Hello and thank you for using JustAnswer.com
Do you have a Service Engine Soon light on?
It comes and goes.
Do you know what code you have when the light is on?
Knock sensor, random multiple cylinder misfire
What brand spark plugs do you have in the engine? Do you know?
I just replaced them with the autolites from autozone. The same fault exists before and after replacing them.
First thing I would recommend is using Factory NGKs
Every time I ever see misfire codes it's due to other brand spark plugs
These engines don't like other brand spark plugs
So the first thing I would start with is putting NGK spark plugs in this engine
Then run it and see how it is.
Now the distributor you replaced, you got that from your local auto parts store also?
Do you have access to a scanner, not a code reader?
Yes I did. I understand it's not recommended, however the exact same condition existed before and after replacing it, so logic says that it was never the cause. The bearing in the original distributor was shot (had rusty metal shavings all around it).
I dont have direct access to a scanner.
Well this is not going to be one magic answer. It's going to take a few tests
The first thing I would start with is the plugs, make sure they are NGKs
Then, I don't like after market electrical parts, but I am wondering if what your seeing is the fuel trim lean out, then the computer correct it and then it lean out again.
I would like to have the fuel trim checked and monitored
That will help tell me what is going on.
When the car idles in park, it is fine because the RPMs are higher. When i put the car in drive, and the car is warm, the rpms drop and it begins to shake rather bad. Occasionally (maybe once every minute or two) it will correct itself and the idle will go back up and it will be fine, then 30 seconds later return to shaking
If the fuel trim can't be controlled, it's possible the problem is the MAF sensor is not able to meter air properly
Most of the time MAF sensors they don't completely fail, they fall out of spec. So they meter air, but don't meter air properly
I considered the MAF sensor today, but after researching the symptoms it just didnt match up. Is there an inexpensive way to test it?
So you can get lean or rich conditions due to the MAF sensor not metering air properly
With a scanner, and you have to watch it for a about a second after you unplug it when the truck is running to see if it drops to default before it stalls
Also, if you do have a Bad Maf
Don't and I mean Don't
Replace it with after market
They never work!
Would i be better off with a junk-yard one?
They cause 02 sensors to flat line and cause more running conditions which will have you replace more parts that you don't need to
You have to watch Junk Yard ones
you don't know how they have been handled
If you drop a MAF sensor once
It can cause it to fail
I don't like using Junk Yard electrical parts,
I would use a distributor before a MAF sensor
I will replace the spark plugs and troubleshoot the MAF. The other causes I saw during my research was a leak in the intake manifold. Does this sound possible?
Intake manifold normally if they leak, it's in the back and it's a little coolant that it leaks.
It's never really a vacuum leak if that is what your saying
Ok, well you are the first person to suggest the MAF, which is promising. Ive been thinking since day one that it was a sensor or something, because of the way the computer obviously tries to correct the condition.
The valve cover gaskets were replaced recently (a few months before this started)
And the engine has been run low on oil in the past. I feared compression problems but the way the problem comes and goes had me wondering
Wait a min
I want you to check something
You mentioned you had valve covers done
There is one thing I have seen I would like you to check for me
I have seen where 02 sensors on the passenger side can get plugged in backwards
I want you to go to the 02 sensors on the passenger side.
and If you can do this for me it would help me to help you.
what I need you to do is this
bank 1 is the passenger side, and bank 2 is the drivers side
I want you to look at the wire colors for Bank 1 sensor 1 02 sensor, and Ban 2 sensor 1 02 sensor and give me the wire colors on the harness side of the connector
So I can check to make sure they are plugged in correctly
Then I want you to do the same thing for the rear 02 sensors.
Cause if backwards that can also confuse the computer
Are the 1 o2 sensors the ones I see plugged into the exaust manifolds?
Yes, there is one in the manifold and after the manifold
there is two 02 sensors on each side
This can also cause the possible misfire if what I am thinking maybe your problem.
But you should still put the NGK plugs in the truck
I will go look right now... standby
Take your time
I am online till 10 or 11 pm tonght EST
Gotcha, thanks for your help so far. I hope you're onto something
Lets see if my gutt instinct is right on this.
You sir, are a genius.
you found something?
When I looked at the connectors, I noticed there was a white paint marker drawn across the male and female connectors, but the marks didnt line up. I switched the two connectors, and they matched up perfectly.
The car idles smooth now :)
As soon as you said you did valve covers, that thought came into my head
That is why knowing all the information is important
That was the kind of thing only a nissan guy would know, anyone else would have just started listed off stuff to replace
I know nothing about Nissans...
Thanks a million for your help Jay
you're a pro
Your welcome and thank you for using JustAnswer.com
I still have the CEL engine light on, but im sure its because of the knock sensor which I read isnt a real concern. Im looking for the sell the car soon anyway
Thanks again. Take care! :)
To clear the SES light
Just disconnect the Negative battery terminal for 10 mins
The Misfire can cause the knock sensor code
So since we have it all straight now, lets clear all the codes
and I am sure you will be fine from this point on..
But still get rid of those autolites
If I have any more issues can I send my question to you directly?
Yes you can
Let me give you a link so you can book mark it
I am normally online in the evenings around 6 pm till 10 or 11 pm EST
So that is when you can find me if you ever have any more questions you need help with.
Thanks again :)
You got it
Have a good evening
and thank you for using JustAnswer.com
You too. Feed your gut well for its instincts
You like that line.. hehe