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MAF reading High

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  • MAF reading High

    I got a 2008 LMM with compounds, 100% over S&S injectors, twin CP3, 220 fass, and my MAF is reading 302.6 g/s at idle and it is supposed to be 30-35 g/s. I've hit a dead end and not sure what way to go next. Any ideas? It has a known good sensor and connection.

  • #2
    Alex- While I cant answer this (at least with an educated answer) I will see if I can get DMAXDR to chime in. As I believe he has seen this before. Who tuned your truck?
    Last edited by DmaxStoreJimmy; 07-19-2017, 10:14 PM.

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    • #3
      Alex, there are several things that can cause this. Higher that normal air inlet velocity in relation to MAF sensor and possible MAF table in the tune.

      Some more info on your tuning ,air inlet pipe and MAF position will help.



      Sent from my SAMSUNG-SM-G890A using Tapatalk

      2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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      • #4
        Originally posted by DMAXDR View Post
        Alex, there are several things that can cause this. Higher that normal air inlet velocity in relation to MAF sensor and possible MAF table in the tune.

        Some more info on your tuning ,air inlet pipe and MAF position will help.



        Sent from my SAMSUNG-SM-G890A using Tapatalk


        The truck is tuned by Wade at Diesel Day Dreams In Co, it has a 6" inlet pipe and the MAF sensor is in the center of the pipe slightly to the side. I will try to get a picture and post it here shortly. The truck used to have a s475 over stock kit and it functioned properly and now after a motor rebuild and different chargers it reads super high.

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        • #5

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          • #6
            Might want to give Wade a call if you haven't already.

            Sent from my SAMSUNG-SM-G890A using Tapatalk

            2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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            • #7
              I also just noticed that the MAF connector has been replaced , most likely to extend it. Is that a new addition as well ?

              Sent from my SAMSUNG-SM-G890A using Tapatalk

              2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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              • #8
                Originally posted by DMAXDR View Post
                I also just noticed that the MAF connector has been replaced , most likely to extend it. Is that a new addition as well ?



                Sent from my SAMSUNG-SM-G890A using Tapatalk

                So originally what happened was the MAF sensor never used to read after the motor rebuild and it had a 12v ignition 5v signal, and ground at the plug. So we ran a separate harness from the ECM to the MAF and now it reads it just reads at 302.6 g/s

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                • #9
                  What is the MAF key on engine off? I would make sure there are no resistance problems between MAF connector and ECM as well as ECM ground at engine block. Test to make sure none of the IAT / MAF circuits are shorted to each other.
                  2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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                  • #10
                    Originally posted by DMAXDR View Post
                    What is the MAF key on engine off? I would make sure there are no resistance problems between MAF connector and ECM as well as ECM ground at engine block. Test to make sure none of the IAT / MAF circuits are shorted to each other.

                    I am not sure what it reads Key on Engine off but I will get back to you on that here shortly. As for IAT's I don't have one on the Y bridge anymore as I was told it could be tuned out and didn't need it.

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                    • #11
                      The IAT is part of the MAF Sensor, the other is a defferent sensor, lets call the first inlet temp and the other intake temp, thats the one in the t-bridge.
                      2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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                      • #12
                        Originally posted by DMAXDR View Post
                        The IAT is part of the MAF Sensor, the other is a defferent sensor, lets call the first inlet temp and the other intake temp, thats the one in the t-bridge.
                        So the one I don't have is the one of the Y bridge.

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                        • #13
                          ok, no worries the IAT that is part of the MAF sensor is the one I was referring to in regards to being shorted to the MAF sensor Signal circuit. I still believe that there is a MAF table that is off in the tuning.
                          2006 LBZ Daily Driver, Tractor, School Bus, Hot Rod Diesel , Crew Cab, Lifted, Hunting Rig , Cowboy Cadillac

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                          • #14
                            Originally posted by DMAXDR View Post
                            ok, no worries the IAT that is part of the MAF sensor is the one I was referring to in regards to being shorted to the MAF sensor Signal circuit. I still believe that there is a MAF table that is off in the tuning.

                            So I finally had a chance to dig into this issue, and come to the conclusion of it being the ECM. Every reading from the MAF to the ECM was what it's supposed to be. I graphed the reading out of the MAF while having a scan tool hooked up, and the graph was graphing as throttle changed but my reading on the scan too stayed at 302.6 g/s. Ill find out for sure tomorrow after I swap out the ECM and reload my tunes.

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                            • #15
                              Originally posted by Alex


                              So I finally had a chance to dig into this issue, and come to the conclusion of it being the ECM. Every reading from the MAF to the ECM was what it's supposed to be. I graphed the reading out of the MAF while having a scan tool hooked up, and the graph was graphing as throttle changed but my reading on the scan too stayed at 302.6 g/s. Ill find out for sure tomorrow after I swap out the ECM and reload my tunes.
                              Any new updates today?


                              Sent from my iPhone using Tapatalk

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