

 

I think you guys are arguing over nothing. It seems to me CFI is talking about an open loop system. This is a concept totally independent from GM's implementation of engine control. If there is no feedback about the result altering the control, it is an open loop. It really is that simple.

Anesthes is talking about GM's specific implementation. It may be that GM sets the "closed loop" status bit, or that it uses fields in PE that it doesn't use in other open loop operation. This is an implementation (an imperfect one) of a general concept.

So within the context of each argument, both appear to be correct (to uneducated me). You just have different contexts. Why not just acknowledge that and move on.

 

I have been looking around since Joe made the comment about pump volume going down as pressure goes up. I think this tech fact from the Holley Fuel Pump Tech page is where Joe is coming from.

FUEL PRESSURE AND VOLUME
The relationship of pressure to volume is inversely proportional. That is, as
pressure increases the volume will decrease, everything else being equal. A
certain amount of fuel pressure is always required to maintain engine performance
by assuring that fuel is available on demand. Also, other factors
and conditions must be taken into account such as acceleration G-forces and
friction within the fuel system itself. At the same time,however, an adequate
fuel volume is needed to ensure that the proper amount of fuel can always
flow to the engine, especially during peak demand situations. A basic understanding
of this critical pressure/volume relationship is needed when designing
the proper fuel supply system for your vehicle.

Now this does dot say the pump volume decreases but , I think, it is talking about the fuel system volume. I really hate to stir the pot but I think Joe got more than his share of flames. Later! Frank

 

I thought you weren't going to do that anymore? In fact, you actually sait it, right here, post #46!...
A persons current vehicle, job, religion, who their friends with, etc, etc has nothing to do w/the accuracy of the content which they post. You may not prefer the manor or tone which is used by some, but in this case, CFI's posts are technically accurate and technically correct. Some of yours are too, but not always. Admitting when you are wrong (or when you typed something wrong) would go along way toward helpng your credibility, IMO.

-Tom

 

I don't know the answer to this. my "facts" were based on release notes from the pump manufacturers, which is why I posted the walbro table.

I was dead serious about what I said regarding finding me a pump whose volume won't decrease with pressure increase. I'm using an FMU and will see pressure increase at a ratio of 8:1 with boost. if you look at the walbro table, I'll be getting the same volume with max boost as at idle.

It doesn't bother me. At first I was a but stunned by the guy, but I get too many PM's from folks telling me to not let him get to me. I figure, they've been here longer so they must know something..

-- Joe

 

Guys, don't argue so much. You will end up like me, banned for life 3 times.

 

Amen! That is what I am saying. The PE mode is an open loop mode. In the PE mode the ECM isn't reading and adjusting the fuel delivery based on O2 output. Even if it wanted to, the A/F ratios in PE are unreadable by the O2. ECM reads the O2 and adjusts the fuel mixture based on O2 input = closed loop. If the O2 isn't in the loop, the loop isn't closed. (With apologies to Aurora 40)It is just that simple.



It wouldn't matter. The pump volume far exceeds the demands of the system. It is a moot point in the context of the question asked by the OP.



Thank you. I appreciate the support. I too, get a number of PMs, mostly encouraging me to continue my crusade against all the misinformation that is being posted. I have to admit it is fun to have someone so interested in me as to try to find out all about me, my vehicles, vocation, and who knows what all else. Some of it is even right; horribly incomplete, but not too inaccurate. I find it quite flattering, actually. My own personal, private, groupie.

RACE ON!!!