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Thread: Erratic maf after cam see pics

  1. #1
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    Erratic maf after cam see pics

    Installed a BTR stg 3 PD cam in my lsa. I have a vararam intake on it. Before the cam all was well. After the install i have a decently smooth maf signal at idle but very erratic at hwy speed 1600rpm. It does smooth out the higher the rpm. It causes crazy swings in the wideband and you can slighty feel it. Is there anything that can be done to straighten this signal? It does have a honeycomb in it, but is this typical or does it depend on intake flow? Or is there a filter in the tune cuz ve is solid. Or just go SD? Here are the screen shots.
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    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

  2. #2
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    Sorry, pics are upside down... smh
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

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    my vararam does not have a honey comb in it so i am going to rig up my stock air box and see what happens with the maf reading when I run it...
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

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    Post a tune file so we can see the settings for Dynamic Airflow High RPM Disable and Re-enable.

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    Here is the tune. I have flashed 30 times chasing this issue to realize its the erratic maf signal that is the underlying issue.

    I was changing all the setting under oxygen sensors- proportional and integral along with rich/lean vs airflow thinking its was the closed loop swings making it surgy feeling with some success but it was when i looked at a buddys same car with a stg 2 cam but NA that had smooth maf signal in all the questionable areas on mine.
    Attached Files Attached Files
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

  6. #6
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    here is the log
    Attached Files Attached Files
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

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    Well i fixed the issue. I jimmied up the stk ss airbox on the LSA to go for a ride and MAF signal is perfect smooth at speed and through out. My vararam works good for the stock LSA cam but not for the more reversion style cams... that was a couple weeks and couple tanks of gas to figure this out LOL

    So I can go to CL SD with the vararam or get the stock or another known intake that works better...


    So what is a recommended aftermarket intake that is confirmed working good for MAF with cams?

    log of the stock airbox run
    Attached Files Attached Files
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

  8. #8
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    Quote Originally Posted by doorev800 View Post
    Here is the tune. I have flashed 30 times chasing this issue to realize its the erratic maf signal that is the underlying issue.

    I was changing all the setting under oxygen sensors- proportional and integral along with rich/lean vs airflow thinking its was the closed loop swings making it surgy feeling with some success but it was when i looked at a buddys same car with a stg 2 cam but NA that had smooth maf signal in all the questionable areas on mine.
    My P59 run 383 SBC L31 based engine was doing the same with a LS3 MAF in a 4" Spectre tube. Jason @ Saxon PC supplied me a 100mm 6:1 flow straightner. Started over with the proportional gain and integrator delays. Multiplied by 0.8 and 1.4 and it is nearly seemlessly smooth with Thorley Tri-Ys. Nice smooth rolling 02 voltage readings that switch about about 1x per second. No more STFTs oscillating +/-5% because of the erratic MAF signal caused fueling swing. At idle the MAF generally stays in 1 cell versus rolling through 3-4. Best part is no more bucking with the converter locked at low speed in overdrive.
    Last edited by Fast4.7; 10-01-2022 at 08:38 PM.

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    Quote Originally Posted by Fast4.7 View Post
    My P59 run 383 SBC L31 based engine was doing the same with a LS3 MAF in a 4" Spectre tube. Jason @ Saxon PC supplied me a 100mm 6:1 flow straightner. Started over with the proportional gain and integrator delays. Multiplied by 0.8 and 1.4 and it is nearly seemlessly smooth with Thorley Tri-Ys. Nice smooth rolling 02 voltage readings that switch about about 1x per second. No more STFTs oscillating +/-5% because of the erratic MAF signal caused fueling swing. At idle the MAF generally stays in 1 cell versus rolling through 3-4. Best part is no more bucking with the converter locked at low speed in overdrive.
    Yes! exactly, i was wondering why I did not have the typical response from changing prop gain and integrator. I will check into the flow straightener and thanks for the info/tips!


    EDIT- Ordered a 4" flow straightener and will report back the results for my vararam system
    Last edited by doorev800; 10-02-2022 at 12:13 AM.
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

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    Well after installing the airflow straightener my maf signal is perfectly smooth. I also have to retune the whole maf curve beacuse it is richer in alot of areas.
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

  11. #11
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    Good feedback. Thanks mate

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    Quote Originally Posted by doorev800 View Post
    Well after installing the airflow straightener my maf signal is perfectly smooth. I also have to retune the whole maf curve beacuse it is richer in alot of areas.
    I noticed the same thing. The Lingenfelter MAF chart was actually very close after the 6:1 grid straightner went in. I had to add some fuel at the bottom and take away some at the top. At very low flow from 1,500-2,000 hz was roughly double, then above 7,500 hz had to remove 4%. Between 2,000 and 7,000 hz the error was less than 1%. With a little tuning the MAF curve is very smooth now. The bottom of the curve makes me question the injector data provided with my AUS 48 lb/hr spider. Its not staying much longer though. I have a clone of an Edelbrock 7137 going on my SBC 383 along with factory GM flex fuel injectors that I have known good GM data for. I will be switching to a Vette fuel filter regulator when I swap intakes as well.

    At light throttle I have zero bucking at 1,200 rpm, the engine will take full load smoothly at 1,600 rpm. That is will 61.5* of overlap at 0.006 and a 61.5* IVC.
    Last edited by Fast4.7; 10-19-2022 at 01:24 PM.

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    any chance you guys have a pic of the straightener installed? ive been chasing a hiccup issue for quite some time now and am wondering if this may help.

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    Quote Originally Posted by LS ROB View Post
    any chance you guys have a pic of the straightener installed? ive been chasing a hiccup issue for quite some time now and am wondering if this may help.
    20221019_134402.jpg

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    Quote Originally Posted by LS ROB View Post
    any chance you guys have a pic of the straightener installed? ive been chasing a hiccup issue for quite some time now and am wondering if this may help.
    Goes on the air cleaner side of the MAF.

    20221019_134402.jpg

  16. #16
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    I used on of the inserts from Performance MRP on one of my projects. They also make MAF housings that included straightener.
    https://performancemrp.com/c-1389190...er-screen.html

  17. #17
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    Here is my Vararam I installed it in.
    Attached Images Attached Images
    2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now

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    Awesome! thanks for the link; i appreciate it guys!

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    Quote Originally Posted by gtstorey View Post
    I used on of the inserts from Performance MRP on one of my projects. They also make MAF housings that included straightener.
    https://performancemrp.com/c-1389190...er-screen.html
    My maf housing is an inexpensive Spectre and the SaxonPC screen is also $6 less before shipping.

    http://www.saxonpc.com/100mm-cells-for-100.html

    I will say I do like the fact that their housing does not use a plastic adapter. Maybe someday I will get one from them. For now my Spectre/SaxonPC is working great. I also like the lip their housing includes on it for holding a silicone hose in place better
    That being said on my NA build, the 4" silicone hose grips the MAF well enough you have to smear it with water for it to want to slide over the Spectre.
    Last edited by Fast4.7; 10-20-2022 at 10:54 AM.

  20. #20
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    I do like that the Saxon has additional thickness available, although I don't know that I could have fit in more than the 1/2" that the MRP is.