Code 34 and smoke

[Sallion55]

Hello everyone, I posted on here about a month ago with a few problems I was having with my car and I just wanted to update on them and bring forth the new problems I am having.

1: when it cold starts sometimes the rpm bobs between 100-900rpm, and almost cuts out

2: The car seems to idle lean, when I'm driving it seems to be fine and in stoich, and when I'm pinning it it just goes into rich, so I was wondering if it idling lean is bad and what I can do to fix it

3: when in 2nd and 4th gear, I can feel constant rubbing against the shifter, it is pretty light and it doesn't sound or feel like grinding but I could be wrong. When I'm standing still it's fine, and you don't feel the whole shifter shake but you can feel the vibration come from lower and you can slightly hear it.

I thank NolimitZ32 and DCaff300ZX for there help as I cleaned my IACV and electrical connectors which solved my first problem, and I put in a different shifter which solved the third problem. The new problems I now have are:

1: I have error code 34, I am pretty sure it is my knock sensor because I tested to make sure all of my cylinders are firing after seeing the code. It is weird though because my car runs VERY poorly sometimes, and then mostly regularly other times. During the rough times it idles fine but the car seems to shake a little bit, and under any sort of low rpm acceleration (under 4000) it is VERY boggy and the car sounds completely different from what it normally does. Other times though, it runs close to normal, but you can feel it studder very slightly when at a constant rpm. When it was running rough today it started running extremely lean, not just idling lean, but very lean under acceleration as well and I got worried. Then. after 5 more minutes of driving the car seemed to just switch over to running better and it ran in stoich like it normally does

2: Since I bought my car (4 weeks ago), it has smoked when it idles but does not smoke while driving and sometimes after a long period of driving (over a hour), it wont smoke when idling. Just very recently (in the last 2 days) it has been worse, and sometimes smokes while i am driving and under acceleration. Its weird because sometimes the smoke seems blueish, and sometimes it is white. Today while driving with my friend behind me, he told me it was smoking blue for about 5-10 minutes. then stopped randomly after being at a red light. This issue has greatly confused me because sometimes i know it is burning coolant from the smell, and sometimes i know its oil from the blue colour, my engine was rebuilt at 122000 km but that was also in the year 2000. It has 151000 KM now. So I am worried it is my piston rings starting to go, and that my head gasket has a crack in it, but I am taking guesses.

3: There is a constant gear moving sound coming from under my shifter since i replaced my old one. The grinding stopped in 2nd and 4th and this is more of a constant sound that can be heard even when idling and standing still so I know it is not something to do with my drive shaft

4: The car is idling lean still , and I know I have a vacuum leak, so I was wondering if anyone had any tips on finding vacuum leaks



THANK YOU VERY MUCH for any feedback

[frapjap]

Glad we were able to help you out and keep you going with the Z!

Your symptoms do sound like a vacuum leak and potentially more, but we'll knock them all out one by one.

In order to check for those vacuum leaks, you'll need a bit of time and patience since there are so many hoses in that engine bay.

Get the car running and spraying carb cleaner around any and all vacuum hoses (one by one) and listen for the engine to rev up. If it does, you've found the general area. Spray again and isolate the area little by little to identify the potential hose. Replace it and see if a difference is made. Rinse and repeat. If you don't want to buy the exact part from Nissan (which some hoses may require you to), you can go to a NAPA auto parts and they'll have various diameters of vacuum hoses on a spool that they'll let you take as much or as little of as you need.

Have you looked into fueling at all?
A quick test is to spray that carb cleaner right into the throttle body when the engine is idling poorly to see if anything changes. If it does, you might want to start looking at the injectors or have them bench tested.

[RED_DET]

The knonck sensor code is going to cause the car to run horrible. Fix that issue first and then move onto to the next problem. You will have to relocate the knock sensor because you are not going to be able to get to the sensor or harness in the car unless you remove the plenum and lower intake manifold.

[Sallion55]

Thank you very much for the help! I found a diagram of where all the vacuum lines are, so I will try to find the leak this week, I am going to purchase a new sensor and harness asap, I have looked up the relocation method but I met a friendly Z owner that said he will help me replace it. I want it in the original location because when the car is running well, I plan on getting a manual boost control and increasing my boost to 13psi. The Z owner I met also has a tuning program and we cut each of my cylinders to make sure each one was running. When cylinder 3 was cut you could not hear a difference from the engine, so I replaced my spark plugs and it is now working just fine . The only time my engine idles poorly is if it idles for awhile, then sometimes the idle bobs very very slightly.

[DCaff300ZX]

Glad to hear you were able to work through the earlier issue, but you may still have some corrosion hunting to do after the knock sensor and upgraded harness replacement as part of your #1 problem. The PTU and CTS sensors also can affect idle through corrosion of their connectors, be sure to clean any of them with the green death. Check your injector connectors as well as they also suffer from corrosion. This may help get you past problem #1.
#2 is harder but possibly an oil or coolant seal failing in one or both turbos. There is coolant and oil both sealed in the center section, and it is common for them to fail at some point and smoke is the usual result but I have never studied colors and such. Checking your oil for water contamination and a compression check should clear up whether or not it's a bad HG or something else like a turbo.
#3 is a tough one that I have no experience with, or answers...sorry.
#4 is something best tackled with a boost tester arrangement: a compressor and an adjustable valve to allow 5 psi of pressure into the engine through the intake tract to then isolate where there's a vacuum/boost leak. There are so many places a boost leak can be that it's impossible to help more than to advise use of the tester, and sometimes smoke or soapy water spray to try and find the leak...I spent a lot of time hunting for one myself before finding my solution, as many others have as well.

I see that you have found some solutions as I wrote this, but still take a look at the things I outlined if for no other reason than peace of mind.
Good Luck!

[Sallion55]

Thank you very much for the insight, I really appreciate you guys taking the time to help me out. I really love my Z and I'm excited to keep working on it until it is running in perfect condition , after I fix the sensor, and the vacuum leak, if it is running well I am going to put on a manual boost controller and bring my boost up to 13psi. I'm wondering if I should fix the smoke issue first before doing so. I'm also going to do a diff fluid change later this week.