Dash Daq boost readings

[bigrpowr]

Dustin mentioned that him and Mike Haller had discovered the DD boost readings were off. He sent me some sort of dongle so I could get analog overall boost reading (mgp). Needless to say I went from seeing 52-53 to seeing 57-60. I also confirmed this by plumbing a boost gauge to a dyno jet and the readings were identical. Just some food for thought when dialing bp. I was pretty amazed it was that far off.

 

[Jeff@Spartan]

If that is so, back pressure is even closer to 1:1 than previously thought....

It reads off the factory sensor, so the factory sensor must be 5-7 psi off.

 

[jdgleason]

Crazy...

 

[bigrpowr]

If that is so, back pressure is even closer to 1:1 than previously thought....

It reads off the factory sensor, so the factory sensor must be 5-7 psi off.

Not really. That most likely means the bp is off as well. It would be interesting to test that as well.

 

[Erikclaw]

Not really. That most likely means the bp is off as well. It would be interesting to test that as well.

Exactly, I remember hearing this once but nothing really came of it.

 

[Dzchey21]

The craziest part is I'm using the factory map to get that reading.... its something in yhr computer that skews the number.


I'm actually planning on trying it out on the back pressure sensor...

Mike you can try it. Just unhooking from the factory map and plug my harness in to the back pressure sensor instead of the map sensor. Ill dial the settings and then u can verify... I'm curious as well but I'm pretty sure back pressure is accurate as it carries out to the sensor maximum unlike the map

 

[Jeff@Spartan]

The back pressure sensor should be accurate. Doesn't the fact that barometric pressure and exhaust back pressure are the exact same with the key on show the accuracy of the back pressure sensor? And if in fact the back pressure sensor is reading low as well, then the stock valve train is much stronger than we originally thought.

 

[bigrpowr]

The back pressure sensor should be accurate. Doesn't the fact that barometric pressure and exhaust back pressure are the exact same with the key on show the accuracy of the back pressure sensor? And if in fact the back pressure sensor is reading low as well, then the stock valve train is much stronger than we originally thought.

I think it's actually the way it process's the signal and the higher it goes the further off it gets. The factory map also reads the same barometric pressure with key on, just gets skewed somewhere along the line.

 

[Danbonzo]

I think it's actually the way it process's the signal and the higher it goes the further off it gets. The factory map also reads the same barometric pressure with key on, just gets skewed somewhere along the line.

It could a progressive false reading. The calculation that is causing the error would become exponential over due course. But being so close to barometric at benchmark the error would still be off (albeit 5-7psi at full boost). Curious, how was this discovered, as a hunch or by accident?

 

[bigrpowr]

It could a progressive false reading. The calculation that is causing the error would become exponential over due course. But being so close to barometric at benchmark the error would still be off (albeit 5-7psi at full boost). Curious, how was this discovered, as a hunch or by accident?

my guess is mike and dustin hooked up to the boost sensor on the dynojet or ran a mechanical gauge when they were dialing the wastegates.

 

[Dzchey21]

you are right , i think its a skewed number that gets worse the high the boost gets, i just verified that over 50 psi it was no longer accurate.

Mike haller actually discovered it on Mals truck when he put mechanical guages on it for a couple reasons, for one, there was no way to read low pressure turbo boost, so he put a guage in for that, also his factory egt sensor was messed up, and the only guage pods you could get were 3 pods, so they did two boost gauges. Every time mike would data log with IDS on the dyno his numbers were always higher on the gauge than the ford computer would pick up.

So i decided that i was going to make my harness for the dash daq so a guy could data log a run without IDS if if wanted to, when i was setting it up i realized that the factory map wasnt reading right with what i had for guage pressure to verify that my calibrations for the dash daq were correct.

There must me some table in the ecm that isnt quiet right, and it doesnt really suprise me considering that the factory turbos only make like 36psi on a stock setting.

 

[Klutch]

On my race truck the DD and ams controller read the same, even at high boost, ams gets source from hot side just after turbo. You would think all trucks would be the same if the numbers are getting skewed in the computer.

 

[Jeff@Spartan]

This is pretty interesting to say the least. Does Shone have a mechanical boost gauge he can verify with as well?

 

[bigrpowr]

This is pretty interesting to say the least. Does Shone have a mechanical boost gauge he can verify with as well?

i have a mechanical gauge i can verify with.

 

[Dzchey21]

On my race truck the DD and ams controller read the same, even at high boost, ams gets source from hot side just after turbo. You would think all trucks would be the same if the numbers are getting skewed in the computer.

Whats the max boost you see?

This is pretty interesting to say the least. Does Shone have a mechanical boost gauge he can verify with as well?

Yep and one of my harness's

i have a mechanical gauge i can verify with.

Didnt you already check with your mechanical gauge?

 

[Jeff@Spartan]

The reason I brought Shone's truck up is because Cole says his DD and AMS read the same number. Doesn't sound like every truck is having the issue. I need to do a mechanical gauge as well to see.

 

[bigrpowr]

Didnt you already check with your mechanical gauge?

no, i used the dynojet sensor, it read a peak of 60.1 , 58.8, and 57.9 ... on 3 different pulls. matched the dd to a tee. i think maybe tomorrow me and beefy will hook up the gauge to see. the gauge is only 60 psi ..but that should do just fine.

 

[Dzchey21]

no, i used the dynojet sensor, it read a peak of 60.1 , 58.8, and 57.9 ... on 3 different pulls. matched the dd to a tee. i think maybe tomorrow me and beefy will hook up the gauge to see. the gauge is only 60 psi ..but that should do just fine.

Thats good enough for me...

 

[Klutch]

I've seen 67psi on xstreet not really a wide open throttle run tho, I'm still using stock trans/converter at the moment. No time to install suncoast or go racing. Project is pretty much on hold.

 

[Craig@MFI]

Mines dead on accurate with my edge cts