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Thread: How to make your fuel and timing maps AKA "TP/LOAD" scales

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Posts: 101-110 of 193
2013-02-27 13:32:14
#101
WTF is your problem? why are you always talking down to someone in this thread like your all mighty powerful that knows it all. Just cause your shit don't stink to you don't mean it doesn't stink to someone else.
2013-02-27 14:03:34
#102
Alright Guys, My knowledge on this subject exceeds most, so what I'm about to say is not up for debate and needs to be understood by you guys so that this discussion doesn't come up again! Ready?

TP.. (also called tipi and teepee) is a conical tent traditionally made of animal skins and wooden poles used by the nomadic tribes and sedentary tribal dwellers (when hunting) of the Great Plains. Tipis are stereotypically associated with Native Americans in the United States in general.

So you see, in order to fully calculate your torque curve and/or find the relation of Tp to engine load, you must run into a village of Native Americans with your se-r, knocking down every TP, then count the number of survivors. This number will help you build your maps! Its quite simple really...

2013-02-27 15:55:45
#103
I've taken Vadim's data for the stock N/A RR setup and put in a simulated MAP trace. I've also expanded the TP trace (in the lower graph) to a comparable data window so the shape can be compared to the torque and power curves above.

It should be clear that TP does not follow pressure, and it does mimic the torque curve more than anything else. I will explain the discrepancies between the torque curve and the TP curve after I do the same for the DET T25 @ 7 psi data.

Last edited by BenFenner on 2013-02-27 at 16-16-43.
2013-02-27 16:49:30
#104
Here is the DET with T25 at 7 psi. Again, I've put in a simulated MAP trace, and below you will find the expanded TP trace to compare similar scale with the torque curve.

2013-02-27 17:01:04
#105
I'll offer up an explanation for why the TP and torque trace shapes don't match as well as they should.

The TP trace is the estimated (theoretical) injector pulse width needed to provide enough fuel to produce a stoichiometric mixture. The incoming amount of air is read by the MAF and this is an estimation of power. The RPM is used in the TP calculation to turn this estimation of power into an estimation of torque. The torque is then treated to a scaling factor (the K value) based on injector size which results in the theoretical pulse width (TP) number.

(MAF VQ / RPM) * K value = TP

(estimated power / RPM ) * injector flow-rate scale factor = TP

(estimated torque) * injector flow-rate scale factor = TP

This is the theoretical amount of fuel needed for a 14.7:1 AFR at a given RPM and injector size. As you should know by now, injector pulse width on a properly tuned engine for a given AFR will follow the torque curve. More air and fuel for a single combustion event means more torque. Less air and fuel for a single combustion event means less torque. Assuming a proper ignition timing setup.

For this reason, TP can be thought of as the ideal torque curve based on the available air as read by the MAF sensor, and scaled by RPM and the K value. The actual torque curve measured on a dyno should be very, very similar once you have the fueling and ignition timing down correctly. It can be seen that on the first of Vadim's examples he's missing a good bit of torque between 4,500 RPM and 6,500 RPM. He obviously has the air to work with, as evidenced by the TP readings, but for whatever reason he is not making use of it efficiently.

The same goes for the second graph where you can see early on at 3,400 - 4,500 RPM the engine is not making efficient use of the available air. And again there is 5,200 - 6,200 RPM where there could be higher torque numbers if it weren't for some issue in the tune. The air is there, but the measured dyno torque does not follow for whatever reason.


And once again, for the final time, TP does not mimic MAP readings.
Last edited by BenFenner on 2013-02-27 at 17-30-58.
2013-02-27 17:19:16
#106
wheel torque will have more factors measured...

If an engine dyno was used, i believe it would be closer...
2013-02-27 17:57:39
#107
Originally Posted by BenFenner
I can see I've confused things.

Call me a skeptic. I want to believe though. All you have to do is show me a graph or a log where pressure stays nearly the same throughout a large RPM range and TP stays nearly the same. That's all it will take to make me a believer. Until then, I'll still operate under the assumption that TP follows the torque curve, and not any pressure/load curve.

X2
There its no way of correlating pressure to TP !!!! period!!! Even a small change in the Kvalue will make the TP change and a whether change too so there its all a guess game trying to correlate it!!!!
2013-02-27 18:03:08
#108
To be fair, he's saying you have to keep the K value constant. If it changes, the conversion factor will change too, he admits that.
We're having a deeper debate than that.

The weather/temperature change does relate to this discussion though, and is one of the reasons you can't properly go between TP and pressure even on a single engine where the K value is kept the same.
2013-02-27 21:40:37
#109
It seems like you guys are looking for an exact number or magical formula here and you shouldn't be cause your not gonna figure it out easily, I do believe it can be figured out but its not relly important to me at this point maybe in this whole thread discussion will be closer to figuring it out,

But you ever notice during a log how TP/LOAD will jump abruptly depedning on the aggressiveness of a throttle blip, or if you roll into the throttle nice and slowly being very linear in your application of throttle you wont see the large quick jumps in TP LOAD, I believe there are triggers for certain conditions that are applied that are throwing you guys off in your quest to figure out a formula for solving this and by the ECU advancing the TP LOAD always to the right its a SAFE thing to do as timing is less as TP rises and fueling increases as TP rises, for example sitting at idle blip the throttle quick and you will jump to the far right of the map, now ofcourse your are also going from ~21in/hg to ~0 in/hg almost instantenious but during this situation at idle it will actual exceed 0 in/hg during this blip and access a TP LOAD much more higher than 0 in/hg and onto the positive side.


But first you gotta accept that TP follows pressure, I mean just look at my logs, follow the snake you see the relationship between TP and BOOST its pretty clear to see ~----~~~~-----~~~~~--~~-~~---~------~~~----~~~~ they follow eachother but only pay attention to the vacuumits clear to see when I boosted and my map sensor cannot measure map above 1 bar.

As vacuum get lower = TP increases
As vacuum get higher = TP decreases












Last edited by UNISA JECS on 2013-02-27 at 21-45-48.
2013-02-27 22:25:08
#110
Originally Posted by BenFenner
I'll offer up an explanation for why the TP and torque trace shapes don't match as well as they should.

The TP trace is the estimated (theoretical) injector pulse width needed to provide enough fuel to produce a stoichiometric mixture. The incoming amount of air is read by the MAF and this is an estimation of power. The RPM is used in the TP calculation to turn this estimation of power into an estimation of torque. The torque is then treated to a scaling factor (the K value) based on injector size which results in the theoretical pulse width (TP) number.

(MAF VQ / RPM) * K value = TP

(estimated power / RPM ) * injector flow-rate scale factor = TP

(estimated torque) * injector flow-rate scale factor = TP

This is the theoretical amount of fuel needed for a 14.7:1 AFR at a given RPM and injector size. As you should know by now, injector pulse width on a properly tuned engine for a given AFR will follow the torque curve. More air and fuel for a single combustion event means more torque. Less air and fuel for a single combustion event means less torque. Assuming a proper ignition timing setup.

For this reason, TP can be thought of as the ideal torque curve based on the available air as read by the MAF sensor, and scaled by RPM and the K value. The actual torque curve measured on a dyno should be very, very similar once you have the fueling and ignition timing down correctly. It can be seen that on the first of Vadim's examples he's missing a good bit of torque between 4,500 RPM and 6,500 RPM. He obviously has the air to work with, as evidenced by the TP readings, but for whatever reason he is not making use of it efficiently.

The same goes for the second graph where you can see early on at 3,400 - 4,500 RPM the engine is not making efficient use of the available air. And again there is 5,200 - 6,200 RPM where there could be higher torque numbers if it weren't for some issue in the tune. The air is there, but the measured dyno torque does not follow for whatever reason.


And once again, for the final time, TP does not mimic MAP readings.



BenFenner you’re trying to make a connection between TP and Torque, when there is none.
Seem like you got torque out of the blue. There is no torque input in Nissan’s TP calculation. You are artificially manufacturing one.

The TP is not an "estimated/theoretical injector pulse width to provide enough fuel to produce a 14.7 afr". TP is more basic than that. It’s only a injector pulse width in milisecond. It might or might not hit 14.7 afr, it all up to you. You’re the one adding or subtracting the TP/ injector pulse width in order to hit 14.7 or whatever afr you want.


TP = (MAF VQ x K Value/ RPM) + injector latency and enrichment


The final product of the TP formula = injector pulse width in miliseconds.



Like I said before, TP does not follow the torque curve period. Anybody with map trace capability can see this when they do a full throttle pull.

I thank you and Vadim for providing the raw data logs and excel graphs to illustrate my point. TP does not follow the virtual dyno torque curve. If you think TP will follow the torque curve of a real dyno more closely , you’re going to be disappointed. The difference between the two will be even greater.

As we all can see, when you try to put TP on the same graph as the torque, the TP curve will be flat as a witch tit.
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