1990 Nissan 300ZX - Answered Questions & Fixed issues

Plug in a scan tool and watch everything as it bogs down.

If the security light is on then the car thinks someone is trying to steal it. If you can’t make the remote work then you might be able to clear it by disconnecting the Negative battery cable for about 10 minuets

check for a vacuum hose leak ( brake booster , transmission actuator module, vent controls )

have them check the tranny solinoid

Clutch fluid, commonly referred to as transmission oil or break fluid, is one of the vital liquids required for a vehicle engine to function. Since the fluid level reduces with time during vehicle usage, it becomes necessary to top it off in the clutch reservoir as need arises. But a leak in the clutch reservoir will also result in declining levels. Leaks are more likely to occur at either the slave cylinder or master cylinder, and if left unattended, low fluid levels can cause serious damage to your vehicle. You can ascertain the level by inserting a dipstick in the reservoir; however, certain signs of insufficient fluid will be apparent while driving. Below are six signs of low transmission oil. 6 Symptoms of Low Clutch Fluid DoItYourself com

Could be your distributor. Duralast Camshaft Position Sensor SU4090 Read Reviews on Duralast SU4090

have the fault codes read first to determine the problem area

Check out the ignition module or ESC for proper operation. It works in conjunction with your ecm to control and regulate engine timing.

call pop a lock. Asking questions about breaking into cars, bypassing security systems, and getting around other security equipment is frowned upon here.

I'd start by checking your injectors I have a 90 300zx also check if you have water in your fuel...I could be more serious but check those first

first check the condition of the battery in the key Check by using the extra key. Next run the fault codes.

Check the power transistor unit (the small black box on the front of the engine, passenger side, slightly beneath the main black intake hose coming to the intake manifold). It has six or seven wires coming in one side and out the other. That part was the one warranty recall for the Z from 90-96. I'm not sure what year yours is since the question is listed as a generic 300ZX question, but the recall affected 1990 models and a few early 91s. The PTU was redesigned with a heat sink to keep it from overheating (the main reason determined to cause the failure). This is the unit that drives the signal to the coil packs to fire the plugs. If it dies, you'll have no spark and the car won't run unless it decides to revive itself or you change it. If that doesn't fix the problem, I'd look into the CAS (metal circular sensor, front of the engine, driver's side, one harness plugged into the side) - that is the cam angle sensor and can cause you to lose ignition as well.

sounds like the injector on time is too long. you may have to see why they are open too long. the regulators that you put on where they new or used?

Possibly a computer (ECCS control unit) malfunction, but first check the white/black wire going to each injector. All should have power on them with ignition key in on. This white/black wire comes from the computer's pin # 58, then is spliced to all 6 injectors. If no power to injectors, check the wire continuity from the ECCS' #58 pin to the injectors. The ground wire from each injector also goes into the control unit, but individually, so that the control unit may ground the injector circuit and cause pulse. If the wiring is good, no breaks or shorts, it may be a computer malfunction, but first find out if the variable valve timing affects injector pulsing. I don't know anything about it, but you have 2 VTC (valve timing control) solenoids, one for each side of the engine. Both are located near or on the firewall behind the engine, near the middle. Looks like 3 solenoids there, the middle one is the EGR solenoid, and the VTC solenoids are on each side of the EGR solenoid. Best I can do from a very poor wiring diagram I was looking at. You checked for spark, but did you check on all six plugs for spark?

There is a leak, possibly a brake line or internal leak in Master Cylinder.

Sounds like a vacuum leak. If you or someone you know knows about vehicles you can deduce the problem, otherwise you may want to go to a mechanic who understands vacuum leaks.

The most probable cause is a cylinder temperature sensor. It's located on the right side if you are faceing the engine. Look at where you put your coolant in, follow that housing down on the right side and look further down near the bottom of the front of the cylinder head. The color of the sensor will be yellow. The computer is looking for a certain resistance value which makes it change the pulse width of the depending on the temperature of that sensor. Nissan technicians do what is called a pinout check at the harness which plugs into the computer, using a digital volt ohm meter. You can get the information off the internet or go to a book store (Barnes an Nobel) and they carry a wide variety of auto repair manials. Haynes typically publishes manuals on different makes and model cars. Each manual is specifically for the kind of car you are driving and usually will cover several years of your model car. In those manuals they will show instructions most of the time on how to do things on nearly everything on the car except body. The resistance values for that sensor and where to check it should be in the book. I can't give you a specific value because engines get hotter when you initially shut them off and some cars run hotter than others, consequently the values will not be the same ubless the cars are both within a close temperature range of each other. The connections can even be corroded which will cause the problem. Be sure to check the plug as well as the sensor for corrosion..SCRAPE THEM CLEAN and put a little "dialectric" grease in the plug before you snap it into place.There is a box on the right hand inner fender which has a labeled cover The head light relays are in there. I think the efi relay is in there and one or two more, I can't recall and at hom with no references in front of me. To make matters worse, I have Parkinson's disease which can affect memory so what I use to be able to rattle off, I can no longer do unless it's an old 240Z or something in that era. I'm in my 60's and have worked for and witth Datsun/Nissan. (as I refer to it) since 1968..I was talking about the relays. Some of them are the same and will switch out. if you see a relay that looks the same as the EFI relay, swap them and try to start the car. I hope I might have been of some help.Right now, it's early in the morning and hard for me to think clearly. If I have any other ideas, I will surely add them.

Does it make noise? Squealing, etc? Is the fluid low? Tire pressure correct?

trust me its one of the turbos if you take it out for a spin get the turbos working there will be no smoke leave it ticking over for 2-3 mins and the smoke will start if this is the case it is one of the turbos i had it with a new pair

My first suspicion when I read this is that your air conditioner pump has seized..... This very quickly burns the belt in two... Either that or your alternator or water pump or power steering pump... You have to find out what doesn't want to turn..