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ohhh the maf IS maxing out? Yeah, that'll do it. What actual PSI are you running? I don't think anything matters when you max out the MAP now that I think about it, but my scans are from 2009-2010 and are on a computer from 2007-ish so trying to go back and look at them isn't going to happen :rofl:

I'm just having such a hard to remembering if it read over 200kpa or not.

You'll need to get or make one of those pigtails that scale the maf for you. Once I put that on my car I wasn't anywhere near to top of the maf scale and everything was happy.
 

v6buicks

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I really need to get my POS going again so that I can compare and follow along. I don't have one of those AFCs that 10sec 10sec is talking about, but I also have not done any data logging. Maybe I'm having similar issues and don't know it.
 

bs009

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The MAP is only a 2 bar map so it will range from 0-200kpa. Luckily the PCM almost never uses it so that's not the problem. My car will always show 200kpa at WOT since I'm running 20 psi. I'm using a blow through MAF though so I haven't ever hit the limit on my stock MAF sensor. With a blow through MAF in front of the supercharger it's easy to max it out. Even easier if you have it in front of the turbo.

Seems weird to see the duty cycle going down like that because of the MAF being maxed, but it looks like that's what's happening. You can see it's definitely going way lean by the O2 readings too so things aren't happy.
 

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The stock one in the TB should max out at 20psi... Did you remove the screen or something?
 

bs009

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I was wondering about that for the longest time too. My GP is way faster than my brother's old ssei was, but his was maxing out the MAF under less boost and mine wasn't.

My idea I had until 5 minutes ago was that the MAF can't see pressure (apparently it can adjust for pressure? still learning more about that now), so it would just look at air velocity and if you increase the boost the air velocity wouldn't change, again looks like I'm wrong here.
I'll need to look into this though to see if pressure has some factor on its readings being lower.

It probably has more to do with the tight bend I have in front of my throttle body if that's the case. I still have the screen. I need to go look at my latest logs now I guess to verify...

So ignore everything I said about blow-through vs draw-through in my last post for now.
 

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Yes, maxing the map won't cause your issue. The maf will. Put your screen back in if you have it. That'll help. If it's still maxing you'll have to get an afc.
 

v6buicks

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I was wondering about that for the longest time too. My GP is way faster than my brother's old ssei was, but his was maxing out the MAF under less boost and mine wasn't.

My idea I had until 5 minutes ago was that the MAF can't see pressure (apparently it can adjust for pressure? still learning more about that now), so it would just look at air velocity and if you increase the boost the air velocity wouldn't change, again looks like I'm wrong here.
I'll need to look into this though to see if pressure has some factor on its readings being lower.

It probably has more to do with the tight bend I have in front of my throttle body if that's the case. I still have the screen. I need to go look at my latest logs now I guess to verify...

So ignore everything I said about blow-through vs draw-through in my last post for now.
I think I can help break this down a little bit. I only have an Auto Tech degree, but I worked in a fluid metrology lab for four years. The MAF measures mass flow. Hence grams per second. You are right in that a MAF cannot read pressure, but it does not need to. Regardless of pressure, flow is flow. The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.

In theory, you could meter air where ever you want because it has to move at the same rate everywhere. However, because of several factors there will be a slight delay the further the meter gets away from the throttle body. The variable of pre/post turbo comes to play depending on the performance of the MAF. From what I'm gathering, it seems that our MAF is much better at calculating a SLOWER (per seconds) but DENSER (grams) charge (blow through) than a faster less dense charge (draw through)
 

v6buicks

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Also air is a very tough fluid to measure. It does not want to be laminar so having an elbow right in front of the sensor is bad, but the screen helps straighten it out a bunch.
 

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If you want a direct result of not being able to meter the air anywhere you want, take the maf sceen out of your car and start it up. See just how badly the airflow goes past the hotwire on the maf without that screen in there to even it all out.

My guess for bs009 bs009 your bend right before the TB is forcing the air around the MAF so it isn't picking up all of the airflow.
 

bs009

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I think I can help break this down a little bit. I only have an Auto Tech degree, but I worked in a fluid metrology lab for four years. The MAF measures volumetric flow. Hence grams per second. You are right in that a MAF cannot read pressure, but it does not need to. Regardless of pressure, flow is flow. The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.

In theory, you could meter air where ever you want because it has to move at the same rate everywhere. However, because of several factors there will be a slight delay the further the meter gets away from the throttle body. The variable of pre/post turbo comes to play depending on the performance of the MAF. From what I'm gathering, it seems that our MAF is much better at calculating a SLOWER (per seconds) but DENSER (grams) charge (blow through) than a faster less dense charge (draw through)
This is helpful, but now I want to know how it can do that to see if there's a possibility of error in higher pressure situations. I need to consult with the internet more now :LOL:
 
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TurboTPI

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Thanks guys for all the input. So this basically is just making me lean more towards going to the stock maf sensor and location. I didn’t want to have to buy one (my stock one went bad, part of the reason I went to the LQ4 maf) but I’d rather not mess around tuning the draw thru if it’s going to limit my combination.
 

m_dogg

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I have 2 stock mafs laying around somewhere if you need one.
 
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TurboTPI

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Your the man! I can bring you your downpipe too hahaha. Let me know if you find one of them, I’ll stop by
 

b4black

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The MAF measures volumetric flow. Hence grams per second.
Not volume - it measures mass. Mass Air Flow. Grams is mass. Volume would be cubic centimeters or liters etc.

Volume would be effected by air density. A given volume of air at twice the density will have twice the mass. The MAF will 'sense' this increased mass. A MAF compensates for different barometric pressures and altitude.

The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.
Correct (y)
 

v6buicks

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This is helpful, but now I want to know how it can do that to see if there's a possibility of error in higher pressure situations. I need to consult with the internet more now :LOL:
I don't recall the set up on your brother's SSEi. Is it supercharged? Turbo only? If its twin charged or supercharged then the speed across his MAF would be higher than yours (assuming you are running the same total boost pressure).
Not volume - it measures mass. Mass Air Flow. Grams is mass. Volume would be cubic centimeters or liters etc.

Volume would be effected by air density. A given volume of air at twice the density will have twice the mass. The MAF will 'sense' this increased mass. A MAF compensates for different barometric pressures and altitude.


Correct (y)
Yes, my mistake. Mass flow. Durr. I even spelled it out for myself and still said it wrong.

Original post edited for future readers.
 

bs009

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I don't recall the set up on your brother's SSEi. Is it supercharged? Turbo only? If its twin charged or supercharged then the speed across his MAF would be higher than yours (assuming you are running the same total boost pressure).
Yeah it's twincharged with an ST5 cam so it has tons of potential, it makes some of the coolest noises too but it's been just sitting for the longest time.
 
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TurboTPI

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I had this laying around, so might as well try and use it. Cheapo eBay core, 12x24x3. Should work better than nothin I guess.

8BF33F8E-0EE1-463E-8C34-5600DE958002.jpeg
 

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That'll work very nicely, it'd work even better if you removed the useless blower.
 
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TurboTPI

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Well, that didn’t take long. Another broken trans. I see why people get out of these platforms. Funny part is it happened literally behind a blue 97-04 GTP with license plates that had turbo in them (can’t remember exact what they said)
 
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TurboTPI

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Yeah, I guess it’s either time to step it up on the trans build or get out of it haha. I really like the car especially as a daily. So I don’t know.
 

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