at a loss. replaced MAF

[Nad_Yvalhosert]

No its not low pressure. disconnecting the maf. I pull a long grade hill. its over a mile long straight up. with MAF connected barely 42. disconnected and floored Full power got to 72 mph at 10k weight. I thought it was pressure too, but it NEVER skipped a beat, and i had it buried the whole run, and trims were perfect.

That's good, you didnt mention you tested it, so I had to ask...

 

[ralmo94]

If you have hot restart issues you could have a bad vacuum line on fuel pressure regulator, or bad regulator. When I tore into mine there was 3 bad injector o rings and it was sucking fuel in the vacuum line for the fuel pressure regulator.

 

[Chevy Express]

I also understood lean/rich was only one bank...

What are the MAF numbers? You can pretty much determine if MAF sensor is bad by looking at live data and accelerating the engine at multiple rpm ranges.

There's a way to test it with a DVOM with Hertz reading, but takes longer. Do you have a wrecking yard nearby? Popping in a MAF from there is probably cheaper.

Did you clean your old one? I've read if that little filament gets dirty it can produce numbers that are inaccurate.

I did clean my old one, it made no difference. ft were garbage, everything was +25,

I can get live readings, but I don't know what the MAF values are suppose to be compared to normal. what I don't understand is how it went from +25 to -18

i read on a amazon review of the old ac delco ones getting out of calibration. it was extremely cleaned though when i took it apart.

 

[Chevy Express]

If you have hot restart issues you could have a bad vacuum line on fuel pressure regulator, or bad regulator. When I tore into mine there was 3 bad injector o rings and it was sucking fuel in the vacuum line for the fuel pressure regulator.

I had them, but disconnecting, and or replacing it has fix this now, just don't understand why the FT are now negative? is the delphi a good unit? or does everyone go back to the ac delco unit?

I don't have a known good starting point can someone give me some baselines of what i should be seeing?

 

[stutaeng]

Here's a source. Your engine displacement will be on the higher end of the range they say.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.alldata.com/mx/en/support/tech-assist/article/maf-sensor-testing%23:~:text%3DWith%2520the%2520engine%2520at%2520idle,rpm%252C%2520depending%2520on%2520engine%2520size.&ved=2ahUKEwjU99HZmdv5AhX5kmoFHTCUDRIQFnoECAoQBg&usg=AOvVaw3eFHgTlBRURONY-nXLnVr1

 

[HotrodZ06]

Possible you have a bad new part. Delphi is usually a decent brand, I've used quite a but of Delphi with no issues but could be a new bad part. I would try to get them to warranty swap you for another sensor or if you could get a known good MAF to test with. Could also be wires with too much resistance or loose connector terminals, I have seen both several times.

 

[ralmo94]

If you have hot restart issues you could have a bad vacuum line on fuel pressure regulator, or bad regulator. When I tore into mine there was 3 bad injector o rings and it was sucking fuel in the vacuum

 

[Chevy Express]

Possible you have a bad new part. Delphi is usually a decent brand, I've used quite a but of Delphi with no issues but could be a new bad part. I would try to get them to warranty swap you for another sensor or if you could get a known good MAF to test with. Could also be wires with too much resistance or loose connector terminals, I have seen both several times.

I have ordered a rebuilt ac delco. I will return the delphi, I am just mind blown how it goes from +25 to -18, I would think that would rule out bad wiring. I also repulled the pins to get better contact, they didn't seem loose.

The problem is I don't know the baseline for the MAF, and from my reading, I need a scope to catch the hertz, as a DVM is to slow to catch it if there is a glitch etc.

For a vehicle is that is only driven 1k a year. i may just end up leaving it unplugged.

 

[stutaeng]

The problem is unplugging the MAF puts the transmission in maximum line pressure.

Shifts are harsh and it's not good for the transmission.

When I get home tonight I'll give you readings from my trucks for the MAF. I don't have a 7.4, but it should get you in the ballpark.

 

[df2x4]

Possible you have a bad new part. Delphi is usually a decent brand, I've used quite a but of Delphi with no issues but could be a new bad part. I would try to get them to warranty swap you for another sensor or if you could get a known good MAF to test with. Could also be wires with too much resistance or loose connector terminals, I have seen both several times.

I am suspicious of the new Delphi MAF as well. When it comes to sensors on GM vehicles, I like to stick to OEM GM parts whenever possible. I've had issues on other vehicles where brand new aftermarket sensors ended up being the problem.