What is the expected vacuum at idle for a 2001 nissan sentra?
Seeing 15" of mercury atm and not sure if that is too low for this 1.8L engine. System is
running lean and won't stay started. Replaced fuel pump, oxygen sensors, fuel pressure
regulator and inspected fuel injectors and rail (all clean and working).
Have you cleaned or replaced your Mass Air Flow sensor? It can cause all sorts of engine problems, including causing it to run lean.stutter/stall/significantly lack power, etc.. If you read around the internet, you will find all sorts of problems related to exactly what you are describing and they all have to do with the MAF. If you have not done so, go to the auto parts store, and buy a can of MAF Cleaner (about $6)and clean it (just google how to clean one for this model), let it dry for a couple of hours, reinstall it, then disconnect your negative battery terminal and wait twenty minutes (to reset the computer), then reconnect your neg bat terminal and start it up and see how it runs. I have been battlling these issues with mine (same model and year as yours) and it is NOT fuel related, it has turned out to be the MAF causing everything!!! As for your fuel question, sorry, I can't help you with that one.
Also, one other question: Have you done any mods, such as a cold air intake, K&N air filter, or other performance options? From what I understand, they can reak havok on the MAF..
I have cleaned the maf and have also tried disconnecting the maf to run in SD mode but problem is similar.
Hmmmm.... well, the MAF's on this thing CAN just nose dive at times and no amount of cleaning will help. It might be worth your while to swing by a junk yard and pull one out of a junker, clean it, and install it and see what it does. I know you can get them here at the pull-it-yourself junkyards for $24. If you cleaned yours, did you disconnect the neg battery terminal like I said AFTER you cleaned it? If not, it will NOT make a difference. You have to reset the computer by unhooking the neg terminal for at least 20 minutes. This will make it go through and recalibrate everything....
I have pulled the negative terminal for about 2 hours while I charged the battery as it got low from all the attempts of figuring this out. If I pull the maf cable off the car will start and idle which is more than I can say if it is plugged in. On cold start it runs for the first few seconds and sounds perfect then bogs down and dies with the maf plugged in. Does anyone know what the expected g/s of airflow that the maf should be reporting around idle? That would really help me as I have a scanner that reports the maf in g/s.
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