alantoy13 Posted October 30, 2009 Report Share Posted October 30, 2009 I am having and issue with this car. It runs rough after it warms up but when its cold its good to go. So here is what I know. it will burn 1/4 tank fuel in 15 miles, runs like a mis-fire or the cylinders are being flooded, changed MAP sensor, changed plugs and wires changed thermostat. Have a pathfinder data scanner but have no numbers to compare them to. O2 sensors rises and falls like it should i believe. Don't think it has a MAF sensor. I can see how long the injectors are on but can't find info on how long they should be on for. Exhaust is rich when this happens. It bogs down for most of the time but will have little spells when it will run good for a second or two. I believe it to be a sensor problem but having hard time locating which one. Any help would be great! Quote Link to comment Share on other sites More sharing options...
ns87 Posted October 30, 2009 Report Share Posted October 30, 2009 Unfortunately this is a really common symptom for the 3.1MPFI, with a lot of diff problems that could cause it. If I had to guess, it sounds like one or a few injectors going bad to me. If you remove the plenum (the thing that says 3.1MPFI on it), and use a Multimeter to test the injector resistance of each injector, I have a feeling one or two of them won't be in spec. They should be around 12.6ohms. Be careful of the vacuum hose that connects the PCV valve into the top of the plenum, it's hard to see Quote Link to comment Share on other sites More sharing options...
Andrew Posted October 31, 2009 Report Share Posted October 31, 2009 i bet your EGR and tube needs a thorough cleaning. Quote Link to comment Share on other sites More sharing options...
BXX Posted October 31, 2009 Report Share Posted October 31, 2009 Change your coolant temp sensor.. Quote Link to comment Share on other sites More sharing options...
1QUICKHATCH Posted October 31, 2009 Report Share Posted October 31, 2009 Change your coolant temp sensor.. x2 but check your fuel pressure first. Quote Link to comment Share on other sites More sharing options...
Mach 5 Posted October 31, 2009 Report Share Posted October 31, 2009 check your injectors many times a couple are bad leaking or weak and will not thogh a code, check the air and coolant temp sensors. If it thinks its too cold out or the engine isn't warmed up it can dump fuel in but look at these sensors first. No check engine light Im guessing...? Quote Link to comment Share on other sites More sharing options...
alantoy13 Posted November 2, 2009 Author Report Share Posted November 2, 2009 No check engine light that ive seen. Pulled up the codes from memory and got #12, book said system normal and thats all. Could The EGR valve and pipe really allow that much fuel to be dumping into the cylinder? Fuel pressure is a notch above 40psi. A guy I work with seems to think that the cat. converter is blocked after it warms up. That would cause poor power but not a fuel eater! Quote Link to comment Share on other sites More sharing options...
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