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I’ve inspected the hose, and I also ran the hoses in the opposite of what they were installed to double check ( one is a solid rubber hose, the other is a flexible hose ) I wish it were that simple.
The check engine light went off again today, due to it being 40 and misting. However, when I checked my fuel trim numbers at idle, LTFT was a 20 and short term was hovering around 7. The fuel trim numbers in the freeze frame data were lower than what I was seeing at idle ( the code was set at idle ). I’m starting to wonder exactly what needs to set this code actually…doesn’t seem like it’s necessarily based strictly on the fuel trim numbers. My MAF was reading .73, which was lower than the MAF reading….The CEL went off under similar conditions ( moist air ), so I do agree that this seems to have something to do with the MAF. I think I may have to swing by the JY and pick up another MAF and see if I experience any difference. I’m sure the fuel trim numbers are mostly due to the computer learning to adapt for the bad MAF readings. I wish I had either a graphing DVOM or a scope to check the MAF.
Okay, Check engine light came back on this morning…it was cold enough to have frozen all that mist into black ice…that was fun.
After work, I decided to look at the freeze frame data and compare it against the live data…granted the engine was in open loop while I was running it at idle looking at these numbers.
Freeze Frame data PO171
Calculated load 4.3
MAF 1.28
MAP 9.4
RPM 811Running open loop ( cold )
Calculated load 3.9
MAF 1.11
MAP 8.0
RPM 936LTFT for each bank was between 18 and 19%
STFT for each bank was between -0.8 and 3When I’ve tested my wifes Explorer ( also a V8 ) her MAF readings with the same scanner are usually around 8.0
It makes me wonder if my MAF is dirty, damaged or ??? When the relative humidity is high enough that moisture could likely get through the cone filter and potentially be running through the heated elements of the MAF, the check engine light goes off. I believe I may have checked the MAF reading when the CEL went off and I’d like to say that my MAF reading was around 8 at idle.
I guess there’s potential that something got messed up with the MAF when I was working on the E Fan install and then trying to fit a stock airbox in with the hardware I had available.
Seems to me that either I need to put a scope on the signal wire of the MAF like Scanner Danner does in his videos and see what it’s up to, or find a donor MAF and see if I get different results.
Okay, Check engine light came back on this morning…it was cold enough to have frozen all that mist into black ice…that was fun.
After work, I decided to look at the freeze frame data and compare it against the live data…granted the engine was in open loop while I was running it at idle looking at these numbers.
Freeze Frame data PO171
Calculated load 4.3
MAF 1.28
MAP 9.4
RPM 811Running open loop ( cold )
Calculated load 3.9
MAF 1.11
MAP 8.0
RPM 936LTFT for each bank was between 18 and 19%
STFT for each bank was between -0.8 and 3When I’ve tested my wifes Explorer ( also a V8 ) her MAF readings with the same scanner are usually around 8.0
It makes me wonder if my MAF is dirty, damaged or ??? When the relative humidity is high enough that moisture could likely get through the cone filter and potentially be running through the heated elements of the MAF, the check engine light goes off. I believe I may have checked the MAF reading when the CEL went off and I’d like to say that my MAF reading was around 8 at idle.
I guess there’s potential that something got messed up with the MAF when I was working on the E Fan install and then trying to fit a stock airbox in with the hardware I had available.
Seems to me that either I need to put a scope on the signal wire of the MAF like Scanner Danner does in his videos and see what it’s up to, or find a donor MAF and see if I get different results.
Well, I cleaned the MAF again and within a few miles the CEL went off. At cold start the MAF was showing 1.13, but after it warmed up to operating temp ( outside temp was 22F ) I was watching the MAF hover around 8 and the MAP would hop between 9.7 and 10 on my scan tool. The light went off again after it was misty out, but it stayed off all day. I’ll just have to keep monitoring the van to see how long the CEL stays off and what my MAF readings are. Interestingly, my STFT readings were showing negative numbers, yet the LTFT didn’t seem to register much of a change. Once it gets warmer, I’m certainly going to get the water bottle out and really give the motor a good shake down for vacuum leaks.
I also picked up a used MAF from the local pick and pull. This one has the screen on it that straightens the airflow. I’m going to keep it handy, and if the CEL comes back on, I’m going to swap out the new used MAF and see if anything improves.
By all accounts, the MAF looked clean when I cleaned it again, so unless there was some sort of thin film on it ( I used the CRC MAF cleaner, so it shouldn’t have ) I don’t know if cleaning it did anything to the MAF.
The last Freeze Frame data showed it kicking the CEL at 950 rpm.
Well, I cleaned the MAF again and within a few miles the CEL went off. At cold start the MAF was showing 1.13, but after it warmed up to operating temp ( outside temp was 22F ) I was watching the MAF hover around 8 and the MAP would hop between 9.7 and 10 on my scan tool. The light went off again after it was misty out, but it stayed off all day. I’ll just have to keep monitoring the van to see how long the CEL stays off and what my MAF readings are. Interestingly, my STFT readings were showing negative numbers, yet the LTFT didn’t seem to register much of a change. Once it gets warmer, I’m certainly going to get the water bottle out and really give the motor a good shake down for vacuum leaks.
I also picked up a used MAF from the local pick and pull. This one has the screen on it that straightens the airflow. I’m going to keep it handy, and if the CEL comes back on, I’m going to swap out the new used MAF and see if anything improves.
By all accounts, the MAF looked clean when I cleaned it again, so unless there was some sort of thin film on it ( I used the CRC MAF cleaner, so it shouldn’t have ) I don’t know if cleaning it did anything to the MAF.
The last Freeze Frame data showed it kicking the CEL at 950 rpm.
Hold on. Your MAF doesn’t have the screen for straightening the air? If that’s the case this could have been the problem all along. That’s actually a very important component in the MAF sensor and needs to be there for it to read correctly. Remember that the MAF measurers the incoming air. If it’s not able to do that properly the fuel mixture will not be correct.
Hold on. Your MAF doesn’t have the screen for straightening the air? If that’s the case this could have been the problem all along. That’s actually a very important component in the MAF sensor and needs to be there for it to read correctly. Remember that the MAF measurers the incoming air. If it’s not able to do that properly the fuel mixture will not be correct.
[quote=”EricTheCarGuy” post=49525]Hold on. Your MAF doesn’t have the screen for straightening the air? If that’s the case this could have been the problem all along. That’s actually a very important component in the MAF sensor and needs to be there for it to read correctly. Remember that the MAF measurers the incoming air. If it’s not able to do that properly the fuel mixture will not be correct.[/quote]
Well, it never had the honeycomb. I’ve seen them with and without. However, the CEL hasn’t come back on for the lean bank codes in a time period on which I would have expected it to come back on in. I DO have a different MAF with the screen that I plan to put on the van to see if there is any change in my fuel trim numbers. I’m still seeing 18% LTFT numbers, though I seem to catch the van making adjustments on the short trim to negative numbers on occasion. I suppose it depends on what cell it’s running out of the fuel tables. I may just reset my computer and do a relearn on it to see if there is any change once I put the screened MAF in it. I’m waiting until I put fuel in the tank as I will have run through 1 1/2 tanks of gas since doing the MAF clean to see if there is any difference in the mileage I’m experiencing. Then I will change the MAF, reset the computer and run my scanner and watch to see what happens with the fuel trim numbers. If they go back up to double digits, then I’ve definitely got something else going on in the way of some kind of vacuum leak or ….
[quote=”EricTheCarGuy” post=49525]Hold on. Your MAF doesn’t have the screen for straightening the air? If that’s the case this could have been the problem all along. That’s actually a very important component in the MAF sensor and needs to be there for it to read correctly. Remember that the MAF measurers the incoming air. If it’s not able to do that properly the fuel mixture will not be correct.[/quote]
Well, it never had the honeycomb. I’ve seen them with and without. However, the CEL hasn’t come back on for the lean bank codes in a time period on which I would have expected it to come back on in. I DO have a different MAF with the screen that I plan to put on the van to see if there is any change in my fuel trim numbers. I’m still seeing 18% LTFT numbers, though I seem to catch the van making adjustments on the short trim to negative numbers on occasion. I suppose it depends on what cell it’s running out of the fuel tables. I may just reset my computer and do a relearn on it to see if there is any change once I put the screened MAF in it. I’m waiting until I put fuel in the tank as I will have run through 1 1/2 tanks of gas since doing the MAF clean to see if there is any difference in the mileage I’m experiencing. Then I will change the MAF, reset the computer and run my scanner and watch to see what happens with the fuel trim numbers. If they go back up to double digits, then I’ve definitely got something else going on in the way of some kind of vacuum leak or ….
Well, I put in the other MAF yesterday. It ran like crap on the drive home. WOT it stuttered, there would be one spot where it actually felt like I had more power, but my fuel trim numbers were in the 30’s and 40’s.
So, I thought perhaps due to the cold I hadn’t gotten a good enough seal because the rubber was hard and I did the install outside before I went home for the day. So, I took it inside and let everything warm up. I sprayed it with MAF cleaner and took my DVOM and decided to check it against the other MAF that was in the van and running well. All of the values were almost identical. I checked resistances across each of the thermistors ( all 3 ). Two ohmed out low, the other higher. I’d assume this is to use for comparisons/verification of airflow or something to that matter. Beyond that, I don’t have a reliable way to watch the MAF function.
I didn’t reset the computer, reset the codes, or do anything other than swap out MAF sensors. Am I missing something here? I’m thinking I got a bad MAF from the recycler.
Well, I put in the other MAF yesterday. It ran like crap on the drive home. WOT it stuttered, there would be one spot where it actually felt like I had more power, but my fuel trim numbers were in the 30’s and 40’s.
So, I thought perhaps due to the cold I hadn’t gotten a good enough seal because the rubber was hard and I did the install outside before I went home for the day. So, I took it inside and let everything warm up. I sprayed it with MAF cleaner and took my DVOM and decided to check it against the other MAF that was in the van and running well. All of the values were almost identical. I checked resistances across each of the thermistors ( all 3 ). Two ohmed out low, the other higher. I’d assume this is to use for comparisons/verification of airflow or something to that matter. Beyond that, I don’t have a reliable way to watch the MAF function.
I didn’t reset the computer, reset the codes, or do anything other than swap out MAF sensors. Am I missing something here? I’m thinking I got a bad MAF from the recycler.
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