Auto engine diag help, o2 sensor data

[dthames 0]

My car has a rough idle and shows a code of P0300 random multi cylinder misfires. It runs well off idle, so it seems.

I have one of those scan tools and have been trying to see if I can determine the problem. The car is 2005 Altima v6. I am about ready to replace it but want to give it to my son without spending a lot of money or pushing the problem off onto him.

Have record the sensor data at several different RPMs and I see what I think might be wrong, but I have no experience with modern cars of this level if sophistication. Any experts out there that might help confirm?

http://pyrodan.privatedata.com/o2-sensors-1.pdf

Thanks in advance.
Dan

Instructor quote, “What's weird is that you're older than my dad!”

[skyjumpenfool 2]

Try this...
https://www.google.com/?gws_rd=ssl#q=2005+Altima+PO300

Birdshit & Fools Productions

"Son, only two things fall from the sky."

[normiss 855]

Coil packs, plugs, wires would be my first guess.
Does the code tell which cylinder is misfiring?
You can get OBD-II WIFI, Bluetooth, or wired readers for cheap these days.
OBD2 readers
I like the WIFI model connected while running and data logging to my cell phone to show when the misses occur.

[GD64 1]

Some good suggestions by others.

My first thought was dirty or malfunctioning injectors.
Try an injector cleaning additive.....(admitted long shot).
If your vehicle starts fine cold, but not as well warm this could be the problem. Also there is usually an added smell of gasoline outside your vehicle on starting (un burnt fuel).

Good Luck.

[dthames 0]

normiss

Coil packs, plugs, wires would be my first guess.
Does the code tell which cylinder is misfiring?
You can get OBD-II WIFI, Bluetooth, or wired readers for cheap these days.
OBD2 readers
I like the WIFI model connected while running and data logging to my cell phone to show when the misses occur.

The data in the URL attached is from the OBD2 code reading program, from my car. There is no specific cylinder(s) recorded that are missing, just a P0300 and P0011. I have replaced the bank 1 cam position sensor without effect. I am trying look for reasons of the rough idle and the sensors are suspect because it seems to not really be missing off idle. So I think I am getting good fire.

The data shows some odd O2 sensor readings. I had hopes that someone with good experience could help interrupt the data.

Instructor quote, “What's weird is that you're older than my dad!”

[normiss 855]

What do you mean to interrupt the data.

Problem with misfires is:
plugs
wires
coil packs
o2 sensor(s)
injectors
tps sensor
cp sensor

Those tend to be the most common, although there can be other issues as well.

My most recent misfire code pops were specific to the cylinder.
That's also why I like to data log while running...tends to give a better indicator of where the problem is - especially with multiple codes at the same time.


Any luck in the Nissan forums?

[LiveAction 0]

I had something like that once, and it turned out to be a worn timing chain. It was so loose that it was throwing off the spark timing in random cylinders and at random times. Expensive!

How many miles are on this vehicle?

[skydiver30960 0]

I'll throw out one other seemingly unrelated, but often culpable cause of rough idling and misfires: a bad battery.

I KNOW, I KNOW, I KNOW, it makes no sense: it seems to me that if it starts and the alternator is pushing enough juice into the system, that it shouldn't matter. BUT: I do as much of my own work as I can on my '99 Wrangler and therefore spend a LOT of time on a Jeep-specific forum. There are MILES of threads about misfires, error codes, and rough idle that come back to a battery that needed replaced. It even happened to me once, so that may be a reason for me being a bit biased, but if the voltage going to the ECM (the computer) isn't stable and within the right range, all bets are off.

SO, get the battery bench load tested to see how it's doing. If it's shot, replacing it may solve the problem.

Elvisio "was flabbergasted, and pleasantly relieved when it happened to me" Rodriguez

[justme12001 0]

It could be the catalytic converter(s) as well. When they start to get clogged or the refractory starts to break up, the computer can give some pretty weird reading.

This recently happened with my work truck. The fuel mileage dropped dramatically and it lost all power. It was giving bad O2 censer, bad cylinder, faulty injector along with other readings. Changed both converters (refractory was broken), and it's like a new truck.

[dthames 0]

normiss

What do you mean to interrupt the data.

Problem with misfires is:
plugs
wires
coil packs
o2 sensor(s)
injectors
tps sensor
cp sensor

Those tend to be the most common, although there can be other issues as well.

My most recent misfire code pops were specific to the cylinder.
That's also why I like to data log while running...tends to give a better indicator of where the problem is - especially with multiple codes at the same time.


Any luck in the Nissan forums?

What data?
The data the 4 O2 sensors that is in the PDF file that I posted on the original post. Cold, engine off bank B upstream sensor shows 0.6volts, while the other three sensors show 0.3 volts. But running hot, Bank A upstream says 0.3v (lean) while Bank A downstream shows 0.9v (rich).

Searching the Nissan Forum, no luck but I plan to post something tonight. I figured someone in the skydive world might be my best first shot. Sort of a thing for the skydive family.

Instructor quote, “What's weird is that you're older than my dad!”

[normiss 855]

I understand what you meant by data from o2 sensors, but interrupt it how?
A good O2 sensor should produce an oscillating waveform at idle that makes voltage transitions from near minimum (0.1 v) to near maximum (0.9v).

[dthames 0]

normiss

I understand what you meant by data from o2 sensors, but interrupt it how?
A good O2 sensor should produce an oscillating waveform at idle that makes voltage transitions from near minimum (0.1 v) to near maximum (0.9v).

Okay, I am with you now. With the power on and the engine off the bank 1 upstream and the bank 2 upstream voltages are not at all the same. That is confusing, making me wonder if one is bad.

Bank 1 upsteam (while in park) was always below 0.45v and bank 1 downstream was about 0.8+ volts. That also was confusing.

I was trying to avoid jumping to conclusions based on those readings. I did a road test and recorded the voltages while underway. I updated the PDF with those tests.

The numbers don't add up (in my understanding) to show anything conclusive.

Thanks
Dan

Instructor quote, “What's weird is that you're older than my dad!”

[J-S 0]

Change coil packs and plugs (gap and torque plugs to factory specs), clean throttle body and MAF sensor while you're in there (car will run smoother). You can disconnect the MAF too and run the car to see if it runs better. Runs better with MAF disconnected, need a new MAF sensor.

Disconnect battery before working with anything electronic related obviously.

I suspect coil packs and plugs, maybe a worn out wiring harness, to be your culprit.

Good luck!

[shift 0]

How many miles?

Start with the simple/cheap stuff and go from there. Plugs, wires, coils, catalytic converter (just disconnect the exhaust to test before spending a bunch of money on new ones).

A possible issue is a blown head gasket. If it is getting water into the cylinder, it would cause misfires. You can test check this by pulling some spark plugs after it has been misfiring and see if they are wet, checking if your oil is a milky white color (presence of water), or starting the engine (cold) without the radiator cap on and watching for air bubbles.

Did you power wash the engine bay recently? Drive through deep water?

[dthames 0]

96K miles, to someone at that asked.

I stopped being hung up on the fact that the O2 sensor voltages made no sense, with the 2 banks showing wildly different numbers, and just thought, "Fix the rough idle".

I replace the plugs and coils. Because the intake plenum was off, I had to have gaskets and the gasket kit also had a throttle body gasket, so I replace that as well. The throttle body was gunky and so I cleaned it. I found out later that might not be such a good idea as they are sensitive computer servos and can get "off" and only the dealer shop can recalibrate them, IF they can.

The car was showing a P0011 valve timing problem as well as missing at idle. I had replaced the cam position sensor with no change and not with it exposed, I removed and cleaned the valve timing solenoids on both banks.

All back together it started and ran smooth. A 90 minute trip showed it to be idling too fast and the cruise control was a bit rough being on and off the gas going down long hills. I put it into a "idle relearn" mode and I think it is all 100% okay now.

Thanks for the suggestions and tips that everyone offered. Wow, it is hard to change the plugs on some of these newer beasts.

Instructor quote, “What's weird is that you're older than my dad!”

[GD64 1]

dthames...Thanks, glad you have it solved.

Yes, changing the plugs can be a real "knuckle buster".

Happy motoring.