Electrical Map Sensor: What Makes It Go Bad?

I recently bought one of those high-speed digital multimeters that measure frequency so that I could test my MAP sensor (see jrichker's tech notes on code 22). Welp, turns out my MAP was bad (0 Hz), so I bought a new one and installed it today. Haven't cleared and dumped codes yet, but the new sensor passes the frequency test.

I understand that MAPs rarely fail, but what causes MAPs to fail when they DO go bad? I'd like to identify any potential "upstream" problems so the MAP won't fail again in the future.

BTW, I REALLY like my new frequency-testing DMM, and it was only $23! It's on a number of "best DMM" reviews, and this duder swears by em: http://easyautodiagnostics.com/misc-index/choosing-a-digital-multimeter-1

If you're looking for an affordable DMM that measures Hz, then I recommend that you consider the Mastech.

(Note: I have no affiliation with this multimeter brand nor the aforementioned duder).

jrichker said:

Stuff happens...

MAP sensors, just like any other electronic device don't last forever. Considering +20 years of service in an automotive environment is pretty good considering the heat, moisture, voltage transients, RFI and other hazards.

Click to expand...

Thanks! Good to know..

The MAP sensor may have been the origin of my problems all along. I took the car out today for the first time in several weeks and it ran better than ever! I'm thinkin that replacing those bad eec caps may have something to do with it as well. Keeping fingers crossed though.. I've been fooled before.

Thanks for all of your help!

Looks like my jubilation was premature (again). Took the car to work yesterday and all was good--gate guard even commented on how bada$$ it sounded--but it almost stranded me on base after work. I got it running, but it limp-mode`d me all the way home.

Oh well. The MAP needed replaced anyway so I'll chalk it up as progress. Back to ye olde drawing board..

Will do, but probably not until this weekend. Thanks guys!

DuderMcMerican said:

Will do, but probably not until this weekend. Thanks guys!

Click to expand...

I warmed up the car and dumped *some* codes this weekend and got code 11s on KOEO and Continuous Memory. Hurray! But then the car wouldn't run long enough to dump KOER. Doh! I don't know what was up... why it ran for 15 minute warmup but then died after like 5 seconds of running thereafter. It happened several times... sometimes it was hard to start, sometimes not, but it always died after ~5 seconds. It has behaved this way before--nothing new (it's so unpredictable; anything is possible, from Crank/No Start to RUNS GREAT and everything in between).

I checked for vacuum, and it was a lower than normal (~16"), so I poked around and found that the PCV was hanging by its hose--grommet nowhere to be found! That's on me, though, because last year I was too impatient to wait for a PCV/grommet/screen from LMR, so I ran out and get them at Advance. I now have a new PCV kit on its way from LMR, so I'll install that when it arrives. Meanwhile, I rigged the old Motorcraft PCV and grommet with a length of bent plastic vacuum tubing (in between rubber ends), and it seems to keep the PCV seated in the hole pretty firmly. After that, the vacuum was pretty steady at around 18 1/2". I tried running the car several times after fixing vacuum, and still a NO-GO. I even tried it later in the evening after the car was plenty cool, and still nope.

When messing with the PCV, I noticed that there was oil all up in the valve and hose, so for now, I rigged a harbor freight fluid/air separator in the hose between the oil fill tube and the intake. We'll see how much it catches.

After dumping KOER, the plan was to check/adjust timing... Suppose that will have wait.