Tuning school

[Big Bore]

Use this to convert the PSI to MPa

http://www.chapelsteel.com/mpa-psi.html

All of the tables are metric but Bill does have a PSI ICP map.

Just convert the PSI over then you should be able to figure out the PW

Ok so somewhere around 1.9 ms? The MFD of 65 from the first table doesn't transfer directly to the ICP, or the PW table, so you have to guesstimate the ICP at around 2550 psi. Which comes out to 17.6 MPa, and the PW table doesnt have that value (goes from 17 to 19) so you have to guesstimate that lol.

For Daves injectors thats a massive amount of PW at 2000rpm and 3/4 throttle I would think.

 

[Shaw]

Close enough, I would go with 1.8 but you did figure it out correctly.


I do believe these maps are just stock PMT1. Im not sure how Dave is planning on explaining this but we will let him have a go at it. I am not very good at trying to teach things :/

 

[Big Bore]

Ok looking at that intersectionnagain of 17-19 MPa and 60-70 MFD I can see where you came up with 1.8ms.

 

[Powerstroke Cowboy]

Shaw I saved that conversion link you gave to my Favorites bar!!! With that conversion chart it made it easy!!!!


I came up with 1.86 to 1.9pw What you would do with that all depends on the size of injectors and nozzles.. Like for my 300/200 that would be a lot of fuel for 2000RPMs

I might be reading it wrong..... But when you look at all three table and try to put them together.. It looks backwards to me.. There is way to much PW at lower RPMs on the tables you have listed.. Then as the RPMs build the PW goes down... And the ICP only jumps by maybe 600 psi..

I was just looking at the 3/4 throttle position.. at 1000 RPMs the table shows 1958 ICP (or a 13.5 MPa) and the PW is 2.1 to 2.2...

now @ 2000 RPMs 3/4 throttle there is 2550 ICP (Or a 17.6 MPa) and the PW is 1.8 to 1.83....

Now @3400 and 3/4 throttle the ICP is now @ 2465 PSI.. (Or a 17 MPa) and the PW is 1.65 Roughly speeking...

So is the table messed up or backwards?? I know the ICP plays a big role in how much fuel is injected at a given PW.. Like in the lower RPM range..

I could just be all wet,, I am trying to learn here, That is main reason I posted what I did..


So Dave If you could point me in the right way that would be great!!!

I have Bills software on the way just ordered it last night!

 

[Shaw]

Don't forget this is for a stock PMT1 truck with stock splitshot injectors. Pressure plays a huge roll in amount of fuel injected and smoke control. I'm sure 500psi doesn't seem like it is a big difference but it is.

When you get into the single shot injectors the numbers will be much lower especially with your size injectors.

 

[Big Bore]

Don't forget this is for a stock PMT1 truck with stock splitshot injectors.

I guess I misunderstood that, because in the post referenced the scenario is...

Cruising down the highway with the converter locked in at 2000 RPM's, overtaking slower moving traffic you hammer down to 3/4 throttle (no downshift). APP jumps up to 750AD. Now the truck is blowing cornflake size coal from the tailpipe.

That does not sound like a stock split shot to me.:shrug:

 

[907DAVE]

Nice work quys!

Now that we know where on the map our problem are is what would happen to ICP if we dropped PW?

Nothing.

Since the ICP map doesn't care what the PW is, it will remain the same. What will happen if you lower PW in an "area" is it will be lower for that ICP, but the next time you see that amount of PW, ICP will be higher.

See it now?

 

[907DAVE]

That does not sound like a stock split shot to me.:shrug:

Again, its just a typical situation. I used the maps that were already posted. The point was to understand the PCM's train of thought, NOT question what size injectors or how many turbo's he has.

I will throw a real life 450/400 PW map out there, and another one showing how I resolved my fueling concerns soon.

 

[2000wa250]

Nice work quys!

Now that we know where on the map our problem are is what would happen to ICP if we dropped PW?

Nothing.

Since the ICP map doesn't care what the PW is, it will remain the same. What will happen if you lower PW in an "area" is it will be lower for that ICP, but the next time you see that amount of PW, ICP will be higher.

See it now?

this makes a lof of sense now. The ICP wasnt high enough for the PW, but you dont need to adjust this at all because when you pull the PW back, ICP will remain the same because they are not related (at least from a map/table standpoint). Therefore at that RPM and APP with a shorter PW ICP will have the effect of being higher.

Basically the gist of what I'm understanding from this is the K.I.S.S. principle applies to tuning as well. It was mentioned that we could mess with ICP, SOI, PW and MFD and get the same result, with a lot more work, or we could simply decrease the PW, and the PCM will take care of the rest without us having to mess with much more.

 

[907DAVE]

Cool stuff huh?

This does not mean the ICP map will not need work to get things closer to where they need to be, but at least now we understand these maps.

 

[2000wa250]

Cool stuff huh?

This does not mean the ICP map will not need work to get things closer to where they need to be, but at least now we understand these maps.

Of course, but it is amazing to actually understand some of what goes into these trucks. Pretty cool how something a simple as a bit too much PW can give you all these issues.

 

[Vader's Fury]

Well damn! I really over though that.

 

[2000wa250]

Haha you and me both Robert....however we both had the same IDEA of what was going on, just not the simple fix.

 

[Big Bore]

Now that we know where on the map our problem are is what would happen to ICP if we dropped PW?

Nothing.

Since the ICP map doesn't care what the PW is, it will remain the same.

Ok, so I was wrong then? I thought the pcm would raise ICP to meet the MFD.

What will happen if you lower PW in an "area" is it will be lower for that ICP, but the next time you see that amount of PW, ICP will be higher.

And now I'm confused.

 

[2000wa250]

And now I'm confused.

I'm gonna take a shot at explaining...

When you lower PW in a certain spot, such as this example, the computer will not change ICP, however the next time you see the original PW, which was causing the smoke, it will be at a higher ICP because you have lowered the table for PW.

Think of it as a sliding scale. You have simply shifted where the PW is at. ICP still is referencing the same thing, so it stays the same, where as the PW is now changed, so that now if you see PW x, the original one, it will be at a different point on the ICP table, giving it more ICP that it needs.

 

[Big Bore]

I'm gonna take a shot at explaining...

When you lower PW in a certain spot, such as this example, the computer will not change ICP, however the next time you see the original PW, which was causing the smoke, it will be at a higher ICP because you have lowered the table for PW.

Think of it as a sliding scale. You have simply shifted where the PW is at. ICP still is referencing the same thing, so it stays the same, where as the PW is now changed, so that now if you see PW x, the original one, it will be at a different point on the ICP table, giving it more ICP that it needs.

Ahh got it. That makes more sense.

 

[2000wa250]

Yea. Took me a second and I had to go back and look at everything, but it does make sense.

 

[Powerstroke Cowboy]

This is realy cool!!!! We have 5 7.3L on the place that could use some help...

 

[907DAVE]

Nice work guys! We are not quite finished with fueling as there are a few more ways of adding and removing fuel by use of limiters and multipliers.

First limiter is the Fuel Limit vs. RPM.

This one is pretty strait forward, the vertical is mg/stroke and horizontal is RPM.

This is the Low Boost Fuel map.

I cannot say I completely understand this map, but it is suppose to limit mg/stroke by comparing boost pressure and RPM. I feel this map is more of a delay, but cannot say for sure. Bottom left is boost and bottom right is RPM.

Pulse width Multiplier.

This map in stock form is used to increase PW when the engine is cold and uses ICP (bottom left) and EOT(bottom right) to determine how much fuel needs to be added. The outcome is multiplied by "base" PW to determine total PW. Typically the aftermarket uses this map to add fuel when the engine is at operating temp and ICP is high. This is the best way to add fuel because it reduces the chances of YOU harming the engine when you try to lay down the powah when the engine is cold. Also its great because you can easily add fuel when ICP is up (helps keep smoke under control).

Here's a modified version over top of a stocker.

Here is the Adder to Pulse width Multiplier

This map is where you get your de-fuel. Boost bottom left (in Kpa) and RPM lower right. Typically this map gets all zero's in a modified program.

 

[Powerstroke Cowboy]

now you switch to 3D!!!!

LOL will look long and hard at them..

Is there anything you want us to try and figure out by these 3D maps??