Spark Knock noise?
 

09, Touring, 7AT with 61,000 miles....I got gas today, and immediately had a CEL. Got back to the office, and it was a P0300, cleared, has not come back in the 20 miles I've driven so far... but Its making an odd sound... exactly like the one in the sound clip from this post...

http://www.the370z.com/engine-drivet...ml#post2541785

I mean exactly, but a lot more audible, just not all the time, just from a slow gradual start. Is this from crap gas? I've always put in 93, but I'm not sure what else could be causing it.

First thing that comes to mind is the flex plate for the torque convertor is cracked. Hopefully it ain't that.

or its a bad batch of gas being that your notheren could be water what with the cooler weather and all try a couple bottles of heet and burn the gas down some to see if it goes away.

P0300 is a Cylinder Misfire Detected Random Cylinders error. By itself, doesn't mean much.

How immediate is "immediately"? As soon as you started the engine? If so, then it may not be the gas as the new gas takes a while to make it from the tank to the engine.

The easy things to check are:
* Battery condition - a weak battery can cause problems, especially with modern, computer-controlled engines.
* Water/dirt in fuel - try some fuel system cleaner with methanol to clear the water. May need to change fuel filter.

Not so easy:
* Dirty TBs - after 61k miles, they probably need a good cleaning. DIYs on this site. If you decide to clean the TBs, go ahead and clean the MAFs while you are there.

I bought the car at 47,000 and took apart the intakes and cleaned the TBs and the MAFS, just to be sure there was no oil buildup on the MAFs since the previous owner had installed K&N Typhoons.

Immediately as within a few minutes, which is what led me to believe it was just the gas....

but another issue is, only around 1000 rpm, I hear a rattle, I took off the strut tower brace, all the plastics, looked around with a flashlight, cannot find what or where its coming from, it almost sounds like a pipe hitting off something metal... its not valve tap or the spark knock noise, and its not rhythmic enough that it goes exactly with the engine speed, hopefully this isn't the flex plate. Is there a plate you can remove to inspect the flexplate? or is dropping the transmission the only way? Thanks.

I added a bottle of octane booster and filled it up with 93 at a BP, there was half a tank of the Sheetz 93, so hopefully filling it up dilutes the crap gas.

I'd have just syphoned it out, but its about 15 degrees here and no where to put 10 gallons of gas.

I love sheetz but at the same time hate them, I avoid putting their gas in my Z, I know locally many of the stations use the same fill plant(there is a gulf fill station in delmont and altoona) but I do not think sheetz uses them, my friends and I have all experience less mpg and some minor issues time to time with sheetz gas, I put it in my civic but not in my Z, all the other stations around my area seem to use that gulf fill station.

I would also run a can of seafoam through it then change the plugs...

What about the fuel pump? SouthArk370Z you brought up the fuel filter, but I know they are all-in-one units where the fuel filter/pump/sending unit/level sensor is one contraption, is it worth pulling out to clean?

The filter is just a possibility. I'd have to be pretty sure it was the filter before I would go to the trouble of pulling the pump.

Here's the rattle noise coming from under the car at low RPM, between 800 - 1200 RPM.... sounds like it might be the flex plate..

http://youtu.be/M0RsMaWbCqQ

UPDATE: jacked up the car, took off the preview plate on the transmission. Flex Plate is fine, honestly looks brand new..., started/stopped the engine to rotate it the who's way around and not a single crack...

If your are ever in the greensburg area and cannot get this figured out I can have one of my techs take a look at it for you. I also have some connections to Cochran( I work with their former Service Manager) and West and East Nissan dealers if you get to that point, let me know.

Thanks JoePro, I'm taking it to my local mechanic Tuesday but if he isn't successful I'll let you know.

I did end up taking out the fuel pump, its fairly simple. I used this how-to on upgrading the fuel pump for instruction on how to disassemble the fuel pump/filter/level sensor:

CJM Tech Site: A First Look: The 370z Fuel Pump Assembly

It was pretty funky, before pics of it disassembled, there was flakes and chunks of sewt, and the actual fuel filter wassaturated with more sewt, turned the water black when I cleaned it:

Attachment 83397

Attachment 83398

After everything was cleaned, ran biodegradable degreaser and warm soapy water through the fuel pump (using a 9 volt battery and the green and black wires on the pump itself), then plain clean water, then used an air compressor and let it sit to dry everything out

Attachment 83399

Attachment 83400

Its not a difficult unit to disassemble, just have to be patient, and I'm clueless as to why Nissan says it's not serviceable, and doesn't sell the fuel filters separate?

Mechanic said the rattle is coming from the passenger side cat - and other than one time they could not replicate the spark knock. The odd thing is it will only spark knock/diesel when in gear it can idle perfect and goes through the RPM range fine when in park or neutral. If it's in gear say at a stop light... if you press the gas slowly it'll hesitate and you'll hear the dieseling noise. It will also drop RPMs to 500 randomly when stopped in gear.... thoughts? If it was an issue with the cat I'd assume it would have the issue regardless of being in gear or not?

Putting the car in gear can cause the exhaust system to move and result in a rattle.

The P0300 can also be triggered by a loud enough rattle. The knock sensor is very sensitive. If the rattle is loud enough for the knock sensor to pick it up, you'll get the code.

I put it up and yeah... it sounds like the entire inside of the passenger side cat is disconnected from the casing....

Look on the bright side- now you're within the letter of the law to swap them out for a set of HFCs. :rofl2: I'll bet you can get a set of good HFCs for what one OEM cat costs.

HAH yep stock is $375 for just one side... Kinetix are $399 for the set..

Then you know what you have to do :rofl2:

Ordered the parts, but in the mean time did a data log.... wondering if anyone wants to take a look and see if they notice anything weird? Specifically between 23:07 and 23:17... It was stop sign, 1/4 to a red light, then the spark knock happened.....I'm not really sure what all I'm looking at, just curious what all the sensors think is happening.

Excel spreadsheet, delimited by comma Attachment 83815

all you have to do to be int the "letter of the law" for cat replacement is pull the upper o2's out grab a funnel, pour in some 30 weight, take it to a shop and say they are fouled, instant blown cats lol

Nissan replaced the passenger side cat under warranty for free, I did see what it would have cost if I had to pay... $976.

Later that night... I pulled the plugs...

(***to replace them... which I did but 3 miles later I had to pull them all off, to make a long story short 3 of them broke... that's another story though.. anyway***)

.. I checked the gap on the stock plugs which all were fine, put them back on, and installed newer coil packs off a wrecked 2011 with 9000 miles. This solved my idling and spark knock issue.

But now, at low RPM, only when in gear, I get valve chatter, the spark knock was masking it, as its a similar sound but now the spark knock/dieseling gone, you can more clearly hear it I've read this could be anything from crappy oil or need to run synthetic (I've only ever run 5w30 conventional oil by Castrol, Valvoline or Quaker State, even in my 350z)

I've heard of a lot of G37's having this issue, if I can I'll make a recording of it.

Try using ester oil.

So what you're calling spark knock was the dead cat rattling around setting off the knock sensor?

After they replaced the cat, obviously the rattle was gone, then I switched coil packs, which got rid of the spark knock, but now I hear... Valve noise? I recorded this by just setting my phone on the windshield, its only at low rpm, while in gear, you can feel hesitation, but when you give it gas, it goes away, and its not constant either:

http://youtu.be/Uf9PjW9PJcc

ah yes the second law of auto repair "If thou fixith one noise, thou shalt hear another"

It just sounds.. Sooo... Awful...

I was gonna say, that rattle sounds like something in the exhaust, so could be loose heatshield.

Random misses are frequently caused by intermittent vacuum leaks -- which may also cause the car to stall or the RPM's to drop as it attempts to get within the programmed idle range.

I'd check for a vacuum leak -- anything near the primary O2 could be the cause (including where the headers meet the cats), and definitely double check everything along the intake tract.

Good luck!

EDIT: wait, so you had bad coilpacks? Hmm.

Not sure about the other noise -- doesn't sound like valve tap to me. Any other symptoms?

It hesitates when it happens, but other that that, gas mileage is good, cruising there's no noise or issues...

I'd still search for vacuum leaks -- if more air gets sucked in than is measured, it will run lean and attempt to correct with fuel trims; that could cause the running rough and hesitation issues.

Nissan says that because what you cleaned is not the fuel filter. That is the fuel pump pickup. It has a rough mesh to prevent large debris from entering the pump which could damage it or jam it.

The fuel filter is insert molded into the fuel pump module. If you notice how your fuel pump has a black hose coming out the top of it, which then turns 180 degrees back down into the fuel pump module. That is the filter, and it cannot be replaced or serviced as you cannot open the molded housing.

Generally, you dont have to worry about that filter for a VERY long time.

The rule of thumb for fuel injected cars is to get about a 100 micron mesh before the fuel pump, to protect the pump. After the pump, you want a 10-40 micron mesh filter to protect the fuel injectors.

Update:

I pressure tested the intakes/plenum and found a leak, it was the passenger side breather that goes to the valve cover (I have K&N Typhoon Intakes) Needed some thread seal tape. Also looked at other K&N installs, and the previous owner left on the baffles/sound dampeners, which after reading the installation instructions I downloaded, K&N says to remove, so those are gone, ordered the z1 motorsports replacements.

Changed the oil with Mobil 1 Synthetic 5w30 (I was using conventional 5w30 the last 2 oil changes since I got the Z) and the violent valve/chain/whatever noise now rarely happens, as does the slight hesitation related to it. I'm wondering if the hydraulic chain tensioner was stuck from the thicker oil, causing the chain to slack and the timing go goofy?

I still have the odd issue of when I'm accelerating at a normal pace (not WOT) it'll just drop RPMs like before, but not as drastic as before I fixed the intake leak, only 200 - 300RPM.

Spoke too soon...

It's still making that awful noise, only when in gear, only when from a stop, only when I slowly accelerate, and it still hesitates when it happens. Give it more gas, and it catches up with itself. But, still, intermittently.

I re-pressure tested the intakes after I installed the Z1 Motorsports breather tubes, and there are no leaks, also got under the car, and except for a small leak at the passenger side muffler (that I was able to tighten and fix) there are no leaks at any of the other flanges, no leaks at the 02 sensors, and no CEL or codes. Even when the issue occurs, there's no CEL or other warning light.

Gas mileage is good, power at WOT is good, and no other weird noises.

I'm at a loss on this. :shakes head:

Did you check the mafs? We had a,civic run like crap, because it caught a small bug on the sensor, probably not it but worth a shot.

YYYep, I used that CRC mass airflow sensor cleaner, also did the idle air learning procedure just in case.

Seafoam? Id do a, can in the gas and intake..cant hurt at this point

Did that too lol, I actually just ran that tank that I put the Seafoam in down to E and filled up at BP

I'll try it through the intake tomorrow - you mean the brake booster vacuum tube?