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Discussion Starter · #1 ·
A few days ago, my car would crank and start and a few seconds later it would die. The codes I'm getting are P0174, P1407, and P0171. I discovered that with the MAF sensor disconnected, my car would run. Sometimes it'll randomly die on the road, but it'll go places, rather than not going places. (Though the gas mileage is so bad the gas gauge falls fast enough to notice.) If I reconnect the MAF sensor, my car returns to the described not-going-places mode.

I cleaned the MAF sensor. That didn't fix it.

I looked around to see if any of the hoses had holes or were disconnected or whatnot and didn't see anything, except one of the tubes (the shorter one) coming out of the DPFE wasn't connected to anything and there was a lonely looking hard plastic tube nearby (jammed against the underside of the big air tube past the MAF), so I connected those together. I don't know if I knocked it loose when working on the housing or if it has been like that or what but that didn't fix the problem either.

The lid on the air filter housing was coming off because of missing screws or nuts or broken plastic where those parts go. The filter had fallen in as well. I bodged a fix and now three of the corners are screwed down, but the forth is missing a screw so the filter rubber can be seen through a 1/4 inch gap on that side. I figure the rubber on the filter is doing a good enough sealing job as it is, even though the lid isn't all the way down, but I'm going to work up a bolt/washer solution tomorrow when the hardware store is open anyway. As far as I know, that's the only part of the air intake system that isn't closed up properly.

Those are the details of what I found, in case any of it has bearing, but my big question is:

Is my Mass Air Flow sensor definitely bad if my car runs with it disconnected but not when it is connected?

I was going to just buy a new MAF sensor, but I figured I should ask someone before I spent money on a part that wasn't the fix.

The code reader I'm using is the Innova 3130lat. I rented it from AutoZone.
 

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Welcome to the FFO!

P0174 is a lean condition bank II and P0171 lean condition bank I which is not surprising based on what you have described above. Un metered air into the engine is a problem. Whether is it a traditional vacuum leak or air getting into the system because air intake issues. You state you have air intake issues. Fix those first and make a permanent fix.
P1407 is EGR not functioning. Either hose is off or the valve is stuck

With the issues above (and there may be more) the system is attempting to compensate to make the air fuel ratio work. However unmetered air is getting into the system and the compensation for that condition comes too late. It is the O2 sensor that is telling the system is too lean then it goes rich to make the difference.

The MAF sensor may be bad but it sounds like so much air is getting past the sensor that the signal is useless.
In addition the MAF may be rather dirty with the air filter situation. Getting the air filter housing fixed correctly then cleaning or replacing the the MAF may be your best bet. Since cleaning did not do much, replacement may be the next step. But that has to take place AFTER the lean conditions are handled.
Then you would need to get the EGR system functioning. EGR flow richens the mixture. Without a working EGR, you have another lean condition at speeds greater than 30 to 40.
With the age and use the O2 sensors may be rather slow at sending a signal. Slow signal to the computer and the computer is making fast air fuel ratio adjustments based on old data.

How many miles on the car?

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Discussion Starter · #3 ·
The EGR is the last thing Firestone fixed a couple of years ago. The engine light came back on soon after but the EGR guy was on vacation so I had to take it to a different location and they said the EGR was fine and started to try to get me to pay for lots of random repairs that "might" be the problem. When the EGR guy came back at the original location he said it was just a loose tube and the light went off. It's weird that the EGR would be broken again so soon.

If I don't fix the lean issues first, will having a new MAF still not let the car run with it connected?

The miles are 222270.
 

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With that kind of miles, changing all of the O2 sensors is going to be part of the fix.
The O2 signal takes a chemical signal and changes it to electronics. A newer one will do this very fast after it is heated up. Older ones take much longer to send signals but will past a self test. Bad ones will not send a signal and not pass a test and trip the light. Since the computer has the ability to adjust fuel mixture as fast as part of a crankcase rotation, the computer relies on all of the O2 sensors for data as to how rich or lean the exhaust coming out of the engine. Old sensors just can not report as fast as the computer needs to make the kind of adjustments necessary for good air fuel mixtures.

Couple that with unmetered air in the front of the air stream and a non-functioning EGR system and you have a hot mess going on.

The issue with the MAF is it is sending signals to the computer that just don't make sense. The MAF is saying X air is coming in and in reality X plus air is coming in. So the computer is adjusting for X and in reality X plus is real.

The MAF may be a problem, but until you fix the unmetered air entry it won't matter what you do with the MAF sensor.

Do confirm the EGR valve moves. I think you can just put a hose on the end and apply vacuum. If you do this at idle the engine should stall or stumble. This is because EGR is NOT supposed to be on at idle. EGR only comes on a hot engine at speed. If the engine does NOT stumble at idle with vacuum applied at the EGR either the EGR is not functioning or the engine is already running poor because the EGR is stuck open.

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Discussion Starter · #5 · (Edited)
Do confirm the EGR valve moves. I think you can just put a hose on the end and apply vacuum....
I supposed that I didn't have the equipment to do the tests you were suggesting so I took it down to Pepboys for their $99.99 diagnostic. They said that the MAF was definitely broken and that I needed to spend $438 to have the MAF replaced before they could continue the diagnostic because the car wouldn't run without it. I opted to order a new one from Autozone and replace it myself. Even with the new sensor, the problem persists, but there's a new code.

When I got the codes to begin with, all of the ovals at the top of the display were green and I had only the codes previously mentioned. I read that I should reset the ECU after replacing the MAF sensor, so I disconnected the battery. Now, four of the ovals are flashing red and the only code it says is P0102. (I didn't know if driving it around with the MAF sensor disconnected would fulfill the requirements for the ovals to go back to green so I didn't bother wasting the gas.)

The description of that code mentions things I assume the technician would have checked (leaks and tubes and circuits and whatnot) to be sure it was the sensor that was broken before telling me that was the case. Knowing how to check those things is what I was paying them to do in the first place. So, I don't know what to do next.

...incidentally, the replacement harnesses I'm being suggested for my vehicle have six leads instead of only four. The computer at Autozone included.
 

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The green dots on the tester may be specific to the tester. I assume they mean the difference between a hard fault versus a fault in memory.

You sure you connected the MAF completely?
P0102 FORD Possible Causes
What does this mean?
  • Faulty mass air flow sensor
  • Intake air leaks
  • Dirty mass air flow sensor
  • Dirty mass air filter
  • Mass air flow sensor harness is open or shorted
  • Mass air flow sensor circuit poor electrical connection

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Discussion Starter · #7 · (Edited)
The green dots on the tester may be specific to the tester. I assume they mean the difference between a hard fault versus a fault in memory.
The manual for the scanner calls the ovals "I/M monitors": "When DTCs are erased from the vehicle's computer memory, the I/M Readiness Monitor Status program resets the status of all Monitors to a not run "flashing" condition. To set all of the Monitors to a DONE status, an OBD2 Drive Cycle must be performed."

The manual doesn't mention color, only solid and flashing. It just happens that solid is green, and flashing is red.

My solid/green monitors are MIS, FUE, CCM.
My flashing/red monitors are CAT, O2S, HTR, EGR.
In case those are helpful (and decipherable) to this conversation.


You sure you connected the MAF completely?
As far as I can tell. I went ahead and followed the instructions that came with it, even though it's pretty straight forward. The connector is seated all the way in as well.

The only thing I can think of that's left of your "possible causes" is poor electrical connection or shorted harness, but that's all stuff I figured the technician would have tested before saying the sensor itself was bad. I did in fact mention to them up front that I wanted to know if the sensor was bad. I guess I'll have to ask them if they actually did.
 

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Discussion Starter · #8 ·
Update:

The latest thing I did (since I had the scanner attached and I hadn't done it yet and what did I have to lose) was to erase the codes. Now there are no codes and the check engine light is off. The I/M monitor ovals are the same as after I had disconnected the battery. The car doesn't run any better. I just don't have any stored codes anymore.

I've noticed that it actually runs worse since I disconnected the battery. I now have to drive it (without the MAF sensor connected) a few miles to warm it up for it to go back to running like it did before battery disconnection. But, that whole time, it'll die after about 10 seconds (regardless of rpm or gear) and I'll have to stop the car and restart the engine. Eventually I can drive miles at a time without it dying all the time. But it will still die randomly, like before.

The pepboys folks gave me guff when I went back in for the post MAF sensor replacement portion of the diagnostic and I pointed out that replacing the MAF sensor didn't do what they said it would do (let the car run so they could continue diagnosing). The corporate office made them give me a refund. When I was talking to the manager about the circumstances surrounding the refund, it was confirmed that they were just getting me to pay for repairs that may or may not have been needed. She didn't say it that way. She said they were "eliminating problems". Well, the first repair they wanted me to pay for didn't fix any problems. What they did was wash their hands of me because I didn't want a series of over priced repairs just so I could get a complete diagnosis. Of course they said that because I replaced the sensor (at their insistence) myself that they weren't responsible for the cost of it. I will never know what all the technician actually checked before determining that replacing the MAF sensor was required. Since replacing it did absolutely nothing, I suspect that's also what the technician had done.

In any case, I'm taking my refund to a place I'm told is super reputable, on Monday. On the phone the guy mentioned IMRC rods. I looked at my engine to find such things, but I couldn't find any. It could be my inexperience or it could be that my version of the 1995 Ford Windstar 3.8L engine didn't have any. The Haynes manual suggests that system only for "1996 and later 3.8L, 3.8L and 4.2L engines". None of the youtube videos cover 1995's and for some reason everything changed with the 1996's. In videos I've seen (for not my car), the rods are in plain sight.

I'll update again when I find out what the new garage thinks.
 

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Discussion Starter · #11 ·
The new place said the new MAF sensor I put in was broken. (And that Autozone parts are bad and are always broken when you get them.) He also said there was no way to further diagnose without replacing it, except that he suspected that the idle air control valve might be broken, too. At least he didn't charge me to get my car back. Autozone had to order the MAF sensor so I ended up putting it in again myself. It still did not fix the problem. I also removed the IAC and cleaned it. That didn't improve anything either.

I ran my car with the IAC removed entirely to see what would happen. It did seem to have an easier time idling and would stay running without my foot on the gas. I thought maybe that meant that a new IAC valve would do the trick, but it eventually died like has been. So, now I'm not sure that the second new MAF sensor isn't also broken from the factory (because why would it still be dying if there's no IAC valve getting in the way of the idle air). I'm weighing wether I should bother buying a new IAC valve to see if that and the new new MAF sensor together will fix the problem or if I should just to sell the car to someone else and let it be their problem to figure out.
 

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Discussion Starter · #12 ·
I talked to the top dog at Autozone. He was confused why anyone would claim they couldn't diagnose a car if the MAF sensor was broken. He brought up a page about IAC valves on his computer (because I brought it up) and the thing it said would happen if it was broken matched what I described above about running the car with that valve removed (surging high then falling low RPM's). I'm going to try to make some time to go to the pick-a-part and see if they have any IAC valves. I've never been to such a place, but the cost will be 10x cheaper than buying new just to inevitably learn that it wasn't the right thing to replace again, so I'm going to give it a try. But, they only have 1998 and 2000 Windstars.

Can I use an IAC valve from a 1998 or 2000 Windstar on a 1995?
 

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I talked to the top dog at Autozone. He was confused why anyone would claim they couldn't diagnose a car if the MAF sensor was broken. He brought up a page about IAC valves on his computer (because I brought it up) and the thing it said would happen if it was broken matched what I described above about running the car with that valve removed (surging high then falling low RPM's). I'm going to try to make some time to go to the pick-a-part and see if they have any IAC valves. I've never been to such a place, but the cost will be 10x cheaper than buying new just to inevitably learn that it wasn't the right thing to replace again, so I'm going to give it a try. But, they only have 1998 and 2000 Windstars.

Can I use an IAC valve from a 1998 or 2000 Windstar on a 1995?
They are Different
 

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More likely they are different

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Discussion Starter · #16 · (Edited)
I ended up going to pick-a-part and I got an IAC off of a Lincoln Continental. Turns out they're compatible. I don't know what year it was (had to be 1992-1994, in any case), but the engine was exactly the same as mine. Rock Auto, it turns out, will give you a list of compatible vehicles and I just happened to find one on the lot. Of course it was right at the far end of the row! :rolleyes:

I'm not sure if it did anything, or if it was because I monkeyed around with the tubes on the DPFE again today or if it was because I really tightened the hose clamp on the air intake connected to the MAF sensor extra hard, but I was able to connect the MAF sensor and drive around my neighborhood at 20mph maximum. That's about as fast as it would go. I had to pump the gas a few times to keep it from dying, but I was able to keep it going for much longer than before (several minutes without having to restart before I figured I was done testing and went home). I didn't let off the gas completely because I was expecting it to die. When I got home, however, it had warmed way up, and I was able to get it to idle on its own. That is, until I turned on the air conditioner. It died when the compressor kicked in. I got up to 30 with the MAF sensor disconnected but I didn't want to go much faster on those streets. It didn't fight me. I could zip around and it accelerated real good. With the MAF sensor connected, the acceleration was ultra sluggish and sometimes it seemed to accelerate better when I gave it less gas. Putting the pedal to the metal did not make it go faster than 20.
 

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Discussion Starter · #19 ·
Thanks for the advices, but it looks like this thread is going to be yet another thread that ends with "I sold it instead". :rolleyes:

But, I did learn about the Lincoln Continental thing. Pretty neat. When I saw that engine I thought "hey that's my engine!". It's interesting that such a big fancy car has the same engine as a minivan.
 

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The Continental was down sized previously to a Fox platform. (Think Mustang) The 8th gen, 88-94, shared the Taurus/Sable platform had had several firsts. Front wheel drive, 21st time ever. And a six cylinder engine which was a first since 1948.
Really at that point the Continental Model lost it's way in the market place and was discontinued in 2003.

Revived in 2017 and discontinued again for 2020.

The company has missed the mark in full sized or near full sized luxury four door vehicles. To gain that market they have to come back on the cheap and buy the market until their reputation has been built back up. The market won't buy a car if it gets discontinued.

There is your auto market report for the day

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