I have a '88 Z31 NA. I have been having electrical issues as well as I have lost a lot of my HP and Torque...... It has 160k miles on it and most of the car is original. (Except these parts I have replaced, Fuel Pump, Master Cylinder, Slave Cylinder, Water Pump, Fan Clutch, and a few water hoses.....) Just wondering what I should replace to get back my HP and Torque?

 

Welcome to ZDriver!

If you don't already have it, pick up a freebie factory service manual at XenonZ31 Reference - and check out the other docs avail there.

You should run the computer (ECCS) self-diagnostic. The procedure is described in your FSM beginning on EF&EC-61. The codes your Z is putting out may send you in one or more directions, depending on what the issues are at this point. The computer isn't exactly a HAL9000 model but does occasionally know what is going wrong or at least where to check.

Torque and HP drop could have a number of causes so I would start with the diagnosis codes to rule out some of those. Then let us know if you have checked your compression in your cylinders, if you are losing oil anywhere (like in the exhaust...) and what octane gas you are/have been using. Just for a start... You can check your air intake for clean passage, filter, etc. And your battery/alternator system has to be putting out a minimum of 14+ volts at all times. A retail battery seller can check that out for you for free in 5 minutes. Let us know more about your 'elec issues' too.

Don't worry, that motor was born to run forever if it is treated right. We will get you up to speed again. So try to report back here when you can.

Thanks and welcome again.

 

for starters:
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.

get your fuel pressure. get your vacuum readings. vacuum leaks the bane of the FI engine. when you say you want torque and HP back what are you comparing your car to? the NA z31 wasn't all that high performance. Any modern honda or toyota stock out the box would probably smoke an 88 NA.

 

stick or auto ?
engine seems smooth , not chugging at idle?
like the other post's said you want to know the conditions of the engine ,maintenance up-keep , elect. system .
a cold compression test is a good place to start . care taken on this design pulling plugs .
and a vac. reading

 

I guess he didn't need advice.... still hasn't replied.

 

Or just another drive-by post? Post it and ferget it!

 

at 160,000 & stock and wanting top performance from it , perhaps he now has larger problems , that he knows what is wrong.