Pickle Rick

Ok, so I need some advice with my 03 Z's mechanical issues. I understand the basic functions of most engine systems, but I do lack knowledge and experience when it comes to repairing cars. With that said, I know enough to do most maintenance on my Z. Most of my technical knowledge comes from doing my research and repairing any problems myself (usually with consultation from an experienced mechanic friend).
So I've known for a short amount of time that I need to address my leaky valve cover but for the most part everything was running smoothly and properly. But that changed after I let my mechanic friend clean out my throttle body as it had become quite dirty. Note, I don't know if or how that lead to my current problems, but everything started after that. At first my SES light came on after about 5-10 min of driving. At this point the only thing I noticed was a high idle rpm but I was told it should even out. I get the code checked and it was just that, p0507 I believe (high idle). I tried the ecu, throttle body, accelerator reset procedures to no avail. So I drove for almost a week with no other problems, but the high idle continued. Then one day I started having intermittent misfire problems, but it wasn't constant. Get the code again and in addition to p0507 I had p0300, multiple random misfires. It wasn't long until my car was constantly misfiring, blinking SES and all. So I changed all 6 spark plugs, checked all the coil packs and did the relearn procedures again. BUT I did have oil in spark plug cylinder wells 3 and 5 (passenger side), and not just a light coating, but about half way up the spark plug. So as I expected, same issues. Get code again, this time I got it at Autozone, who provided me with a nifty print out. It listed p0300 twice this time (p0507 is gone). It also stated "ASE certified master techs have seen this issue on your type of vehicle and the most likely solution is: Replace Valve Cover Assembly." Also note that the previous mention of my leaking valve cover was the driver side, opposite the oil filled wells. There is a small build up of oil around the valve cover, while the passenger side is clean. No dripping oil, nothing in the driveway.

So obviously I need to address those valve covers. But here is where I am in need of advice (I'm sure not just here lol).
1. If I'm getting oil in my spark plug wells, does that mean I need to replace the valve cover on that side? (As the plug seals arent independent of the valve cover)
2. The passenger side has the oil in the plug wells, the driver side has a leak from the edge of the valve cover itself, but the plugs were dry. Are these from the same leak or seperate? Like I stated before, I had noticed oil on the driver side, so I assumed i just needed a new gasket.
3. Am I able to just replace the gasket on the driver side if the valve cover isn't damaged?
4. Did cleaning the throttle body have anything to do with these issues? Or was it a catalyst or just a coincidence?
5. I know that my valve covers had been leaky, but why after messing with the TB did I start to misfire?
6. Could my misfire problems unrealated to the leaking valve covers?

Any insight/comments/answers/help or advice would be greatly appreciated. The car has about 130k and Ive owned her since 2009. I do regular maintenance and haven't had any major problems at all. I've searched and read through many threads and learned a lot, but I wasn't able to find everything I needed. So I apologize in advanced if there is already a similar thread that I may have missed, and in that case, please direct me to the right place. Also this is my first time posting, so if Im not in the right section, please let me know. Thanks.

Bak3rme

iTrader: (1)

1. If I'm getting oil in my spark plug wells, does that mean I need to replace the valve cover on that side? (As the plug seals arent independent of the valve cover)
Yes, I would replace valve cover on both sides if they are leaking. You can definitely get the spark plug seals but they are a pain to remove. Might as well replace with new cover that comes with new gaskets and spark plug seals.

2. The passenger side has the oil in the plug wells, the driver side has a leak from the edge of the valve cover itself, but the plugs were dry. Are these from the same leak or seperate? Like I stated before, I had noticed oil on the driver side, so I assumed i just needed a new gasket.
Again, since a new valve cover comes with valve cover gasket and spark plug gasket, I would replace the whole valve cover. When you take off the valve cover you can check for cracks on all gaskets. The driver side is known to have an issue with spark plug closest to cabin for gasket failure. the valve cover has its own gasket as well as spark plug gasket on it.

3. Am I able to just replace the gasket on the driver side if the valve cover isn't damaged?
There are replacement gaskets which are a lot cheaper than the valve cover assembly (which includes gaskets and installed spark plug gaskets. It is a lot easier to me at least to replace the whole valve cover assembly. The answer is Yes, you can just replace the gasket itself.

4. Did cleaning the throttle body have anything to do with these issues? Or was it a catalyst or just a coincidence?
Not too sure on this one, but my guess is issues are independent. Throttle body is on top of plenumn which is on top of valve covers. Just cleaning throttle body would be just to disconnect the air filter and the air filter tube that runs to the throttle body. I could be wrong here

5. I know that my valve covers had been leaky, but why after messing with the TB did I start to misfire?
This i cannot comment on

6. Could my misfire problems unrealated to the leaking valve covers?leaking into the spark plugs YES, leaking into the engine bay, No

MicVelo

Pretty common discussion subject around these parts:

https://www.google.com/search?q=clea...w=1622&bih=887

Cut to the chase: https://my350z.com/forum/vq35hr/6160...le-thread.html

This one is recent and has a link to that poster's solution.

dboyzalter

iTrader: (3)

Never let anyone mess with your throttle body unless you wanna get a new one. They have alien technology inside and when us normal humans mess with them bad things happen.... (have you seen the new spider man movie?)


But seems like new valve covers are a good place to start, and maybe a new throttle body.

Pickle Rick

Wow, you guys are awesome. Thank you for the quick replies. I'm going to start with the valve covers and gaskets and go from there. I'm just so curious to know why I had these problems after messing with the TB. It just doesn't make sense to me. As a lot of people say on this site about cleaning the TB, I wish I would have read the posts here before messing with anything lol.
@ Bak3r- Thank you for spending the time to answer my questions and helping me get on the right track.

@Mic- I'm aware of the threads on this topic and I learned a lot from reading them, but I haven't seemed to find one related to the same problems I have. The link you posted addresses the high idle problem but that issue seemed to resolve itself (maybe it was the reset procedures?). The only codes Im throwing now are the random misfires.

@dboy - Yea, learned that one the hard way. At the time it seemed like a good idea that couldn't hurt, "just a cleaning, couldn't possibly cause too much trouble.........." I did ask him if he touched the butterfly valve, swears he didn't because he "knows better."

Thanks again guys, I'm going to order my parts and install and Ill post my results when I get there. If anyone else has any experience or insight into these problems Id love to hear from you.

kauai1800

I agree with the above...if you so much as breathe on the MAF sensor wires or mess with/clean/etc the position sensor in the throttle body it really screws up the signals to ECU and chaos (but not hilarity) ensues...

tmdz

Maybe its a Washington State thing...

Pickle Rick

Awesome sticker tmdz!

UPDATE. Thanks everyone for the help. It ended up being the oil in the spark plug wells. As I was on a budget, I kept my original valve covers, changed the gaskets and used some rtv around the problem spark plug seals as talked about somewhere on the site. 3000 miles in and I'm still dry as can be. After I got it put back together, it ran great for a day, then a coil pack went out :l But that was easy to pinpoint and fix. Still don't know how or why this all started when my throttle body was cleaned, but I'm just glad to have my Z back! I can't stress enough how much I appreciate how helpful everyone on this site is and how much great info is here. Definitely would have taken me a lot more time with out my350z.com! Thanks guys!

tmdz

Good suggestion - Noticed oil around my spark plug in the no. 6 cylinder so I’m going to go ahead and replace. Looks like about $70 on EBay.

Not warm enough to start the body work (rock chips) so this will keep me occupied for another weekend.

Might be a good time to polish that plenum up...