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Jay
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 18727
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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Salutation, having one car problem to another. I have a 1997

Customer Question

Salutation, having one car problem to another. I have a 1997 Nissan Pathfinder 3.3 with a P0300 multiple misfire code. It chugs and buckles under low load from 1000 to 2000rpm, thats when the engine light flashes and therefore throwing a p0300 code. I
already replaced the distributor, spark plugs, and egr valve. Still having the same symptons. Please help.
Submitted: 1 year ago.
Category: Nissan
Expert:  Jay replied 1 year ago.

Hi, My name is*****'m happy to help you. During our conversation, I may be presenting you with different things to try, and ask you some Questions to get a better understand of the issue so I can answer your question properly. So stick with me to the end, and I am sure we should be able to get this issue resolved for you!

When I see a P0300 or a P1320 code with a running issue, that is a Distributor issue. If you replaced the Distributor with one from your local auto parts store, they never work right. You would need to get a distributor from the dealer. Also, if you changed the spark plugs, make sure you used NGK spark plugs. These engines don't like any other brand spark plugs, especially Bosch!

If you have any more questions on this, please feel free to ask.

If not, and you're satisfied with my help, please Rate me. I hope I have provided you with Excellent Service.

Thanks Jay!

Customer: replied 1 year ago.
Hi Jay, distributor is from original oem from the dealer, and sparks plug are indeed NGK.
Expert:  Jay replied 1 year ago.

Wow, and you still are getting those codes.. Did you change the spark plug wires also?

Expert:  Jay replied 1 year ago.

Did you change a Knock sensor or something also?

Customer: replied 1 year ago.
It runs good. Just buckle and misses on low rpm. Spark plug wires are original oem. Knock sensor been replaced also from previous owner.
Expert:  Jay replied 1 year ago.

Did you just get this truck? How long has it been running like this?

Customer: replied 1 year ago.
Checked compression and is all good on all cyonder 170 all across.
Customer: replied 1 year ago.
Been running like this for a year, since the last owner. I even checked timing belt alignment, all looks good.
Expert:  Jay replied 1 year ago.

Ahh.. ok.. So it's been that long.. Do me a favor. Go on the passenger side of the trucks engine. There are two 02 sensor connectors. I have seen when doing a knock sensor these can get crossed. When they get crossed, it runs like crap!

You can either simply try swapping those two plugs, or go tell me the wire colors to Bank 1 Sensor 1 02 sensor wire colors are so I can see if they are plugged in right for you.

Customer: replied 1 year ago.
Bank 1 sensor 1 is blue/white, purple/green, black, and black/white.
Expert:  Jay replied 1 year ago.

1 sec

Customer: replied 1 year ago.
Are they air fuel ratio sensors or just oxygen sensors?
Customer: replied 1 year ago.
Could it be the fuel pressure regulator or dirty injectors?
Expert:  Jay replied 1 year ago.

02 sensors. A/F sensors came out in 06 or 07 Pathfinders.

That is Bank 1 Sensor 2 02 Sensor. Follow that down and make sure it's on the passenger side

Customer: replied 1 year ago.
It is on the passenger side and after the catalytic converter
Expert:  Jay replied 1 year ago.

That is correct. So the rears are good.

The only other thing that I have seen is a clogged up Catt restricting exhaust flow. That won't allow the engine to breath right and can cause Misfire codes as well.

Has that been checked?

Customer: replied 1 year ago.
How can I check if the catalytic converter is partially clogged?
Expert:  Jay replied 1 year ago.

The only real way is to drop the exhaust to inspect it.

Customer: replied 1 year ago.
What do I look for in the catalytic converter?
Expert:  Jay replied 1 year ago.

What I do is remove the front 02 sensor, and shine a flash light into the exhaust and then look on the other end where the 2nd pre-catt bolts to the catt and see if I can see light shining though.

Customer: replied 1 year ago.
How many catalytic converter does this truck have? Are they common to clog up?
Expert:  Jay replied 1 year ago.

You have 2 primary that are monitored that bolt right off the exhaust manifold. Then you have two pre-catts that are not monitored.

Expert:  Jay replied 1 year ago.

It's not to common. but when I see these trucks with high mileage it can happen

Customer: replied 1 year ago.
you don't think the fuel pressure regulator is bad?
Expert:  Jay replied 1 year ago.

That is not common. You can certainly check fuel pressure. You should have 36 psi of pressure. These trucks didn't have to may fuel pump issues.

Customer: replied 1 year ago.
This truck only has 140xxx miles....could TPS to give false reading?
Expert:  Jay replied 1 year ago.

I don't know why everyone jumps to think TPS. These TPS's never fail! I mean in my 20 plus years working for Nissan, I can't tell you how many I have working on and I think I can count on one hand how many I have seen go bad. I have replaced more after market ones that were installed cause people think it goes bad and just changes them.

Customer: replied 1 year ago.
Oic, so basically if the cats are good, any other places that can be the culprit. Am just spending to much money on this Truck and can't even smog it.
Expert:  Jay replied 1 year ago.

Well you want to start from the basic's.

First checking fuel pressure if you like. Also make sure the fuel filter is good and not clogged. That is located above the rear diff.

Then if you have access to a scanner, monitor fuel trim readings and graph 02 sensors and you maybe able to see if the catt is clogged or not based on the front 02 sensor readings.

Customer: replied 1 year ago.
If b1s2 and b2s2 readings are zero during idle and low rpm. Could that be a bad cat, even though it doesn't through any cat codes.
Expert:  Jay replied 1 year ago.

They will read zero, but should switch every so often then go back to zero

Customer: replied 1 year ago.
Fuel filter was replaced earlier today...b1s1 and b2s1 also has zero reading at times.
Expert:  Jay replied 1 year ago.

Oh.. They should never be Zero.. The only time I normally have see the front 02 sensors flat line is when a after market MAF sensor is installed. They tend to never meter air properly and can flat line 02 sensors.

Do you know if it's oem or not?

Customer: replied 1 year ago.
The MAF looks old, but it is oem..
Expert:  Jay replied 1 year ago.

If you are building to much back pressure due to clogged catts, the 02 sensors won't read any flow which can make them read steady and zero, cause they can't switch rich to lean

Customer: replied 1 year ago.
Hi Jay, I checked the catalytic converters and they are good. I even dropped them down and startEd the truck, and it still have the same symptons, this time I can hear it pop and buckles between 1k-2krpm. Check engine light flashes to as misfire.
Expert:  Jay replied 1 year ago.

That sound almost like a bad MAF sensor based on the rpms your telling it's bucking at

Customer: replied 1 year ago.
I replaced the afm earlier today. Same symptoms.
Expert:  Jay replied 1 year ago.
Did you replace it with one from the dealer, or after market?
Customer: replied 1 year ago.
Aftermarket
Expert:  Jay replied 1 year ago.
Is the distributor after market as well?
Customer: replied 1 year ago.
The distributor is oem
Expert:  Jay replied 1 year ago.

Well I certainly am not a fan of after market parts, so it's good you put a OEM distributor in. How ever, after market Maf sensors never work right. If you even get one that meters air properly it will flat line 02 sensors and cause running issues. So that may not have helped your situation.

Do you know if this had a engine put in?

Customer: replied 1 year ago.
I don't know if this engine was replaced.
Customer: replied 1 year ago.
Could it be possible of bad primary O2 sensors?
Expert:  Jay replied 1 year ago.

Hard to say with out seeing readings. I normally graph these type of issues. You can certainly unplug 02 sensors one at a time and see if the running issue changes at all. Since the truck had a knock sensor done so long ago, and it's been like this ever since, you could have a vacuum leak also. That can certainly cause a misfire also.

Customer: replied 1 year ago.
Replaced lower and upper intake gaskets. Could a idle control or egr valve be leaky
Expert:  Jay replied 1 year ago.

Can you grab the EGR diaphragm and lift it and stall the engine when it's running?

Customer: replied 1 year ago.
It does stall
Expert:  Jay replied 1 year ago.

Ok, so the Egr is most likely good. The truck idles ruff doesn't it?

Customer: replied 1 year ago.
A little shakey and studded a lil
Customer: replied 1 year ago.
I noticed when its cold, it's smooth and once it heats up, that's when it acts up and misfire code comes up
Expert:  Jay replied 1 year ago.

Think you can take a video clip on how it idles and revs up. Also span over the 02 sensor connectors on the passenger side. It sounds so much like the could be backwards, but based on the info, it does't sound like they are.

Customer: replied 1 year ago.
I noticed they aftermarket o2 sensors. Should I get original primaries o2 sensor, they are the most important ones right? Not the secondaries
Expert:  Jay replied 1 year ago.

As I said, I am not a fan of after market electrical parts cause they never work right and can have you spending money on things you don't need to spend time or money on. So I would certainly work on putting as much as you can back to OEM.

I would certainly put OEM sensors in and I would make sure the MAF sensor is OEM also.

Customer: replied 1 year ago.
The primary o2 are the important ones right?
Expert:  Jay replied 1 year ago.

They are all important.

Customer: replied 1 year ago.
Hi Jay, am still on this truck. I checked the compression. Bank one has the highest compression at 190psi each cylinder, but bank 2 has 155, 155, and 160. Can that cause the low rpm misfire?
Expert:  Jay replied 1 year ago.

The compression should be all around 5 PSI from each other, which is what you have. But bank 1 has that to high. Did you check compression with the fuel pump fuse removed?

Customer: replied 1 year ago.
I removed the distributor plug only
Expert:  Jay replied 1 year ago.
You need to disable fuel when you do a compression check. Failure to do so, the fuel will still get into the cylinder and it will wash out the cylinder walls which will lower compression.
You want to do a cylinder leak down. That is what you will need to do
Customer: replied 1 year ago.
How would I do that? Just say the compression is where they are on both banks, would that cause the misfire?
Expert:  Jay replied 1 year ago.

You can have compression, but have a bad leak down. This sounds like something that will require more hands on to determine with a scanner.

I will re-open this question back up to see if anyone else can help you with this.

Please do not reply as it would take it out of Que..

Thanks Jay!

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