Guest hjc Posted December 3, 2005 Share Posted December 3, 2005 I just bought a 91 Pathfinder v6. It ran great for a week. It still runs great but only when its cold.When it gets to temp she runs but feels like she is starving for gas.she just bucks.I changed the fuel filter,plugs,cap and rotor.Have any ideas? Link to comment Share on other sites More sharing options...
Precise1 Posted December 3, 2005 Share Posted December 3, 2005 Have you tried the ECU diagnostics that I linked you to yet ? Thats the place to start... B Link to comment Share on other sites More sharing options...
Guest hjc Posted December 3, 2005 Share Posted December 3, 2005 Thanks for info.will try it today.thanks again.Will let you know how I made out. Link to comment Share on other sites More sharing options...
Guest hjc Posted December 3, 2005 Share Posted December 3, 2005 Ok just finished the tests .mode 3 got 55 no malfunctions all other test in modes 1,2,4,5, were normal.where do I go from here.When I purchased the truck there was no exhaust from cat back. I did install muffler and tail pipe.Truck did run good after that install.Just wondering if it could be blocked cat?Ireally appricate all your info. Thanks Link to comment Share on other sites More sharing options...
Precise1 Posted December 3, 2005 Share Posted December 3, 2005 Hmm, I expected something... I suppose it could be the cat, but I would think clogged is clogged, regardless of the motor temp. Try checking the wire connection for the MAF and clean it. Here is the link for that... http://www.nissanpathfinders.net/forum/index.php?showtopic=5194 Did the running rough happen at once or did it occur gradually ? I'm assuming the 'bucking' occurs when you step on the gas. How does it idle, at what rpm ? B Link to comment Share on other sites More sharing options...
Guest hjc Posted December 3, 2005 Share Posted December 3, 2005 Im with you about the cat. It did start gradualy but with in a day or two.she idles around 1300 but the needle is dancing.Thats at temp.Think it could be the coil? I will clean the MAF and let you know. Thanks again. Link to comment Share on other sites More sharing options...
Precise1 Posted December 4, 2005 Share Posted December 4, 2005 Again, with the coil, one would think that it would act the same all the time. Did the problem start before or after you changed the parts listed in your first post ? If the answer is before, inspect all vacuum lines for cracks and holes while you are under the hood. Is your truck manual or automagic ? B Link to comment Share on other sites More sharing options...
Guest hjc Posted December 4, 2005 Share Posted December 4, 2005 It stared before.I already checked all vacume lines. Its a manual tranny.Thanks again.Really got me stumped. Link to comment Share on other sites More sharing options...
88pathoffroad Posted December 4, 2005 Share Posted December 4, 2005 Try unplugging the O2 sensor wiring harness. It will leave the ECU/FI system in closed-loop mode and may run a little richer, but otherwise will be perfectly fine. Oh, and if it warms up and doesn't run crappy with it unplugged, then you know what comes next, heh. Link to comment Share on other sites More sharing options...
packie88 Posted December 4, 2005 Share Posted December 4, 2005 my pathfinder had close to the same problem on it. running hihg rpm runs fine in the cold and is close to starving gas. and it turned out to be a feul injector was bad. so you mite want to chekc those. Link to comment Share on other sites More sharing options...
Precise1 Posted December 4, 2005 Share Posted December 4, 2005 Thanks packie88, glad someone else had a similiar/same experience; you know what I mean. That was something I was working up to, fuel pressure and regulator but never having a bad injector problem, I don't know it first hand. Theoretically the ECU will pick up a leaky injector, but that is not the only type of failure... I remember reading something about how to measure the pulses/timing of the injectors, I'll see if I can find it... hjc, FYI, the idle for a manual should be about 800rpm +/-50 or 100. Thats close enough to be acceptable... B Link to comment Share on other sites More sharing options...
Guest hjc Posted December 5, 2005 Share Posted December 5, 2005 When she runnig good she idles right at 750. can any one tell me were the plug for the o2 senser plugs in? Thanks Link to comment Share on other sites More sharing options...
Precise1 Posted December 5, 2005 Share Posted December 5, 2005 I'm fairly certain there is a connector underneath, just follow the wire up... Someone correct me if I'm wrong, but I'm pretty sure. It's 36 degrees outside and I am too lazy to go look right now. B Link to comment Share on other sites More sharing options...
94extreme Posted December 5, 2005 Share Posted December 5, 2005 yeah it terminates about halfway between the battery and the windshield.. i think htere were 2 other relays there.. just follow the wire, you'll have to to replace anyway.. btw. that's my guess for your troubles but it could be other stuff.. regardless it's a good thing to replace if nothing else for the MPGs. i think nissan calls for 60k mi replacement on those. Link to comment Share on other sites More sharing options...
Guest hjc Posted December 6, 2005 Share Posted December 6, 2005 Ok I cleaned the maf.Didnt do anything. Iunplugged the 02 senser nothing.really feels like its misfiring. Im very interested in checking fuel rail and injectures,maybe fuel pressure regulator.I just tryed cpu when it was running like crap. Still ok from that stand point,dont know sh-t about all this emmission crap,build old GTO`S for fun.Thanks again ,This is a great site Link to comment Share on other sites More sharing options...
Precise1 Posted December 6, 2005 Share Posted December 6, 2005 Ok, here is some information but it isn't very specific. Maybe Sniper15 will chime in or you can PM him to see what better information he has like the injector tester tool , and what he finally determined. http://npora.ipbhost.com//index.php?showto...injectors&st=20 Do you have a manual for the truck ? The knock sensor and crank angle sensor should be diagnosed by the ECU. While it shouldn't be the issue, it couldn't hurt to check the EGR and AIV systems, but they are mainly for smog. I'm kind of running out of ideas, but I'm still thinking about it. B Link to comment Share on other sites More sharing options...
Diesel Boy Posted December 6, 2005 Share Posted December 6, 2005 It could be the coil. Coils can start to break down when hot. Could also be the cold start circut on the engine not switching off when up to opperating temp, and the engine is actually overfueling causing it to run rough. There will be a vacum hose that can be dissconnected and blocked off to make a simple test to rule out the cold start circut out. Someone with the v6 will point out were to look for the hose!! Link to comment Share on other sites More sharing options...
87pathy Posted December 6, 2005 Share Posted December 6, 2005 My first GUESS, would be O2 sensor. its one of the few items that will cause it to run differently at different temperatures. That and the MAFS Link to comment Share on other sites More sharing options...
94extreme Posted December 6, 2005 Share Posted December 6, 2005 Ok I cleaned the maf.Didnt do anything. Iunplugged the 02 senser nothing.really feels like its misfiring. Im very interested in checking fuel rail and injectures,maybe fuel pressure regulator.I just tryed cpu when it was running like crap. Still ok from that stand point,dont know sh-t about all this emmission crap,build old GTO`S for fun.Thanks again ,This is a great site when you unplugged the o2 was engine warm or cold? if warm then the sensor is prob ok for now. the system has to be warm to work precisely but seems to run a wee bit rich when cold normally. Link to comment Share on other sites More sharing options...
Guest hjc Posted December 6, 2005 Share Posted December 6, 2005 unpugged 02 when she was a temp.I dont have manual yet local stores dont have,trying to get one on ebay.I will try fuel pressure next.Anyone Know what hose to block to check cold circuit?Thanks Link to comment Share on other sites More sharing options...
Tinker Posted December 6, 2005 Share Posted December 6, 2005 Possible intake manifold leak at head or block junction resulting in lean run at temperature? Had several old Dodge vans with same condition and seem to remember a Nissan dealer mechanic warning me about Pathy intakes. Check with water or light oil spray in the vicinity of the gasket - momentary improvement in idle after spraying indicates air leak. Link to comment Share on other sites More sharing options...
Precise1 Posted December 6, 2005 Share Posted December 6, 2005 The only thing I could find is the Idle-Up solenoid valve "An idle-up solenoid valve is attached to the intake collector to stabilize idle speed when the engine load is heavy due to electrical load, PS load, etc. An air regulator provides an air bypass when the engine is cold in order to increase idle speed during warm up (fast idle). A bimetal, heater and rotary shutter are built into the air regulator. When the bimetal temp is low, the air bypass port is open. As the engine starts and current flows through the heater, the bimetal begins to rotate the shutter to close off the air bypass port. The air passage remains closed until the motor is shut off and the bimetal temp drops" Thats all it says with no pictures. You may want to pull the rubber hose leading into the throttle chamber, and inspect it's operation and perhaps clean it, they get crapped up and stick sometimes. When it is all back together, I'd check for intale leaks at suggested, but everywhere, not just the manifold gasket. I prefer to use WD-40 for this, I've had good luck with it. B Link to comment Share on other sites More sharing options...
Guest hjc Posted December 6, 2005 Share Posted December 6, 2005 Thanks ,will try Ill let you know. Link to comment Share on other sites More sharing options...
88pathoffroad Posted December 8, 2005 Share Posted December 8, 2005 As a simple check, double-check your plug wires to make sure one of the tips didn't pull off or something when you changed the plugs...look for cracks in the insulation on each plug wire also. Link to comment Share on other sites More sharing options...
87pathy Posted December 9, 2005 Share Posted December 9, 2005 As a simple check, double-check your plug wires to make sure one of the tips didn't pull off or something when you changed the plugs...look for cracks in the insulation on each plug wire also. good call! I can't tell you how many Gosh darn, piec of crap, screwed up.. piss me off spark plug wires, i've pulled apart on my pathy trying to get the damn plug wires off. Just pulled 2 of the off last week when i changed my plugs!. Been so long i forgot how to "be carefull" Luckily i know have a crimping tool to properly fix them Link to comment Share on other sites More sharing options...
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