ZSaulx

My 1985 Nissan 300zx N/A 5speed

So its summer time here in Oregon and i was driving in about 90* weather and My car randomly started decelerated while going 45mph, i pulled off on the side of the road and it wouldn't rev past the 2000rpm. when pressing on the gas slightly it feels like it wanted to die but when i stomp on it it revs hard until it hits the 2000rpm then bounces at 1800-2000. I can shift into gears but i can only go about 20mph dues to it only being able to rev so high. I also noticed that my car runs great in mornings or night but never in the mid day when its hot or when the engine is fully warmed up after like 20mins or driving. this is my only drivable car and i need help fast. I have cleaned the MAF sensor with the spray but problem persist.


ps; Im Only 19 and its my first car but im confident that with the knowledge of all you people i can fix the problem with out going to a mechanic.

rogerz

possible you have a bad O2 sensor or chts. pull the connector off the O2 sensor and see if that cures the problem. Download the fsm from xenon. test the maf per the book. if you are anywhere near Portland there is a z club there and you might well find someone willing to help you out they are a good bunch of guys and often join up with our seattle club. Maf generally don't just go bad unless someone stuck a screwdriver in there. they are a pretty simple device. but the 2000 rpm thing does sound sort of maflike. Never hurts to replace the chts and inspect the wiring to it. look on line for procedure to replace it without taking half the engine apart.

rogerz

here is some general z31 advice that may help avert problems in the future.:
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. DON'T USE DIELECTRIC GREASE.

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 got a junkyard in the area with a z31 get the maf out of it. any year turbo/na all same same

zxguy1986

Welcome to ZDriver Being young and new to Zs isn't a problem if you are patient with us old guys and love the Z.

Old Codger (he's a pro) pays me to translate for the pros here so the newbies understand what they mean. The Xenon website for your free Factory Service Manual (FSM) is XenonZ31 Reference. Check out the other docs there. Very useful and also free. The more time you spend reading and learning from them, the longer your Z will run well.

You got MAF (Mass Air Flow) meter. Cylinder Head Temperature Sensor (CHTS) is a big deal because a bad one sends the wrong signals to your ECU (Engine/Electronic Control Unit i.e. computer) and that screws up stuff. Has to be right. Locate it (your CHTS) on the front of the engine in your FSM and switch it out. Your part store will call it something else. Bring the old one with you and check the store computer screen for it before you order.

Welcome and thanks!