My Z32 last bit of worries! Help is appreciated!

[Cloud123]

After a few months of owning the car, I have been going through a great learning process about the Z. It is a 1994 NA 2+0 300zx Automatic (136k miles).
Please check out the current issues with the car and let me know if you have any feedback as to what it may be. Thanks again for all your help guys!

Things that I have done so far:
120k factory recommended service a week after buying the car (belts, spark plugs, pulleys, seals etc.)
New Battery (yellow top)
JWT Pop Filter installed
New rims/wheels
New exhaust
HIDs, and LED upgrades all around
Lots of exterior buff/polishing done
New side blinker light housing and lights (Clear)
Small weight reduction getting the spare/jack/back cover out

Things that I want to have done:
New Leather seats
New Diff/Trans/Brake fluid
New Rotors/Brakes
JDM Clear rear lights (orange delete )
Smoke/Plastidip top brake light thing (turned red)
Fix rear panel rust (posted about this before, temporary look fix by using some spare vinyl wrap for now )
Fix acceleration whine issue (SEE BELOW!)
Fix poor acceleration from 0 (SEE BELOW!)
Fix random check engine/car shake issue (SEE BELOW!)


Issues:

Acceleration Whine/issue: Whenever I have the car from cold start to about 45minutes of driving, every time I accelerate, there is somewhat of a beeping/whining noise coming from the rear of the vehicle. Based on my research, It can be the fuel pump, ABS system, or something else. The symptoms point to the ABS because I feel it is coming from that rear right area of the car. Any other ideas as to why this can occur? The sound also happens when I cold start the car and turn the key. Makes the noise for about 3 seconds on startup.

Poor acceleration from 0: I have been trying to do some tests on the acceleration, and whenever I floor it at zero, It seems to lag/hesitate from 0-20. After automatic sets it into second gear, it starts picking up drastically. I know the NA isnt supposed to be an insanely fast car but it does seem there is an issue here. Oil pressure issue?. I might have a vacuum leak? What are some things I can check?

Random check engine light/car vibration: This seems to happen maybe once every 10 drives I have with this car. Usually occurs after a sharp turn but I dont know for certain. The car starts "chugging" and vibrating heavily on idle. The check engine light comes on immediately, and the car is still driveable but it just does not sound good at all. I usually put it in park somewhere safe in a parking lot, and after revving it once or twice, the shaking and the light goes away. I have very little idea as to what can be the case of this issue. Bad spark plug? I had those replaces with new ones so I dont know. Injectors? Engine Temp sensor? I think this may be the culprit because whenever I wiggle around the connection to the coolant sensor plug, the car seems to go up in RPM for a bit then go back down. Might be a faulty coolant temp sensor or connection?


Thanks for reading, and any help is appreciated!

[everpresentnoob]

I would definately read the codes stored in the ECU. if it is doing odd things and has a check engine light illuminate there should be a code stored. to check codes in a nut shell, pull back carpoet in passenger footwell, and remove 4 10mm screws from piece of wood. remove wood. look on right side of ECU. there is a goldish screw. with car off, key at the on position turn screw fully clockwise wait 2 seconds turn fully counter clockwise. ECU is now in diagnostic mode. just above the screw is a small window and there will be a red led flashing in it. count the flashes. I believe the long flashes are the first number and short flashes are the second number. 55 is the code for "No trouble codes stored" or - - - - - . . . . . there are better instructions here somewhere that have descriptions for all the codes, but I cant find it right now.

You say you put in new spark plugs... when i bought my 90 Z the owner said he had replaced the plugs about a month prior. But he did not use the reccomended plugs and I had hesitation/bogging from 2000-3000 RPM. one of the things I did was go to Nissan and get the reccomended plugs from them and that helped a LOT. if you go to your local parts store they will have plugs that their computer says will work, but after reading here a lot about them not actually working and seeing what i pulled out of my car when I replaced them i believe that you really should use the reccomended plugs. again a simple search on here will yeild the proper plug.

There are also some issues with the pop charger allowing to smooth of an airflow or something and the MAF not reading it right. simple fix is a piece of tape on the bottom of the element. again search and you will find the details.

Im not tryig to be a keyboard commando and telling you to search for everything to be a d***, just that I was fighting some of these same issues and printed all the info off at home, but do not have it here to give to you now since Im at work.

Good luck. Post back with results or more issues and Im sure those smarter than a noob like me will help you solve it all.

[Cloud123]

Thank you for your reply.

I guess I got to take the time to read into the ECU codes. Thank you for suggesting that, did not know it would be stored like that, and I had a feeling it would have been hard to diagnose because the check engine thing is a totally random occurrence while driving.

The spark plugs were bought from Z1, almost positive they were the factory recommended ones. The shop installed the ones I provided. The car during normal driving and idle is not bad which throws me off when I try to figure out what is wrong.

Definitely will look into the filter fix. I currently have the filter mostly pointing downward, and the plastic guard that was below the stock filter housing is now bent to sit above the filter. Also, the three issues did not really start after the JWT filter installation. They were occurring before most of the changes I have made so far.

I appreciate it

[DCaff300ZX]

You can download the online service manual here which has lots of tests and such for researching and fixing your issue, a problem which has a lot of possible sources so it's hard to just guess.
Regarding the pop charger addition before your issues that's a good clue, and you saying you put the plastic shield above the element says you are probably getting wind across the filter and MAF element which can cause hesitation issues. The filter and MAF should be turned as high and "up" in the bumper area as possible and the plastic shield used to mount the bottom of the filter, and therefore properly shield the filter from the airflow. Oh, and the MAF needs cleaning periodically as it can get dirty and cause drivability issues- MAF cleaner can be bought at Autozone/etc. so check that out as well.
Check those codes (ALWAYS your first step if you get a CEL) and do your research and tests, hopefully you find/fix your issue and learn something new about your Z or at worst have new questions to ask here.
Good Luck!

[Cloud123]

Thank you for your help.

So for some updates:

I took a look into the code reading with the ECU, and I came up to some bad news. It seems like a mechanic had previously opened that area up (there was only 2 screws holding the board rather than 4) and I took a look at the screw on the side of the ECU and it is non existent. I have no idea how else I can check the codes now that it seems someone broke that piece off. Can I use a small flathead?
. Would a OBD scanner work for this? Any suggestions?

I still have yet to re-position the filter and clean the MAF, will do that this weekend.

I have also bought a new harness for the coolant temp sensor (was broken, the rubber holding the wire and harness is broken and is being held with electrical tape atm). With that, I also bought a new coolant sensor as well just to make sure and make things right. Currently the sensor and harness when wiggled around does increase the RPM and the car for the longest time has been making very faint putting noises that can be heard from the exhaust. I am hoping this fix will get the car back up to speed and not have the irregular idle and putting.

It seems I also have to change out the new LEDs for the rear brake lights. The car does not light up the rear lights when it is dark. I am assuming that may be from the LEDs, or possibly a fuse? They light up only when I brake. It also shows the high beam light (red) on my dash whenever I brake.

[everpresentnoob]

Um, High beam indicator should be blue. is the red light on the dash that lights with the brakes in the lower right side under the cluster? Red square that says lights? that is for your brakes. it is lighting because you have LEDs in the back and the resistance is out of spec for the factory sensor. You can pull the bulb out of that warning light and just check the brake fluid level and bulds on your own. THat is what I did. Its more of a nusance than anything else.

You should post a pic of the side of your ECU. Hard to imagnine the test screw missing. Not that Im saying your wrong, but I kinda wanna see that!!

[Cloud123]

UPDATE:

The light that was appearing was a red light that appeared to be a high beam icon on it. It would happen every time i braked. Thankfully it fixed when I replaced the coolant temp sensor! Took the old one out and placed the new one in. The connector is seated kind of awkwardly but it did end up fixing some of the idle issues and the brake light "highbeam" indicator thing. Car used to have putting in idle but now it a lot less noticeable. Still happens and but is a lot harder to hear.

I will go ahead and snap a pic of the ECU. I also have a video for the "abs?/fuel pump?" Humming noise when the car is cold. Will post that soon.

Car still has not thrown any check engine lights as of yet, and only drove the car 3 times since the sensor replacement and filter positioning/cleaning. More testing is needed of course, but it seems to be getting a lot better.

The only small thing ive noticed is that it very rarely makes a double click noise when i slowly brake. Kind of the same sound the emergency brake makes? Only happens once, and does not happen to frequently either, might be the colder weather.

Last thing that is coming up is its oil change and trans fluid change. Ive heard 10w40 is standard for a Z. Any suggestions on the type and brand? Also how could I check to see if it has been filled with synthetic. I heard switching over to synthetic is not recommended for cars with higher mileage so I have to be careful.

Thanks all.

[Cloud123]

10w30 i meant.

[DCaff300ZX]

10w30 i meant.

Glad you corrected that...big difference, and with higher mileage 30w may work best except in the coldest climates.

Looks like you are on your way, just keep looking up any small issues in the fsm and do what you can, and ask away here if that doesn't work or if you have further questions.
The Z32 as it ages (as I've found now after 14 years ownership of 2) sheds old parts at an rather alarming rate the older it gets, and due to some manufacturing issues (injectors/harness, connectors), and now my TT has almost no old OEM sensors or running gear left in it. Suspension, tires, brakes, almost ALL engine electrical components and sensors, and many heavy use mechanical items (turbos and support gear) have all gone away due to age and use. Therefore careful/purposeful upgrading and trying to kill multiple problems with singular efforts becomes your job, and the key to long term success with a Z32 that gets used...plus a LOT of patience, and the ability to park it until you get back in a way mentally and/or fiscally to deal with it again.
A labor of Love, and not good sense!
Good luck and stay with it...