Any of you descreening the MAF?
Registered User
Joined: Aug 2000
Posts: 1,901
From: Houston, Tx USA
Originally posted by JimMueller
3-4RWHP on the dyno is common tolerance with no change in mods, I don't see how anyone can attribute that to any kind of mod, much less the screen.
3-4RWHP on the dyno is common tolerance with no change in mods, I don't see how anyone can attribute that to any kind of mod, much less the screen.
Check out todays dyno runs to see! In my sig... Review section..
I wont descreen.. I call it a fad.. I dont see how people can make themselves believe it.
Registered User
Joined: Jan 2001
Posts: 81
From: big "T"
Originally posted by JimMueller
Had mine de-screened and ported for a few years. Never had any noticeable problems with stuff getting caught on the MAF wires which the screen would have prevented.
But after getting autotap and reading about how to tune the car, it became more apparent to me (for my application) that I wanted to revert to a complete stock MAF to make tuning easier. I personally don't think the long term gains are worth the miniscule gains you may receive from leaning out the AF ratio.
3-4RWHP on the dyno is common tolerance with no change in mods, I don't see how anyone can attribute that to any kind of mod, much less the screen.
Had mine de-screened and ported for a few years. Never had any noticeable problems with stuff getting caught on the MAF wires which the screen would have prevented.
But after getting autotap and reading about how to tune the car, it became more apparent to me (for my application) that I wanted to revert to a complete stock MAF to make tuning easier. I personally don't think the long term gains are worth the miniscule gains you may receive from leaning out the AF ratio.
3-4RWHP on the dyno is common tolerance with no change in mods, I don't see how anyone can attribute that to any kind of mod, much less the screen.
1st paragragh: I thought the screen was in place to straighten out air flow after bouncing around inside the stock in-box; the filter is for filtering. the screen is for straightening. That's what I thought anyway.
2nd par.: How would a stock MAF make tuning easier with autotap?? as opposed to gutted?
3rd par.: Trueism....descreening the MAF on an LS1 (original ?) won't do much of anything.....but porting /polishing from there on is going to make a difference in the ambient temp. drop as well as increase vol. eff. don't you think??....it's always been about the WOT with this mod!!!
Guest
Posts: n/a
PAIN IN THE ***
I don't think I will do it.... sounds like a hassle to me....... even for 2 HP is it worth the hassle of pulling apart your bellows, clamps, etc....... throwing out your lower back.....? You risk scratching your paint fenders, risk setting off your MAF sensor then you gotta go back to your "I don't care about you now" Chevy dealer!!!!
It's a F'n hassle! Why do it? Take that time and throw another coat of Z5 on.......
It's a F'n hassle! Why do it? Take that time and throw another coat of Z5 on.......
Registered User
Joined: Feb 2000
Posts: 607
From: Casselberry FL USA
Amood: I don't recognize your handle, do we know each other?
Well, the screen was advertised to straighten the airflow before it hits the MAF wires. Some have found that their air filter has allowed some things past the seal and found it stuck against their MAF screen.
I didn't (and one can't directly) use AutoTap to tune the car. Techincally I have custom tuning. But in preparation for buying LS1-Edit I put mine back to stock. I'll cut'n'paste a response made by Tim Sloper from C&S Performance on another site, since he states it very well:
Well, the screen was advertised to straighten the airflow before it hits the MAF wires. Some have found that their air filter has allowed some things past the seal and found it stuck against their MAF screen.
I didn't (and one can't directly) use AutoTap to tune the car. Techincally I have custom tuning. But in preparation for buying LS1-Edit I put mine back to stock. I'll cut'n'paste a response made by Tim Sloper from C&S Performance on another site, since he states it very well:
The problem with the ported MAFs (or aftermarket ends) is that the stock MAF transfer function no longer applies. This leads to a "guesstimate" on how the stock curve should be manipulated to compensate for the change in physical characteristics. It's not a simple shift or scale of the existing curve as you might think. After the holidays I'm going to spend the $ to have a MAF with aftermarket ends flowed against a stock unit so that I can get the exact data I need to tune with aftermarket ends "correctly and accurately". The professional tuners may or may not have done this but they obviously aren't going to share the info if they did.
As for Granatelli... it is supposed to be "calibrated" but there again know one knows what it is calibrated against. Theoretically I should be able to run it back to back against a stock MAF and see absolutely no significant change in reported airflow but this is not usually the case.
For those of you not familiar with ported MAFs... they increase power but not because they are allowing you to flow more air. When you port the MAF you cause less air to hit the sensor elements. This in turn leads to less air flow reported to the PCM. This causes two things... 1) the car will deliver less fuel leaning the car out, sometimes this is good (stock type setup) but usually the PCM will then compensate but in doing so over-compensate. You will then ultimately run richer than desired. 2) There are two variables used by the timing tables. RPM and air flow. With a ported MAF you make the PCM believe that there is less air flow than there actually is. This results in increased timing which may or may not increase power output.
As you can see it is tough to dial in a PCM in when the data from one of the most influencial sensors is not accurate. The MAF sensor itself is also inherently less accurate (very significant actually) as air flow increases. You start compounding errors upon errors and the system overall becomes very difficult to bring in line.
Once I flow a ported unit I won't have so much concern about them but the reality is that if you are able to tune the PCM directly there is absolutely no reason to deviate from the stock MAF especially on anything below 400 CI.
Hope this helps.
Tim
As for Granatelli... it is supposed to be "calibrated" but there again know one knows what it is calibrated against. Theoretically I should be able to run it back to back against a stock MAF and see absolutely no significant change in reported airflow but this is not usually the case.
For those of you not familiar with ported MAFs... they increase power but not because they are allowing you to flow more air. When you port the MAF you cause less air to hit the sensor elements. This in turn leads to less air flow reported to the PCM. This causes two things... 1) the car will deliver less fuel leaning the car out, sometimes this is good (stock type setup) but usually the PCM will then compensate but in doing so over-compensate. You will then ultimately run richer than desired. 2) There are two variables used by the timing tables. RPM and air flow. With a ported MAF you make the PCM believe that there is less air flow than there actually is. This results in increased timing which may or may not increase power output.
As you can see it is tough to dial in a PCM in when the data from one of the most influencial sensors is not accurate. The MAF sensor itself is also inherently less accurate (very significant actually) as air flow increases. You start compounding errors upon errors and the system overall becomes very difficult to bring in line.
Once I flow a ported unit I won't have so much concern about them but the reality is that if you are able to tune the PCM directly there is absolutely no reason to deviate from the stock MAF especially on anything below 400 CI.
Hope this helps.
Tim
Registered User
Joined: Jan 2001
Posts: 81
From: big "T"
Jim Mueller:
Yeah, probably 1 1/2 years ago we bantered back and forth on some subject that was popular at the time. I haven't been to the site that much recently, and your name I recognized from "back in the day".
I had always wondered about the calibration issue. On another post someone was asking 'which LS1...98-00, or 01-02 or something like that and I raised the issue about the later year models running a little leaner than the earlier years. It seemed every time somebody with the later years descreened and ported the MAF they quickly got the SES lite and a lean code to go with it. You've done the homework on the subject so whattaya think about this:?
According to what Tim said, the everyday tinkering back and forth to work type driving would most likely have less affect on over-correction of fuel or timing curves, because airflow is still relatively slow at least before the throttle body. Again, this mod has always really been about WOT. And with the history of '98 models having more lattitude at the fuel curve than newer years, I can't help but think that the occasional flooring would benefit from the leaner/advanced time conditions, because the PCM's "memory" will always want to go back home. Zat make sense??
Yeah, probably 1 1/2 years ago we bantered back and forth on some subject that was popular at the time. I haven't been to the site that much recently, and your name I recognized from "back in the day".
I had always wondered about the calibration issue. On another post someone was asking 'which LS1...98-00, or 01-02 or something like that and I raised the issue about the later year models running a little leaner than the earlier years. It seemed every time somebody with the later years descreened and ported the MAF they quickly got the SES lite and a lean code to go with it. You've done the homework on the subject so whattaya think about this:?
According to what Tim said, the everyday tinkering back and forth to work type driving would most likely have less affect on over-correction of fuel or timing curves, because airflow is still relatively slow at least before the throttle body. Again, this mod has always really been about WOT. And with the history of '98 models having more lattitude at the fuel curve than newer years, I can't help but think that the occasional flooring would benefit from the leaner/advanced time conditions, because the PCM's "memory" will always want to go back home. Zat make sense??
Thread
Thread Starter
Forum
Replies
Last Post
tommalcolm
Computer Diagnostics and Tuning
2
Sep 11, 2015 03:39 PM