So, I've got a new toy (FORscan ODBII software) and a new code that isn't turning on the CEL (yet) but also didn't show up in OBDWiz either.

P1100 - Mass Air Flow (MAF) Sensor Circuit Intermittent

I cleared it, drove a few miles, checked again and it's set again.

The little troubleshooting advise window in FORscan says to monitor the MAF voltage while wiggling the MAF harness and see if the voltage goes below 0.23v or above 4.60v. I was unable to manually make that occur, no matter how I tapped on the MAF or wiggled the wiring.

However, in oscilloscope mode, look at this (at idle):



It sure looks like it went below 0.23v here.

I have no time tonight to do any research. This is a relatively new MAF (one week old, Delphi unit). I think I'll swap it out for one of my two old OEM MAFs sometime this week. But if anyone has an opinion about this, pipe up.

I do damned little work with scanners these days, and the tech keeps changing.

 

I wouldn't think that short a duration intermittent would cause any major problems or even affect air/fuel mix trim values but who knows.

intermittents, sure wish they made wives with intermittents ya could turn off at will.

you may have got a new toy that's going to make more work for you, al?

I just got one in, SAT TV alignment meter unit, microprocessor based with that mind numbing word that causes hairpulling and nights without sleep. SOFTWARE/FIRMWARE with upgrades.
what happened to the quiet days of tent camping with NO tv?

 

Well, I'm actually chasing a P0171. I know, I know, but I'll be damned if I can find a vacuum leak, I've near worn out my Mity-Vac, and I need the STFT on the FORscan to let me see what the O2 sensors are seeing as I use supplemental external hydrocarbon testing (carb cleaner) to try to find the probable leak -- I've already done the plenum gaskets & injector rings.

Anyway, one thing at a time.

 

how about that vacuum tube from hell?
the semi rigid formed tube from the vapors evac tank to the throttle body under the alternator?
mine had at least 1 crack in a bend that only opened intermittently from heat and god knows what. maybe motor mount flex since the gas vapors tank is body mounted and the tube runs across the engine to the TB. tube looked like it had been thru hell, all heat checked.
inside from the gas fumes, god only knows.
the vapors tank short molded lines were garbage, falling apart in my hand. had to cut off the remnants with jack knife.

what's worse, an all electronics engine control or all this vacuum control garbage?

 

I have replaced all the evap lines around the canister, and pulled a high vacuum on the long one to the TB. I actually bought replacement line for the long one, but mine is in good condition and, as I said, holds a good vacuum. I did replace the factory elbow right at the TB with flex + a 90°. I wiggled & bent that line under vacuum, but could not get it to lose vacuum. Same with the line running around the back and passenger side that feeds the fuel pressure regulator & HVAC.

Anyway, first things first: the P1100 has to go.

 

That MAF is most likely faulty. I would only use a Motorcraft unit, its the only brand I've had luck with. A bad MAF can cause lean codes.

 

Since I installed it six days ago, I've gotten stalling in my driveway (after driving 50 miles, mostly at 75-80), which this van has never done, ever. Mileage has dropped about 1 MPG. Idle is slightly rougher.

I cleared codes this morning, and by the time I got to work (50 miles) the P1100 had returned. Cleared it again before driving home, and in the driveway it was set again. No CEL at any time, but that's no surprise.

So, I cleared it again, and swapped my old MAF back in. More data tomorrow.

I'd have bought the Motorcraft unit, but it's three times the price of competing parts! Until & unless I'm dead certain it's needing to be replaced, I'm not going to spend that kind of money. At the time, I didn't have FORscan working; now I have more diagnostic options. There's only so much you can do with a DMM; I doubt even my high-end Fluke DMM would catch a short-duration glitch like the one shown above. I do own a very good digital storage oscilloscope, but I hadn't gotten to the point of dragging it out to the garage.

You'd think an outfit like Delphi would have the know-how to do a MAF right. Oh, well: if the old MAF picks up the mileage again, and the stalling goes, I'll 'scope it and if no anomalies, I'll battle with Amazon trying to return the Delphi.

I thought the screenshot of FORscan in o'scope mode on the Delphi MAF was interesting enough to post.

 

can you run your scan tool while driving to monitor continually for that short duration glitch on the MAF sensor.

must be kicking out lots of them to set a code. perhaps cheap faulty sensor element, they are delicate.

 

I think its his sensor, Delphi is getting ****ty with QC as are others with cheap Chinese products. I would go get one out of a junk yard "factory" before I bought any cheap knock off. I seen coils leak AC voltage and kill a car engine, all kinds of voltage leakage will jump across wires and short out sensors.

 

Sure, I could, but why?

If I see it once, that's enough for me: the MAF output should (AFICT) never go below 0.20v, and I've see it go down to 0.16 twice today at idle in the driveway.

For the money they get for these things, I expect more engineering and R&D than I got in this Dephi. Reading around, many people complain about the MAF they bought at their LAPS. Nobody seems to complain about a bad Motorcraft MAF, though (well, I found ONE person who got a bad one).

 

I swapped the old MAF back in last night, drove it to work (no P1100), drove it home (no P1100). That's 100 miles with no MAF code, where the Delphi set P1100 twice in that interval yesterday.

The hot idle voltage range on the MAF is 0.64-0.68v, which is a lot less than the graph above. No stalling anymore. 'Scope looks clean.

I'd say that Delphi is a bad'un.

 

Glad you got it sorted. I use only genuine Motorcraft replacements for parts like that.

 

Al,
thanks for the heads up on the Delphi MAFs, might can't last much longer all the times I've pulled and soaked it.

 

With the help of FORScan's ability to show LTFT & STFT, I was quickly able to find a vacuum leak: the EGR valve. Not the usual leak via the diaphragm and EGR control system, which I'd already checked with the Mity-Vac. No, this was different. I was able to use a long wand (heat-shrink tubing to a couple of tubes) to pinpoint it to the valve itself.



The STFT went down dramatically when I sprayed around the top of the valve, and even more when when under the top. Not when I sprayed the stainless vacuum tube leading to the intake. I thought maybe the vacuum-side gasket (although I'd replaced it back in March), perhaps the flange was warped.

However, when I pulled it off, the gasket looks good and the flange is pretty flat.



I kissed the vacuum-side hole of the EGR and am able to draw air through it just sucking on it. I think I may have found my P0171.



The closest Echlin version is in Virginia, and I'm not really interested in a Delphi version, which is what NAPA thinks is an OE part, and which is available new about 15 miles away.

I think I'll go pull one from the JY tomorrow, as the weather is supposed to be decent and well above freezing for a change.

The EGR leaking vacuum to the intake port wasn't really on my radar, but I'm glad to have found something definitive toward solving the P0171. Maybe it's not my only vacuum leak, but if not, it's a start.

 

the price of gas and time now, I've found FedEx overnight often cheaper.


got DPFE EGR feedback code and rough running issues with mine, but not doing the DPFE V. tests until it gets warmer or the wife cleans out the garage, looks like June.
will go with MC replacement and cough over the price but like u, do it right and only have to do it once. lots of water vapor corrosion issues with these.

may order the MC EGR valve Motorcraft CX1560 and replace while I'm in there at the same time 16 years and 200k
DPFE is easy to find in MC but the MC EGRV is rare.