20 Most Recent 1986 Nissan 300ZX - Page 5 Questions & Answers

That wire from injector to ecm is the grounding side of the circuit. The computer grounds the circuit inside when it is time for the injector to open. Not sure but I think all three wires on pass. side splice into a single wire going to the ecm. Check the continuity of the wires from pass, side to ecm. Any corrosion on the ecm pins?Am I understanding right that you have power to both banks of injectors, but only one side, or bank, is firing? If it's not a wiring problem, it could be the computer.

I took the car to a garage

How are the motor mounts? After all that work, you are down to only a few things it could be. good luck. Look for any bent suspension pieces. Does it have a sway bar up front? Check linkage and bushings on that.

jsierra90: I'll bet you are wanting to replace it because it doesn't light up and operate any more? Correct? 9 out of 10 times that is the primary reason people think the dash needs to be replaced.
Good news. The power supply for the digital dash is a lot easier and cheaper to replace than the digital dash.

Here are the symptoms if it was the power supply: The dash would be intermittent in operation where it would start off sometimes just flickering or going on and off. You might experience a loss of the tachometer or the entire dash. The problem would continually get worse until it would become more off than on. IF SO, your power supply to the dash is the problem.
The power supply is located under the dash just to the right of the steering column. When you remove the lower panel which is 2 screws # 6 phillips screw driver. A screw at the bottom right hand corner and same on the left hand corner. The top part of the panel just hooks into the dash, so by lowering it 30 degrees it should drop loose.
Now you will see a box about 4' X 4 ' if I recall correctly dull Silver in color with two harness connectors plugging into it.
(NOTE, IT WILL BE THE ONLY BOX ON THAT SIDE IN THAT LOCATION WHICH FITS THAT DESCRIPTION.) The box is secured by 3 or 4 bolts requiring a 10mm wrench and/or socket to break them loose. Most of the Nissan hardware that size have a place for a phillips bit screw driver as well. They have been doing that since the early seventies and it'f I'm not mistaken, I think I have seen some hardware like that on the old SRL-and SPL-311's
The old Datsun Roadster's. OOOPS! (1960's) I think I might have given a hint as to how old I am. BUT, I don't FART DUST YET!
ANYWAY, I hope I had given you some in-site to your problem. If it is not the solution, you can reach me through the FIXYA channels and I'll walk you through Diagnosing the other aspect of the dash as well as give you blow by blow instructions on how to pull the digital instrument cluster.
Again, have been business for 29 years and when I first opened, I opened up as the "Datsun Specialist". My shop was always packed after the first we made it through the first three months.Nissan Forced us to change our name telling us that we were infringing on their registered trade name. Failure to comply will find us in court!
They suggested Grand Prairie Auto Repair" . I couldn't have thought of a more original name! So I named my dog Rover and the other one Spot! I wrote back to them: What about the fact what I am one of the earliest Nissan Master tech's in the Nation? What about the fact that I use Only Genuine Nissan products on the cars that come through my shop? Your dealers don't even do that!
I promote the product and act as a liaison between disgruntled customers who felt they got screwed by Nissan dealers..
Their reply: It was a nice way of saying "we could give a damn, why don't you stick it where the sun don't shine?!"
So, My wife of 37 years and I decided to bring Mercedes, Toyota Mazda and Honda into our lineup. I was the only Nissan master tech back then, I had stolen one of the tech from the dealership I had worked at. I hired a Mazda Master tech, a woman technician who had all her ASE certifications and had worked ina general repair shop as well as a transmission shop for two years.
I hired one other man. A Vietnamese who hardly spoke English but I just had this feeling about him. The woman tech turned out to be my best tech, she's in her 40's and she flat kicks ***! I would pit her against techs with 10-15 years more experience over her.
I am one of the few exceptions to the rule, but she gives me a run for my money and I'm in I'm 60's! The Vietnamese: has a mind like a steel trap! You only have to show him once and his learning curve which is exponential. He ended up stiffing me though. I had given him a crash course in auto repair. ( love teaching and would be called in to sub for companies that train in collision repair and other ones that has classes in EFI and other subjects.) My first few years, I was working 7 days a week and 12-18 hour days. The Vietnamese tech would hang around even after he was off the clock to watch me work and just pump me with questions. He also picked up English within 3 months to where he could understand me and I him! He went from earning$11,500 the first year on the clock to putting him on flat rate like all my other techs. He made $26,500 the second year and $31,254 before he felt he was educated enough to open his own business in "Little Vietnam".
As for your options on sources? Used is the cheapest way out.
I found one on EBAY for $80.00
All Z's in Ft. Worth Tx 817-438-4300 call and see if he has any.
Let me know what area you are in in the country and I might be able to round you up a good one. Other than that, a new one is your last resort. There are some salvage yards that sell extended and lifetme warranties
Good luck.

Typically a well tighten spark plug will never back it self out so this and maybe a few others were not tightened properly the last time the plugs were changed. You probably have been blowing some smoke from that same cylinder for some time. This could be from worn valve guide seals, blown head gasket or worn out rings. These Z engines are usually pretty bullet proof on the bottom ends but issues with head gaskets or valve guide seals can happen more often. With all the oil being sucked into the piston chamber and the added pressure as you can not compress oil, this could have push an already semi loose spark plug out. Any thing could have happened at this point. The possibilities of metal thread fragments falling into the chamber ,as the plug tore the last few threads and it was forced out, could have caused some damage to the cylinder walls (although this is rare). Also, if additional oil came into the cylinder chamber and you started the engine (after the new plug was installed) this could have almost caused hydrolock situation. Since the engine did turn over and start then instead of the oil locking the engine it could have blown a seal or gasket more if there was already a small defect that let the oil into the chamber in the first place. This would cause a more sever leak and a more noticeable smoke. Try pulling the same spark plug out and running the engine to see if the smoke lessons or stops. You can also get ahold of a cylinder compression gauge to screw into the spark plug hole and check the reading against all the other cylinders. Either way though, once you are burning oil there is no easy fix (please do not waste your money on any oil additives that claim to stop oil leaks as those never work in such situations). As far as the oil gauge not working; it is very unlikely that this is related. If the oil gets so low from burning it all off through the engine then the pressure could start to be erratic but only if you were almost bone dry would it not register at all. I'm sure you have checked the oil and added more if it was low and that would have brought the pressure up again. Hopefully you have been changing the oil regularly as this is the main key to keeping any engine running for years without these issues of these kinds.

Check that the choke is not stuck open or not working at all. THe chole has an accelerated idle cam which increases the idle speed when the engine is cold and the choke is supposed to be closed and as it starts to open.

If a vehicle has been standing for 2 years yuou need to clean out the whole fuel system because the fuel turns gummy and clogs up small passages, valves and jets.

The engine runs rough and then dies because the fuel quantity delivered by the injectors is too low and the mixture becomes too lean to light up so the engine stalls. Even if you have replaced the fuel filter the dirt might have got past it and clogged the injectors. You will have to clean them professionally. Also check the fuel that you still have in the tank - it might be contaminated with dirt and water.

check fuses

sounds like a radiator problem and the smoke is the lack of compression due to worn piston rings and valve guides

it can be done but you need all the wiring and the ECM also the the drive shafts are not the same, it is allot of work the best way to do it is to buy a wrecked 300ZX with and automatic transsmission and then remove all the stuff you need for the swap. you will also need and automatic flywheel for the engine, dip stick tube and dip stick the list just goes on and on.

i am not saying it cant be done but i would nor recommend it.