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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Nissan
Satisfied Customers: 560
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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Have a 2000 xterra with a code of p0325. also the SES light

Customer Question

have a 2000 xterra with a code of p0325. also the SES light flashes. it had code 328 too, but has since stopped showing that one. I replaced and relocated the KS, but the code comes back in seconds.
Submitted: 11 months ago.
Category: Nissan
Expert:  camerontech replied 11 months ago.

hi there,

im cam, a licenced diagnostic tech.

2 things are coming to mind on your issue.

1 . wiring from pcm to the sensor connector.

if there is corrossion or a open wire, this will store and a code immidiatley. you will need to to a continuity check from sensor connector to the pcm.

2. distributor.

i have seen bad bushings and bearings in the distributor on these and the knock will pick up the noise.

Expert:  camerontech replied 11 months ago.

Tests/Procedures:1. Use a regular Digital Volt Ohm Meter (DVOM) and check for the 5.0 volts to the knock sensor with the knock sensor unplugged and key on.

2. If the 5.0 volts is present, reconnect the knock sensor and backprobe and check the knock sensor voltage. Should read approximately 2.5 volts plugged in and backprobing

Expert:  camerontech replied 11 months ago.

also...

generally when the ses light is flashing, this is a warning that cat damage is possible.

is it running ok?

a lean running condition or misfire will set the ks code.

this could be cause from tune up condition to a mass airflow sensor causing a lean condition . fuel trims will need to be checked to determine a lean misfire

Customer: replied 11 months ago.
The engine (147,000) has what sounds like rocker chatter and could even be from the distributor. during driving if you hard accelerate it sounds like the engine is misfiring and overall seems to be low on power.
Expert:  camerontech replied 11 months ago.

ok.

have a good look at the distributer.

i think this is the area that we should be focusing as this will cause a misfire and your lack of power.

to check the mass airflow sensor, you will need a scanner to monitor airflow and the fuel trims. they should be "0" plus or minus 2.

g/s should be about 4 to 6 and wide open be plus 60 to 80

Customer: replied 11 months ago.
I checked the MAF Flow and the reading are 0.42 key on, and 5.92 engine at idle. I'm not sure what gs is, so I couldn't check that.
Expert:  camerontech replied 11 months ago.

thats grams per second

Customer: replied 11 months ago.
well we're over my head. I have no idea how to check that. I'm at a loss at this point. I replaced the distributor last year, it might have 5000 miles on it, but I could do it again and see what happens.
Expert:  camerontech replied 11 months ago.

is the distributer under warranty possibly?

Customer: replied 11 months ago.
it is. Would it be easier to call me and I give you readings from the scanner as it's running or do we think it's running lean due to the distributor?
Expert:  camerontech replied 11 months ago.

sure,

i can call no problem.

most other techs on this site charge for this. I dont, all that i ask is a postive rating wether you figure it out or not.

i am available for a call in a couple of hours as im not by a phone right now.

1 thing to check before that is fuel trim.

can you see the trims?

there should be lt for long term and st for short term

Customer: replied 11 months ago.
lt is 2.3 and st is -3.4 to -4.9 at idle
Customer: replied 11 months ago.
st is now running from -4.9 to -7.7 with engine at normal temp lt is still 2.3
Customer: replied 11 months ago.
MAF flow GR/SE 5.07 at idle
Customer: replied 11 months ago.
st firm 2 is 0.8 to 2.2 and lt firm 2 is 10.4
Expert:  camerontech replied 11 months ago.

ok,

if you hold full throttle snaps, can you capture maf rate and ft?, might have to do it a couple times to capture

Customer: replied 11 months ago.
with engine running?
Expert:  camerontech replied 11 months ago.

yes, sorry

justa couple full throttle snaps while monitoring those items

Customer: replied 11 months ago.
MAF appears to jump between 15 and 19. it's different each time. lt ftrm 1 jumps to 9.3 and st ftrm1 from 0.0 to 2.3
Expert:  camerontech replied 11 months ago.

ok.

those reading are a little low for the maf. its about a 1/3 of what it should be.

so..

its either the scanner itself is just not quick enough to catch the reading , the mass airflow sensor is faulty or the cat could be plugged .

i think we should focus on the distributer and if that noise is coming from is or not.

if you suspect it is than while its still under warranty , replace it to eliminate it as the source of the problem.

the idle fuel trims arent too bad, but full throttle trims should jumo to "99" on the short term. so it still could be a distributer problem or the mass airflow sensor

Customer: replied 11 months ago.
the scanner has a lt and st ftrm1, lt and st ftrm 2, 11, 21. is there a particular one I should be reading?
Expert:  camerontech replied 11 months ago.

those are bank 1 and bank 2.

1 and 2 should always be relativley equal on both st and long term.

"0" i a perfect fuel mixture

Customer: replied 11 months ago.
I checked the MAF sensor with a volt meter and the voltage appears to be good. .3v with key on, 1.3v at idle and 2.4v to 3.4v above idle
Customer: replied 11 months ago.
my p0300 code is back in addition to the p0325 I started with and the SES light is on solid
Customer: replied 11 months ago.
Ok, I'm going to go back inside till I come up with something else to check
Customer: replied 11 months ago.
I can't wait any more today, it's getting late. bye
Expert:  Jay replied 11 months ago.

Hello my name is ***** ***** thank you for your Question.

Cameron Brookhouse has opt'd out cause he feels he can no longer help you. So I will be taking over this question.

What brand spark plugs do you have in the truck? Also how did you relocate the knock sensor? I have seen this done and work and not work. The key thing is the shielded wire. If that is not wired properly you can continue to get knock sensor codes also. But then again, if you are getting P0300 that can cause the knock sensor code also.

Let me know..

Customer: replied 10 months ago.
I have autolight double platinum plugs in the vehicle that I put in a few months before it started running bad. I had an issue with the distributor at that time so I replaced it and did a tuned up. I replaced the distributor again today and plug wires yesterday with no difference. I have replaced the KS with a 95 maxima sensor and harness, then relocated it to the top of the intake and still get the same code. Currently I have still have code P0325 however the issue appears to be related to the flashing SES light which eventually may trigger a p0300 multiple misfire. While driving the vehicle it feels low on power, sounds like it backfires in the intake with acceleration to get up to speed and the SES light flashes.
Expert:  Jay replied 10 months ago.

Do you recall what brand plugs were in this engine before you changed the plugs?

The reason is cause these engines are very sensitive to the spark plugs used. These engines only like NGK spark plugs. When any other spark plug is used, you can get misfire codes. Of course if you have a misfire issue, it can produce a knock sensor code.

Also, the distributor you installed, did you get it after market?

Customer: replied 10 months ago.
Both distributors were aftermarket. It was still under warranty. As for the plugs, I don't remember the brand. I'll be happy to try NGK.
Expert:  Jay replied 10 months ago.

You may need to get a Dealer Distributor also. I have had After Market ones not work a number of times brand new out of the box.

Customer: replied 10 months ago.
Is there a way to know for sure?
Expert:  Jay replied 10 months ago.

You need a Oscilloscope to monitor the signal from the distributor to know for sure.

Customer: replied 10 months ago.
I must have left that in my other tool box. I'll see what the price is, but I'm guessing first born. Maybe I can get lucky at the junk yard.
Expert:  Jay replied 10 months ago.

I would perfer a used Distributor that is OEM verses after market.

So yeah, give that a try.

Let me know how you make out.

Expert:  Jay replied 10 months ago.

A Oscilloscope is expensive. It would be cheaper to have a shop that has one check the signal for you.

Customer: replied 10 months ago.
I seem to remember them from 30 years ago. I'll see what I can do and let you know.
Expert:  Jay replied 10 months ago.

You got it!

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