MAF Sensor!?!?! 97 5.0 AWD

[Mitchs07explorer]

Had Jiffy Lube do a radiator and flush and 4x4 service last week. About a day after I had the service done I noticed coolant underneath the car after coming out of the store. I popped the hood and saw coolant pooled on top of the water pump and timing chain cover. Since the engine had just been gone through and reassembled I thought perhaps the flush had exposed week spots in the seals on the water pump and/ or timing chain cover. When I got it home and had a better chance to look at it, I let it run and watched. I saw coolant dripping from the bottom of the T-stat housing. I assumed they did a proper flush and pulled the thermostat and perhaps goofed on installing the T-stat gasket. I pulled the housing and replaced the gasket and cleaned some rust off the steel pipe that comes off the housing. I put it all back together and tightened everything and viola no leaks. I went inside and let it run for a good 20 minutes to make sure. I came back out and still no leaks but now for whatever reason it’s running rough and misfiring. I did pull off the snorkel and unplugged the MAF sensor and the other senso. I also unplugged the connections to the alternator because the wires were in the way of effectively cleaning the surface where the housing bolts to. It was then I realized I had forgotten to unhook the battery and got massive sparks when wire that bolts to the alternator made contact with the alternator itself. I quickly undid the battery hoping to god I didn’t fry anything crucial. Such a dumb mistake.

I got DTC codes P0171 and p0174 when I went to pull codes and these both have to do with MAF. I also noticed in the last couple of weeks when I’m driving I get kind of a slight jerking and hesitation, pretty subtle but also annoying. So I’m wondering if the sensor was ready to go and maybe I fried it when I didn’t unhook the battery before disconnecting the MAF. The MAF sensor wasn’t near the car when I shorted that hot wire on the alternator.

So to all of you out there, does this sound like a bad sensor!? It was driving fine before I messed with it, the connection looks fine. The sensor is probably the original and the vehicle has 167k on it. Is there anything else I should be looking at?

 

[Mitchs07explorer]

Oh yeah it’s probably worth noting that this vehicle has always seemed to put off a lot of white exhaust. I always thought it was water vapor especially because it had a bad head gasket when I picked it up although it never lost coolant but exhaust was leaking into the coolant. I had a used engine swapped in and the exhaust looks pretty much the same as before so I’m wondering if that’s also an indication there unburnt fuel in my exhaust. The exhaust does have a stronger odor that I wouldn’t describe as raw fuel but I always chalked that up to it being an older car.

 

[Mitchs07explorer]

And I don’t think I’ve ever gotten better than 10mpg outta that truck.

 

[410Fortune]

P0171 and p0174 do not point to the mas
Lean codes both banks

Usually is caused by air leaks in the intake, after the mas air flow sensor
Check your intake tubes, connections at MAS and throttle body. Check air hose to valve cover from intake hose (crank case breather)
check intake tube for cracks/holes.
Check fuel rail pressure

So P0171 and P0174 means that the computer is seeing a lean condition on both banks (cyl 1-4 and 5-8)
The computer has tried to compensate by adding fuel from the injectors and is still not able to correct the condition, the system is still lean even with full fuel dump by the injectors
This usually means air is entering the system after the MAS sensor, so it is called "un metered air" that cannot be accounted for
On the V6 engines this is almost always a large leak in the intake O rings.
On the 5.0L with metal intakes it is usually a leaky intake hose, unhooked vacuum or EVAC system hose, or large air leak from a different source
You need to check your work, around the alternator and thermostat housing are a few different hoses that can be overlooked
After you confirm everything is tight and hooked up I would consider checking fuel rail pressure (weak fuel pump can also cause this because the PCM cannot add enough fuel)

 

[Mitchs07explorer]

P0171 and p0174 do not point to the mas
Lean codes both banks

Usually is caused by air leaks in the intake, after the mas air flow sensor
Check your intake tubes, connections at MAS and throttle body. Check air hose to valve cover from intake hose (crank case breather)
check intake tube for cracks/holes.
Check fuel rail pressure

So P0171 and P0174 means that the computer is seeing a lean condition on both banks (cyl 1-4 and 5-8)
The computer has tried to compensate by adding fuel from the injectors and is still not able to correct the condition, the system is still lean even with full fuel dump by the injectors
This usually means air is entering the system after the MAS sensor, so it is called "un metered air" that cannot be accounted for
On the V6 engines this is almost always a large leak in the intake O rings.
On the 5.0L with metal intakes it is usually a leaky intake hose, unhooked vacuum or EVAC system hose, or large air leak from a different source
You need to check your work, around the alternator and thermostat housing are a few different hoses that can be overlooked
After you confirm everything is tight and hooked up I would consider checking fuel rail pressure (weak fuel pump can also cause this because the PCM cannot add enough fuel)

Thanks for giving me a good starting places, I’m hoping it’s just a hose I overlooked or something simple like that. As much as I’ve invested in this project my wife might kill me if I need to buy any more “expensive” parts. She’s already telling to dump it and get what I can for it lol. I better figure this out soon

 

[Mitchs07explorer]

P0171 and p0174 do not point to the mas
Lean codes both banks

Usually is caused by air leaks in the intake, after the mas air flow sensor
Check your intake tubes, connections at MAS and throttle body. Check air hose to valve cover from intake hose (crank case breather)
check intake tube for cracks/holes.
Check fuel rail pressure

So P0171 and P0174 means that the computer is seeing a lean condition on both banks (cyl 1-4 and 5-8)
The computer has tried to compensate by adding fuel from the injectors and is still not able to correct the condition, the system is still lean even with full fuel dump by the injectors
This usually means air is entering the system after the MAS sensor, so it is called "un metered air" that cannot be accounted for
On the V6 engines this is almost always a large leak in the intake O rings.
On the 5.0L with metal intakes it is usually a leaky intake hose, unhooked vacuum or EVAC system hose, or large air leak from a different source
You need to check your work, around the alternator and thermostat housing are a few different hoses that can be overlooked
After you confirm everything is tight and hooked up I would consider checking fuel rail pressure (weak fuel pump can also cause this because the PCM cannot add enough fuel)

I looked around the alternator and T-stat housing, I didn’t see any unplugged hoses or anything in that vicinity that looked wrong. The intake tube looks to be in good shape. The only hose I could definitely say looked questionable was what appears to be a vacuum host that sits off the front of the engine. It’s dried and cracked looking even though there’s flexibility to it, I’ll replace that for good measure but so far no obvious visible clues as to issue other than that hose. I’ll have to wait until next weekend before I can really poke around in there now.

 

[Mitchs07explorer]

I wonder if the PCV valve popped out, I hadn’t thought about checking that....

 

[Mitchs07explorer]

I hooked my smoke machine up on my lunch break just to screw around with it and see if I could find anything obvious. This is what I found, I think my mechanic for got to bolt the EGR up all the way. Didn’t have enough time to wrench on it too but I think that’s the culprit and maybe I can square it away this weekend. The smoke looked like it was coming from the bolt holes, hopefully the gasket is still good.