Maf reading 2.5 g/s with engine OFF

[John Moore]

I’ve been chasing an intermittent high idle and I noticed the maf sensor reading elevated to ~8g/s at idle.

With the engine off and key in the run position, the maf still reads 2.5 g/s. Assuming this was a bad maf sensor, I replaced it but the numbers remain.

Is this an issue? Surely it affects the mixture?

 

[454cid]

I haven't checked MAF flow rates for quite some time, but I'd assume that if it's showing air flow when the engine is off, that something is very wrong. Maybe you've got a short someplace in the wiring. I think it's three wires..... hot, ground, and signal? The signal is a frequency, so more complicated than just checking voltage. I've never had to do it, so can't advise you with specifics, but maybe someone else here can, or you can start Youtubing for answers. ScannerDanner videos are very helpful, on Youtube.

 

[xXxPARAGONxXx]

Any time someone mentions a high idle, first thing that comes to mind is a vacuum leak. Time to do a smoke test.

With a Vortec 5.7L. I'd check the seal on the air cleaner adapter (19) that seals the intake against the throttle body.

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In 20+ years, it's bound to be allowing a vacuum leak. No aftermarket replacement available.

 

[L31MaxExpress]

Its normal. The Airflow in the MAF Frequency table will always show some unit higher than Zero.

 

[454cid]

Its normal. The Airflow in the MAF Frequency table will always show some unit higher than Zero.

That seems odd it's designed that way.

The 8g/s seems a little high. Spec (engine Idling/Lower Radiator Hose Hot/Closed Throttle/Park or Neutral/Accessories Off) is 5.80g/s for the small block according to the 99 manual.

 

[OBS_Trash]

1996-5.7

I’m chasing down a P0102 - Circuit Low Frequency, scan tool arrived today and using the great service Manuals from this group. Page 6E-518. Step 2/ Says engine running should be 2g/s, mine reads 10.2g/s, with engine off its reading 9.9g/s

Has a new MAF, voltage checks out (5vSig, 11.8vPWR) ground seemed good I’d have to check again.leaning toward VCM, but going to follow the steps

I’ve hit it with propane to check for vacuum leaks, but about to do a smoke test.

 

[Dannyboy97]

1996-5.7

I’m chasing down a P0102 - Circuit Low Frequency, scan tool arrived today and using the great service Manuals from this group. Page 6E-518. Step 2/ Says engine running should be 2g/s, mine reads 10.2g/s, with engine off its reading 9.9g/s

Has a new MAF, voltage checks out (5vSig, 11.8vPWR) ground seemed good I’d have to check again.leaning toward VCM, but going to follow the steps

I’ve hit it with propane to check for vacuum leaks, but about to do a smoke test.

Did you ever come to a conclusion for the P0102? I'm going through the same now, gentlemen who I purchased the truck from said he replaced it but doesn't remember what brand. I'm leaning towards a cheap MAF sensor that's not working right. So far all voltages and ground check out, only thing left is to do a smoke test.

 

[OBS_Trash]

MAF - Parts Cannon Story - Paying it Forward

1996 Chevy 5.7 300,000 High mile truck, nice truck, nothing crazy on mods, (long tube headers, straight pipe) sounds and looks great, lots of miles though. I clean up the interior, replaced carpet, new dash skin, basic tune up (plugs, wires, oil, air filter, etc) I Do a 4/6 drop with...

www.gmt400.com

Here is the Long Version of this issue. End the end I replaced a ton of stuff. All in all it was and still is the MAF (3 total) , or how the VCM is reading it. But with all codes cleared, I can drive the truck much better with MAF unplugged. So i installed a switch in the cab to start it with the MAF on. Once i'm about 60ish or so MPH it starts acting up, i switch it off and she drives great. I left it at that, the only thing i didn't replace was the distributer. But the whole thing is a head scratcher.

I do recommend getting a BT Reader and use an App called DashCommand. Cheap and SOOOOOOOOOO worth it. Good Luck