So I did a turbo swap on my 09 lmm and when I was done I flashed my new tune to the truck for the turbo swap. Started it and went for a test drive and it had no power, no smoke, and no codes. So I grabbed my scan tool started to look over live data. Noticed the maf was jumping all over, 0 to 75 to 15 to 170 and this was just at idle. So I figured maf was junk, got a new Delphi in and then went for a drive again. Still no power, no smoke, no codes. So put the scan tool back on and the maf at idle reads 14-17g/s, brake boost it and with the truck floored the best it will do is 37-40g/s. If I do out and floor it and keep it floored for awhile the rpms will get up to a point and then all of a sudden the truck starts to buck, the turbo starts to spool up and make some boost some smoke out the back. So I contacted my tuner he said that in very rare occasions he’s see issues with mafs on lmms and the only way to get rid of the issue is to tune it out pretty much. so he sent me a mafless tune file, flash it in, and it still reads and acts the same way. Talked to the tuner again, he said that it has to be a wiring issue. I ordered up a brand new ecm harness from GM, put it in, and flashed my first tune file back on, maf still reads very low, no power, no codes. I had a new ecm laying around installed that and flashed it to factory GM programming and then flashed it with efilive and maf reading is still the same. So I’m at lost here. Just for shits and giggles I installed the first maf that was jumping around all over to see what it would read and it still jumps all over like it did before. So I have no idea what to do or look for at this point. If someone has any ideas please let me know. I do have videos of scan data if anyone wants to see those. Q
Low maf reading
- Thread starter Kunz111
- Start date
Sounds like the first sensor was junk but the maf calibration needs to be raised to match the intake you have on it since it is reading about half of what it should be at idle. That's where I would start with it.:thumb:
That was the first thing the tuner asked was what intake I am running so I’m assuming that part has been taken care of, he’s a very knowledgeable guy.
Full hsp piping kit on the truck with a 10mm cp3, lift pump, downpipe, exhaust, and marks 63.5 stage 2 turbo
And the low reference ref also. You have to have a steady 5v, and a good ground (low reference) in order to get an accurate MAF reading. The face that the reading is erratic tells me there is a circuit problem.
What kind of harness did you buy? I have seen a lot of problems on LMM truck with the wires to the MAF sensor breaking right at the connector. It is hard to tell though because the insulation is still intact.
Bought the harness right from the dealer.
I’ll check the 5v and ground wires tonight after work.
It sounds like the sensor calibration is off. What size is the pipe on your intake where the sensor is mounted? This may be a dumb question, but you don't have any open ports in the intake where it could pull in air after the MAF do you? Are you sure the MAF is facing the right direction? I know you said you got a new Delphi sensor (should be good, but is it possible you got a bad sensor out of the box? Do you have a buddy with an LMM you could trade sensors with to test it?
I see that. Shouldn't the "signal" from the ECM be 5v?
I understand that the ECU raw data measured is hz, but if the voltage or the amperes is not correct, I would bet that has a direct effect on frequency
Correct me if I'm wrong please, but isn't this the type of MAF sensor the lmm and newer Duramax use?
"A Kármán vortex sensor works by disrupting the air stream with a perpendicular bow. Providing that the incoming flow is laminar, the wake consists of an oscillatory pattern of Kármán vortices. The frequency of the resulting pattern is proportional to the air velocity.
These vortices can either be read directly as a pressure pulse against a sensor, or they can be made to collide with a mirror which will then interrupt or transmit a reflected light beam to generate the pulses in response to the vortices. The first type can only be used in pull-thru air (prior to a turbo- or supercharger), while the second type could theoretically be used push- or pull-thru air (before or after a forced induction application like the previously mentioned super- or turbocharger). Instead of outputting a constant voltage modified by a resistance factor, this type of MAF outputs a frequency which must then be interpreted by the ECU."
Also, the correct operation of the air temp 1 sensor, and in the case of the LML at least, the post cac temp sensor are critical to the ECU calculating the correct g/sec
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I have full HSP piping kit on the truck so it should be 4inch. Never measured it but that’s what they say it is. I have a boost gauges sensor in the only port I have on the cold side of the piping. Maf sensor is mounted the right way. The hole are staggered so you can only mount it one way. So a buddy of mine is parting out a lmm. I ask if I could borrow the maf sensor from him. He said it was cool to do that. Just installed it and it is jumping all over the place. Doesn’t consistently read low like the new Delphi. It’s a tight fit putting the maf sensors in the hole, am I just damaging the sensors each time I install them? I don’t hammer them in at all but I do have to wiggle them back and forth to get them in all the way.
Also I just noticed that the Delphi that I bought from Napa looks differently then the one I took out of my truck and the one I got from my buddy. It’s all black where the ones that came out of the trucks have a metal plate on one side.
