First ill start by saying I've changed the fuel filter, distributor cap and rotor and plug wires. My 1996 pathfinder starts up and idles fine when I take off it goes fine as long as I'm 1/4 throttle or less. As soon as I press it pass that it loses power and barely accelerates. Some times it snaps out of it and accelerates fine and gets power but it won't last long and will lose power again. When it loses power and i let off to 1/4 throttle it will start accelerating fine. Any help would be greatly appreciated!!! I want to add also there is no engine light.
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Last edited by skidoo; Jan 24th, 2013 at 08:06 PM.
The best thing you can do with the MAF is to check the harness connector pins for any oxidation and to clean it. To clean it, you need to remove it. Use only ELECTRICAL CONTACT CLEANER or a cleaner specifically made for MAF hot wire cleaning. This is the only thing you should use to clean your MAF. No windex, no carb cleaner, no brake cleaner, no rubbing alcohol, and no Q-Tips.
To check the fuel pressure, tee-in a tempoarary fuel pressure gauge at the output side of the fuel filter. The readings at idle should be approximately 34 psi.
I hooked up a scan tool and set it to monitor everything while running and when I rev the engine way up o2 sensors go to zero. Why would that happen? Is it normal? While idling they range from 0.050 to 0.500.
I unlugged the maf while it was running so I had a code for that and an o2 code (bank1 sensor1) but I figured the maf being unplugged could have caused that one. But still no engine light ever came on. I know the light works bwcuse when I turn the key on it lights up but turns off as soon as it starts.
Make sure everything is replugged; clear all the DTC codes with the scan tool. Now let the engine run for a while at various RPMs. If the same O2 code comes back, then the sensor is probably bad. Post the actual DTC here.
Been having a somewhat similar problem with an old D21 pickup. Have you tried checking the ignition coils with a multimeter to see if they're still good? Also, making sure distributor leads are secure.
Bad coils can cause rough idle, and can foul spark plugs (among other things). It's a shot in the dark, but might be worth a quick check.
I tend to agree with the bad coil as well. It will short from the back side of the coil to the metal distributor casing. It's got weak spark would be my guess. The engine will run fine at part throttle, not requiring much spark to ignite the gases inside the combustion chamber. But under load, it will bog and lose power as the coil tries to find the quickest way to ground i.e. short out. Had to replace mine, but found the 3.3 Liter Nissan coil on eBay for $36 with free shipping.
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