My blazer is killing MAFs
 

So my 2000 blazer has been killing Mass air flow sensors after just a couple of days. A few months ago my MAF went bad and i bought a cheapo from Amazon (I know I shouldn't get cheap ones). And they accidentally sent me 2. So I put one of those in and it went bad in just a couple of days so I figured no big deal since it was cheap. So I put the other one in and it also died again in a few days. So I bought a Walker from Rock Auto and that one died in a couple of days. I bought a Delphi but I don't want to put a new one in and have the blazer kill that one too. I checked the tubes and air filter and they were all clean. I didn't dig into the wiring yet. Has anyone ever come across that issue before? Any input is appreciated.

Killed how? No output? Wrong output? Broken filament?

George

Oh yeah, I guess that information would have been helpful. So when it goes bad that blazer will start and then immediately stall. If I replace the MAF everything is fine, for a couple of days at least. There is no obvious damage to the MAF. I even took one apart and there no visible damage on the board. What is really weird is that if i start it and then plug the MAF in it runs fine.

is the MAF reporting normal values in live data on a scanner? Does that change between a “good” and “bad” MAF?

When you start the vehicle with no MAF attached the ECM defaults to speed density mode and uses other sensors as an alternate method of estimating airflow mass. When you plug the MAF into a running engine I don’t believe that it changes sensor modes on the fly.

I believe that the engine dies if the MAF is disconnected while running on these engines. When I get a chance I’ll go out and confirm. When you restart - speed density mode.

You need to determine if the MAF’s are failing, the wiring/connectors are failing, or the ECM is failing. After looking at the MAF output in live data you should check the power and ground and examine the connector.


George

I believe the MAFs are going bad because as soon as I plug a new one in it runs fine. I checked the wiring and everything looks fine. I haven't really had a chance to test the connector voltage because it has been raining for 4 days now. What kind of scanner would I need to check the output data?

Most scanners with live data will work. Members here Like Les have done a nice job of identifying value options for scanning. The one that comes up often is the BT BAFX Amazon dongle, an Android device and some fairly inexpensive software like Car Gauge Pro.

I'm not convinced that you are killing MAF's but if I am wrong then you probably have a power/ground problem. That's why you need to see what data is being reported. Our MAF's output a varying frequency waveform that gets converted by the ECM for ODB display. First I would look at the ODB reported value for a "dead" MAF and then I would look at the MAF output itself if there is no reported output, best if you have a scope, still valuable if you have a dvm with frequency measurement capability.


George

BTW, your MAF uses fused non regulated 12V power on the pink wire, a basic chassis ground on the Blk/wht wire and the signal output on the yellow wire. Since this sensor has such a simple power scheme you can provide a fused 12V source and a solid battery ground for testing/debugging.


George

I will probe the wires after work today to see if I can see anything. This is the first day in almost a week that it hasn't rained here, or course it is only 29 degrees. I think I need a garage lol.

Scanner discussion:

https://blazerforum.com/forum/2nd-ge...oblems-102727/


George

So I checked the wiring and I don't see any damage. I tested the voltage and it is at 11.75 at the connector and at 14.3 at idle. Other than that I didn't make much other progress.