MAP sensor questionable
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
MAP sensor questionable
I have to admit I've been through this dance more than once before and I am again forced to come up with a solution as to why my truck runs absolutely horrible when the barometric pressure drops. It still doesn't run top notch during good weather either. I know... I've stated multiple times a eureka when I solve an oil leak at the oil filter base or some other issue that brings temporary relief to the bad behavior exhibited by my engine. While all these recent fixes have made it run better, it eventually loses it's composure again in time. There has been a gradual improvement from all of the fixes I've done so far (during higher barometric pressure operation) but man it falls off the cliff when before, during and shortly after a storm rolls in.
When the barometer drops it misses and clatters like the injectors are in very sad shape and the PERDEL readings bounce around on most cylinders while it passes the cylinder contribution test and injector buzz test every time. This problem is not related to rain or a water leak into the electrical system somewhere, just a lowered barometric pressure condition outside.
I checked the MAP through AE and it read 14.17 psi while the engine was cold and not running. I would pinch the MAP sensor tubing and watch the reading take a very brief and slight dip lower. I pulled the connector from the MAP sensor to clean it out and it went to a reference value of 13.56 psi if I remember correctly. Once re-connecting the MAP sensor I get a different value of 13.92 psi (28.34 inHg). Now when I try to squeeze the MAP sensor tubing there's no fluctuation in psi readout. I theorize that I have either fouled up the wiring or just strengthened a poor connection since I see a different reading now.
Of course I'm dying to re-start my engine tonight at 12:30pm to see if my problem is cleared up, but my truck is sitting tin the driveway right next to my neighbors house where their master bedroom is no more than 25 feet away.
In the meantime I wanted to see what you all thought. My research in the current local weather conditions translate to 14.9 psi based on taking the current barometric pressure of 30.06 inHg X .4911 giving 14.76 psi.
So my MAP sensor is reading off by 1 psi or 1.72 inHg. Whether this is a problem or not will likely be revealed tomorrow morning when I start the truck up.
I'll keep you all posted on what I find...
-Drake
When the barometer drops it misses and clatters like the injectors are in very sad shape and the PERDEL readings bounce around on most cylinders while it passes the cylinder contribution test and injector buzz test every time. This problem is not related to rain or a water leak into the electrical system somewhere, just a lowered barometric pressure condition outside.
I checked the MAP through AE and it read 14.17 psi while the engine was cold and not running. I would pinch the MAP sensor tubing and watch the reading take a very brief and slight dip lower. I pulled the connector from the MAP sensor to clean it out and it went to a reference value of 13.56 psi if I remember correctly. Once re-connecting the MAP sensor I get a different value of 13.92 psi (28.34 inHg). Now when I try to squeeze the MAP sensor tubing there's no fluctuation in psi readout. I theorize that I have either fouled up the wiring or just strengthened a poor connection since I see a different reading now.
Of course I'm dying to re-start my engine tonight at 12:30pm to see if my problem is cleared up, but my truck is sitting tin the driveway right next to my neighbors house where their master bedroom is no more than 25 feet away.
In the meantime I wanted to see what you all thought. My research in the current local weather conditions translate to 14.9 psi based on taking the current barometric pressure of 30.06 inHg X .4911 giving 14.76 psi.
So my MAP sensor is reading off by 1 psi or 1.72 inHg. Whether this is a problem or not will likely be revealed tomorrow morning when I start the truck up.
I'll keep you all posted on what I find...
-Drake
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
Now that I've had to start the truck this morning, it runs like crap while on AE, the MAP psi is hovering around 14.1 psi.
Shouldn't I be able to see some readout when monitoring (Manifold Absolute Pressure - Hz) on AE? I ask because it reads 0.0 with engine running. Is that right?
Drake
Shouldn't I be able to see some readout when monitoring (Manifold Absolute Pressure - Hz) on AE? I ask because it reads 0.0 with engine running. Is that right?
Drake
Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
I wonder if there's no movement because there's no connection or it is still showing a default value. Does simply plugging it back in "reconnect" it like an ICP sensor, or do you have to "reset" somehow? I don't know. Can you swap in a buddy's sensor and see if you get the same results?
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
Well, today I finally had my fill of my truck running like crap. Even though the barometric pressure is back up today the engine is still not running right. Even though it's better than when the weather turns bad.
I went out and bought a new MAP sensor from Ford for $161.00 (that's including tax. Installed it and before re-starting the engine again to see the results, I unplugged both negative battery cables for at least 2 minutes then re-connected them. Started it up and it was rough at first then began to smooth out after driving around for a while and laying my foot into the skinny pedal a few times. The engine runs a whole lot better now.
I spoke with a guy here in KC who services nothing but powerstrokes and I explained to him all the symptoms my truck had and he even drove around with me for a bit. He felt a really good candidate was my MAP sensor and he said it sounded like my truck's timing was off which would be caused by it going bad. He said that most of the time there are no codes for the MAP sensor when it's not functioning properly.
Using his scanner he looked at the difference between the MAP sensor psi and the Exhaust Back Pressure sensor psi and there was a difference of a about 0.5 psi. He said that 0.5 psi is the upper limit of deviation between these two sensor readings according to Ford. The funny thing was that through AE, I was repeatedly reading only a 0.1 - 0.3 psi difference. He said it was probably a bad MAP sensor. He told me that I should disconnect the negative battery cables for at least 2 minutes to allow the PCM to identify the the new MAP sensor, relearn the sensor readings and not simply think of the new data as incorrect readings (or something along those lines) once the engine is started back up again with new sensor in place. He said it's not necessary to do this with every sensor I replace, just ones that are important in controlling the engine timing. I don't know which others would fall into this category (maybe CPS?).
I'll keep driving it over the next few days to make extra sure the gremlins don't come back and let you know if it's continued to improve or not. The only thing that could get better is the ever so slight hint of a miss, but it's becoming almost imperceptible the more I drive around. My PERDELS are back into check now at about 0 - 0.2 for all cylinders except cylinder 8 which is about 0.4 - 1.2. EGT's are down, power is up, engine racket is nearly gone, runs more smoothly, CCV smoke coming from the tube routed under my truck has a different smell to it (I know that's weird), excessive black smoke upon hard acceleration is going away and is now more grey and much less of it.
My fingers are crossed.
Drake
I went out and bought a new MAP sensor from Ford for $161.00 (that's including tax. Installed it and before re-starting the engine again to see the results, I unplugged both negative battery cables for at least 2 minutes then re-connected them. Started it up and it was rough at first then began to smooth out after driving around for a while and laying my foot into the skinny pedal a few times. The engine runs a whole lot better now.
I spoke with a guy here in KC who services nothing but powerstrokes and I explained to him all the symptoms my truck had and he even drove around with me for a bit. He felt a really good candidate was my MAP sensor and he said it sounded like my truck's timing was off which would be caused by it going bad. He said that most of the time there are no codes for the MAP sensor when it's not functioning properly.
Using his scanner he looked at the difference between the MAP sensor psi and the Exhaust Back Pressure sensor psi and there was a difference of a about 0.5 psi. He said that 0.5 psi is the upper limit of deviation between these two sensor readings according to Ford. The funny thing was that through AE, I was repeatedly reading only a 0.1 - 0.3 psi difference. He said it was probably a bad MAP sensor. He told me that I should disconnect the negative battery cables for at least 2 minutes to allow the PCM to identify the the new MAP sensor, relearn the sensor readings and not simply think of the new data as incorrect readings (or something along those lines) once the engine is started back up again with new sensor in place. He said it's not necessary to do this with every sensor I replace, just ones that are important in controlling the engine timing. I don't know which others would fall into this category (maybe CPS?).
I'll keep driving it over the next few days to make extra sure the gremlins don't come back and let you know if it's continued to improve or not. The only thing that could get better is the ever so slight hint of a miss, but it's becoming almost imperceptible the more I drive around. My PERDELS are back into check now at about 0 - 0.2 for all cylinders except cylinder 8 which is about 0.4 - 1.2. EGT's are down, power is up, engine racket is nearly gone, runs more smoothly, CCV smoke coming from the tube routed under my truck has a different smell to it (I know that's weird), excessive black smoke upon hard acceleration is going away and is now more grey and much less of it.
My fingers are crossed.
Drake
Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
I have changed IPR, ICP, AIT, EBP, and CPS without unplugging batts. I just installed my OCR and had to unplug my MAP without unplugging batts. Slight miss at idle could be the CPS. Let us know how it goes, but it sounds like you're on the right track!
Trending Topics
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
If you simply unplugged and plugged back in the same MAP sensor, there's no need to unplug batts. It's only when swapping out to install a new MAP sensor. I think just about every other sensor doesn't benefit from unplugging the batts upon installation of a new sensor. The tech. explaining this to me said the goal was to reset the KAM (or something along those lines) and I didn't know if I could accomplish this through AE so I unplugged the batts.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
If you simply unplugged and plugged back in the same MAP sensor, there's no need to unplug batts. It's only when swapping out to install a new MAP sensor. I think just about every other sensor doesn't benefit from unplugging the batts upon installation of a new sensor. The tech. explaining this to me said the goal was to reset the KAM (or something along those lines) and I didn't know if I could accomplish this through AE so I unplugged the batts.
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
Thanks Justin.
Slowly I'm working towards getting this truck to run well. I am making strides in the right direction recently. Replacing the MAP sensor was a big improvement. There Is still a little miss that remains and it's most evident in Park with me revving the engine at 1300 to 1700 rpms. In this rpm range the truck has this annoying shake. It's not dramatic, just annoying. It clears up at about 1800 rpms and beyond.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
I am skeptical the MAP sensor (with good readings at idle) is the sole issue. I can see a MAP reading good at KOEO, then going sideways at higher pressures... but before/after should have been the same at idle. I wonder about the "reboot"... it may have been helpful right there.
Thread Starter
|
Elder User
Joined: Feb 2010
Posts: 721
Likes: 1
I am still experiencing an engine miss. Of course it came back. It seems after each remedy I employ, the miss will temporarily leave and then come back gradually. To better describe the engine's behavior, I would say it acts like the timing is off.
I've even recently changed the PCM too. That change gave the engine a pretty big boost in the get up and go area (I have no idea why this cold be possible but it is true), but still have the miss. And yes, the miss rears it's ugly head the most when the weather turns bad (lower baro. pressure) and that's why I tried a different PCM (where the baro. sensor is). I'm not sure why the PCM swap gave me an improvement in power, but at this point I'll believe anything is possible after what I've experienced.
So today I decided that I would mess around with the CPS (black one) to see if I have any contact marks on it made by a cam gear that has walked off. Looked OK to me. I cleaned off the wire connector and CPS with contact cleaner and put it back in. Afterwards, I drove around a while and it ran better, but there was still evidence that the timing was not right (at least what I've concluded is a timing issue).
So I decided to try the battery disconnect for 2 minutes trick. Holy Cow! It went through a few miles of hunting for the right parameters while I varied my throttle pedal and all of the sudden it was running spot-on. Of course this will probably be a temporary relief seeing that I've had improvements in the past after I replaced this or changed that. But honestly, this is the BEST the engine has ran since I've installed it in my truck. It runs how I've always wanted it too right now. I'll report to you all if it holds up.
Now the question- Why did this help what I believe to be a timing problem with my engine? I believe I've read a thread somewhere here on FTE where someone took out their CPS and re-installed it and their truck ran better.
Just when you thought this was the end of the story for today.... I do have a strange thing that happens still when I mash the throttle until I get the EGT's up to the 1200 range, let off the throttle until the EGT's drop a bit and mash the throttle again. Nothing, no power AT ALL. It's ability to accelerate is completely gone. All I get is loads of grey smoke billowing out of the tailpipe. After I let it cool down for a few seconds it recovers it's power again. Anybody know what could cause this?
Drake
I've even recently changed the PCM too. That change gave the engine a pretty big boost in the get up and go area (I have no idea why this cold be possible but it is true), but still have the miss. And yes, the miss rears it's ugly head the most when the weather turns bad (lower baro. pressure) and that's why I tried a different PCM (where the baro. sensor is). I'm not sure why the PCM swap gave me an improvement in power, but at this point I'll believe anything is possible after what I've experienced.
So today I decided that I would mess around with the CPS (black one) to see if I have any contact marks on it made by a cam gear that has walked off. Looked OK to me. I cleaned off the wire connector and CPS with contact cleaner and put it back in. Afterwards, I drove around a while and it ran better, but there was still evidence that the timing was not right (at least what I've concluded is a timing issue).
So I decided to try the battery disconnect for 2 minutes trick. Holy Cow! It went through a few miles of hunting for the right parameters while I varied my throttle pedal and all of the sudden it was running spot-on. Of course this will probably be a temporary relief seeing that I've had improvements in the past after I replaced this or changed that. But honestly, this is the BEST the engine has ran since I've installed it in my truck. It runs how I've always wanted it too right now. I'll report to you all if it holds up.
Now the question- Why did this help what I believe to be a timing problem with my engine? I believe I've read a thread somewhere here on FTE where someone took out their CPS and re-installed it and their truck ran better.
Just when you thought this was the end of the story for today.... I do have a strange thing that happens still when I mash the throttle until I get the EGT's up to the 1200 range, let off the throttle until the EGT's drop a bit and mash the throttle again. Nothing, no power AT ALL. It's ability to accelerate is completely gone. All I get is loads of grey smoke billowing out of the tailpipe. After I let it cool down for a few seconds it recovers it's power again. Anybody know what could cause this?
Drake
Elder User
Joined: Jun 2012
Posts: 536
Likes: 2
From: N. Va.
Have you removed the F5 to see if the problems are still present?
Loads of grey smoke... sounds like unburnt fuel. Have you looked into the IDM? Flooring it and having ZERO power sounds like none of the sticks are firing and just dumping raw fuel into the cylinders = not Bueno.
Loads of grey smoke... sounds like unburnt fuel. Have you looked into the IDM? Flooring it and having ZERO power sounds like none of the sticks are firing and just dumping raw fuel into the cylinders = not Bueno.
Thread
Thread Starter
Forum
Replies
Last Post
Tugly
1999 - 2003 7.3L Power Stroke Diesel
0
Dec 25, 2016 09:58 AM
itlkick
1997 - 2006 Expedition & Navigator
8
Feb 16, 2004 09:36 PM
