97 Pathy SE wont start when warm?

[JeffsR50]

hey thanks very much you guys - Man these forums can be a lifesaver!

 

update-

OK a few real good days of driving the misfire is 99% better. She did give a cel and the po302 p0325 codes early Saturday but no flashing and no noticeable shimmy.

yesterday it was fairly hot and I did a lot of running- she started on all cylinders every time and no sign of a cel. sweet!

 

The only other thread Ive found with this same model and same codes was a vacuum leak/vapor lock thing - I think the EGR tube fixed it but its just taken her several days to relearn. I'll update again after some more road time but yep big difference.

 

thanks again friends

[fixinto]

Effin sweet!! Happy to hear you are pretty much there!!!! Been a long road, congratz. Hopefully its not a premature gratz "again"

 

 

Pat

[FriedEGs]

Soo.... been reading through this thread for the last hour. (Stopped to hit the restroom and grab some snacks) The information has been very insightful and hopefully leading me to the right track with my own issue.

 

Question to JeffsR50: Is the picture below the same as the cut valve that you replaced? I haven't been under the vehicle yet, but what simple tests did you perform in order to determine that the valve was stuck open?

 

 

 

Edited January 6, 2016 by FriedEGs

[JeffsR50]

Hey FreidEGs, yup that's it...as I remember, the cut valve is supposed to stop intake vacuum from reaching the fuel tank, when I applied pressure to mine it made a sick sort of whistle instead of preventing flow. There are a few tests to do, blow through one side and it should flow, blow through the other and it should have some resistance, then its also supposed to prevent any flow when suction is applied from the intake side. I found the specific test procedure in the service manual that has been posted in these forums. good luck!

 

Since figuring out the different little vacuum leaks (cut valve to the tank, then leak at bottom little hose of the egr control valve) She's performed perfect!!

-Im sure replacing the entire ignition system didn't hurt, but in the end my issue was the vacuum leaks IMHO.

Edited January 21, 2016 by JeffsR50

[FriedEGs]

Jeff, thanks so much for the response. You mentioned the whistling sound which is what I've been hearing for the last 6 months which is the dead give-away to my problem. I ordered the part and replaced it.

 

Take a look at the old part in the top of the pic. Wonder how the heck that blew up the way it did?

 

[JeffsR50]

Holy smokes!! yep Id say you found a bad part looks like you are on the right track

[cdq109]

Howdy Guys,

 

Well I am glad someone has blazed this path for me...a Pathfinder.

 

Seriously though I am having the EXACT same issue.

 

Mine started after I was getting an intermittent failure from a bad distributor, after about 180,000 miles, I believe the code was for the crank position sensor. At low RPM signal was good, but at higher RPM, under high load, it would just cut power. A great local garage diagnosed all that, said I needed new distributor.

 

I ended up getting one on my own and installed it. First one was bad (Amazon, SMH), as it would not fire at all (and checked it being 180 degrees off, it was not). Popped the old bad one back in, and VROOM (but still had the issue at high RPM where the signal from the crank sensor would cut out, and power would cut out because of it). Second one I finally got to start.

Two things.

 

1.) PCM Diagnostic Mode when timing is set. (PCM control of timing must be disabled when setting timing baseline adjustment).

2.) MAF sensor programming.

 

1.) According to my Hayne's manual the timing is supposed to be set with the PCM control disabled.

 

• I did not do this. I was just happy to get the dumb thing firing at all, after the first distributor was crap from the factory.
• I wonder if perhaps the original poster had someone work on his, and did a tune up without putting the PCM in this mode, and adjusted the timing.
• I am guessing if the timing is already being dynamically tweaked by the computer when you are adjusting it, there are just too many damned variables, so you really aren't setting the basline timing, but "fighting" a computer that is trying to set timing advance based upon the bazillion of sensor feedbacks, and when you do get it lined up, it might not be so much the baseline being set right, but the computer setting it right, under THOSE conditions. Soon as those conditions are no longer there (i.e. HOT engine after prolonged running) the computer adjustment for the ignition advance is off, and thus the hard/no start.
• I am going to try this next (setting timing with PCM in disabled or "maintenance mode". By the pictures and trying to find the blame thing, it is not an easy task.
• I've seen several "shortcut" suggestions to doing this, but I hope to "do it by the book" and report back and see if I have any luck.

 

2.) MAF programming. Haynes manual has a separate procedure for this. For me I don't see how it could have been corrupted, but then again if computer gets reset everytime you have a dead battery for long...just tossing it out there.

 

 

 

Oh, a third thing. My Haynes manual also mentions making sure the ground connections for the PCM are clean and corrosion free.

 

I know my old beater has bad negative/ground connection issues, as my stereo always has a terrible "whine" feedback that changes if you hit the door lock button...gonna try cleaning out my electrical connections.

Way back when I was diagnosing the bad distributor from the factory I had an oscilloscope hooked up to check for the PCM fuel pump triggering signal, the distributor's power transistor to operate the coil, the signal from the fuel injection computer portions of the ECM has to be detected at the distributor wire at 6-8 Hz.

Anyway if you have a noisy electircal connection, I would imagine that 6-8 Hertz signal is apt to get garbled too, and confuse the circuits that are trying to detect it.

I did get some venting when loosening the gas cap just today, but I think it was from positive pressure built up not a vacuum. All great ideas.

[cdq109]

Also this guy did an excellent work up, not so much of the issue of not starting when engine is warmed, but in general, and may be useful too:

 

http://easyautodiagnostics.com/nissan/3.0L-3.3L-3.5L/how-to-test-the-ignition-system-1

[cdq109]

Ok, so I pulled off all the panels inside the cab to access the PCM in order to put it "diagnostic mode" in order to set the ignition timing, in accordance with the instructions in the Haynes manual.

Nothing changed.

 

I am going to try changing out my fuel filter and if that does not work, my fuel pump.

 

I tried the fuel pump relay, replaced it, same exact problem.

 

ALWAYS starts RIGHT up when the coolant temperature is cool. After I've driven it for a bit, you have a 50/50 chance if it not starting, and once it fails to start, it REFUSES to start.

I cleaned out all the ground connections. No improvement.

 

 

[cdq109]

Well it was the cheap crappy distributor.

Lesson learned. OEM or NAPA parts only for critical components.

 

Since using NAPA Distributor I have not had a problem with the hot engine no start.

 

Since then I've failed the "Enhanced" California SMOG like 10 times. (bastards keep making emissions standards MORE stringent, AFTER the vehicle was manufactured, and as the vehicle gets OLD. Total, and Absolute BS!!!!.

This thing usually passes the normal Smog tests fine. Put it on the dyno and they lug it in 3rd gear at 25 mph and ~1900 rpm.

This last time my hydrocarbons were out by only 1 part in a million over the max, and that was the only thing that failed. I was at 51 ppm and the limit is 50 Grrrr....

Things replaced so far:

• Distributor
• Driver Side Exhaust Manifold (several substantial cracks)
• Driver Side Catalytic Converter (CA approved, SMH)
• Right Side Downstream Oxygen Sensor
• Right Side Upstream Oxygen Sensor
• Left side Upstream Oxygen Sensor
• Knock Sensor
• New Plugs (gapped, good Bosch or NGK Platinums)
• New Plug wires (good NGK OEM equiv's)