A buddy dropped a 97 Pathfinder in my lap that has been sitting around for a while and I keep getting a P0300 code. The car doesn't have much power and in neutral with the pedal floored it will rev to 3.5k and bounce from there to 4k.

So far I have changed the fuel filter, put fresh gas in the tank with marvel mystery oil and ran the car for hours, checked fuel pressure (by removing the filter and tapping into the line there) which reads 42 PSI with the ignition on and 38 PSI with the car running, swapped the distributor, swapped the spark plugs, swapped the plug wires, and cleaned the MAF and connector with contact cleaner.

Please help my try and clear this code, I'm at a loss so far.

Is it throwing any other codes? My understanding is that a p0300 is a random misfire code and usually you’ll have another to show what cylinder is misfiring. My first guess would be coil pack or maf sensor.

Only code being thrown is the p0300, unless I'm mistaken the coil pack is in the distributor and I've already replaced that. I have not replaced the the MAF sensor but I have cleaned it. Is there a way to test or troubleshoot the MAF sensor?

More likely (in order from most to least common): Bad O2 sensor, bad injector, bad catalytic converter, dirty EGR valve / passages, bad cam position sensor, problem with the ECU.

Check whatever transmits your crank signal. Not familiar with your engine, but there should be a crankshaft sensor somewhere near the.
Typically, I start with the free stuff. Clean off the sensor, check the signal plate, then replace the sensor.

AZhitman wrote: ↑

Wed Jan 09, 2019 11:33 pm

More likely (in order from most to least common): Bad O2 sensor, bad injector, bad catalytic converter, dirty EGR valve / passages, bad cam position sensor, problem with the ECU.

Wouldn't I get a different or specific code if an O2 sensor is bad?

I'll be checking the cam position sensor at some point today.

I don't think they got that specific in 97.

I ohmed out the O2 sensors, they all had resistance. when I get some time off of work soon I'll pull the intake manifold and check all of the injectors. In the mean time I loosened up the exhaust just before the cat to make a bit of an air gap and test if the cats are clogged. That didn't make the issue go away either.

EdBwoy wrote: ↑

Thu Jan 10, 2019 1:52 am

Check whatever transmits your crank signal...

Not saying this is certainly your issue, but it should be simpler and more accessible than what you've done and are about to do. No?

EdBwoy wrote: ↑

Sat Jan 12, 2019 7:50 pm

EdBwoy wrote: ↑

Thu Jan 10, 2019 1:52 am

Check whatever transmits your crank signal...

Not saying this is certainly your issue, but it should be simpler and more accessible than what you've done and are about to do. No?

I'm not sure what transmits the crank signal other than the crank position sensor. I have a new one coming on Thursday and will pull the old one/swap it out then. The distributor is new and that should control the main spark/coil and have its own sensor in place of a cam position sensor from what I gather.

maf

It's not the MAF or the crank position sensor, just swapped those out. I just got brand new distributor because I realized the one I previously used was refurbished and had bad reviews of how it may or may not work. Swapping that out now.

I swapped out to the new distributor and set the timing to 15 BTDC and the code cleared. But then I got code P0120 for the throttle position sensor. I found this video https://www.youtube.com/watch?v=_EFvu76 ... erformance and went through the process to adjust the TPS to 0.50 V and reset the timing to 15 BTDC and now I have the P0300 code back. Any ideas as to what I'm missing?

There is a second part to checking fuel pressure. Disconnect the vacuum hose to the fuel pressure regulator. Check for gas in the hose - any gas means the regulator is bad. Fuel pressure with the hose disconnected chould be 43 psi or more. Thats in the FSM at EC-342.

You might be starving for gas at high rpm. Seems like you have covered the ignition pretty well.

Did you swap the maf out with an oem one? There’s known issues with aftermarket ones

Rockwood wrote: ↑

Sat Jan 26, 2019 4:58 pm

There is a second part to checking fuel pressure. Disconnect the vacuum hose to the fuel pressure regulator. Check for gas in the hose - any gas means the regulator is bad. Fuel pressure with the hose disconnected chould be 43 psi or more. Thats in the FSM at EC-342.

You might be starving for gas at high rpm. Seems like you have covered the ignition pretty well.

I feel like I'm blind, I cant seem to find where the fuel regulator is.

And the MAF was new from Kragen.

I understand that it was new.....but if it wasn’t an oem Nissan part and was from another aftermarket manufacturer it almost always causes problems

heavy hitter wrote: ↑

Sat Jan 26, 2019 10:42 pm

I understand that it was new.....but if it wasn’t an oem Nissan part and was from another aftermarket manufacturer it almost always causes problems

I hear you, I can get with a local dealer to order the MAF. They’re expensive and I don’t want to hang onto the part or eat the cost if I don’t have to. And I don’t think I can return a “special ordered” part through the dealership, but I could be wrong.

Over the weekend I’ll hook my Blue Driver up to the car and see if I can get a reading off of the MAF while the car is running.

Don’t buy a pathfinder maf from the dealer. Get a 2001 Nissan Maxima maf instead. It’s exactly the same and tons of people swap them and you’ll only pay about 80-90 for it at most dealershipsor Nissan-parts instead of the 400 or so for the pathfinder one

I’m wondering if I’m not setting the base timing correctly. As far as I know to set the timing all I have to do is let the motor warm up to operating temp, then unplug both cables to the throttle position sensor, set it to 15 BTD, plug the wires back in and away you go. Am I missing something? Because I just found some procedure that says I need to rev the engine to 2k for a few minutes, crack the throttle, shut the motor down, unplug the tps, start it back up, hop one one foot and do the funky chicken.

Go to page EC-30 for the "official" procedure to set timing. You are supposed to rev the engine a few times and disconnect the TPS with the engine turned off. Weird procedure for sure. But since you are trying to track down your issue, I guess you get to do the funky chicken.

Rockwood wrote: ↑

Sun Feb 03, 2019 3:25 pm

Go to page EC-30 for the "official" procedure to set timing. You are supposed to rev the engine a few times and disconnect the TPS with the engine turned off. Weird procedure for sure. But since you are trying to track down your issue, I guess you get to do the funky chicken.

Page EC-30 for what book? And can I find that procedure online?

heavy hitter wrote: ↑

Sun Feb 03, 2019 3:21 pm

https://m.youtube.com/watch?v=MILRd7cV9MQ

Awesome, I'll start looking into this tomorrow if its not snowing too badly.

Ec-30 of the factory service manual
https://nicoclub.com/archives/nissan-pa ... nuals.html
Scroll down to 1997 an click. Click on section ec. Scroll to page 30 for the timing light procedure