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Does this engine use a MAF sensor? If so removing the air cleaner is not helping. If it doesn’t use a MAF then disregard that.
Low fuel pressure can also cause a P0171 so be sure you have accurate fuel pressure readings. A fuel pressure drop of even a couple PSI can adversely effect an engine in some cases.
Does this engine use a MAF sensor? If so removing the air cleaner is not helping. If it doesn’t use a MAF then disregard that.
Low fuel pressure can also cause a P0171 so be sure you have accurate fuel pressure readings. A fuel pressure drop of even a couple PSI can adversely effect an engine in some cases.
It uses both a MAF and a MAP sensor. I have done a fuel pressure test. I know that at idle setting this code is a decent indicator of a vacuum leak as vacuum is high at idle, but I’ve set freeze frame data slightly off idle and at higher RPMs.
It uses both a MAF and a MAP sensor. I have done a fuel pressure test. I know that at idle setting this code is a decent indicator of a vacuum leak as vacuum is high at idle, but I’ve set freeze frame data slightly off idle and at higher RPMs.
BTW Eric, I did watch that video shortly after you posted it. Unfortunately, the only thing I can check for leaks is the visible side of the intake. I can’t check to see if I’m sucking air out of the lifter valley. I was looking for a more definitive way to see if I’m truly experiencing a gasket leak at the manifold, or if I have another culprit. Part of me wants to say I have something going on Bank 1 that is affecting Bank 2 since it’s an open plenum. I would think that there would be a way to tell if it’s a leak, or another issue.
It’s times like these that I really wish I had access to a graphing scanner like Scanner Danner! I really get into that kind of info. However, I have to deal with more down and dirty methods since I don’t have anything fancy like that.
Would there be any reason to run the engine with the MAF disconnected, or with the MAP disconnected to see how the idle quality is, or would I have to disconnect the IAC as well, or ??? Having both MAF and MAP sensors let the computer know how much air is coming in, and how much atmospheric pressure is in the intake itself. The problem lies within the simple fact that I don’t know how the engine should run in the event I pulled one sensor offline when the engine is running the proper way.
I have no BASELINE to compare against.
BTW Eric, I did watch that video shortly after you posted it. Unfortunately, the only thing I can check for leaks is the visible side of the intake. I can’t check to see if I’m sucking air out of the lifter valley. I was looking for a more definitive way to see if I’m truly experiencing a gasket leak at the manifold, or if I have another culprit. Part of me wants to say I have something going on Bank 1 that is affecting Bank 2 since it’s an open plenum. I would think that there would be a way to tell if it’s a leak, or another issue.
It’s times like these that I really wish I had access to a graphing scanner like Scanner Danner! I really get into that kind of info. However, I have to deal with more down and dirty methods since I don’t have anything fancy like that.
Would there be any reason to run the engine with the MAF disconnected, or with the MAP disconnected to see how the idle quality is, or would I have to disconnect the IAC as well, or ??? Having both MAF and MAP sensors let the computer know how much air is coming in, and how much atmospheric pressure is in the intake itself. The problem lies within the simple fact that I don’t know how the engine should run in the event I pulled one sensor offline when the engine is running the proper way.
I have no BASELINE to compare against.
At this point, I’m not ruling anything out. Right now I’m leaning towards just pulling the intake off and replacing the gaskets just to rule it out. I never got anywhere spraying around the topside of it with propane or carb cleaner. I’m going to wait until spring and I’ll try using a spray bottle with water and see if I can’t find anything that way.
Interestingly, when we had a relatively moist/foggy day on my drive into work, the CEL turned off for 2 days. It came back on and has stayed on since I had it go back out after putting my vacuum lines for my heater controls in the right place with the right sized lines.
However, the CEL has gone out on me randomly only to reappear. My LTFT numbers are usually 15-19% and my STFT is all over the board depending on the situation. Part of me questions whether I’m having fuel pump issues that are so minor that it’s not causing noticeable driveability problems, but just enough to cause the engine to run lean. The van starts up ( even when it was -15F this morning ) beautifully, it idles well and seemingly has good power. However, in the summer when I have the windows down, you can SMELL the exhaust. It didn’t smell before.
The van has no catalytic converters, no rear O2 sensors or EGR…O2sensors and EGR were deleted from the computer. I don’t have the EGR removed with a block off plate, I just have the EGR in place to keep the hole plugged. The Air cleaner is a non oiled cone style filter.
At this point, I’m not ruling anything out. Right now I’m leaning towards just pulling the intake off and replacing the gaskets just to rule it out. I never got anywhere spraying around the topside of it with propane or carb cleaner. I’m going to wait until spring and I’ll try using a spray bottle with water and see if I can’t find anything that way.
Interestingly, when we had a relatively moist/foggy day on my drive into work, the CEL turned off for 2 days. It came back on and has stayed on since I had it go back out after putting my vacuum lines for my heater controls in the right place with the right sized lines.
However, the CEL has gone out on me randomly only to reappear. My LTFT numbers are usually 15-19% and my STFT is all over the board depending on the situation. Part of me questions whether I’m having fuel pump issues that are so minor that it’s not causing noticeable driveability problems, but just enough to cause the engine to run lean. The van starts up ( even when it was -15F this morning ) beautifully, it idles well and seemingly has good power. However, in the summer when I have the windows down, you can SMELL the exhaust. It didn’t smell before.
The van has no catalytic converters, no rear O2 sensors or EGR…O2sensors and EGR were deleted from the computer. I don’t have the EGR removed with a block off plate, I just have the EGR in place to keep the hole plugged. The Air cleaner is a non oiled cone style filter.
This could be more simple that you think. The MAF sensor measures the incoming air and the computer calculates a fuel mixture based on that. If you have any air leaks in the tube that goes from the MAF sensor to the engine the computer will not be able to calculate the proper fuel mixture. Also, don’t run the engine without the MAF sensor connected.
This could be more simple that you think. The MAF sensor measures the incoming air and the computer calculates a fuel mixture based on that. If you have any air leaks in the tube that goes from the MAF sensor to the engine the computer will not be able to calculate the proper fuel mixture. Also, don’t run the engine without the MAF sensor connected.
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.
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