Keith Browning Posted January 16, 2006 Share Posted January 16, 2006 There is a thread over on TDS about cleaning MAF sensors. The guy claims to have restored "lost power" and his fuel economy came up 2 MPG! I was skeptical so I did some reading on the 6.oL OBD theory and operation concerning EGR, but I am not yet convinced either way. Perhaps we can/should start playing with this concept to confirm or decline these claims and here is why: From what I was able to find and read, the interesting thing is that the MAF signal and data is not used on the 6.0L for fuel calculations at all. The MAF signal is used to calculate exhaust gas recirculation (EGR) and for fault detection. Basically, EGR flow is estimated based on the difference between the Mass Air Flow (MAF) sensor reading, and, the total mass flow calculated by the speed density calculation. The estimated EGR flow is then compared to the expected EGR flow to determine if there is insufficient or excessive flow. From what I can tell this actually serves as a feedback mechanism to verify that the EGR emissions system is operating properly. This is a function of the OBD 1&2 Systems and Comprehensive Component Monitors. Now, if this sensor is providing biased readings they would have to be way off to be considered out of range and set a code or even have an effect... right? /forums/images/%%GRAEMLIN_URL%%/shrug.gif The only trucks I have heard of having a problem with this sensor are those with aftermarket "performance" intake filters due to contamination or airflow characteristics. This idea in my opinion is actually worth a closer look because any anomaly that COULD affect EGR operation COULD theoretically affect performance and fuel economy. Doesen't cleaning this sensor cause damage to it? Would it really matter? If I am way off, then could somebody please come to my home and smack me /forums/images/%%GRAEMLIN_URL%%/hammer2.gif around a little for thinking way to hard about this! Quote Link to comment Share on other sites More sharing options...
Cetane Posted January 16, 2006 Share Posted January 16, 2006 Your explanation was right on. If the MAF was contaminated the sensor would likely require more voltage to keep the hot wire at the reference temperature. If the computer thinks there is too much airmass it will open the EGR further trying to decrease it. Depending on a how off the EGR is this could make a substantial difference in actual EGR flow and engine efficiency. That being said I am a little skeptical on 2 mpg. Anything is possible I guess. Quote Link to comment Share on other sites More sharing options...
Torqued_Up Posted January 16, 2006 Share Posted January 16, 2006 So it's not too far fetched to see an overoiled K&N foul up a MAF? Hmmmm, food for thought. Okay. What about excessive turbo flutter? Couldn't that send crankcase vent vapours back out and through the MAF fouling it too? I have heard of cleaning the sensor but you have to use something that won't leave a residue. I know that much! /forums/images/%%GRAEMLIN_URL%%/laugh.gif Quote Link to comment Share on other sites More sharing options...
Cetane Posted January 17, 2006 Share Posted January 17, 2006 An over oiled K&N could definitely bias the MAF. I never run them in my vehicles for this very reason(gas or diesel). As for the turbo flutter I guess its possible but that is not something I have ever experimented with. I would think with the volume of air that these engines process, it probably would dilute the mixture enough not to contaminate it. Electronics cleaner supposedly does a good job but we throw them away whenever they start showing signs of contamination. Quote Link to comment Share on other sites More sharing options...
HGM Posted January 17, 2006 Share Posted January 17, 2006 Your explanation was right on. If the MAF was contaminated the sensor would likely require more voltage to keep the hot wire at the reference temperature. If the computer thinks there is too much airmass it will open the EGR further trying to decrease it. Depending on a how off the EGR is this could make a substantial difference in actual EGR flow and engine efficiency. That being said I am a little skeptical on 2 mpg. Anything is possible I guess. Cetane,I have always looked at it a bit differently. Wouldnt the contaminates be an insulator causing the current demand to be less(showing less airflow)? Quote Link to comment Share on other sites More sharing options...
Cetane Posted January 18, 2006 Share Posted January 18, 2006 I apologize I should have been a little more clear. I do a different kind of testing so I dont always think of things in a real world situation. The MAF will over estimate the airflow near idle conditions and under estimate it at higher airflow conditions. You are right in most cases. The contaminates will start to act as a insulator at some point depending on the actual substance and how much of it there is. There was a good TSB or SSM at one point that described this condition but I dont remember the number. It was several years ago. Thanks for calling me out on that one..... Quote Link to comment Share on other sites More sharing options...
Cetane Posted January 18, 2006 Share Posted January 18, 2006 I kind of regret posting anything on this topic. I probably should have held off on any definitive answer. My experience is based on ford diesel but not the 6.0L. The more I think about it, the way the 6.0 handles EGR may be a lot different than the way I am used to dealing with it. Based on the way FordDoc described it I think it is similar but if what I say doesnt make sense I would appreciate the correction. I have been doing some MAF contamination studies in the recent past but the MAF sensor as the line techs are used to seeing it does some different things in the config I use. I need to go back to the 6.0L PCED before I throw anymore opinions out there on this topic. Quote Link to comment Share on other sites More sharing options...
HGM Posted January 18, 2006 Share Posted January 18, 2006 Sounds about right to me.I usually key in on the fact that it is for EGR calculations only. On the other hand, the EBP is the primary sensor for the air management system. Even if the MAF was contaminated the EBP would show the incorrect value and the PCM should make the compensations. This is why the MAF went away in '05. I do agree that it could effect in some way, but I too doubt the 2MPG claim. Another thing to add to the topic is with the EGR, you cannot relate it to a gasburner where we have a throttle plate. On the diesel, it can flow just about anytime it wants even at idle and under accel because of the unrestricted airflow. Basicly, it has air to spare. Dont mean to "call you out" just wanted to make sure I have been explaining it right. Quote Link to comment Share on other sites More sharing options...
Cetane Posted January 18, 2006 Share Posted January 18, 2006 Well, it appears based on that descripition that my experience is very different from the way 6.0L handles EGR. Sounds like everybody should take your posting on this topic as more factually based than mine. The MAF basics should be the same but I wasnt even aware the MAF had been deleted so it doesnt matter much. I should probably stay off the 6.0L part of this forum. Quote Link to comment Share on other sites More sharing options...
HGM Posted January 18, 2006 Share Posted January 18, 2006 Cetane, Please dont let that discourage you, you have alot of valuable info in this area as well. I also believe it may have come back for '06, so things change on a daily basis and my info may not be 100% either. Quote Link to comment Share on other sites More sharing options...
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