MAF readings

[astoor]

2015.5 LML GMC DENALI

So my MAF reads between 15.4 and 17.3 g/ps at idle and will only read up to about 280-320 g/ps. Fuel is capped because of air so that varies. Every thing worked before I installed a compound setup and head studs.

I have put a new MAF and humidity sensor in.

I have tested all the wiring

I have put in another ECM that had my previous tune installed before the compounds.

I have put in my own harness from the ECM to the MAF.

I have checked all my grounds.

After all of that the readings will not change. The only way I can get it to run kind of right is to scale the MAF at 600g/ps for the whole table which comes with its on set of issues. Also I have had several tunes in it from different tuners and the MAF still wont read correct. Yes they all scaled the tune for the size of the intake.

Thoughts?

 

[JoshH]

You need to have the maf sensor calibrated for the new size intake tube.

 

[gmduramax]

Is your maf in backwards? Or you aren’t telling the tuner the correct size of the intake tube. Or they all messed up rescaling the maf.

 

[astoor]

You need to have the maf sensor calibrated for the new size intake tube.

They all have "calibrated" or "scaled" the MAF.

 

[astoor]

Is your maf in backwards? Or you aren’t telling the tuner the correct size of the intake tube. Or they all messed up rescaling the maf.

No Its not backwards. I doubt that all three of them messed it up. Also they all went back and looked at the scaling to verify that.

 

[JoshH]

Doesn't sound like they did it correctly or the sensor was installed backward as was said above.

 

[S Phinney]

It is definitely not scaled correctly.


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[Ron Nielson]

Make sure you are getting almost exactly 5V on pin 3

 

[astoor]

Make sure you are getting almost exactly 5V on pin 3

It is 4.98VDC

 

[Ron Nielson]

Another discussion about this subject that may be of interest to you https://www.duramaxdiesels.com/foru...af-still-reading-0-00-g-s.88182/#post-1173323

 

[astoor]

Another discussion about this subject that may be of interest to you https://www.duramaxdiesels.com/foru...af-still-reading-0-00-g-s.88182/#post-1173323

Thank you for the information.

 

[JoshH]

I just noticed you mentioned you tried setting the whole MAF table to 600. When you did that, did it read 600 g/s at idle? If you have access to your tune file, post a screenshot of your MAF calibration table.

 

[astoor]

I just noticed you mentioned you tried setting the whole MAF table to 600. When you did that, did it read 600 g/s at idle? If you have access to your tune file, post a screenshot of your MAF calibration table.

Yes it reads 600 g/s at all times. I dont have access to the tune file. I have been working with the tuner and that was a solution to make it driveable to get the trans learned.

 

[S Phinney]

Yes it reads 600 g/s at all times. I dont have access to the tune file. I have been working with the tuner and that was a solution to make it driveable to get the trans learned.

If he could see that it read 600 all the time then it is a very easy fix to make it read correctly.


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[astoor]

If he could see that it read 600 all the time then it is a very easy fix to make it read correctly.


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It reads like that because we wanted it to. if you look at the table you can assign a g/s value for any given frequency. So we maxed out the g/s value for the whole table so it wont limit fuel for AFR. Kind of like a low boost fuel tune just incredibly aggressive. If I understand it correctly you should see about 35 g/s at idle and maximum effort on a stock turbo is about 450g/s. Theoretically I should be able to flow over 600g/s at max effort. So with the MAF scaled for the size of the intake at 40PSI I am barely getting 280 g/s which is about 9700Hz and the truck hates it then shudders and you have to pull over. I had an LBZ with the same setup and it would max out the sensor all day long.

 

[S Phinney]

LML will see more at wot than previous years. You should see 40 at idle and around 500 at wot early generations. LML 40 idle and usually 500-600 at wot.


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[astoor]

LML will see more at wot than previous years. You should see 40 at idle and around 500 at wot early generations. LML 40 idle and usually 500-600 at wot.


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I agree thats why I said about. Im sure there are other factors too.

 

[JoshH]

I'm not going to instruct a professional tuner how to do something as simple as scaling a MAF sensor because it is a very simple procedure, but I will say with 100% certainty, the MAF sensor is not scaled correctly. If you can enter 600 across the boar in the scaling table and see 600 g/s at idle, and a normal scale on the MAF sensor table reads consistent at idle and increases with airflow, there is nothing else it can be but a scaling issue. My suggestion is to find a new tuner or tell him to learn how to scale the sensor correctly. I will say this is not the first time I have seen this.

 

[astoor]

I'm not going to instruct a professional tuner how to do something as simple as scaling a MAF sensor because it is a very simple procedure, but I will say with 100% certainty, the MAF sensor is not scaled correctly. If you can enter 600 across the boar in the scaling table and see 600 g/s at idle, and a normal scale on the MAF sensor table reads consistent at idle and increases with airflow, there is nothing else it can be but a scaling issue. My suggestion is to find a new tuner or tell him to learn how to scale the sensor correctly. I will say this is not the first time I have seen this.

If my post came across as that I was trying to instruct anything that wasn’t my intention. As far as I know my truck is the anomaly. This is a very well known tuner who has done a lot of these kits.

Right now at idle my truck reads around 3700Hz. And with any tune that uses the MAF it will max out at around 10000Hz. It takes a long time for the truck to get up to that too. I’m just trying to get an idea or a direction to try next.


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[gmduramax]

If my post came across as that I was trying to instruct anything that wasn’t my intention. As far as I know my truck is the anomaly. This is a very well known tuner who has done a lot of these kits.

Right now at idle my truck reads around 3700Hz. And with any tune that uses the MAF it will max out at around 10000Hz. It takes a long time for the truck to get up to that too. I’m just trying to get an idea or a direction to try next.


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New tuner