I have an 85 300zx 5 speed turbo. When I start this car, it will run for about 2 minutes fine for the most part. Then it starts to act as if its not getting any gas and sputters REALLY bad. It will die if you dont give it any gas. The tach has gone down as low as 300rpm trying to stay running when I'm giving it gas so it doesn't die. After another 2 minutes, it stops and the cars power returns and runs just fine. You can drive it for hours after that and it runs fine. Its just those first few minutes that is has this problem. Once the sputter has stopped and it runs fine, you can turn it off, turn it back on, and its still fine. This sputter will happen again if you leave the car off for maybe an hour or so. I have changed the tps sensor, crank angle sensor, and the fuel filter. I thought if the fuel pump was bad, then you could simply NOT hear it run when you turned the car to the "on" position. I have two videos below. One outside the car, and one while driving.

 

The problems you describe sound temperature related to me. Meaning your ECU is getting bad or no input from a sensor for that time when it the engine runs bad - then gets the right info at running temperature.

If you are good enough with a multimeter, you could check out the two solenoids on the air regulator - and maybe replace your cylinder head temperature sensor (chts) which you didn't mention above - and any other critical temperature sensor. Other guys here will have suggestions too. Be sure to report back with what you find.

 

likely a chts or O2 sensor problem. If the fuel pump wasn't running neither would the engine be. put a fuel pressure gage in the ring so you now what is going on with fuel pressure. check the vacuum -vacuum leaks the bane of the FI engine.

 

I have the same issue with my 85 na. Thanks for the info.

 

I agree with Roger CHTS, O2 or vacuum. I would check the ECU for helpful codes before changing anything.

 

For the record, the computer has never given any codes for this. The only code it shows is for the clutch neutral switch or what ever its called since the car can start without the clutch.

 

I'm curious what was changed as a "crank angle sensor". Both of my VG30 engines used a conventional distributor for ignition timing.

Fuel pump noise and proper fuel pressure do not always correlate. You need to diagnose fuel pressure with an in-line gauge.

I agree with the comments that the problem is vacuum related.

 

Ok, I am updating because I decided to take it to a shop. I'm going to type everything that they did and said in the report.



Test drove. During warm up, started running bad and hesitated. Only ran bad for a few minutes then ran ok. Checked codes. Has a code 12 for MAF problem. Tested MAF and passed in ALL DATA. I even checked input at the ecm. It matches the reading at the MAF.

Test Drove and coolant sensor input at ECM did not drop out or jump at too (I can't tell what they wrote here. I could be mistaken but I think it says "too cold or too hot") input when it acted up.

Scoped ignition system. All looks normal. Check ignition timing at 20 degrees BTDC. Spark plug #3 was loose. Tightened to torque specs.

There is a rattling, squeaking noise from behind the timing belt cover. Sounds like a bearing trying to lock up. If timing belt jumps on this engine it will bend the valves.

Test drove while monitoring MAF input at (I want to say it says ecm but it looks like pcm). The input did not drop out when car acted up. So I think the MAF is ok.

Checked fuel pressure. Has 30 psi with vacuum to regulator. 40psi with no vacuum. Has 30 psi when shut off. Spec is 30 psi and 37 psi. Fuel pressure is not the problem.

Every time my hand is near the distributor cap I get shocked. Found there is a secondary leakage out the cap around the #2 plug wire connection area. Needs a new cap but probably won't fix the problem.

I give up. I don't know whats wrong with this vehicle!



I found it funny that a certified auto mechanic put that last part in the report. I'm going to change the distributor cap tonight. Any other ideas?

 

you went to your average mechanic in todays world NO obdc no can fix. or throw parts at it. like I said chts or O2 sensor your most likely culprits. stop putzing around and replace them chts the easiest because if you are getting noise out of the timing belt cover you might as well pull the tin off and see what is going on. chts real easy to access at that point. dizzy cap def a good idea. also new wires. you got two problems ignition leakage which will cause not to run so good. and something heat related CHTS READ THIS. i DON'T think I would put a lot of faith in that mechanic's opinion altho he did at least find the timing and fuel pressure were correct. nothing wrong with the car the problem is with the people who cant diagnose the problem. If a Z31 is running it is fixable. forget the codes they are generally useless at this point in history. Also pay attention to Ken99. Z31 crank angle sensor is inside the distributor. WHAT DID YOU REPLACE??

 

More Advice:
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. Get new boots for power steering. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. You need to get the car realigned after messing with the front. Have your tires in good shape and rebalance. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone. If you have the electro adjustable shocks they are DEFINITELY GONE.

If you are doing a turbo car shocks (electro adjust I think may be only on the turbos) then you need the adapter plates to fit modern shocks to the car. Easiest way is find an n/a at the junkyard and take the mounting plates. They may be available thru NAPA (listed) but I had the n/a plates.

 

1. When I was suggested the crank angle sensor I changed the entire distributor.

2. What does chts stand for? I'm assuming a temperture sensor but if thats the case, they said both of them were fine.

3. Is there any way to make the electro shock adjuster work again?

 

Cylinder head temp sensor

On the electro shocks, what exactly is the problem you are having ? Does the switch light up and changed when you move it ? There is a possibility the connections at the shocks are corroded or broken, they are a bit delicate and if not disassembled with some care you could break or bend one. There is a control box behind the spare tire, fun to get to, check the connections there too. The trouble shooting steps for the adjustable shocks is in the Front Axel & Suspension section.


The problem you are having could be the fuel injection relay. In the Engine Fuel Emission Control section page 62/ 109 covers fuel pump and relay troubleshooting. The reason I say this, it has a priming function and a main running function, sounds like it is priming, but turns off in run mode, bad relay !

 

When you say Front Axle and suspension section, do you mean on this site?

 

He means in the FS manual.

 

don't believe that hooey about the electro shocks. you have thirty year old technology that is worn out. Just replace with something made in this century.
chts=cylinder head temp sensor.

 

If you have the turbo adj shocks and they is not working anymore, you will need to replace them with something else as the OEM shocks are not available anymore.

Tokico, Koni, Bilsteins, and KYB have shocks that fit the Z31T.

 

They said the temperture sensors were alright.

I'm sure the shocks on mine are wore out. If I change them, is it still possible to make the adjuster work? I can move the switch and the selection flashes but thats it. I don't know what is supposed to happen after that. Is there any kind of noise you should hear? How much of an adjustment are these supposed to make?

 

If you do scrap the adjustable shocks, I will buy the console switch from you, Steve has one, but if everyone is junking the shocks, the associated wiring and switch are useless. Some have taken the shocks out and replaced the oil and made them serviceable, but the easy way is to get new shocks, some are mechanically adjustable also, so although you loose the convenience of a switch you gain much better handling.

 

" 86tcoupe

you are right the rears are sealed PredatorZ . but a carefully drilled hole 3/16" at/near the top fixes that. They likely were gas filled at one time but mine were not then , carefull not to get a metal chip inside . After cleaning out the burnt watery oil with brake cleaner I filled with tractor hydro fluid and sealed with a rubber grommet the lipped kind , coated with RTV no problems .

the fronts , you know remove the cap , the same ,I purchased new caps for in 96(? ) I had one frt. actuator inop but working with it and/or the wiring got it going .
the motor cycle shops have different viscosities oil but with my adjustable hard is good and tight "

 

I kind of wanted to make them work again not scrap them.

 

change the o2 sensor dude